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Sheep Anti-Digoxigenin Fab fragments Antibody, AP Conjugated

RRID:AB_514497

Antibody ID

AB_514497

Target Antigen

Digoxigenin

Proper Citation

(Roche Cat# 11093274910, RRID:AB_514497)

Clonality

unknown

Host Organism

sheep

Vendor

Roche

Cat Num

11093274910

Publications that use this research resource

Distribution of vesicular glutamate transporters in the brain of the turtle (Pseudemys scripta elegans).

  • Sarkar S
  • J. Comp. Neurol.
  • 2018 Jul 1

Literature context:


Abstract:

The distribution of glutamatergic neurons has been extensively studied in mammalian and avian brains, but its distribution in a reptilian brain remains unknown. In the present study, the distribution of subpopulations of glutamatergic neurons in the turtle brain was examined by in situ hybridization using probes for vesicular glutamate transporter (VGLUT) 1-3. Strong VGLUT1 expression was observed in the telencephalic pallium; the mitral cells of the olfactory bulb, the medial, dorsomedial, dorsal, and lateral parts of the cerebral cortex, pallial thickening, and dorsal ventricular ridge; and also, in granule cells of the cerebellar cortex. Moderate to weak expression was found in the lateral and medial amygdaloid nuclei, the periventricular cellular layer of the optic tectum, and in some brainstem nuclei. VGLUT2 was weakly expressed in the telencephalon but was intensely expressed in the dorsal thalamic nuclei, magnocellular part of the isthmic nucleus, brainstem nuclei, and the rostral cervical segment of the spinal cord. The cerebellar cortex was devoid of VGLUT2 expression. The central amygdaloid nucleus did not express VGLUT1 or VGLUT2. VGLUT3 was localized in the parvocellular part of the isthmic nucleus, superior and inferior raphe nuclei, and cochlear nucleus. Our results indicate that the distribution of VGLUTs in the turtle brain is similar to that in the mammalian brain rather than that in the avian brain.

Funding information:
  • NCI NIH HHS - U01 CA109265-04(United States)

Depression-resistant Phenotype in Mice Overexpressing Regulator of G Protein Signaling 8 (RGS8).

  • Kobayashi Y
  • Neuroscience
  • 2018 Jul 15

Literature context:


Abstract:

Regulator of G protein signaling (RGS) proteins are negative regulators of heterotrimeric G proteins that act by accelerating Gα-mediated GTPase activity to terminate G protein-coupled receptor-associated signaling. RGS8 is expressed in several brain regions involved with movement and mood. To investigate the role of RGS8 in vivo, we generated transgenic mice overexpressing brain RGS8 (RGS8tg). RGS8 gene and protein expressions were examined by real-time PCR and immunohistochemistry, respectively, and a significant increase in RGS8 protein was detected in the hippocampal CA1 region compared with wild-type mice (WT). We characterized the phenotypic traits, and found that RGS8tg showed decreased depressive-like behavior in the forced swimming test (FST). Previously, RGS8 was identified as a potent negative regulator of melanin-concentrating hormone receptor 1 (MCHR1), whose activation is mainly involved in energy homeostasis and emotional processing. Interestingly, acute oral administration of MCHR1 antagonist SNAP94847 did not have antidepressant-like effects on RGS8tg in the FST, but did show antidepressant effects on WT. In contrast, selective noradrenaline reuptake inhibitor desipramine had a significant effect on RGS8tg in the FST. MCHR1 is enriched in a subset of primary cilia, as sensory organelles that mediate extracellular signaling. Immunohistochemical analyses revealed significant elongation of MCHR1-positive cilia in the CA1 region of RGS8tg compared with WT. Taken together, these findings suggest that RGS8 participates in modulation of depression-like behavior through ciliary MCHR1 expressed in the CA1 region. The present study may support the possible modulation of RGS8 function in mood disorders.

Funding information:
  • NIAID NIH HHS - U19 AI046130(United States)

Molecular anatomy of the alligator dorsal telencephalon.

  • Briscoe SD
  • J. Comp. Neurol.
  • 2018 Jul 1

Literature context:


Abstract:

The evolutionary relationships of the mammalian neocortex and avian dorsal telencephalon (DT) nuclei have been debated for more than a century. Despite their central importance to this debate, nonavian reptiles remain underexplored with modern molecular techniques. Reptile studies harbor great potential for understanding the changes in DT organization that occurred in the early evolution of amniotes. They may also help clarify the specializations in the avian DT, which comprises a massive, cell-dense dorsal ventricular ridge (DVR) and a nuclear dorsal-most structure, the Wulst. Crocodilians are phylogenetically and anatomically attractive for DT comparative studies: they are the closest living relatives of birds and have a strikingly bird-like DVR, but they also possess a highly differentiated reptile cerebral cortex. We studied the DT of the American alligator, Alligator mississippiensis, at late embryonic stages with a panel of molecular marker genes. Gene expression and cytoarchitectonic analyses identified clear homologs of all major avian DVR subdivisions including a mesopallium, an extensive nidopallium with primary sensory input territories, and an arcopallium. The alligator medial cortex is divided into three components that resemble the mammalian dentate gyrus, CA fields, and subiculum in gene expression and topography. The alligator dorsal cortex contains putative homologs of neocortical input, output, and intratelencephalic projection neurons and, most notably, these are organized into sublayers similar to mammalian neocortical layers. Our findings on the molecular anatomy of the crocodilian DT are summarized in an atlas of the alligator telencephalon.

Funding information:
  • NIAID NIH HHS - R01AI64414(United States)

Liver Cancer Initiation Requires p53 Inhibition by CD44-Enhanced Growth Factor Signaling.

  • Dhar D
  • Cancer Cell
  • 2018 Jun 11

Literature context:


Abstract:

How fully differentiated cells that experience carcinogenic insults become proliferative cancer progenitors that acquire multiple initiating mutations is not clear. This question is of particular relevance to hepatocellular carcinoma (HCC), which arises from differentiated hepatocytes. Here we show that one solution to this problem is provided by CD44, a hyaluronic acid receptor whose expression is rapidly induced in carcinogen-exposed hepatocytes in a STAT3-dependent manner. Once expressed, CD44 potentiates AKT activation to induce the phosphorylation and nuclear translocation of Mdm2, which terminates the p53 genomic surveillance response. This allows DNA-damaged hepatocytes to escape p53-induced death and senescence and respond to proliferative signals that promote fixation of mutations and their transmission to daughter cells that go on to become HCC progenitors.

Funding information:
  • Intramural NIH HHS - Z01 ES101765(United States)
  • NCI NIH HHS - R01 CA118165()
  • NIEHS NIH HHS - P42 ES010337()

nox2/cybb Deficiency Affects Zebrafish Retinotectal Connectivity.

  • Weaver CJ
  • J. Neurosci.
  • 2018 Jun 27

Literature context:


Abstract:

NADPH oxidase (Nox)-derived reactive oxygen species (ROS) have been linked to neuronal polarity, axonal outgrowth, cerebellar development, regeneration of sensory axons, and neuroplasticity. However, the specific roles that individual Nox isoforms play during nervous system development in vivo remain unclear. To address this problem, we investigated the role of Nox activity in the development of retinotectal connections in zebrafish embryos. Zebrafish broadly express four nox genes (nox1, nox2/cybb, nox5, and duox) throughout the CNS during early development. Application of a pan-Nox inhibitor, celastrol, during the time of optic nerve (ON) outgrowth resulted in significant expansion of the ganglion cell layer (GCL), thinning of the ON, and a decrease in retinal axons reaching the optic tectum (OT). With the exception of GCL expansion, these effects were partially ameliorated by the addition of H2O2, a key ROS involved in Nox signaling. To address isoform-specific Nox functions, we used CRISPR/Cas9 to generate mutations in each zebrafish nox gene. We found that nox2/cybb chimeric mutants displayed ON thinning and decreased OT innervation. Furthermore, nox2/cybb homozygous mutants (nox2/cybb-/-) showed significant GCL expansion and mistargeted retinal axons in the OT. Neurite outgrowth from cultured zebrafish retinal ganglion cells was reduced by Nox inhibitors, suggesting a cell-autonomous role for Nox in these neurons. Collectively, our results show that Nox2/Cybb is important for retinotectal development in zebrafish.SIGNIFICANCE STATEMENT Most isoforms of NADPH oxidase (Nox) only produce reactive oxygen species (ROS) when activated by an upstream signal, making them ideal candidates for ROS signaling. Nox enzymes are present in neurons and their activity has been shown to be important for neuronal development and function largely by in vitro studies. However, whether Nox is involved in the development of axons and formation of neuronal connections in vivo has remained unclear. Using mutant zebrafish embryos, this study shows that a specific Nox isoform, Nox2/Cybb, is important for the establishment of axonal connections between retinal ganglion cells and the optic tectum.

Funding information:
  • NIDCR NIH HHS - R01 DE018281(United States)
  • NIGMS NIH HHS - R35 GM119787(United States)

Evolution of Cortical Neurogenesis in Amniotes Controlled by Robo Signaling Levels.

  • Cárdenas A
  • Cell
  • 2018 Jun 20

Literature context:


Abstract:

Cerebral cortex size differs dramatically between reptiles, birds, and mammals, owing to developmental differences in neuron production. In mammals, signaling pathways regulating neurogenesis have been identified, but genetic differences behind their evolution across amniotes remain unknown. We show that direct neurogenesis from radial glia cells, with limited neuron production, dominates the avian, reptilian, and mammalian paleocortex, whereas in the evolutionarily recent mammalian neocortex, most neurogenesis is indirect via basal progenitors. Gain- and loss-of-function experiments in mouse, chick, and snake embryos and in human cerebral organoids demonstrate that high Slit/Robo and low Dll1 signaling, via Jag1 and Jag2, are necessary and sufficient to drive direct neurogenesis. Attenuating Robo signaling and enhancing Dll1 in snakes and birds recapitulates the formation of basal progenitors and promotes indirect neurogenesis. Our study identifies modulation in activity levels of conserved signaling pathways as a primary mechanism driving the expansion and increased complexity of the mammalian neocortex during amniote evolution.

Funding information:
  • Wellcome Trust - (United Kingdom)

Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain.

  • Addison M
  • Dev. Cell
  • 2018 Jun 4

Literature context:


Abstract:

The patterning of tissues to form subdivisions with distinct and homogeneous regional identity is potentially disrupted by cell intermingling. Transplantation studies suggest that homogeneous segmental identity in the hindbrain is maintained by identity switching of cells that intermingle into another segment. We show that switching occurs during normal development and is mediated by feedback between segment identity and the retinoic acid degrading enzymes, cyp26b1 and cyp26c1. egr2, which specifies the segmental identity of rhombomeres r3 and r5, underlies the lower expression level of cyp26b1 and cyp26c1 in r3 and r5 compared with r2, r4, and r6. Consequently, r3 or r5 cells that intermingle into adjacent segments encounter cells with higher cyp26b1/c1 expression, which we find is required for downregulation of egr2b expression. Furthermore, egr2b expression is regulated in r2, r4, and r6 by non-autonomous mechanisms that depend upon the number of neighbors that express egr2b. These findings reveal that a community regulation of retinoid signaling maintains homogeneous segmental identity.

Funding information:
  • NCI NIH HHS - R15 CA158767(United States)

Defects in the Alternative Splicing-Dependent Regulation of REST Cause Deafness.

  • Nakano Y
  • Cell
  • 2018 Jun 25

Literature context:


Abstract:

The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that, in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and they identify a potential treatment for a group of hereditary deafness cases.

Funding information:
  • NIMH NIH HHS - 5 F32 MH064339-03(United States)

Dual Requirement of CHD8 for Chromatin Landscape Establishment and Histone Methyltransferase Recruitment to Promote CNS Myelination and Repair.

  • Zhao C
  • Dev. Cell
  • 2018 Jun 18

Literature context:


Abstract:

Disruptive mutations in chromatin remodeler CHD8 cause autism spectrum disorders, exhibiting widespread white matter abnormalities; however, the underlying mechanisms remain elusive. We show that cell-type specific Chd8 deletion in oligodendrocyte progenitors, but not in neurons, results in myelination defects, revealing a cell-intrinsic dependence on CHD8 for oligodendrocyte lineage development, myelination and post-injury remyelination. CHD8 activates expression of BRG1-associated SWI/SNF complexes that in turn activate CHD7, thus initiating a successive chromatin remodeling cascade that orchestrates oligodendrocyte lineage progression. Genomic occupancy analyses reveal that CHD8 establishes an accessible chromatin landscape, and recruits MLL/KMT2 histone methyltransferase complexes distinctively around proximal promoters to promote oligodendrocyte differentiation. Inhibition of histone demethylase activity partially rescues myelination defects of CHD8-deficient mutants. Our data indicate that CHD8 exhibits a dual function through inducing a cascade of chromatin reprogramming and recruiting H3K4 histone methyltransferases to establish oligodendrocyte identity, suggesting potential strategies of therapeutic intervention for CHD8-associated white matter defects.

Funding information:
  • NIMH NIH HHS - R01 MH087592(United States)

Atypical Cadherin Dachsous1b Interacts with Ttc28 and Aurora B to Control Microtubule Dynamics in Embryonic Cleavages.

  • Chen J
  • Dev. Cell
  • 2018 May 7

Literature context:


Abstract:

Atypical cadherin Dachsous (Dchs) is a conserved regulator of planar cell polarity, morphogenesis, and tissue growth during animal development. Dchs functions in part by regulating microtubules by unknown molecular mechanisms. Here we show that maternal zygotic (MZ) dchs1b zebrafish mutants exhibit cleavage furrow progression defects and impaired midzone microtubule assembly associated with decreased microtubule turnover. Mechanistically, Dchs1b interacts via a conserved motif in its intracellular domain with the tetratricopeptide motifs of Ttc28 and regulates its subcellular distribution. Excess Ttc28 impairs cleavages and decreases microtubule turnover, while ttc28 inactivation increases turnover. Moreover, ttc28 deficiency in dchs1b mutants suppresses the microtubule dynamics and midzone microtubule assembly defects. Dchs1b also binds to Aurora B, a known regulator of cleavages and microtubules. Embryonic cleavages in MZdchs1b mutants exhibit increased, and in MZttc28 mutants decreased, sensitivity to Aurora B inhibition. Thus, Dchs1b regulates microtubule dynamics and embryonic cleavages by interacting with Ttc28 and Aurora B.

Funding information:
  • NIGMS NIH HHS - R15GM100402(United States)

Intracellular Calcium Mobilization Is Required for Sonic Hedgehog Signaling.

  • Klatt Shaw D
  • Dev. Cell
  • 2018 May 21

Literature context:


Abstract:

Graded Shh signaling across fields of precursor cells coordinates patterns of gene expression, differentiation, and morphogenetic behavior as precursors form complex structures, such as the nervous system, the limbs, and craniofacial skeleton. Here we discover that intracellular calcium mobilization, a process tightly controlled and readily modulated, regulates the level of Shh-dependent gene expression in responding cells and affects the development of all Shh-dependent cell types in the zebrafish embryo. Reduced expression or modified activity of ryanodine receptor (RyR) intracellular calcium release channels shifted the allocation of Shh-dependent cell fates in the somitic muscle and neural tube. Mosaic analysis revealed that RyR-mediated calcium mobilization is required specifically in Shh ligand-receiving cells. This work reveals that RyR channels participate in intercellular signal transduction events. As modulation of RyR activity modifies tissue patterning, we hypothesize that alterations in intracellular calcium mobilization contribute to both birth defects and evolutionary modifications of morphology.

Funding information:
  • NIAID NIH HHS - R01 AI043458(United States)

CALHM3 Is Essential for Rapid Ion Channel-Mediated Purinergic Neurotransmission of GPCR-Mediated Tastes.

  • Ma Z
  • Neuron
  • 2018 May 2

Literature context:


Abstract:

Binding of sweet, umami, and bitter tastants to G protein-coupled receptors (GPCRs) in apical membranes of type II taste bud cells (TBCs) triggers action potentials that activate a voltage-gated nonselective ion channel to release ATP to gustatory nerves mediating taste perception. Although calcium homeostasis modulator 1 (CALHM1) is necessary for ATP release, the molecular identification of the channel complex that provides the conductive ATP-release mechanism suitable for action potential-dependent neurotransmission remains to be determined. Here we show that CALHM3 interacts with CALHM1 as a pore-forming subunit in a CALHM1/CALHM3 hexameric channel, endowing it with fast voltage-activated gating identical to that of the ATP-release channel in vivo. Calhm3 is co-expressed with Calhm1 exclusively in type II TBCs, and its genetic deletion abolishes taste-evoked ATP release from taste buds and GPCR-mediated taste perception. Thus, CALHM3, together with CALHM1, is essential to form the fast voltage-gated ATP-release channel in type II TBCs required for GPCR-mediated tastes.

Funding information:
  • European Research Council - 233417(International)

Comprehensive analysis of area-specific and time-dependent changes in gene expression in the motor cortex of macaque monkeys during recovery from spinal cord injury.

  • Higo N
  • J. Comp. Neurol.
  • 2018 May 1

Literature context:


Abstract:

The present study aimed to assess the molecular bases of cortical compensatory mechanisms following spinal cord injury in primates. To accomplish this, comprehensive changes in gene expression were investigated in the bilateral primary motor cortex (M1), dorsal premotor cortex (PMd), and ventral premotor cortex (PMv) after a unilateral lesion of the lateral corticospinal tract (l-CST). At 2 weeks after the lesion, a large number of genes exhibited altered expression levels in the contralesional M1, which is directly linked to the lesioned l-CST. Gene ontology and network analyses indicated that these changes in gene expression are involved in the atrophy and plasticity changes observed in neurons. Orchestrated gene expression changes were present when behavioral recovery was attained 3 months after the lesion, particularly among the bilateral premotor areas, and a large number of these genes are involved in plasticity. Moreover, several genes abundantly expressed in M1 of intact monkeys were upregulated in both the PMd and PMv after the l-CST lesion. These area-specific and time-dependent changes in gene expression may underlie the molecular mechanisms of functional recovery following a lesion of the l-CST.

Co-translational protein targeting facilitates centrosomal recruitment of PCNT during centrosome maturation in vertebrates.

  • Sepulveda G
  • Elife
  • 2018 Apr 30

Literature context:


Abstract:

As microtubule-organizing centers of animal cells, centrosomes guide the formation of the bipolar spindle that segregates chromosomes during mitosis. At mitosis onset, centrosomes maximize microtubule-organizing activity by rapidly expanding the pericentriolar material (PCM). This process is in part driven by the large PCM protein pericentrin (PCNT), as its level increases at the PCM and helps recruit additional PCM components. However, the mechanism underlying the timely centrosomal enrichment of PCNT remains unclear. Here, we show that PCNT is delivered co-translationally to centrosomes during early mitosis by cytoplasmic dynein, as evidenced by centrosomal enrichment of PCNT mRNA, its translation near centrosomes, and requirement of intact polysomes for PCNT mRNA localization. Additionally, the microtubule minus-end regulator, ASPM, is also targeted co-translationally to mitotic spindle poles. Together, these findings suggest that co-translational targeting of cytoplasmic proteins to specific subcellular destinations may be a generalized protein targeting mechanism.

Funding information:
  • NIA NIH HHS - R01 AG039756(United States)
  • University of California, Davis - New Faculty Startup Funds()

Identification of a neuronal population in the telencephalon essential for fear conditioning in zebrafish.

  • Lal P
  • BMC Biol.
  • 2018 Apr 25

Literature context:


Abstract:

BACKGROUND: Fear conditioning is a form of learning essential for animal survival and used as a behavioral paradigm to study the mechanisms of learning and memory. In mammals, the amygdala plays a crucial role in fear conditioning. In teleost, the medial zone of the dorsal telencephalon (Dm) has been postulated to be a homolog of the mammalian amygdala by anatomical and ablation studies, showing a role in conditioned avoidance response. However, the neuronal populations required for a conditioned avoidance response via the Dm have not been functionally or genetically defined. RESULTS: We aimed to identify the neuronal population essential for fear conditioning through a genetic approach in zebrafish. First, we performed large-scale gene trap and enhancer trap screens, and created transgenic fish lines that expressed Gal4FF, an engineered version of the Gal4 transcription activator, in specific regions in the brain. We then crossed these Gal4FF-expressing fish with the effector line carrying the botulinum neurotoxin gene downstream of the Gal4 binding sequence UAS, and analyzed the double transgenic fish for active avoidance fear conditioning. We identified 16 transgenic lines with Gal4FF expression in various brain areas showing reduced performance in avoidance responses. Two of them had Gal4 expression in populations of neurons located in subregions of the Dm, which we named 120A-Dm neurons. Inhibition of the 120A-Dm neurons also caused reduced performance in Pavlovian fear conditioning. The 120A-Dm neurons were mostly glutamatergic and had projections to other brain regions, including the hypothalamus and ventral telencephalon. CONCLUSIONS: Herein, we identified a subpopulation of neurons in the zebrafish Dm essential for fear conditioning. We propose that these are functional equivalents of neurons in the mammalian pallial amygdala, mediating the conditioned stimulus-unconditioned stimulus association. Thus, the study establishes a basis for understanding the evolutionary conservation and diversification of functional neural circuits mediating fear conditioning in vertebrates.

Funding information:
  • European Research Council - Starting Grant 335561(International)
  • Japan Agency for Medical Research and Development - National BioResource Project()
  • Japan Agency for Medical Research and Development - NBRP()
  • Japan Society for the Promotion of Science - KAKENHI Grant Number JP15H02370()
  • Japan Society for the Promotion of Science - KAKENHI Grant Number JP16H01651()
  • NCATS NIH HHS - UL1 TR000439(United States)

Pericyte ALK5/TIMP3 Axis Contributes to Endothelial Morphogenesis in the Developing Brain.

  • Dave JM
  • Dev. Cell
  • 2018 Mar 26

Literature context:


Abstract:

The murine embryonic blood-brain barrier (BBB) consists of endothelial cells (ECs), pericytes (PCs), and basement membrane. Although PCs are critical for inducing vascular stability, signaling pathways in PCs that regulate EC morphogenesis during BBB development remain unexplored. Herein, we find that murine embryos lacking the transforming growth factor β (TGF-β) receptor activin receptor-like kinase 5 (Alk5) in brain PCs (mutants) develop gross germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH). The germinal matrix (GM) is a highly vascularized structure rich in neuronal and glial precursors. We show that GM microvessels of mutants display abnormal dilation, reduced PC coverage, EC hyperproliferation, reduced basement membrane collagen, and enhanced perivascular matrix metalloproteinase activity. Furthermore, ALK5-depleted PCs downregulate tissue inhibitor of matrix metalloproteinase 3 (TIMP3), and TIMP3 administration to mutants improves endothelial morphogenesis and attenuates GMH-IVH. Overall, our findings reveal a key role for PC ALK5 in regulating brain endothelial morphogenesis and a substantial therapeutic potential for TIMP3 during GMH-IVH.

Funding information:
  • NHLBI NIH HHS - R01 HL125815()
  • NHLBI NIH HHS - R01 HL133016()
  • NIAID NIH HHS - AI49371(United States)
  • NINDS NIH HHS - R21 NS088854()

Expression profile of N-cadherin and protocadherin-19 in postnatal mouse limbic structures.

  • Schaarschuch A
  • J. Comp. Neurol.
  • 2018 Mar 1

Literature context:


Abstract:

Cadherins are a superfamily of calcium-dependent cell adhesion molecules that are involved in brain development and organization. Previous genetic studies revealed that mutations in protocadherin-19 (Pcdh19) lead to an epilepsy syndrome with a variable degree of cognitive disability. Seizure origins are located in the frontotemporal and limbic structures. Expression studies of Pcdh19 in mouse confirmed a widespread presence during brain development while the function and the pathogenesis of Pcdh19 are still unknown in mammals. The neuronal cadherin (N-cadherin; Ncdh) is known for its important role in neurulation, brain development and regulation of synaptic function. Studies in zebrafish revealed that both cadherins can interact with each other in cell adhesion. We investigated the expression pattern of Pcdh19 and Ncdh in limbic structures at four postnatal stages of C57BL/6J mice by using double-label in situ hybridization. Results confirm a strong expression of both, Ncdh and Pcdh19, in structures of the limbic system with overlapping expression patterns particularly within regions of the amygdala, the hippocampus and the ventral hypothalamus. A detailed analysis of the limbic system highlight clear expression boundaries between several nuclei and reveal the fine regulation of Pcdh19 and Ncdh expression during the first postnatal week. Most expression patterns of both cadherins remain constant with a few exceptions particularly between P2 and P5.

Funding information:
  • NIAAA NIH HHS - R01 AA17442(United States)

Neocortical Association Cell Types in the Forebrain of Birds and Alligators.

  • Briscoe SD
  • Curr. Biol.
  • 2018 Mar 5

Literature context:


Abstract:

The avian dorsal telencephalon has two vast territories, the nidopallium and the mesopallium, both of which have been shown to contribute substantially to higher cognitive functions. From their connections, these territories have been proposed as equivalent to mammalian neocortical layers 2 and 3, various neocortical association areas, or the amygdala, but whether these are analogies or homologies by descent is unknown. We investigated the molecular profiles of the mesopallium and the nidopallium with RNA-seq. Gene expression experiments established that the mesopallium, but not the nidopallium, shares a transcription factor network with the intratelencephalic class of neocortical neurons, which are found in neocortical layers 2, 3, 5, and 6. Experiments in alligators demonstrated that these neurons are also abundant in the crocodilian cortex and form a large mesopallium-like structure in the dorsal ventricular ridge. Together with previous work, these molecular findings indicate a homology by descent for neuronal cell types of the avian dorsal telencephalon with the major excitatory cell types of mammalian neocortical circuits: the layer 4 input neurons, the deep layer output neurons, and the multi-layer intratelencephalic association neurons. These data raise the interesting possibility that avian and primate lineages evolved higher cognitive abilities independently through parallel expansions of homologous cell populations.

Funding information:
  • NIEHS NIH HHS - P01ES022831(United States)

Innate Immune Response and Off-Target Mis-splicing Are Common Morpholino-Induced Side Effects in Xenopus.

  • Gentsch GE
  • Dev. Cell
  • 2018 Mar 12

Literature context:


Abstract:

Antisense morpholino oligomers (MOs) have been indispensable tools for developmental biologists to transiently knock down (KD) genes rather than to knock them out (KO). Here we report on the implications of genetic KO versus MO-mediated KD of the mesoderm-specifying Brachyury paralogs in the frog Xenopus tropicalis. While both KO and KD embryos fail to activate the same core gene regulatory network, resulting in virtually identical morphological defects, embryos injected with control or target MOs also show a systemic GC content-dependent immune response and many off-target splicing defects. Optimization of MO dosage and increasing incubation temperatures can mitigate, but not eliminate, these MO side effects, which are consistent with the high affinity measured between MO and off-target sequence in vitro. We conclude that while MOs can be useful to profile loss-of-function phenotypes at a molecular level, careful attention must be paid to their immunogenic and off-target side effects.

Funding information:
  • NICHD NIH HHS - R01HD046236(United States)

Hypoexcitability precedes denervation in the large fast-contracting motor units in two unrelated mouse models of ALS.

  • Martínez-Silva ML
  • Elife
  • 2018 Mar 27

Literature context:


Abstract:

Hyperexcitability has been suggested to contribute to motoneuron degeneration in amyotrophic lateral sclerosis (ALS). If this is so, and given that the physiological type of a motor unit determines the relative susceptibility of its motoneuron in ALS, then one would expect the most vulnerable motoneurons to display the strongest hyperexcitability prior to their degeneration, whereas the less vulnerable should display a moderate hyperexcitability, if any. We tested this hypothesis in vivo in two unrelated ALS mouse models by correlating the electrical properties of motoneurons with their physiological types, identified based on their motor unit contractile properties. We found that, far from being hyperexcitable, the most vulnerable motoneurons become unable to fire repetitively despite the fact that their neuromuscular junctions were still functional. Disease markers confirm that this loss of function is an early sign of degeneration. Our results indicate that intrinsic hyperexcitability is unlikely to be the cause of motoneuron degeneration.

Funding information:
  • AFM-Téléthon - HYPERTOXIC()
  • Consejo Nacional de Ciencia y Tecnología - CONACYT()
  • Fondation Thierry Latran - OHEX()
  • National Institute of Neurological Disorders and Stroke - R01NS077863()
  • NIDDK NIH HHS - DK063311(United States)
  • Ulm University - Baustein Program()

Bombesin receptor subtype-3-expressing neurons regulate energy homeostasis through a novel neuronal pathway in the hypothalamus.

  • Maruyama M
  • Brain Behav
  • 2018 Mar 24

Literature context:


Abstract:

Objectives: Bombesin receptor subtype-3 (BRS-3) has been suggested to play a potential role in energy homeostasis. However, the physiological mechanism of BRS-3 on energy homeostasis remains unknown. Thus, we investigated the BRS-3-mediated neuronal pathway involved in food intake and energy expenditure. Materials and Methods: Expression of BRS-3 in the rat brain was histologically examined. The BRS-3 neurons activated by refeeding-induced satiety or a BRS-3 agonist were identified by c-Fos immunostaining. We also analyzed expression changes in feeding-relating peptides in the brain of fasted rats administered with the BRS-3 agonist. Results: In the paraventricular hypothalamic nucleus (PVH), dorsomedial hypothalamic nucleus (DMH), and medial preoptic area (MPA), strong c-Fos induction was observed in the BRS-3 neurons especially in PVH after refeeding. However, the BRS-3 neurons in the PVH did not express feeding-regulating peptides, while the BRS-3 agonist administration induced c-Fos expression in the DMH and MPA, which were not refeeding-sensitive, as well as in the PVH. The BRS-3 agonist administration changed the Pomc and Cart mRNA level in several brain regions of fasted rats. Conclusion: These results suggest that BRS-3 neurons in the PVH are a novel functional subdivision in the PVH that regulates feeding behavior. As the MPA and DMH are reportedly involved in thermoregulation and energy metabolism, the BRS-3 neurons in the MPA/DMH might mediate the energy expenditure control. POMC and CART may contribute to BRS-3 neuron-mediated energy homeostasis regulation. In summary, BRS-3-expressing neurons could regulate energy homeostasis through a novel neuronal pathway.

Funding information:
  • NCI NIH HHS - U01 CA152753(United States)

Essential Role of Nr2f Nuclear Receptors in Patterning the Vertebrate Upper Jaw.

  • Barske L
  • Dev. Cell
  • 2018 Feb 5

Literature context:


Abstract:

The jaw is central to the extensive variety of feeding and predatory behaviors across vertebrates. The bones of the lower but not upper jaw form around an early-developing cartilage template. Whereas Endothelin1 patterns the lower jaw, the factors that specify upper-jaw morphology remain elusive. Here, we identify Nuclear Receptor 2f genes (Nr2fs) as enriched in and required for upper-jaw formation in zebrafish. Combinatorial loss of Nr2fs transforms maxillary components of the upper jaw into lower-jaw-like structures. Conversely, nr2f5 misexpression disrupts lower-jaw development. Genome-wide analyses reveal that Nr2fs repress mandibular gene expression and early chondrogenesis in maxillary precursors. Rescue of lower-jaw defects in endothelin1 mutants by reducing Nr2f dosage further demonstrates that Nr2f expression must be suppressed for normal lower-jaw development. We propose that Nr2fs shape the upper jaw by protecting maxillary progenitors from early chondrogenesis, thus preserving cells for later osteogenesis.

Funding information:
  • Canadian Institutes of Health Research - (Canada)
  • NIDCR NIH HHS - K99 DE026239()
  • NIDCR NIH HHS - R01 DE018405()
  • NIDCR NIH HHS - R35 DE027550()

sept8a and sept8b mRNA expression in the developing and adult zebrafish.

  • Berger C
  • Gene Expr. Patterns
  • 2018 Jan 29

Literature context:


Abstract:

Septins are highly conserved GTP-binding proteins involved in numerous cellular processes. Despite a growing awareness of their roles in the cell biology, development and signal transmission in nervous systems, comparably little is known about precise septin expression. Here, we use the well-established model organism zebrafish (Danio rerio) to unravel the expression of sept8a and sept8b, with special focus on the CNS. We performed whole mount RNA in situ hybridization on zebrafish 1-4 dpf in combination with serial sectioning of epon-embedded samples as well as on brain sections of adult zebrafish to obtain precise histological mapping of gene expression. Our results show a common expression of both genes at embryonic stages, whereas sept8a is mainly restricted to the gill arches and sept8b to specific brain structures at later stages. Brains of adult zebrafish reveal a large spatial overlap of sept8a and sept8b expression with few regions uniquely expressing sept8a or sept8b. Our results indicate a neuronal expression of both genes, and additionally suggest expression of sept8b in glial cells. Altogether, this study provides a first detailed insight into the expression of sept8a and sept8b in zebrafish and contributes to a more comprehensive understanding of septin biology in vertebrate model systems.

Astroglial major histocompatibility complex class I following immune activation leads to behavioral and neuropathological changes.

  • Sobue A
  • Glia
  • 2018 Jan 31

Literature context:


Abstract:

In the central nervous system, major histocompatibility complex class I (MHCI) molecules are mainly expressed in neurons, and neuronal MHCI have roles in synapse elimination and plasticity. However, the pathophysiological significance of astroglial MHCI remains unclear. We herein demonstrate that MHCI expression is up-regulated in astrocytes in the medial prefrontal cortex (mPFC) following systemic immune activation by an intraperitoneal injection of polyinosinic-polycytidylic acid (polyI:C) or hydrodynamic interferon (IFN)-γ gene delivery in male C57/BL6J mice. In cultured astrocytes, MHCI/H-2D largely co-localized with exosomes. To investigate the role of astroglial MHCI, H-2D, or sH-2D was expressed in the mPFC of male C57/BL6J mice using an adeno-associated virus vector under the control of a glial fibrillary acidic protein promoter. The expression of astroglial MHCI in the mPFC impaired sociability and recognition memory in mice. Regarding neuropathological changes, MHCI expression in astrocytes significantly activated microglial cells, decreased parvalbumin-positive cell numbers, and reduced dendritic spine density in the mPFC. A treatment with GW4869 that impairs exosome synthesis ameliorated these behavioral and neuropathological changes. These results suggest that the overexpression of MHCI in astrocytes affects microglial proliferation as well as neuronal numbers and spine densities, thereby leading to social and cognitive deficits in mice, possibly via exosomes created by astrocytes.

Ultraconserved Enhancers Are Required for Normal Development.

  • Dickel DE
  • Cell
  • 2018 Jan 25

Literature context:


Abstract:

Non-coding "ultraconserved" regions containing hundreds of consecutive bases of perfect sequence conservation across mammalian genomes can function as distant-acting enhancers. However, initial deletion studies in mice revealed that loss of such extraordinarily constrained sequences had no immediate impact on viability. Here, we show that ultraconserved enhancers are required for normal development. Focusing on some of the longest ultraconserved sites genome wide, located near the essential neuronal transcription factor Arx, we used genome editing to create an expanded series of knockout mice lacking individual or combinations of ultraconserved enhancers. Mice with single or pairwise deletions of ultraconserved enhancers were viable and fertile but in nearly all cases showed neurological or growth abnormalities, including substantial alterations of neuron populations and structural brain defects. Our results demonstrate the functional importance of ultraconserved enhancers and indicate that remarkably strong sequence conservation likely results from fitness deficits that appear subtle in a laboratory setting.

Funding information:
  • NCRR NIH HHS - S10 RR027303()
  • NCRR NIH HHS - S10 RR029668()
  • NHGRI NIH HHS - R01 HG003988()
  • NHGRI NIH HHS - UM1 HG009421()
  • NHLBI NIH HHS - R24 HL123879()
  • NHLBI NIH HHS - T32 HL094274-01A2(United States)
  • NHLBI NIH HHS - UM1 HL098166()
  • NIMH NIH HHS - R37 MH049428()
  • NINDS NIH HHS - R01 NS034661()
  • NINDS NIH HHS - R01 NS099099()

Long-Range Signaling Activation and Local Inhibition Separate the Mesoderm and Endoderm Lineages.

  • van Boxtel AL
  • Dev. Cell
  • 2018 Jan 22

Literature context:


Abstract:

Specification of the three germ layers by graded Nodal signaling has long been seen as a paradigm for patterning through a single morphogen gradient. However, by exploiting the unique properties of the zebrafish embryo to capture the dynamics of signaling and cell fate allocation, we now demonstrate that Nodal functions in an incoherent feedforward loop, together with Fgf, to determine the pattern of endoderm and mesoderm specification. We show that Nodal induces long-range Fgf signaling while simultaneously inducing the cell-autonomous Fgf signaling inhibitor Dusp4 within the first two cell tiers from the margin. The consequent attenuation of Fgf signaling in these cells allows specification of endoderm progenitors, while the cells further from the margin, which receive Nodal and/or Fgf signaling, are specified as mesoderm. This elegant model demonstrates the necessity of feedforward and feedback interactions between multiple signaling pathways for providing cells with temporal and positional information.

Funding information:
  • NLM NIH HHS - 5T15LM007359(United States)

Hyperinnervation improves Xenopus laevis limb regeneration.

  • Mitogawa K
  • Dev. Biol.
  • 2018 Jan 15

Literature context:


Abstract:

Xenopus laevis (an anuran amphibian) shows limb regeneration ability between that of urodele amphibians and that of amniotes. Xenopus frogs can initiate limb regeneration but fail to form patterned limbs. Regenerated limbs mainly consist of cone-shaped cartilage without any joints or branches. These pattern defects are thought to be caused by loss of proper expressions of patterning-related genes. This study shows that hyperinnervation surgery resulted in the induction of a branching regenerate. The hyperinnervated blastema allows the identification and functional analysis of the molecules controlling this patterning of limb regeneration. This paper focuses on the nerve affects to improve Xenopus limb patterning ability during regeneration. The nerve molecules, which regulate limb patterning, were also investigated. Blastemas grown in a hyperinnervated forelimb upregulate limb patterning-related genes (shh, lmx1b, and hoxa13). Nerves projecting their axons to limbs express some growth factors (bmp7, fgf2, fgf8, and shh). Inputs of these factors to a blastema upregulated some limb patterning-related genes and resulted in changes in the cartilage patterns in the regenerates. These results indicate that additional nerve factors enhance Xenopus limb patterning-related gene expressions and limb regeneration ability, and that bmp, fgf, and shh are candidate nerve substitute factors.

Aberrant Global and Jagged-Mediated Notch Signaling Disrupts Segregation Between wt1-Expressing and Steroidogenic Tissues in Zebrafish.

  • Chou CW
  • Endocrinology
  • 2017 Dec 1

Literature context:


Abstract:

Although the zebrafish interrenal tissue has been used as a model for steroidogenesis and genesis of the adrenal gland, its specification and morphogenesis remains largely unclear. In the present study, we explored how the Wilms tumor 1 (WT1)-expressing cells are segregated from the SF-1-expressing steroidogenic cells in the zebrafish model. The interrenal tissue precursors expressing ff1b, the equivalent of mammalian SF-1, were derived from wt1-expressing pronephric primordia in the zebrafish embryo. Through histochemistry and in situ hybridization, we demonstrated that the size of functionally differentiated interrenal tissue was substantially increased on global inhibition of the Notch signaling pathway and was accompanied by a disrupted segregation between the wt1- and ff1b-expressing cells. As the Notch pathway was conditionally activated during interrenal specification, differentiation, but not ff1b expression, of interrenal tissue was drastically compromised. In embryos deficient for Notch ligands jagged 1b and 2b, transgenic reporter activity of wt1b promoter was detected within the steroidogenic interrenal tissue. In conclusion, our results indicate that Jagged-Notch signaling is required (1) for segregation between wt1-expressing cells and differentiated steroidogenic tissue; and (2) to modulate the extent of functional differentiation in the steroidogenic interrenal tissue.

Distinct projection targets define subpopulations of mouse brainstem vagal neurons that express the autism-associated MET receptor tyrosine kinase.

  • Kamitakahara A
  • J. Comp. Neurol.
  • 2017 Dec 15

Literature context:


Abstract:

Detailed anatomical tracing and mapping of the viscerotopic organization of the vagal motor nuclei has provided insight into autonomic function in health and disease. To further define specific cellular identities, we paired information based on visceral connectivity with a cell-type specific marker of a subpopulation of neurons in the dorsal motor nucleus of the vagus (DMV) and nucleus ambiguus (nAmb) that express the autism-associated MET receptor tyrosine kinase. As gastrointestinal disturbances are common in children with autism spectrum disorder (ASD), we sought to define the relationship between MET-expressing (MET+) neurons in the DMV and nAmb, and the gastrointestinal tract. Using wholemount tissue staining and clearing, or retrograde tracing in a METEGFP transgenic mouse, we identify three novel subpopulations of EGFP+ vagal brainstem neurons: (a) EGFP+ neurons in the nAmb projecting to the esophagus or laryngeal muscles, (b) EGFP+ neurons in the medial DMV projecting to the stomach, and (b) EGFP+ neurons in the lateral DMV projecting to the cecum and/or proximal colon. Expression of the MET ligand, hepatocyte growth factor (HGF), by tissues innervated by vagal motor neurons during fetal development reveal potential sites of HGF-MET interaction. Furthermore, similar cellular expression patterns of MET in the brainstem of both the mouse and nonhuman primate suggests that MET expression at these sites is evolutionarily conserved. Together, the data suggest that MET+ neurons in the brainstem vagal motor nuclei are anatomically positioned to regulate distinct portions of the gastrointestinal tract, with implications for the pathophysiology of gastrointestinal comorbidities of ASD.

Bleb Expansion in Migrating Cells Depends on Supply of Membrane from Cell Surface Invaginations.

  • Goudarzi M
  • Dev. Cell
  • 2017 Dec 4

Literature context:


Abstract:

Cell migration is essential for morphogenesis, organ formation, and homeostasis, with relevance for clinical conditions. The migration of primordial germ cells (PGCs) is a useful model for studying this process in the context of the developing embryo. Zebrafish PGC migration depends on the formation of cellular protrusions in form of blebs, a type of protrusion found in various cell types. Here we report on the mechanisms allowing the inflation of the membrane during bleb formation. We show that the rapid expansion of the protrusion depends on membrane invaginations that are localized preferentially at the cell front. The formation of these invaginations requires the function of Cdc42, and their unfolding allows bleb inflation and dynamic cell-shape changes performed by migrating cells. Inhibiting the formation and release of the invaginations strongly interfered with bleb formation, cell motility, and the ability of the cells to reach their target.

Funding information:
  • NIAMS NIH HHS - R01 AR065439()
  • Wellcome Trust - (United Kingdom)

The Vertebrate Protein Dead End Maintains Primordial Germ Cell Fate by Inhibiting Somatic Differentiation.

  • Gross-Thebing T
  • Dev. Cell
  • 2017 Dec 18

Literature context:


Abstract:

Maintaining cell fate relies on robust mechanisms that prevent the differentiation of specified cells into other cell types. This is especially critical during embryogenesis, when extensive cell proliferation, patterning, and migration events take place. Here we show that vertebrate primordial germ cells (PGCs) are protected from reprogramming into other cell types by the RNA-binding protein Dead end (Dnd). PGCs knocked down for Dnd lose their characteristic morphology and adopt various somatic cell fates. Concomitantly, they gain a gene expression profile reflecting differentiation into cells of different germ layers, in a process that we could direct by expression of specific cell-fate determinants. Importantly, we visualized these events within live zebrafish embryos, which provide temporal information regarding cell reprogramming. Our results shed light on the mechanisms controlling germ cell fate maintenance and are relevant for the formation of teratoma, a tumor class composed of cells from more than one germ layer.

Funding information:
  • NIDA NIH HHS - R01DA024413(United States)

Boundary Formation through a Direct Threshold-Based Readout of Mobile Small RNA Gradients.

  • Skopelitis DS
  • Dev. Cell
  • 2017 Nov 6

Literature context:


Abstract:

Small RNAs have emerged as a new class of mobile signals. Here, we investigate their mechanism of action and show that mobile small RNAs generate sharply defined domains of target gene expression through an intrinsic and direct threshold-based readout of their mobility gradients. This readout is highly sensitive to small RNA levels at the source, allowing plasticity in the positioning of a target gene expression boundary. Besides patterning their immediate targets, the readouts of opposing small RNA gradients enable specification of robust, uniformly positioned developmental boundaries. These patterning properties of small RNAs are reminiscent of those of animal morphogens. However, their mode of action and the intrinsic nature of their gradients distinguish mobile small RNAs from classical morphogens and present a unique direct mechanism through which to relay positional information. Mobile small RNAs and their targets thus emerge as highly portable, evolutionarily tractable regulatory modules through which to create pattern.

Funding information:
  • Wellcome Trust - 089701(United Kingdom)

Lateral Preoptic Control of the Lateral Habenula through Convergent Glutamate and GABA Transmission.

  • Barker DJ
  • Cell Rep
  • 2017 Nov 14

Literature context:


Abstract:

The lateral habenula (LHb) is a brain structure that participates in cognitive and emotional processing and has been implicated in several mental disorders. Although one of the largest inputs to the LHb originates in the lateral preoptic area (LPO), little is known about how the LPO participates in the regulation of LHb function. Here, we provide evidence that the LPO exerts bivalent control over the LHb through the convergent transmission of LPO glutamate and γ-aminobutyric acid (GABA) onto single LHb neurons. In vivo, both LPO-glutamatergic and LPO-GABAergic inputs to the LHb are activated by aversive stimuli, and their predictive cues yet produce opposing behaviors when stimulated independently. These results support a model wherein the balanced response of converging LPO-glutamate and LPO-GABA are necessary for a normal response to noxious stimuli, and an imbalance in LPO→LHb glutamate or GABA results in the type of aberrant processing that may underlie mental disorders.

Direct Dopaminergic Projections from the SNc Modulate Visuomotor Transformation in the Lamprey Tectum.

  • Pérez-Fernández J
  • Neuron
  • 2017 Nov 15

Literature context:


Abstract:

Dopamine neurons in the SNc play a pivotal role in modulating motor behavior via striatum. Here, we show that the same dopamine neuron that targets striatum also sends a direct branch to the optic tectum (superior colliculus). Whenever SNc neurons are activated, both targets will therefore be affected. Visual stimuli (looming or bars) activate the dopamine neurons coding saliency and also elicit distinct motor responses mediated via tectum (eye, orienting or evasive), which are modulated by the dopamine input. Whole-cell recordings from tectal projection neurons and interneurons show that dopamine, released by SNc stimulation, increases or decreases the excitability depending on whether they express the dopamine D1 or the D2 receptor. SNc thus exerts its effects on the visuomotor system through a combined effect directly on tectum and also via striatum. This direct SNc modulation will occur regardless of striatum and represents a novel mode of motor control.

Funding information:
  • NIDCD NIH HHS - R01 DC009405(United States)

Characterization of the axon initial segment of mice substantia nigra dopaminergic neurons.

  • González-Cabrera C
  • J. Comp. Neurol.
  • 2017 Nov 1

Literature context:


Abstract:

The axon initial segment (AIS) is the site of initiation of action potentials and influences action potential waveform, firing pattern, and rate. In view of the fundamental aspects of motor function and behavior that depend on the firing of substantia nigra pars compacta (SNc) dopaminergic neurons, we identified and characterized their AIS in the mouse. Immunostaining for tyrosine hydroxylase (TH), sodium channels (Nav ) and ankyrin-G (Ank-G) was used to visualize the AIS of dopaminergic neurons. Reconstructions of sampled AIS of dopaminergic neurons revealed variable lengths (12-60 μm) and diameters (0.2-0.8 μm), and an average of 50% reduction in diameter between their widest and thinnest parts. Ultrastructural analysis revealed submembranous localization of Ank-G at nodes of Ranvier and AIS. Serial ultrathin section analysis and 3D reconstructions revealed that Ank-G colocalized with TH only at the AIS. Few cases of synaptic innervation of the AIS of dopaminergic neurons were observed. mRNA in situ hybridization of brain-specific Nav subunits revealed the expression of Nav 1.2 by most SNc neurons and a small proportion expressing Nav 1.6. The presence of sodium channels, along with the submembranous location of Ank-G is consistent with the role of AIS in action potential generation. Differences in the size of the AIS likely underlie differences in firing pattern, while the tapering diameter of AIS may define a trigger zone for action potentials. Finally, the conspicuous expression of Nav 1.2 by the majority of dopaminergic neurons may explain their high threshold for firing and their low discharge rate.

Funding information:
  • Biotechnology and Biological Sciences Research Council - (United Kingdom)

Genetic and neuronal regulation of sleep by neuropeptide VF.

  • Lee DA
  • Elife
  • 2017 Nov 6

Literature context:


Abstract:

Sleep is an essential and phylogenetically conserved behavioral state, but it remains unclear to what extent genes identified in invertebrates also regulate vertebrate sleep. RFamide-related neuropeptides have been shown to promote invertebrate sleep, and here we report that the vertebrate hypothalamic RFamide neuropeptide VF (NPVF) regulates sleep in the zebrafish, a diurnal vertebrate. We found that NPVF signaling and npvf-expressing neurons are both necessary and sufficient to promote sleep, that mature peptides derived from the NPVF preproprotein promote sleep in a synergistic manner, and that stimulation of npvf-expressing neurons induces neuronal activity levels consistent with normal sleep. These results identify NPVF signaling and npvf-expressing neurons as a novel vertebrate sleep-promoting system and suggest that RFamide neuropeptides participate in an ancient and central aspect of sleep control.

Funding information:
  • NIDDK NIH HHS - R01 DK090029(United States)

N-Methyl d-Aspartate Receptor Expression Patterns in the Human Fetal Cerebral Cortex.

  • Bagasrawala I
  • Cereb. Cortex
  • 2017 Nov 1

Literature context:


Abstract:

N-methyl d-aspartate receptors (NMDARs), a subtype of glutamate receptor, have important functional roles in cellular activity and neuronal development. They are well-studied in rodent and adult human brains, but limited information is available about their distribution in the human fetal cerebral cortex. Here we show that 3 NMDAR subunits, NR1, NR2A, and NR2B, are expressed in the human cerebral cortex during the second trimester of gestation, a period of intense neurogenesis and synaptogenesis. With increasing fetal age, expression of the NMDAR-encoding genes Grin1 (NR1) and Grin2a (NR2A) increased while Grin2b (NR2B) expression decreased. The protein levels of all 3 subunits paralleled the changes in gene expression. On cryosections, all 3 subunits were expressed in proliferative ventricular and subventricular zones, in radial glia, and in intermediate progenitor cells, consistent with their role in the proliferation of cortical progenitor cells and in the determination of their respective fates. The detection of NR1, NR2A, and NR2B in both glutamatergic and GABAergic neurons of the cortical plate suggests the involvement of NMDARs in the maturation of human cortical neurons and in early synapse formation. Our results and previous studies in rodents suggest that NMDAR expression in the developing human brain is evolutionarily conserved.

Gyrification of the cerebral cortex requires FGF signaling in the mammalian brain.

  • Matsumoto N
  • Elife
  • 2017 Nov 14

Literature context:


Abstract:

Although it has been believed that the evolution of cortical folds was a milestone, allowing for an increase in the number of neurons in the cerebral cortex, the mechanisms underlying the formation of cortical folds are largely unknown. Here we show regional differences in the expression of fibroblast growth factor receptors (FGFRs) in the developing cerebral cortex of ferrets even before cortical folds are formed. By taking the advantage of our in utero electroporation technique for ferrets, we found that cortical folding was impaired in the ferret cerebral cortex when FGF signaling was inhibited. We also found that FGF signaling was crucial for producing Pax6-positive neural progenitors in the outer subventricular zone (OSVZ) of the developing cerebral cortex. Furthermore, we found that upper layers of the cerebral cortex were preferentially reduced by inhibiting FGF signaling. Our results shed light on the mechanisms of cortical folding in gyrencephalic mammalian brains.

Detecting Activated Cell Populations Using Single-Cell RNA-Seq.

  • Wu YE
  • Neuron
  • 2017 Oct 11

Literature context:


Abstract:

Single-cell RNA sequencing offers a promising opportunity for probing cell types mediating specific behavioral functions and the underlying molecular programs. However, this has been hampered by a long-standing issue in transcriptional profiling of dissociated cells, specifically the transcriptional perturbations that are artificially induced during conventional whole-cell dissociation procedures. Here, we develop Act-seq, which minimizes artificially induced transcriptional perturbations and allows for faithful detection of both baseline transcriptional profiles and acute transcriptional changes elicited by behavior/experience-driven activity. Using Act-seq, we provide the first detailed molecular taxonomy of distinct cell types in the amygdala. We further show that Act-seq robustly detects seizure-induced acute gene expression changes in multiple cell types, revealing cell-type-specific activation profiles. Furthermore, we find that acute stress preferentially activates neuronal subpopulations that express the neuropeptide gene Cck. Act-seq opens the way for linking physiological stimuli with acute transcriptional dynamics in specific cell types in diverse complex tissues.

Fgf10-Hippo Epithelial-Mesenchymal Crosstalk Maintains and Recruits Lung Basal Stem Cells.

  • Volckaert T
  • Dev. Cell
  • 2017 Oct 9

Literature context:


Abstract:

The lung harbors its basal stem/progenitor cells (BSCs) in the protected environment of the cartilaginous airways. After major lung injuries, BSCs are activated and recruited to sites of injury. Here, we show that during homeostasis, BSCs in cartilaginous airways maintain their stem cell state by downregulating the Hippo pathway (resulting in increased nuclear Yap), which generates a localized Fgf10-expressing stromal niche; in contrast, differentiated epithelial cells in non-cartilaginous airways maintain quiescence by activating the Hippo pathway and inhibiting Fgf10 expression in airway smooth muscle cells (ASMCs). However, upon injury, surviving differentiated epithelial cells spread to maintain barrier function and recruit integrin-linked kinase to adhesion sites, which leads to Merlin degradation, downregulation of the Hippo pathway, nuclear Yap translocation, and expression and secretion of Wnt7b. Epithelial-derived Wnt7b, then in turn, induces Fgf10 expression in ASMCs, which extends the BSC niche to promote regeneration.

Funding information:
  • NHLBI NIH HHS - R01 HL092967()
  • NHLBI NIH HHS - R01 HL126732()
  • NHLBI NIH HHS - R01 HL132156()

Rac1 Dosage Is Crucial for Normal Endochondral Bone Growth.

  • Suzuki D
  • Endocrinology
  • 2017 Oct 1

Literature context:


Abstract:

Rac1, a member of the small Rho GTPase family, plays multiple cellular roles. Studies of mice conditionally lacking Rac1 have revealed essential roles for Rac1 in various tissues, including cartilage and limb mesenchyme, where Rac1 loss produces dwarfism and long bone shortening. To gain further insight into the role of Rac1 in skeletal development, we have used transgenic mouse lines to express a constitutively active (ca) Rac1 mutant protein in a Cre recombinase-dependent manner. Overexpression of caRac1 in limb bud mesenchyme or chondrocytes leads to reduced body weight and shorter bones compared with control mice. Histological analysis of growth plates showed that caRac1;Col2-Cre mice displayed ectopic hypertrophic chondrocytes in the proliferative zone and enlarged hypertrophic zones. These mice also displayed a reduced proportion of proliferating cell nuclear antigen-positive cells in the proliferative zone and nuclear β-catenin localization in the ectopic hypertrophic chondrocytes. Importantly, overexpression of caRac1 partially rescued the phenotypes of Rac1fl/fl;Col2-Cre and Rac1fl/fl;Prx1-Cre conditional knockout mice, including body weight, bone length, and growth plate disorganization. These results suggest that tight regulation of Rac1 activity is necessary for normal cartilage development.

Distribution and female reproductive state differences in orexigenic and anorexigenic neurons in the brain of the mouth brooding African cichlid fish, Astatotilapia burtoni.

  • Porter DT
  • J. Comp. Neurol.
  • 2017 Oct 1

Literature context:


Abstract:

Integration of reproduction and metabolism is necessary for species survival. While the neural circuits controlling energy homeostasis are well-characterized, the signals controlling the relay of nutritional information to the reproductive axis are less understood. The cichlid fish Astatotilapia burtoni is ideal for studying the neural regulation of feeding and reproduction because females cycle between a feeding gravid state and a period of forced starvation while they brood developing young inside their mouths. To test the hypothesis that candidate neuropeptide-containing neurons known to be involved in feeding and energy homeostasis in mammals show conserved distribution patterns, we performed immunohistochemistry and in situ hybridization to localize appetite-stimulating (neuropeptide Y, NPY; agouti-related protein, AGRP) and appetite-inhibiting (cocaine and amphetamine-regulated transcript, CART; pro-opiomelanocortin, pomc1a) neurons in the brain. NPY, AGRP, CART, and pomc1a somata showed distribution patterns similar to other teleosts, which included localization to the lateral tuberal nucleus (NLT), the putative homolog of the mammalian arcuate nucleus. Gravid females also had larger NPY and AGRP neurons in the NLT compared to brooding females, but brooding females had larger pomc1a neurons compared to gravid females. Hypothalamic agrp mRNA levels were also higher in gravid compared to brooding females. Thus, larger appetite-stimulating neurons (NPY, AGRP) likely promote feeding while females are gravid, while larger pomc1a neurons may act as a signal to inhibit food intake during mouth brooding. Collectively, our data suggest a potential role for NPY, AGRP, POMC, and CART in regulating energetic status in A. burtoni females during varying metabolic and reproductive demands.

Sonic Hedgehog switches on Wnt/planar cell polarity signaling in commissural axon growth cones by reducing levels of Shisa2.

  • Onishi K
  • Elife
  • 2017 Sep 8

Literature context:


Abstract:

Commissural axons switch on responsiveness to Wnt attraction during midline crossing and turn anteriorly only after exiting the floor plate. We report here that Sonic Hedgehog (Shh)-Smoothened signaling downregulates Shisa2, which inhibits the glycosylation and cell surface presentation of Frizzled3 in rodent commissural axon growth cones. Constitutive Shisa2 expression causes randomized turning of post-crossing commissural axons along the anterior-posterior (A-P) axis. Loss of Shisa2 led to precocious anterior turning of commissural axons before or during midline crossing. Post-crossing commissural axon turning is completely randomized along the A-P axis when Wntless, which is essential for Wnt secretion, is conditionally knocked out in the floor plate. This regulatory link between Shh and planar cell polarity (PCP) signaling may also occur in other developmental processes.

Formation and Shaping of the Antirrhinum Flower through Modulation of the CUP Boundary Gene.

  • Rebocho AB
  • Curr. Biol.
  • 2017 Sep 11

Literature context:


Abstract:

Boundary domain genes, expressed within or around organ primordia, play a key role in the formation, shaping, and subdivision of planar plant organs, such as leaves. However, the role of boundary genes in formation of more elaborate 3D structures, which also derive from organ primordia, remains unclear. Here we analyze the role of the boundary domain gene CUPULIFORMIS (CUP) in formation of the ornate Antirrhinum flower shape. We show that CUP expression becomes cleared from boundary subdomains between petal primordia, most likely contributing to formation of congenitally fused petals (sympetally) and modulation of growth at sinuses. At later stages, CUP is activated by dorsoventral genes in an intermediary region of the corolla. In contrast to its role at organ boundaries, intermediary CUP activity leads to growth promotion rather than repression and formation of the palate, lip, and characteristic folds of the closed Antirrhinum flower. Intermediary expression of CUP homologs is also observed in related sympetalous species, Linaria and Mimulus, suggesting that changes in boundary gene activity have played a key role in the development and evolution of diverse 3D plant shapes.

RING Finger Protein 38 Is a Neuronal Protein in the Brain of Nile Tilapia, Oreochromis niloticus.

  • Cham KL
  • Front Neuroanat
  • 2017 Sep 15

Literature context:


Abstract:

Really interesting new gene (RING) finger protein is a type of zinc-binding motif found in a large family of functionally distinct proteins. RING finger proteins are involved in diverse cellular processes including apoptosis, DNA repair, cell cycle, signal transduction, tumour suppressor, vesicular transport, and peroxisomal biogenesis. RING finger protein 38 (RNF38) is a member of the family whose functions remain unknown. To gain insight into the putative effects of RNF38 in the central nervous system, we localised its expression. The aim of this study was to identify the neuroanatomical location(s) of rnf38 mRNA and its peptide, determine the type of RNF38-expressing cells, and measure rnf38 gene expression in the brain of male tilapia. The distributions of rnf38 mRNA and its peptide were visualised using in situ hybridisation with digoxigenin-labelled RNA antisense and immunocytochemistry, respectively. Both were identically distributed throughout the brain, including the telencephalon, preoptic area, optic tectum, hypothalamus, cerebellum, and the hindbrain. Double-labelling immunocytochemistry for RNF38 and the neuronal marker HuC/D showed that most but not all RNF38 protein was expressed in neuronal nuclei. Quantitative real-time polymerase chain reaction showed the highest level of rnf38 mRNA in the midbrain, followed by the preoptic area, cerebellum, optic tectum, telencephalon, hindbrain and hypothalamus. These findings reveal a differential spatial pattern of RNF38 in the tilapia brain, suggesting that it has potentially diverse functions related to neuronal activity.

Heterophilic Type II Cadherins Are Required for High-Magnitude Synaptic Potentiation in the Hippocampus.

  • Basu R
  • Neuron
  • 2017 Sep 27

Literature context:


Abstract:

Hippocampal CA3 neurons form synapses with CA1 neurons in two layers, stratum oriens (SO) and stratum radiatum (SR). Each layer develops unique synaptic properties but molecular mechanisms that mediate these differences are unknown. Here, we show that SO synapses normally have significantly more mushroom spines and higher-magnitude long-term potentiation (LTP) than SR synapses. Further, we discovered that these differences require the Type II classic cadherins, cadherins-6, -9, and -10. Though cadherins typically function via trans-cellular homophilic interactions, our results suggest presynaptic cadherin-9 binds postsynaptic cadherins-6 and -10 to regulate mushroom spine density and high-magnitude LTP in the SO layer. Loss of these cadherins has no effect on the lower-magnitude LTP typically observed in the SR layer, demonstrating that cadherins-6, -9, and -10 are gatekeepers for high-magnitude LTP. Thus, Type II cadherins may uniquely contribute to the specificity and strength of synaptic changes associated with learning and memory.

Funding information:
  • NEI NIH HHS - R01 EY022073()

Alternative Progenitor Cells Compensate to Rebuild the Coronary Vasculature in Elabela- and Apj-Deficient Hearts.

  • Sharma B
  • Dev. Cell
  • 2017 Sep 25

Literature context:


Abstract:

Organogenesis during embryonic development occurs through the differentiation of progenitor cells. This process is extraordinarily accurate, but the mechanisms ensuring high fidelity are poorly understood. Coronary vessels of the mouse heart derive from at least two progenitor pools, the sinus venosus and endocardium. We find that the ELABELA (ELA)-APJ signaling axis is only required for sinus venosus-derived progenitors. Because they do not depend on ELA-APJ, endocardial progenitors are able to expand and compensate for faulty sinus venosus development in Apj mutants, leading to normal adult heart function. An upregulation of endocardial SOX17 accompanied compensation in Apj mutants, which was also seen in Ccbe1 knockouts, indicating that the endocardium is activated in multiple cases where sinus venosus angiogenesis is stunted. Our data demonstrate that by diversifying their responsivity to growth cues, distinct coronary progenitor pools are able to compensate for each other during coronary development, thereby providing robustness to organ development.

Spatial and temporal expression profiles of urocortin 3 mRNA in the brain of the chicken (Gallus gallus).

  • Grommen SVH
  • J. Comp. Neurol.
  • 2017 Aug 1

Literature context:


Abstract:

Urocortin 3 (UCN3) is a neuropeptide believed to regulate stress-coping responses by binding to type 2 corticotropin-releasing hormone receptors. Here, we report the cloning and brain distribution of UCN3 mRNA in a sauropsid-the chicken, Gallus gallus. Mature chicken UCN3 is predicted to be a 40-amino acid peptide showing high sequence similarity to human (93%), mouse (93%), and Xenopus (88%) UCN3. During the last third of embryonic development, UCN3 mRNA levels changed differentially in the various brain parts. In all brain parts, UCN3 mRNA levels tended to increase toward hatching, except for caudal brainstem, where a gradual decrease was observed during the last week of embryonic development. In cerebellum, a rapid increase in gene expression occurred between embryonic days 17 and 19. Using in situ hybridization, UCN3 mRNA was found to be expressed predominantly in the hypothalamus, pons, and medulla of posthatch chick brains, but not in some areas that are among the main expression sites in rodents, such as the brain areas where in mammals the median preoptic nucleus and the medial amygdala are located. This suggests that the roles of UCN3 in chicken, and perhaps sauropsids in general, are not all identical to those in rodents.

An Actomyosin-Arf-GEF Negative Feedback Loop for Tissue Elongation under Stress.

  • West JJ
  • Curr. Biol.
  • 2017 Aug 7

Literature context:


Abstract:

In response to a pulling force, a material can elongate, hold fast, or fracture. During animal development, multi-cellular contraction of one region often stretches neighboring tissue. Such local contraction occurs by induced actomyosin activity, but molecular mechanisms are unknown for regulating the physical properties of connected tissue for elongation under stress. We show that cytohesins, and their Arf small G protein guanine nucleotide exchange activity, are required for tissues to elongate under stress during both Drosophila dorsal closure (DC) and zebrafish epiboly. In Drosophila, protein localization, laser ablation, and genetic interaction studies indicate that the cytohesin Steppke reduces tissue tension by inhibiting actomyosin activity at adherens junctions. Without Steppke, embryogenesis fails, with epidermal distortions and tears resulting from myosin misregulation. Remarkably, actomyosin network assembly is necessary and sufficient for local Steppke accumulation, where live imaging shows Steppke recruitment within minutes. This rapid negative feedback loop provides a molecular mechanism for attenuating the main tension generator of animal tissues. Such attenuation relaxes tissues and allows orderly elongation under stress.

Parallel Inhibitory and Excitatory Trigemino-Facial Feedback Circuitry for Reflexive Vibrissa Movement.

  • Bellavance MA
  • Neuron
  • 2017 Aug 2

Literature context:


Abstract:

Animals employ active touch to optimize the acuity of their tactile sensors. Prior experimental results and models lead to the hypothesis that sensory inputs are used in a recurrent manner to tune the position of the sensors. A combination of electrophysiology, intersectional genetic viral labeling and manipulation, and classical tracing allowed us to identify second-order sensorimotor loops that control vibrissa movements by rodents. Facial motoneurons that drive intrinsic muscles to protract the vibrissae receive a short latency inhibitory input, followed by synaptic excitation, from neurons located in the oralis division of the trigeminal sensory complex. In contrast, motoneurons that retract the mystacial pad and indirectly retract the vibrissae receive only excitatory input from interpolaris cells that further project to the thalamus. Silencing this feedback alters retraction. The observed pull-push circuit at the lowest-level sensorimotor loop provides a mechanism for the rapid modulation of vibrissa touch during exploration of peri-personal space.

Single cell transcriptome profiling of developing chick retinal cells.

  • Laboissonniere LA
  • J. Comp. Neurol.
  • 2017 Aug 15

Literature context:


Abstract:

The vertebrate retina is a specialized photosensitive tissue comprised of six neuronal and one glial cell types, each of which develops in prescribed proportions at overlapping timepoints from a common progenitor pool. While each of these cells has a specific function contributing to proper vision in the mature animal, their differential representation in the retina as well as the presence of distinctive cellular subtypes makes identifying the transcriptomic signatures that lead to each retinal cell's fate determination and development challenging. We have analyzed transcriptomes from individual cells isolated from the chick retina throughout retinogenesis. While we focused our efforts on the retinal ganglion cells, our transcriptomes of developing chick cells also contained representation from multiple retinal cell types, including photoreceptors and interneurons at different stages of development. Most interesting was the identification of transcriptomes from individual mixed lineage progenitor cells in the chick as these cells offer a window into the cell fate decision-making process. Taken together, these data sets will enable us to uncover the most critical genes acting in the steps of cell fate determination and early differentiation of various retinal cell types.

Neurosecretory protein GL stimulates food intake, de novo lipogenesis, and onset of obesity.

  • Iwakoshi-Ukena E
  • Elife
  • 2017 Aug 11

Literature context:


Abstract:

Mechanisms underlying the central regulation of food intake and fat accumulation are not fully understood. We found that neurosecretory protein GL (NPGL), a newly-identified neuropeptide, increased food intake and white adipose tissue (WAT) in rats. NPGL-precursor gene overexpression in the hypothalamus caused increases in food intake, WAT, body mass, and circulating insulin when fed a high calorie diet. Intracerebroventricular administration of NPGL induced de novo lipogenesis in WAT, increased insulin, and it selectively induced carbohydrate intake. Neutralizing antibody administration decreased the size of lipid droplets in WAT. Npgl mRNA expression was upregulated by fasting and low insulin levels. Additionally, NPGL-producing cells were responsive to insulin. These results point to NPGL as a novel neuronal regulator that drives food intake and fat deposition through de novo lipogenesis and acts to maintain steady-state fat level in concert with insulin. Dysregulation of NPGL may be a root cause of obesity.

Left Habenular Activity Attenuates Fear Responses in Larval Zebrafish.

  • Duboué ER
  • Curr. Biol.
  • 2017 Jul 24

Literature context:


Abstract:

Fear responses are defensive states that ensure survival of an organism in the presence of a threat. Perception of an aversive cue causes changes in behavior and physiology, such as freezing and elevated cortisol, followed by a return to the baseline state when the threat is evaded [1]. Neural systems that elicit fear behaviors include the amygdala, hippocampus, and medial prefrontal cortex. However, aside from a few examples, little is known about brain regions that promote recovery from an aversive event [2]. Previous studies had implicated the dorsal habenular nuclei in regulating fear responses and boldness in zebrafish [3-7]. We now show, through perturbation of its inherent left-right (L-R) asymmetry at larval stages, that the dorsal habenulo-interpeduncular (dHb-IPN) pathway expedites the return of locomotor activity following an unexpected negative stimulus, electric shock. Severing habenular efferents to the IPN, or only those from the left dHb, prolongs the freezing behavior that follows shock. Individuals with a symmetric, right-isomerized dHb also exhibit increased freezing. In contrast, larvae that have a symmetric, left-isomerized dHb, or in which just the left dHb-IPN projection is optogenetically activated, rapidly resume swimming post shock. In vivo calcium imaging reveals a neuronal subset, predominantly in the left dHb, whose activation is correlated with resumption of swimming. The results demonstrate functional specialization of the left dHb-IPN pathway in attenuating the response to fear.

Funding information:
  • NICHD NIH HHS - R01 HD042215()

Light-Dependent Regulation of Sleep and Wake States by Prokineticin 2 in Zebrafish.

  • Chen S
  • Neuron
  • 2017 Jul 5

Literature context:


Abstract:

Light affects sleep and wake behaviors by providing an indirect cue that entrains circadian rhythms and also by inducing a direct and rapid regulation of behavior. While circadian entrainment by light is well characterized at the molecular level, mechanisms that underlie the direct effect of light on behavior are largely unknown. In zebrafish, a diurnal vertebrate, we found that both overexpression and mutation of the neuropeptide prokineticin 2 (Prok2) affect sleep and wake behaviors in a light-dependent but circadian-independent manner. In light, Prok2 overexpression increases sleep and induces expression of galanin (galn), a hypothalamic sleep-inducing peptide. We also found that light-dependent, Prok2-induced sedation requires prokineticin receptor 2 (prokr2) and is strongly suppressed in galn mutants. These results suggest that Prok2 antagonizes the direct wake-promoting effect of light in zebrafish, in part through the induction of galn expression in the hypothalamus.

A subset of ipRGCs regulates both maturation of the circadian clock and segregation of retinogeniculate projections in mice.

  • Chew KS
  • Elife
  • 2017 Jun 15

Literature context:


Abstract:

The visual system consists of two major subsystems, image-forming circuits that drive conscious vision and non-image-forming circuits for behaviors such as circadian photoentrainment. While historically considered non-overlapping, recent evidence has uncovered crosstalk between these subsystems. Here, we investigated shared developmental mechanisms. We revealed an unprecedented role for light in the maturation of the circadian clock and discovered that intrinsically photosensitive retinal ganglion cells (ipRGCs) are critical for this refinement process. In addition, ipRGCs regulate retinal waves independent of light, and developmental ablation of a subset of ipRGCs disrupts eye-specific segregation of retinogeniculate projections. Specifically, a subset of ipRGCs, comprising ~200 cells and which project intraretinally and to circadian centers in the brain, are sufficient to mediate both of these developmental processes. Thus, this subset of ipRGCs constitute a shared node in the neural networks that mediate light-dependent maturation of the circadian clock and light-independent refinement of retinogeniculate projections.

Funding information:
  • NEI NIH HHS - F32 EY020108()
  • NEI NIH HHS - R01 EY017137()
  • NEI NIH HHS - R01 EY019053()
  • NEI NIH HHS - R15 EY026255()
  • NHLBI NIH HHS - R01 HL089742()
  • NIDCD NIH HHS - R01 DC007395()
  • NIGMS NIH HHS - R01 GM076430()
  • NIGMS NIH HHS - R01 GM104991()

Storage of neural histamine and histaminergic neurotransmission is VMAT2 dependent in the zebrafish.

  • Puttonen HAJ
  • Sci Rep
  • 2017 Jun 8

Literature context:


Abstract:

Monoaminergic neurotransmission is greatly dependent on the function of the vesicular monoamine transporter VMAT2, which is responsible for loading monoamines into secretory vesicles. The role of VMAT2 in histaminergic neurotransmission is poorly understood. We studied the structure and function of the histaminergic system in larval zebrafish following inhibition of VMAT2 function by reserpine. We found that reserpine treatment greatly reduced histamine immunoreactivity in neurons and an almost total disappearance of histamine-containing nerve fibers in the dorsal telencephalon and habenula, the most densely innervated targets of the hypothalamic histamine neurons. The reserpine treated larvae had an impaired histamine-dependent dark-induced flash response seen during the first second after onset of darkness, implying that function of the histaminergic network is VMAT2 dependent. Levels of histamine and other monoamines were decreased in reserpine treated animals. This study provides conclusive evidence of the relevance of VMAT2 in histaminergic neurotransmission, further implying that the storage and release mechanism of neural histamine is comparable to that of other monoamines. Our results also reveal potential new insights about the roles of monoaminergic neurotransmitters in the regulation of locomotion increase during adaptation to darkness.

Neurochemistry of neurons in the ventrolateral medulla activated by hypotension: Are the same neurons activated by glucoprivation?

  • Parker LM
  • J. Comp. Neurol.
  • 2017 Jun 15

Literature context:


Abstract:

Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed.

A Brain-Region-Specific Neural Pathway Regulating Germinal Matrix Angiogenesis.

  • Ma S
  • Dev. Cell
  • 2017 May 22

Literature context:


Abstract:

Intimate communication between neural and vascular cells is critical for normal brain development and function. Germinal matrix (GM), a key primordium for the brain reward circuitry, is unique among brain regions for its distinct pace of angiogenesis and selective vulnerability to hemorrhage during development. A major neonatal condition, GM hemorrhage can lead to cerebral palsy, hydrocephalus, and mental retardation. Here we identify a brain-region-specific neural progenitor-based signaling pathway dedicated to regulating GM vessel development. This pathway consists of cell-surface sphingosine-1-phosphate receptors, an intracellular cascade including Gα co-factor Ric8a and p38 MAPK, and target gene integrin β8, which in turn regulates vascular TGF-β signaling. These findings provide insights into region-specific specialization of neurovascular communication, with special implications for deciphering potent early-life endocrine, as well as potential gut microbiota impacts on brain reward circuitry. They also identify tissue-specific molecular targets for GM hemorrhage intervention.

Funding information:
  • NINDS NIH HHS - R01 NS076729()

Acclimation of Oxygenic Photosynthesis to Iron Starvation Is Controlled by the sRNA IsaR1.

  • Georg J
  • Curr. Biol.
  • 2017 May 22

Literature context:


Abstract:

Oxygenic photosynthesis crucially depends on proteins that possess Fe2+ or Fe/S complexes as co-factors or prosthetic groups. Here, we show that the small regulatory RNA (sRNA) IsaR1 (Iron-Stress-Activated RNA 1) plays a pivotal role in acclimation to low-iron conditions. The IsaR1 regulon consists of more than 15 direct targets, including Fe2+-containing proteins involved in photosynthetic electron transfer, detoxification of anion radicals, citrate cycle, and tetrapyrrole biogenesis. IsaR1 is essential for maintaining physiological levels of Fe/S cluster biogenesis proteins during iron deprivation. Consequently, IsaR1 affects the acclimation of the photosynthetic apparatus to iron starvation at three levels: (1) directly, via posttranscriptional repression of gene expression; (2) indirectly, via suppression of pigment; and (3) Fe/S cluster biosynthesis. Homologs of IsaR1 are widely conserved throughout the cyanobacterial phylum. We conclude that IsaR1 is a critically important riboregulator. These findings provide a new perspective for understanding the regulation of iron homeostasis in photosynthetic organisms.

An Intrinsic Epigenetic Barrier for Functional Axon Regeneration.

  • Weng YL
  • Neuron
  • 2017 Apr 19

Literature context:


Abstract:

Mature neurons in the adult peripheral nervous system can effectively switch from a dormant state with little axonal growth to robust axon regeneration upon injury. The mechanisms by which injury unlocks mature neurons' intrinsic axonal growth competence are not well understood. Here, we show that peripheral sciatic nerve lesion in adult mice leads to elevated levels of Tet3 and 5-hydroxylmethylcytosine in dorsal root ganglion (DRG) neurons. Functionally, Tet3 is required for robust axon regeneration of DRG neurons and behavioral recovery. Mechanistically, peripheral nerve injury induces DNA demethylation and upregulation of multiple regeneration-associated genes in a Tet3- and thymine DNA glycosylase-dependent fashion in DRG neurons. In addition, Pten deletion-induced axon regeneration of retinal ganglion neurons in the adult CNS is attenuated upon Tet1 knockdown. Together, our study suggests an epigenetic barrier that can be removed by active DNA demethylation to permit axon regeneration in the adult mammalian nervous system.

Funding information:
  • NIGMS NIH HHS - T32 GM007814()

Regulatory Role of RNA Chaperone TDP-43 for RNA Misfolding and Repeat-Associated Translation in SCA31.

  • Ishiguro T
  • Neuron
  • 2017 Apr 5

Literature context:


Abstract:

Microsatellite expansion disorders are pathologically characterized by RNA foci formation and repeat-associated non-AUG (RAN) translation. However, their underlying pathomechanisms and regulation of RAN translation remain unknown. We report that expression of expanded UGGAA (UGGAAexp) repeats, responsible for spinocerebellar ataxia type 31 (SCA31) in Drosophila, causes neurodegeneration accompanied by accumulation of UGGAAexp RNA foci and translation of repeat-associated pentapeptide repeat (PPR) proteins, consistent with observations in SCA31 patient brains. We revealed that motor-neuron disease (MND)-linked RNA-binding proteins (RBPs), TDP-43, FUS, and hnRNPA2B1, bind to and induce structural alteration of UGGAAexp. These RBPs suppress UGGAAexp-mediated toxicity in Drosophila by functioning as RNA chaperones for proper UGGAAexp folding and regulation of PPR translation. Furthermore, nontoxic short UGGAA repeat RNA suppressed mutated RBP aggregation and toxicity in MND Drosophila models. Thus, functional crosstalk of the RNA/RBP network regulates their own quality and balance, suggesting convergence of pathomechanisms in microsatellite expansion disorders and RBP proteinopathies.

Automated deep-phenotyping of the vertebrate brain.

  • Allalou A
  • Elife
  • 2017 Apr 13

Literature context:


Abstract:

Here, we describe an automated platform suitable for large-scale deep-phenotyping of zebrafish mutant lines, which uses optical projection tomography to rapidly image brain-specific gene expression patterns in 3D at cellular resolution. Registration algorithms and correlation analysis are then used to compare 3D expression patterns, to automatically detect all statistically significant alterations in mutants, and to map them onto a brain atlas. Automated deep-phenotyping of a mutation in the master transcriptional regulator fezf2 not only detects all known phenotypes but also uncovers important novel neural deficits that were overlooked in previous studies. In the telencephalon, we show for the first time that fezf2 mutant zebrafish have significant patterning deficits, particularly in glutamatergic populations. Our findings reveal unexpected parallels between fezf2 function in zebrafish and mice, where mutations cause deficits in glutamatergic neurons of the telencephalon-derived neocortex.

Funding information:
  • NINDS NIH HHS - DP1 NS082101()

MicroRNAs Establish Uniform Traits during the Architecture of Vertebrate Embryos.

  • Kasper DM
  • Dev. Cell
  • 2017 Mar 27

Literature context:


Abstract:

Proper functioning of an organism requires cells and tissues to behave in uniform, well-organized ways. How this optimum of phenotypes is achieved during the development of vertebrates is unclear. Here, we carried out a multi-faceted and single-cell resolution screen of zebrafish embryonic blood vessels upon mutagenesis of single and multi-gene microRNA (miRNA) families. We found that embryos lacking particular miRNA-dependent signaling pathways develop a vascular trait similar to wild-type, but with a profound increase in phenotypic heterogeneity. Aberrant trait variance in miRNA mutant embryos uniquely sensitizes their vascular system to environmental perturbations. We discovered a previously unrecognized role for specific vertebrate miRNAs to protect tissue development against phenotypic variability. This discovery marks an important advance in our comprehension of how miRNAs function in the development of higher organisms.

Funding information:
  • NHLBI NIH HHS - F32 HL132475()
  • NHLBI NIH HHS - R01 HL130246()
  • NHLBI NIH HHS - R56 HL123998()

Planarian Epidermal Stem Cells Respond to Positional Cues to Promote Cell-Type Diversity.

  • Wurtzel O
  • Dev. Cell
  • 2017 Mar 13

Literature context:


Abstract:

Successful regeneration requires that progenitors of different lineages form the appropriate missing cell types. However, simply generating lineages is not enough. Cells produced by a particular lineage often have distinct functions depending on their position within the organism. How this occurs in regeneration is largely unexplored. In planarian regeneration, new cells arise from a proliferative cell population (neoblasts). We used the planarian epidermal lineage to study how the location of adult progenitor cells results in their acquisition of distinct functional identities. Single-cell RNA sequencing of epidermal progenitors revealed the emergence of distinct spatial identities as early in the lineage as the epidermal neoblasts, with further pre-patterning occurring in their post-mitotic migratory progeny. Establishment of dorsal-ventral epidermal identities and functions, in response to BMP signaling, required neoblasts. Our work identified positional signals that activate regionalized transcriptional programs in the stem cell population and subsequently promote cell-type diversity in the epidermis.

Funding information:
  • NIGMS NIH HHS - R01 GM080639()

Identification of novel candidate regulators of retinotectal map formation through transcriptional profiling of the chick optic tectum.

  • Kukreja S
  • J. Comp. Neurol.
  • 2017 Feb 15

Literature context:


Abstract:

Information from the retina is carried along the visual pathway with accuracy and spatial conservation as a result of topographically mapped axonal connections. The optic tectum in the midbrain is the primary region to which retinal ganglion cells project their axons in the chick. The two primary axes of the retina project independently onto the tectum using different sets of guidance cues to give rise to the retinotectal map. Specificity of the map is determined by attractive or repulsive interactions between molecular tags that are distributed in gradients in the retina and the tectum. Despite several studies, knowledge of the retinotectal guidance molecules is far from being complete. We screened for all molecules that are expressed differentially along the anterior-posterior and medial-lateral axes of the chick tectum using microarray based transcriptional profiling and identified several novel candidate retinotectal guidance molecules. Two such genes, encoding Wnt5a and Raldh2, the synthesizing enzymes for retinoic acid, were further analyzed for their function as putative regulators of retinotectal map formation. Wnt5a and retinoic acid were found to exhibit differential effects on the growth of axons from retinal explants derived from different quadrants of the retina. This screen also yielded a large number of genes expressed in a lamina-specific manner in the tectum, which may have other roles in tectal development. J. Comp. Neurol. 525:459-477, 2017. © 2016 Wiley Periodicals, Inc.

Funding information:
  • NIAID NIH HHS - HHSN272200900047C(United States)

Localization of glutamatergic, GABAergic, and cholinergic neurons in the brain of the African cichlid fish, Astatotilapia burtoni.

  • Maruska KP
  • J. Comp. Neurol.
  • 2017 Feb 15

Literature context:


Abstract:

Neural communication depends on release and reception of different neurotransmitters within complex circuits that ultimately mediate basic biological functions. We mapped the distribution of glutamatergic, GABAergic, and cholinergic neurons in the brain of the African cichlid fish Astatotilapia burtoni using in situ hybridization to label vesicular glutamate transporters (vglut1, vglut2.1, vglut3), glutamate decarboxylases (gad1, gad2), and choline acetyltransferase (chat). Cells expressing the glutamatergic markers vgluts 1-3 show primarily nonoverlapping distribution patterns, with the most widespread expression observed for vglut2.1, and more restricted expression of vglut1 and vglut3. vglut1 is prominent in granular layers of the cerebellum, habenula, preglomerular nuclei, and several other diencephalic, mesencephalic, and rhombencephalic regions. vglut2.1 is widely expressed in many nuclei from the olfactory bulbs to the hindbrain, while vglut3 is restricted to the hypothalamus and hindbrain. GABAergic cells show largely overlapping gad1 and gad2 expression in most brain regions. GABAergic expression dominates nuclei of the subpallial ventral telencephalon, while glutamatergic expression dominates nuclei of the pallial dorsal telencephalon. chat-expressing cells are prominent in motor cranial nerve nuclei, and some scattered cells lie in the preoptic area and ventral part of the ventral telencephalon. A localization summary of these markers within regions of the conserved social decision-making network reveals a predominance of either GABAergic or glutamatergic cells within individual nuclei. The neurotransmitter distributions described here in the brain of a single fish species provide an important resource for identification of brain nuclei in other fishes, as well as future comparative studies on circuit organization and function. J. Comp. Neurol. 525:610-638, 2017. © 2016 Wiley Periodicals, Inc.

Funding information:
  • NINDS NIH HHS - 2 R01 NS029467-16A2(United States)

Antagonistic Self-Organizing Patterning Systems Control Maintenance and Regeneration of the Anteroposterior Axis in Planarians.

  • Stückemann T
  • Dev. Cell
  • 2017 Feb 6

Literature context:


Abstract:

Planarian flatworms maintain their body plan in the face of constant internal turnover and can regenerate from arbitrary tissue fragments. Both phenomena require self-maintaining and self-organizing patterning mechanisms, the molecular mechanisms of which remain poorly understood. We show that a morphogenic gradient of canonical Wnt signaling patterns gene expression along the planarian anteroposterior (A/P) axis. Our results demonstrate that gradient formation likely occurs autonomously in the tail and that an autoregulatory module of Wnt-mediated Wnt expression both shapes the gradient at steady state and governs its re-establishment during regeneration. Functional antagonism between the tail Wnt gradient and an unknown head patterning system further determines the spatial proportions of the planarian A/P axis and mediates mutually exclusive molecular fate choices during regeneration. Overall, our results suggest that the planarian A/P axis is patterned by self-organizing patterning systems deployed from either end that are functionally coupled by mutual antagonism.

Molecular Diversity of Midbrain Development in Mouse, Human, and Stem Cells.

  • La Manno G
  • Cell
  • 2016 Oct 6

Literature context:


Abstract:

Understanding human embryonic ventral midbrain is of major interest for Parkinson's disease. However, the cell types, their gene expression dynamics, and their relationship to commonly used rodent models remain to be defined. We performed single-cell RNA sequencing to examine ventral midbrain development in human and mouse. We found 25 molecularly defined human cell types, including five subtypes of radial glia-like cells and four progenitors. In the mouse, two mature fetal dopaminergic neuron subtypes diversified into five adult classes during postnatal development. Cell types and gene expression were generally conserved across species, but with clear differences in cell proliferation, developmental timing, and dopaminergic neuron development. Additionally, we developed a method to quantitatively assess the fidelity of dopaminergic neurons derived from human pluripotent stem cells, at a single-cell level. Thus, our study provides insight into the molecular programs controlling human midbrain development and provides a foundation for the development of cell replacement therapies.

Expression of homeobox genes in the mouse olfactory epithelium.

  • Parrilla M
  • J. Comp. Neurol.
  • 2016 Oct 1

Literature context:


Abstract:

Homeobox genes constitute a large family of genes widely studied because of their role in the establishment of the body pattern. However, they are also involved in many other events during development and adulthood. The main olfactory epithelium (MOE) is an excellent model to study neurogenesis in the adult nervous system. Analyses of homeobox genes during development show that some of these genes are involved in the formation and establishment of cell diversity in the MOE. Moreover, the mechanisms of expression of odorant receptors (ORs) constitute one of the biggest enigmas in the field. Analyses of OR promoters revealed the presence of homeodomain binding sites in their sequences. Here we characterize the expression patterns of a set of 49 homeobox genes in the MOE with in situ hybridization. We found that seven of them (Dlx3, Dlx5, Dlx6, Msx1, Meis1, Isl1, and Pitx1) are zonally expressed. The homeobox gene Emx1 is expressed in three guanylate cyclase(+) populations, two located in the MOE and the third one in an olfactory subsystem known as Grüneberg ganglion located at the entrance of the nasal cavity. The homeobox gene Tshz1 is expressed in a unique patchy pattern across the MOE. Our findings provide new insights to guide functional studies that aim to understand the complexity of transcription factor expression and gene regulation in the MOE. J. Comp. Neurol. 524:2713-2739, 2016. © 2016 Wiley Periodicals, Inc.

Des-Acyl Ghrelin and Ghrelin O-Acyltransferase Regulate Hypothalamic-Pituitary-Adrenal Axis Activation and Anxiety in Response to Acute Stress.

  • Stark R
  • Endocrinology
  • 2016 Oct 4

Literature context:


Abstract:

Ghrelin exists in two forms in circulation, acyl ghrelin and des-acyl ghrelin, both of which have distinct and fundamental roles in a variety of physiological functions. Despite this fact, a large proportion of papers simply measure and refer to plasma ghrelin without specifying the acylation status. It is therefore critical to assess and state the acylation status of plasma ghrelin in all studies. In this study we tested the effect of des-acyl ghrelin administration on the hypothalamic-pituitary-adrenal axis and on anxiety-like behavior of mice lacking endogenous ghrelin and in ghrelin-O-acyltransferase (GOAT) knockout (KO) mice that have no endogenous acyl ghrelin and high endogenous des-acyl ghrelin. Our results show des-acyl ghrelin produces an anxiogenic effect under nonstressed conditions, but this switches to an anxiolytic effect under stress. Des-acyl ghrelin influences plasma corticosterone under both nonstressed and stressed conditions, although c-fos activation in the paraventricular nucleus of the hypothalamus is not different. By contrast, GOAT KO are anxious under both nonstressed and stressed conditions, although this is not due to corticosterone release from the adrenals but rather from impaired feedback actions in the paraventricular nucleus of the hypothalamus, as assessed by c-fos activation. These results reveal des-acyl ghrelin treatment and GOAT deletion have differential effects on the hypothalamic-pituitary-adrenal axis and anxiety-like behavior, suggesting that anxiety-like behavior in GOAT KO mice is not due to high plasma des-acyl ghrelin.

Funding information:
  • NCRR NIH HHS - P51RR000165(United States)
  • NICHD NIH HHS - 5R03HD055423-02(United States)

Progressive Loss of Function in a Limb Enhancer during Snake Evolution.

  • Kvon EZ
  • Cell
  • 2016 Oct 20

Literature context:


Abstract:

The evolution of body shape is thought to be tightly coupled to changes in regulatory sequences, but specific molecular events associated with major morphological transitions in vertebrates have remained elusive. We identified snake-specific sequence changes within an otherwise highly conserved long-range limb enhancer of Sonic hedgehog (Shh). Transgenic mouse reporter assays revealed that the in vivo activity pattern of the enhancer is conserved across a wide range of vertebrates, including fish, but not in snakes. Genomic substitution of the mouse enhancer with its human or fish ortholog results in normal limb development. In contrast, replacement with snake orthologs caused severe limb reduction. Synthetic restoration of a single transcription factor binding site lost in the snake lineage reinstated full in vivo function to the snake enhancer. Our results demonstrate changes in a regulatory sequence associated with a major body plan transition and highlight the role of enhancers in morphological evolution. PAPERCLIP.

Microconnectomics of the pretectum and ventral thalamus in the chicken (Gallus gallus).

  • Vega-Zuniga T
  • J. Comp. Neurol.
  • 2016 Aug 1

Literature context:


Abstract:

The avian pretectal and ventrothalamic nuclei, encompassing the griseum tectale (GT), n. lentiformis mesencephali (LM), and n. geniculatus lateralis pars ventralis (GLv), are prominent retinorecipient structures related to optic flow operations and visuomotor control. Hence, a close coordination of these neural circuits is to be expected. Yet the connectivity among these nuclei is poorly known. Here, using intracellular labeling and in situ hybridization, we investigated the detailed morphology, connectivity, and neurochemical identity of neurons in these nuclei. Two different cell types exist in the GT: one that generates an axonal projection to the optic tectum (TeO), LM, GLv, and n. intercalatus thalami (ICT), and a second population that only projects to the LM and GLv. In situ hybridization revealed that most neurons in the GT express the vesicular glutamate transporter (VGluT2) mRNA, indicating a glutamatergic identity. In the LM, three morphological cell types were defined, two of which project axons towards dorsal targets. The LM neurons showed strong VGluT2 expression. Finally, the cells located in the GLv project to the TeO, LM, GT, n. principalis precommisuralis (PPC), and ICT. All neurons in the GLv showed strong expression of the vesicular inhibitory amino acid transporter (VIAAT) mRNA, suggesting a GABAergic identity. Our results show that the pretectal and ventrothalamic nuclei are highly interconnected, especially by glutamatergic and GABAergic neurons from the GT and GLv, respectively. This complex morphology and connectivity might be required to organize orienting visuomotor behaviors and coordinate the specific optic flow patterns that they induce. J. Comp. Neurol. 524:2208-2229, 2016. © 2015 Wiley Periodicals, Inc.

Ancient origin of lubricated joints in bony vertebrates.

  • Askary A
  • Elife
  • 2016 Jul 19

Literature context:


Abstract:

Synovial joints are the lubricated connections between the bones of our body that are commonly affected in arthritis. It is assumed that synovial joints first evolved as vertebrates came to land, with ray-finned fishes lacking lubricated joints. Here, we examine the expression and function of a critical lubricating protein of mammalian synovial joints, Prg4/Lubricin, in diverse ray-finned fishes. We find that Prg4 homologs are specifically enriched at the jaw and pectoral fin joints of zebrafish, stickleback, and gar, with genetic deletion of the zebrafish prg4b gene resulting in the same age-related degeneration of joints as seen in lubricin-deficient mice and humans. Our data support lubricated synovial joints evolving much earlier than currently accepted, at least in the common ancestor of all bony vertebrates. Establishment of the first arthritis model in the highly regenerative zebrafish will offer unique opportunities to understand the aetiology and possible treatment of synovial joint disease.

Somatostatin 2a receptors are not expressed on functionally identified respiratory neurons in the ventral respiratory column of the rat.

  • Le S
  • J. Comp. Neurol.
  • 2016 May 1

Literature context:


Abstract:

Microinjection of somatostatin (SST) causes site-specific effects on respiratory phase transition, frequency, and amplitude when microinjected into the ventrolateral medulla (VLM) of the anesthetized rat, suggesting selective expression of SST receptors on different functional classes of respiratory neurons. Of the six subtypes of SST receptor, somatostatin 2a (sst2a ) is the most prevalent in the VLM, and other investigators have suggested that glutamatergic neurons in the preBötzinger Complex (preBötC) that coexpress neurokinin-1 receptor (NK1R), SST, and sst2a are critical for the generation of respiratory rhythm. However, quantitative data describing the distribution of sst2a in respiratory compartments other than preBötC, or on functionally identified respiratory neurons, is absent. Here we examine the medullary expression of sst2a with particular reference to glycinergic/expiratory neurons in the Bötzinger Complex (BötC) and NK1R-immunoreactive/inspiratory neurons in the preBötC. We found robust sst2a expression at all rostrocaudal levels of the VLM, including a large proportion of catecholaminergic neurons, but no colocalization of sst2a and glycine transporter 2 mRNA in the BötC. In the preBötC 54% of sst2a -immunoreactive neurons were also positive for NK1R. sst2a was not observed in any of 52 dye-labeled respiratory interneurons, including seven BötC expiratory-decrementing and 11 preBötC preinspiratory neurons. We conclude that sst2a is not expressed on BötC respiratory neurons and that phasic respiratory activity is a poor predictor of sst2a expression in the preBötC. Therefore, sst2a is unlikely to underlie responses to BötC SST injection, and is sparse or absent on respiratory neurons identified by classical functional criteria. J. Comp. Neurol. 524:1384-1398, 2016. © 2015 Wiley Periodicals, Inc.

Funding information:
  • NINDS NIH HHS - F31NS077750(United States)

Somatostatin in the rat rostral ventrolateral medulla: Origins and mechanism of action.

  • Bou Farah L
  • J. Comp. Neurol.
  • 2016 Feb 1

Literature context:


Abstract:

Somatostatin (SST) or agonists of the SST-2 receptor (sst2 ) in the rostral ventrolateral medulla (RVLM) lower sympathetic nerve activity, arterial pressure, and heart rate, or when administered within the Bötzinger region, evoke apneusis. Our aims were to describe the mechanisms responsible for the sympathoinhibitory effects of SST on bulbospinal neurons and to identify likely sources of RVLM SST release. Patch clamp recordings were made from bulbospinal RVLM neurons (n = 31) in brainstem slices prepared from juvenile rat pups. Overall, 58% of neurons responded to SST, displaying an increase in conductance that reversed at -93 mV, indicative of an inwardly rectifying potassium channel (GIRK) mechanism. Blockade of sst2 abolished this effect, but application of tetrodotoxin did not, indicating that the SST effect is independent of presynaptic activity. Fourteen bulbospinal RVLM neurons were recovered for immunohistochemistry; nine were SST-insensitive and did not express sst2a . Three out of five responsive neurons were sst2a -immunoreactive. Neurons that contained preprosomatostatin mRNA and cholera-toxin-B retrogradely transported from the RVLM were detected in: paratrigeminal nucleus, lateral parabrachial nucleus, Kölliker-Fuse nucleus, ventrolateral periaqueductal gray area, central nucleus of the amygdala, sublenticular extended amygdala, interstitial nucleus of the posterior limb of the anterior commissure nucleus, and bed nucleus of the stria terminalis. Thus, those brain regions are putative sources of endogenous SST release that, when activated, may evoke sympathoinhibitory effects via interactions with subsets of sympathetic premotor neurons that express sst2 .

The Role of Sonic Hedgehog in the Specification of Human Cortical Progenitors In Vitro.

  • Radonjić NV
  • Cereb. Cortex
  • 2016 Jan 15

Literature context:


Abstract:

Impaired sonic hedgehog (Shh) signaling is involved in the pathology of cortical formation found in neuropsychiatric disorders. However, its role in the specification of human cortical progenitors is not known. Here, we report that Shh is expressed in the human developing cortex at mid-gestation by radial glia cells (RGCs) and cortical neurons. We used RGC cultures, established from the dorsal (cortical) telencephalon of human brain at mid-gestation to study the effect of Shh signaling. Cortical RGCs in vitro maintained their regional characteristics, expressed components of Shh signaling, and differentiated into Nkx2.1, Lhx6, and calretinin-positive (CalR(+)) cells, potential cortical interneuron progenitors. Treatment with exogenous Shh increased the pool of Nkx2.1(+) progenitors, decreased Lhx6 expression, and suppressed the generation of CalR(+) cells. The blockade of endogenous Shh signaling increased the number of CalR(+) cells, but did not affect Nkx2.1 expression, implying the existence of parallel Shh-independent pathways for cortical Nkx2.1 regulation. These results support the idea that, during human brain development, Shh plays an important role in the specification of cortical progenitors. Since direct functional studies in humans are limited, the in vitro system that we established here could be of great interest for modeling the development of human cortical progenitors.

Differential expression of id genes and their potential regulator znf238 in zebrafish adult neural progenitor cells and neurons suggests distinct functions in adult neurogenesis.

  • Diotel N
  • Gene Expr. Patterns
  • 2015 Nov 26

Literature context:


Abstract:

Teleost fish display a remarkable ability to generate new neurons and to repair brain lesions during adulthood. They are, therefore, a very popular model to investigate the molecular mechanisms of constitutive and induced neurogenesis in adult vertebrates. In this study, we investigated the expression patterns of inhibitor of DNA binding (id) genes and of their potential transcriptional repressor, znf238, in the whole brain of adult zebrafish. We show that while id1 is exclusively expressed in ventricular cells in the whole brain, id2a, id3 and id4 genes are expressed in broader areas. Interestingly, znf238 was also detected in these regions, its expression overlapping with id2a, id3 and id4 expression. Further detailed characterization of the id-expressing cells demonstrated that (a) id1 is expressed in type 1 and type 2 neural progenitors as previously published, (b) id2a in type 1, 2 and 3 neural progenitors, (c) id3 in type 3 neural progenitors and (d) id4 in postmitotic neurons. Our data provide a detailed map of id and znf238 expression in the brain of adult zebrafish, supplying a framework for studies of id genes function during adult neurogenesis and brain regeneration in the zebrafish.

Funding information:
  • NIDDK NIH HHS - R37 DK050107(United States)
  • NINDS NIH HHS - R03 NS071442(United States)

Hippocampal Synaptic Expansion Induced by Spatial Experience in Rats Correlates with Improved Information Processing in the Hippocampus.

  • Carasatorre M
  • PLoS ONE
  • 2015 Aug 6

Literature context:


Abstract:

Spatial water maze (WM) overtraining induces hippocampal mossy fiber (MF) expansion, and it has been suggested that spatial pattern separation depends on the MF pathway. We hypothesized that WM experience inducing MF expansion in rats would improve spatial pattern separation in the hippocampal network. We first tested this by using the the delayed non-matching to place task (DNMP), in animals that had been previously trained on the water maze (WM) and found that these animals, as well as animals treated as swim controls (SC), performed better than home cage control animals the DNMP task. The "catFISH" imaging method provided neurophysiological evidence that hippocampal pattern separation improved in animals treated as SC, and this improvement was even clearer in animals that experienced the WM training. Moreover, these behavioral treatments also enhance network reliability and improve partial pattern separation in CA1 and pattern completion in CA3. By measuring the area occupied by synaptophysin staining in both the stratum oriens and the stratun lucidum of the distal CA3, we found evidence of structural synaptic plasticity that likely includes MF expansion. Finally, the measures of hippocampal network coding obtained with catFISH correlate significantly with the increased density of synaptophysin staining, strongly suggesting that structural synaptic plasticity in the hippocampus induced by the WM and SC experience is related to the improvement of spatial information processing in the hippocampus.

Funding information:
  • NIDA NIH HHS - R01 DA033150(United States)
  • NIMH NIH HHS - MH101188(United States)

Deletion of the amyloid precursor-like protein 1 (APLP1) enhances excitatory synaptic transmission, reduces network inhibition but does not impair synaptic plasticity in the mouse dentate gyrus.

  • Vnencak M
  • J. Comp. Neurol.
  • 2015 Aug 1

Literature context:


Abstract:

Amyloid precursor-like protein 1 (APLP1) is a transmembrane synaptic protein belonging to the amyloid precursor protein (APP) gene family. Although the role of this gene family-in particular of APP-has been intensely studied in the context of Alzheimer's disease, the physiological roles of its family members remain poorly understood. In particular, the function of APLP1, which is predominantly expressed in the nervous system, has remained enigmatic. Since APP has been implicated in synaptic plasticity, we wondered whether APLP1 could play a similar role. First, using in situ hybridization and laser microdissection combined with reverse transcription-quantitative polymerase chain reaction (PCR) we observed that Aplp1 mRNA is highly expressed in dentate granule cells. Having this examined, we studied synaptic plasticity at the perforant path-granule cell synapses in the dentate gyrus of APLP1-deficient mice in vivo. Analysis of field excitatory postsynaptic potentials evoked by stimulation of perforant path fibers revealed increased excitatory transmission in APLP1-deficient mice. Moreover, we observed decreased paired-pulse inhibition of population spikes indicating a decrease in network inhibition upon deletion of APLP1. In contrast, short-term presynaptic plasticity (STP) as well as long-term synaptic plasticity (LTP) was unchanged in the absence of APLP1. Based on these results we conclude that APLP1 deficiency on its own does not lead to defects in synaptic plasticity, but affects synaptic transmission and network inhibition in the dentate gyrus.

Comprehensive expression map of transcription regulators in the adult zebrafish telencephalon reveals distinct neurogenic niches.

  • Diotel N
  • J. Comp. Neurol.
  • 2015 Jun 1

Literature context:


Abstract:

The zebrafish has become a model to study adult vertebrate neurogenesis. In particular, the adult telencephalon has been an intensely studied structure in the zebrafish brain. Differential expression of transcriptional regulators (TRs) is a key feature of development and tissue homeostasis. Here we report an expression map of 1,202 TR genes in the telencephalon of adult zebrafish. Our results are summarized in a database with search and clustering functions to identify genes expressed in particular regions of the telencephalon. We classified 562 genes into 13 distinct patterns, including genes expressed in the proliferative zone. The remaining 640 genes displayed unique and complex patterns of expression and could thus not be grouped into distinct classes. The neurogenic ventricular regions express overlapping but distinct sets of TR genes, suggesting regional differences in the neurogenic niches in the telencephalon. In summary, the small telencephalon of the zebrafish shows a remarkable complexity in TR gene expression. The adult zebrafish telencephalon has become a model to study neurogenesis. We established the expression pattern of more than 1200 transcription regulators (TR) in the adult telencephalon. The neurogenic regions express overlapping but distinct sets of TR genes suggesting regional differences in the neurogenic potential.

Funding information:
  • European Research Council - 310829(International)

Differential expression of protocadherin-19, protocadherin-17, and cadherin-6 in adult zebrafish brain.

  • Liu Q
  • J. Comp. Neurol.
  • 2015 Jun 15

Literature context:


Abstract:

Cell adhesion molecule cadherins play important roles in both development and maintenance of adult structures. Most studies on cadherin expression have been carried out in developing organisms, but information on cadherin distribution in adult vertebrate brains is limited. In this study we used in situ hybridization to examine mRNA expression of three cadherins, protocadherin-19, protocadherin-17, and cadherin-6 in adult zebrafish brain. Each cadherin exhibits a distinct expression pattern in the fish brain, with protocadherin-19 and protocadherin-17 showing much wider and stronger expression than that of cadherin-6. Both protocadherin-19 and protocadherin-17-expressing cells occur throughout the brain, with strong expression in the ventromedial telencephalon, periventricular regions of the thalamus and anterior hypothalamus, stratum periventriculare of the optic tectum, dorsal tegmental nucleus, granular regions of the cerebellar body and valvula, and superficial layers of the facial and vagal lobes. Numerous sensory structures (e.g., auditory, gustatory, lateral line, olfactory, and visual nuclei) and motor nuclei (e.g., oculomotor, trochlear, trigeminal motor, abducens, and vagal motor nuclei) contain protocadherin-19 and/or protocadherin-17-expressing cell. Expression of these two protocadherins is similar in the ventromedial telencephalon, thalamus, hypothalamus, facial, and vagal lobes, but substantially different in the dorsolateral telencephalon, intermediate layers of the optic tectum, and cerebellar valvula. In contrast to the two protocadherins, cadherin-6 expression is much weaker and limited in the adult fish brain.

The isthmic nuclei providing parallel feedback connections to the avian tectum have different neurochemical identities: Expression of glutamatergic and cholinergic markers in the chick (Gallus gallus).

  • González-Cabrera C
  • J. Comp. Neurol.
  • 2015 Jun 15

Literature context:


Abstract:

Retinal inputs to the optic tectum (TeO) triggered by moving stimuli elicit synchronized feedback signals from two isthmic nuclei: the isthmi parvocelullaris (Ipc) and isthmi semilunaris (SLu). Both of these nuclei send columnar axon terminals back to the same tectal position receiving the retinal input. The feedback signals from the Ipc seem to act as an attentional spotlight by selectively boosting the propagation of retinal inputs from the tectum to higher visual areas. Although Ipc and SLu nuclei are widely considered cholinergic because of their immunoreactivity for choline acetyltransferase (ChAT), contradictory findings, including the expression of the vesicular glutamate transporter 2 (VGluT2) mRNA in Ipc neurons, have raised doubts about the purely cholinergic nature of this nucleus. In this study, in chicks, we revise the neurochemical identity of the isthmic nuclei by using in situ hybridization assays for VGluT2 along with three cholinergic markers: the vesicular acetylcholine transporter (VAChT), the high-affinity choline transporter (CHT1) and ChAT. We found that neurons in the SLu showed strong mRNA expression of all three cholinergic markers, whereas the expression of VAChT mRNA in the Ipc was undetectable in our essays. Instead, Ipc neurons exhibited a strong expression of VGluT2 mRNA. Immunohistochemistry assays showed VGluT2 immunoreactivity in the TeO codistributing with anterogradely labeled Ipc axon-terminal boutons, further supporting a glutamatergic function for the Ipc nucleus. Therefore, our results strongly suggest that, in the chick, whereas the feedback from the SLu to the TeO is indeed cholinergic, the feedback from the Ipc has a marked glutamatergic component.

Funding information:
  • NIDCD NIH HHS - R01 DC012957(United States)

A second corticotropin-releasing hormone gene (CRH2) is conserved across vertebrate classes and expressed in the hindbrain of a basal neopterygian fish, the spotted gar (Lepisosteus oculatus).

  • Grone BP
  • J. Comp. Neurol.
  • 2015 May 1

Literature context:


Abstract:

To investigate the origins of the vertebrate stress-response system, we searched sequenced vertebrate genomes for genes resembling corticotropin-releasing hormone (CRH). We found that vertebrate genomes possess, in addition to CRH, another gene that resembles CRH in sequence and syntenic environment. This paralogous gene was previously identified only in the elephant shark (a holocephalan), but we find it also in marsupials, monotremes, lizards, turtles, birds, and fishes. We examined the relationship of this second vertebrate CRH gene, which we name CRH2, to CRH1 (previously known as CRH) and urocortin1/urotensin1 (UCN1/UTS1) in primitive fishes, teleosts, and tetrapods. The paralogs CRH1 and CRH2 likely evolved via duplication of CRH during a whole-genome duplication early in the vertebrate lineage. CRH2 was subsequently lost in both teleost fishes and eutherian mammals but retained in other lineages. To determine where CRH2 is expressed relative to CRH1 and UTS1, we used in situ hybridization on brain tissue from spotted gar (Lepisosteus oculatus), a neopterygian fish closely related to teleosts. In situ hybridization revealed widespread distribution of both crh1 and uts1 in the brain. Expression of crh2 was restricted to the putative secondary gustatory/secondary visceral nucleus, which also expressed calcitonin-related polypeptide alpha (calca), a marker of parabrachial nucleus in mammals. Thus, the evolutionary history of CRH2 includes restricted expression in the brain, sequence changes, and gene loss, likely reflecting release of selective constraints following whole-genome duplication. The discovery of CRH2 opens many new possibilities for understanding the diverse functions of the CRH family of peptides across vertebrates.

Exorhodopsin and melanopsin systems in the pineal complex and brain at early developmental stages of Atlantic halibut (Hippoglossus hippoglossus).

  • Eilertsen M
  • J. Comp. Neurol.
  • 2014 Dec 15

Literature context:


Abstract:

The complexity of the nonvisual photoreception systems in teleosts has just started to be appreciated, with colocalization of multiple photoreceptor types with unresolved functions. Here we describe an intricate expression pattern of melanopsins in early life stages of the marine flat fish Atlantic halibut (Hippoglossus hippoglossus), a period when the unpigmented brain is directly exposed to environmental photons. We show a refined and extensive expression of melanopsins in the halibut brain already at the time of hatching, long before the eyes are functional. We detect melanopsin in the habenula, suprachiasmatic nucleus, dorsal thalamus, and lateral tubular nucleus of first feeding larvae, suggesting conserved functions of the melanopsins in marine teleosts. The complex expression of melanopsins already at larval stages indicates the importance of nonvisual photoreception early in development. Most strikingly, we detect expression of both exorhodopsin and melanopsin in the pineal complex of halibut larvae. Double-fluorescence labeling showed that two clusters of melanopsin-positive cells are located lateral to the central rosette of exorhodopsin-positive cells. The localization of different photopigments in the pineal complex suggests that two parallel photoreceptor systems may be active. Furthermore, the dispersed melanopsin-positive cells in the spinal cord of halibut larvae at the time of hatching may be primary sensory cells or interneurons representing the first example of dispersed high-order photoreceptor cells. The appearance of nonvisual opsins early in the development of halibut provides an alternative model for studying the evolution and functional significance of nonvisual opsins.

Evolutionarily conserved organization of the dopaminergic system in lamprey: SNc/VTA afferent and efferent connectivity and D2 receptor expression.

  • Pérez-Fernández J
  • J. Comp. Neurol.
  • 2014 Dec 1

Literature context:


Abstract:

The dopaminergic system influences motor behavior, signals reward and novelty, and is an essential component of the basal ganglia in all vertebrates including the lamprey, one of the phylogenetically oldest vertebrates. The intrinsic organization and function of the lamprey basal ganglia is highly conserved. For instance, the direct and indirect pathways are modulated through dopamine D1 and D2 receptors in lamprey and in mammals. The nucleus of the tuberculum posterior, a homologue of the substantia nigra pars compacta (SNc)/ventral tegmental area (VTA) is present in lamprey, but only scarce data exist about its connectivity. Likewise, the D2 receptor is expressed in the striatum, but little is known about its localization in other brain areas. We used in situ hybridization and tracer injections, both in combination with tyrosine hydroxylase immunohistochemistry, to characterize the SNc/VTA efferent and afferent connectivity, and to relate its projection pattern with D2 receptor expression in particular. We show that most features of the dopaminergic system are highly conserved. As in mammals, the direct pallial (cortex in mammals) input and the basal ganglia connectivity with the SNc/VTA are present as part of the evaluation system, as well as input from the tectum as the evolutionary basis for salience/novelty detection. Moreover, the SNc/VTA receives sensory information from the olfactory bulbs, optic tectum, octavolateral area, and dorsal column nucleus, and it innervates, apart from the nigrostriatal pathway, several motor-related areas. This suggests that the dopaminergic system also contributes to the control of different motor centers at the brainstem level.

Funding information:
  • NIMH NIH HHS - R01 MH110404(United States)
  • NINDS NIH HHS - R21 NS081467(United States)

In a nongenomic action, steroid hormone 20-hydroxyecdysone induces phosphorylation of cyclin-dependent kinase 10 to promote gene transcription.

  • Liu W
  • Endocrinology
  • 2014 May 21

Literature context:


Abstract:

The insect steroid hormone 20-hydroxyecdysone (20E) regulates gene transcription via a genomic pathway by forming a transcription complex that binds to DNA with the help of the chaperone proteins, heat shock proteins (Hsps) Hsc70 and Hsp90. However, the nongenomic mechanisms by which 20E regulates gene expression remain unclear. In this study, we found that 20E regulated the phosphorylation of serine/threonine protein kinase cyclin-dependent kinase 10 (CDK10) through a nongenomic pathway to mediate gene transcription in the lepidopteran Helicoverpa armigera. The down-regulation of CDK10 by RNA interference in larvae and the epidermal cell line delayed development and suppressed 20E-induced gene transcription. CDK10 was localized to the nucleus via its KKRR motif, and this nuclear localization and the ATPase motif were necessary for the efficient expression of the 20E-inducible gene. The rapid phosphorylation of CDK10 was induced by 20E, whereas it was repressed by the inhibitors of G-protein-coupled receptors, phospholipase C, and Ca²⁺ channels. Phosphorylated CDK10 exhibited increased interactions with Hsps Hsc70 and Hsp90 and then promoted the interactions between Hsps and ecdysone receptor EcRB1 and the binding of the Hsps-EcRB1 complex to the 20E response element for the regulation of gene transcription. CDK10 depletion suppressed the formation of the Hsps-EcRB1 complex at the hormone receptor 3 promoter. These results suggest that 20E induces CDK10 phosphorylation via a nongenomic pathway to regulate gene transcription in the nucleus.

Funding information:
  • NICHD NIH HHS - HD054691(United States)
  • NINDS NIH HHS - R01 NS057811(United States)

Neurochemical codes of sympathetic preganglionic neurons activated by glucoprivation.

  • Parker LM
  • J. Comp. Neurol.
  • 2013 Aug 15

Literature context:


Abstract:

Glucoprivation or hypoglycemia induces a range of counterregulatory responses, including glucose mobilization, reduced glucose utilization, and de novo glucose synthesis. These responses are mediated in part by the sympathetic nervous system. The aim of this study was to determine the chemical codes of sympathetic preganglionic neurons (SPN) activated by glucoprivation, induced by 2-deoxy-D-glucose (2DG). SPN controlling the adrenal glands and celiac ganglia, which ultimately can innervate the liver and pancreas, were targeted together with the superior cervical ganglia (control). 23.9% ± 1.3% of SPN in the T4-T11 region contained c-Fos immunoreactivity following 2DG; 70.3% ± 1.8% of SPN innervating the adrenal glands and 37.4% ± 3% of SPN innervating celiac ganglia were activated. 14.8% ± 3.5% of SPN (C8-T3) innervating superior cervical ganglia were activated. In the C8-T3 region 55% ± 10% of SPN activated contained PPCART, with only 12% ± 3% expressing PPE mRNA, whereas, in the T4-T11 region, 78% ± 4% contained PPE, with only 6.0% ± 0.6% expressing PPCART mRNA. Thus CART is not involved in glucose mobilization. Two chemically distinct populations of SPN (PPE⁺ 57.4% ± 5%, PPE⁻ ∼40%) were identified to regulate adrenaline release in response to glucoprivation. Multiple chemically distinct SPN populations innervating a specific target could suggest their graded recruitment. The two distinct populations of SPN (PPE⁺ 67.6% ± 9%, PPE⁻ ∼30%) projecting to celiac ganglia activated by glucoprivation could direct pancreatic and hepatic or other counterregulatory responses. Nearly all SPN that expressed PPE mRNA and projected to the adrenal glands or celiac ganglia were activated, suggesting a role for the inhibitory peptide enkephalin in responses evoked by glucoprivation.

Funding information:
  • NIMH NIH HHS - MH092257(United States)

Expression of the ghrelin receptor gene in neurons of the medulla oblongata of the rat.

  • Bron R
  • J. Comp. Neurol.
  • 2013 Aug 15

Literature context:


Abstract:

There is ambiguity concerning the distribution of neurons that express the ghrelin receptor (GHSR) in the medulla oblongata. In the current study we used a sensitive nonradioactive method to investigate GHSR mRNA distribution by in situ hybridization. Strong expression of the GHSR gene was confirmed in neurons of the facial nucleus (FacN, 7), the dorsal vagal complex (DVC), and the semicompact (but not compact) nucleus ambiguus (AmbSC and AmbC). In addition, expression of GHSR was found in other regions, where it had not been described before. GHSR-positive neurons were observed in the gustatory rostral nucleus tractus solitarius and in areas involved in vestibulo-ocular processing (such as the medial vestibular nucleus and the nucleus abducens). GHSR expression was also noted in ventral areas associated with cardiorespiratory control, including the gigantocellular reticular nucleus, the lateral paragigantocellular nucleus, the rostral and caudal ventrolateral medulla, the (pre)-Bötzinger complex, and the rostral and caudal ventrolateral respiratory group. However, GHSR-positive neurons in ventrolateral areas did not express markers for cardiovascular presympathetic vasomotor neurons, respiratory propriobulbar rhythmogenic neurons, or sensory interneurons. GHSR-positive cells were intermingled with catecholamine neurons in the dorsal vagal complex but these populations did not overlap. Thus, the ghrelin receptor occurs in the medulla oblongata in 1) second-order sensory neurons processing gustatory, vestibulo-ocular, and visceral sensation; 2) cholinergic somatomotor neurons of the FacN and autonomic preganglionic neurons of the DMNX and AmbSC; 3) cardiovascular neurons in the DVC, Gi, and LPGi; 4) neurons of as yet unknown function in the ventrolateral medulla.

Brain sources of inhibitory input to the rat rostral ventrolateral medulla.

  • Bowman BR
  • J. Comp. Neurol.
  • 2013 Jan 1

Literature context:


Abstract:

The rostral ventrolateral medulla (RVLM) contains neurons critical for cardiovascular, respiratory, metabolic, and motor control. The activity of these neurons is controlled by inputs from multiple identified brain regions; however, the neurochemistry of these inputs is largely unknown. Gamma-aminobutyric acid (GABA) and enkephalin tonically inhibit neurons within the RVLM. The aim of this study was to identify all brain regions that provide GABAergic or enkephalinergic input to the rat RVLM. Neurons immunoreactive for cholera toxin B (CTB-ir), retrogradely transported from the RVLM, were assessed for expression of glutamic acid decarboxylase (GAD67) or preproenkephalin (PPE) mRNA using in situ hybridization. GAD67 mRNA was expressed in CTB-ir neurons in the following regions: the nucleus of the solitary tract (NTS, 6% of CTB-ir neurons), area postrema (AP, 8%), caudal ventrolateral medulla (17%), midline raphe (40%), ventrolateral periaqueductal gray (VLPAG, 15%), lateral hypothalamic area (LHA, 25%), central nucleus of the amygdala (CeA, 77%), sublenticular extended amygdala (SLEA, 86%), interstitial nucleus of the posterior limb of the anterior commissure (IPAC, 56%), bed nucleus of the stria terminals (BNST, 59%), and medial preoptic area (MPA, 53%). PPE mRNA was expressed in CTB-ir neurons in the following regions: the NTS (14% of CTB-ir neurons), midline raphe (26%), LHA (22%), zona incerta (ZI, 15%), CeA (5%), paraventricular nucleus (PVN, 13%), SLEA (66%), and MPA (26%). Thus, limited brain regions contribute GABAergic and/or enkephalinergic input to the RVLM. Multiple neurochemically distinct pathways originate from these brain regions projecting to the RVLM.

Funding information:
  • Biotechnology and Biological Sciences Research Council - BB/K019988/1(United Kingdom)
  • NINDS NIH HHS - NS-024752(United States)

Brainstem galanin-synthesizing neurons are differentially activated by chemoreceptor stimuli and represent a subpopulation of respiratory neurons.

  • Spirovski D
  • J. Comp. Neurol.
  • 2012 Jan 1

Literature context:


Abstract:

The ventrolateral medulla oblongata (VLM) of the brainstem contains neurochemically heterogeneous neurons that have a critical role in cardiovascular and respiratory regulation. Previous anatomical studies have shown the existence of galanin immunoreactivity in the medulla oblongata, but a detailed characterization is lacking. In this study, we demonstrate three populations of preprogalanin mRNA (PPG)-expressing neurons in the VLM of the adult, male Sprague-Dawley rat: a retrotrapezoid nucleus (RTN) group, a group in the rostral ventral respiratory group (rVRG), and a subpopulation of A1 neurons. PPG(+) neurons express tyrosine hydroxylase (TH) only in the A1 region of the VLM, where approximately 56% of PPG(+) neurons contain TH (79 ± 14; n = 4). PPG(+) neurons do not express vesicular acetylcholine transporter (vAChT) in the VLM (n = 3). However, 33% of PPG(+) neurons contain neurokinin-1 receptor (NK1R) in the rVRG (126 ± 12; n = 12), accounting for ∼28% of all NK1R(+) neurons in the region. Retrogradely transported cholera toxin B injected into the thoracic spinal cord (T1) revealed that bulbospinal PPG(+) neurons are present in the rVRG (n = 3; ∼26% of PPG(+) neurons). PPG(+) neurons in the RTN and locus coeruleus are selectively activated (Fos) following 2 hours of exposure to hypercapnia, but not by hypoxia. Neurons in the A1, nucleus of the solitary tract, and dorsomedial hypothalamus are activated by both chemoreceptor stimuli. The results suggest that PPG(+) neurons represent a population of brainstem neurons that play a critical and differential role in the chemoreflex responses to hypoxia and hypercapnia.

Funding information:
  • Biotechnology and Biological Sciences Research Council - BBE0160651(United Kingdom)
  • NEI NIH HHS - EY11930(United States)

Molecular analysis of neocortical layer structure in the ferret.

  • Rowell JJ
  • J. Comp. Neurol.
  • 2010 Aug 15

Literature context:


Abstract:

Molecular markers that distinguish specific layers of rodent neocortex are increasingly employed to study cortical development and the physiology of cortical circuits. The extent to which these markers represent general features of neocortical cell type identity across mammals, however, is unknown. To assess the conservation of layer markers more broadly, we isolated orthologs for 15 layer-enriched genes in the ferret, a carnivore with a large, gyrencephalic brain, and analyzed their patterns of neocortical gene expression. Our major findings are: 1) Many but not all layer markers tested show similar patterns of layer-specific gene expression between mouse and ferret cortex, supporting the view that layer-specific cell type identity is conserved at a molecular level across mammalian superorders; 2) Our panel of deep layer markers (ER81/ETV1, SULF2, PCP4, FEZF2/ZNF312, CACNA1H, KCNN2/SK2, SYT6, FOXP2, CTGF) provides molecular evidence that the specific stratifications of layers 5 and 6 into 5a, 5b, 6a, and 6b are also conserved between rodents and carnivores; 3) Variations in layer-specific gene expression are more pronounced across areas of ferret cortex than between homologous areas of mouse and ferret cortex; 4) This variation of area gene expression was clearest with the superficial layer markers studied (SERPINE2, MDGA1, CUX1, UNC5D, RORB/NR1F2, EAG2/KCNH5). Most dramatically, the layer 4 markers RORB and EAG2 disclosed a molecular sublamination to ferret visual cortex and demonstrated a molecular dissociation among the so-called agranular areas of the neocortex. Our findings establish molecular markers as a powerful complement to cytoarchitecture for neocortical layer and cell-type comparisons across mammals.

Funding information:
  • NIBIB NIH HHS - R01 EB005034(United States)

The cortistatin gene PSS2 rather than the somatostatin gene PSS1 is strongly expressed in developing avian autonomic neurons.

  • Nishi R
  • J. Comp. Neurol.
  • 2010 Mar 15

Literature context:


Abstract:

Somatostatin and cortistatin are neuromodulators with divergent expression patterns and biological roles. Whereas expression and function of genes encoding somatostatin (PSS1) and the related peptide cortistatin (PSS2) have been studied in detail for the central nervous system (CNS) and immune system, relatively little is known about their expression patterns in the peripheral nervous system (PNS). We compare the expression patterns of PSS1 and PSS2 in chicken embryos. At E14, PSS1 is higher in the CNS versus PNS, whereas PSS2 is higher in the PNS. During early development, PSS1 is transiently expressed in lumbar sympathetic ganglia and is detectable at low levels throughout the development of dorsal root and ciliary ganglia. In contrast, PSS2 expression increases as development progresses in sympathetic and dorsal root ganglia, whereas levels in ciliary ganglia by E8 are more than 100-fold higher than in sympathetic ganglia. Activin, which induces somatostatin-like immunoreactivity in ciliary ganglion neurons in vivo and in vitro, controls PSS2 expression by stabilizing PSS2 but not PSS1 mRNA. We conclude that much of the somatostatin-like immunoreactivity in the developing avian peripheral nervous system is actually cortistatin, the PSS2 product, as opposed to true somatostatin, which is the PSS1 product. The identification of PSS2 as the predominantly expressed somatostatin gene family member in avian autonomic neurons provides a molecular basis for further functional and pharmacological studies.

The mesopontine rostromedial tegmental nucleus: A structure targeted by the lateral habenula that projects to the ventral tegmental area of Tsai and substantia nigra compacta.

  • Jhou TC
  • J. Comp. Neurol.
  • 2009 Apr 20

Literature context:


Abstract:

Prior studies revealed that aversive stimuli and psychostimulant drugs elicit Fos expression in neurons clustered above and behind the interpeduncular nucleus that project strongly to the ventral tegmental area (VTA) and substantia nigra (SN) compacta (C). Other reports suggest that these neurons modulate responses to aversive stimuli. We now designate the region containing them as the "mesopontine rostromedial tegmental nucleus" (RMTg) and report herein on its neuroanatomy. Dense micro-opioid receptor and somatostatin immunoreactivity characterize the RMTg, as do neurons projecting to the VTA/SNC that are enriched in GAD67 mRNA. Strong inputs to the RMTg arise in the lateral habenula (LHb) and, to a lesser extent, the SN. Other inputs come from the frontal cortex, ventral striatopallidum, extended amygdala, septum, preoptic region, lateral, paraventricular and posterior hypothalamus, zona incerta, periaqueductal gray, intermediate layers of the contralateral superior colliculus, dorsal raphe, mesencephalic, pontine and medullary reticular formation, and the following nuclei: parafascicular, supramammillary, mammillary, ventral lateral geniculate, deep mesencephalic, red, pedunculopontine and laterodorsal tegmental, cuneiform, parabrachial, and deep cerebellar. The RMTg has meager outputs to the forebrain, mainly to the ventral pallidum, preoptic-lateral hypothalamic continuum, and midline-intralaminar thalamus, but much heavier outputs to the brainstem, including, most prominently, the VTA/SNC, as noted above, and to medial tegmentum, pedunculopontine and laterodorsal tegmental nuclei, dorsal raphe, and locus ceruleus and subceruleus. The RMTg may integrate multiple forebrain and brainstem inputs in relation to a dominant LHb input. Its outputs to neuromodulatory projection systems likely converge with direct LHb projections to those structures.

Expression and adhesion profiles of SynCAM molecules indicate distinct neuronal functions.

  • Thomas LA
  • J. Comp. Neurol.
  • 2008 Sep 1

Literature context:


Abstract:

Cell-cell interactions through adhesion molecules play key roles in the development of the nervous system. Synaptic cell adhesion molecules (SynCAMs) comprise a group of four immunoglobulin (Ig) superfamily members that mediate adhesion and are prominently expressed in the brain. Although SynCAMs have been implicated in the differentiation of neurons, there has been no comprehensive analysis of their expression patterns. Here we examine the spatiotemporal expression patterns of SynCAMs by using reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunohistological techniques. SynCAMs 1-4 are widely expressed throughout the developing and adult central nervous system. They are prominently expressed in neurons throughout the brain and are present in both excitatory and inhibitory neurons. Investigation of different brain regions in the developing and mature mouse brain indicates that each SynCAM exhibits a distinct spatiotemporal expression pattern. This is observed in all regions analyzed and is particularly notable in the cerebellum, where SynCAMs display highly distinct expression in cerebellar granule and Purkinje cells. These unique expression profiles are complemented by specific heterophilic adhesion patterns of SynCAM family members, as shown by cell overlay experiments. Three prominent interactions are observed, mediated by the extracellular domains of SynCAMs 1/2, 2/4, and 3/4. These expression and adhesion profiles of SynCAMs together with their previously reported functions in synapse organization indicate that SynCAM proteins contribute importantly to the synaptic circuitry of the central nervous system.

Postnatal ontogeny of the transcription factor Lmx1b in the mouse central nervous system.

  • Dai JX
  • J. Comp. Neurol.
  • 2008 Aug 1

Literature context:


Abstract:

The expression profile of Lim homeodomain transcription factor Lmx1b in the mouse brain was investigated at different postnatal stages by immunohistochemistry and in situ hybridization. At postnatal day (P) 7, many Lmx1b-expressing neurons were found in the posterior hypothalamic area, supramammillary nucleus, ventral premammillary nucleus, and subthalamic nucleus. In the midbrain, numerous Lmx1b-expressing neurons were present in the substantia nigra pars compacta and ventral tegmental area. In the hindbrain, Lmx1b-expressing neurons were primarily observed in the raphe nuclei, parabrachial nuclei, principal sensory trigeminal nucleus, nucleus of the solitary tract, and laminae I-II of the medullary dorsal horn as well as spinal dorsal horn. Although expression levels diminished as postnatal life progressed, persistent expression throughout the first year of life was observed in many of these regions. In contrast, Lmx1b was present in a few brain regions (e.g., principal sensory trigeminal nucleus) only in early life with expression expiring by P60. Lmx1b was observed in dopaminergic neurons in the midbrain and serotonergic neurons in the hindbrain, as determined by double labeling with specific markers. In addition, we found that Lmx1b-expressing neurons are not GABAergic, and Lmx1b was colocalized with Tlx3 in the parabrachial nuclei, principal sensory trigeminal nucleus, nucleus of the solitary tract. as well as the medullary and spinal dorsal horns, suggesting that Lmx1b-expressing cells in these areas are excitatory neurons. Our data suggest that Lmx1b is involved in the postnatal maturation of certain types of neurons and maintenance of their normal functions in the adult brain.

Expression of the basal cell markers of taste buds in the anterior tongue and soft palate of the mouse embryo.

  • Nakayama A
  • J. Comp. Neurol.
  • 2008 Jul 10

Literature context:


Abstract:

Although embryonic expression of Shh in the fungiform papilla placodes has a critical role in fungiform papilla patterning, it remains unclear whether its appearance indicates the differentiation of the basal cells of taste buds. To examine the embryonic development of the basal cells, the expression of Shh, Prox1, and Mash1 was determined in the anterior tongue and soft palate in mouse embryos by in situ hybridization. In the anterior tongue, Prox1 was coexpressed with Shh from the beginning of Shh expression in the fungiform papilla placodes at E12.5. Shh was expressed in the soft palate in a band-like pattern in the anteriormost region and in a punctate pattern in the posterior region at E14.5. The number (21.4 +/- 4.3, at E14.5) of locations where Shh was observed (i.e., spots) rapidly increased and reached a peak level (54.8 +/- 4.0 at E15.5). Also in the soft palate, Prox1 was coexpressed with Shh from the beginning of Shh expression. These results suggest that basal cell differentiation occurs synchronously with the patterning of Shh spots both in the anterior tongue and in the soft palate. In contrast, Mash1 expression lagged behind the expression of Shh and Prox1 and began after the number of Shh spots had reached its peak level in the soft palate. Furthermore, immunohistochemistry of PGP9.5 and Shh revealed that epithelial innervation slightly preceded Mash1 expression both in the tongue and in the soft palate. This is the first report describing the time courses of the embryonic expression of basal cell markers of taste buds.

Funding information:
  • NINDS NIH HHS - U24NS050606(United States)

Expression of vesicular glutamate transporter 1 immunoreactivity in peripheral and central endings of trigeminal mesencephalic nucleus neurons in the rat.

  • Pang YW
  • J. Comp. Neurol.
  • 2006 Sep 1

Literature context:


Abstract:

The major neuronal components of the trigeminal mesencephalic nucleus (Vmes) are primary afferent neurons that convey proprioceptive information from the cranioorofacial regions. In the present study, we examined expression of vesicular glutamate transporters (VGLUTs), VGLUT1 and VGLUT2, in the primary afferent neurons of the Vmes (Vmes neurons) in neonatal and adult rats. VGLUT1 immunoreactivity was detected in the cell bodies of Vmes neurons in neonatal rats younger than 11 days old, but not in older rats. However, in situ hybridization signals for VGLUT1 mRNA were detected in both neonatal and adult rats. No VGLUT2 immunoreactivity was detected in Vmes neurons of neonatal or adult rats. VGLUT1 immunoreactivity was also seen in the peripheral sensory endings on the equatorial regions of intrafusal fibers of muscle spindles in the masseter muscles in both neonatal and adult rats. In adult rats injected with cholera toxin B subunit (CTb) into the masseter nerve, central axon terminals of Vmes neurons were identified on masseter motoneurons within the trigeminal motor nucleus (Vm) by transganglionically and retrogradely transported CTb. VGLUT1-immunopositive axon terminals in close apposition to CTb-labeled Vm motoneurons were also detected by dual-immunofluorescence histochemistry for VGLUT1/CTb. Electron microscopy after dual immunolabeling for VGLUT1/CTb by the VGLUT1/immunoperoxidase and CTb/immunogold-silver methods further revealed synaptic contact of VGLUT1- and CTb-immunopositive axon terminals upon CTb-labeled neuronal profiles within the Vm. These data indicate that VGLUT1 is expressed in both the central axon terminals and the peripheral sensory endings of Vmes neurons, although no VGLUT1 immunoreactivity was detectable in the cell bodies of Vmes neurons in adult rats.

Funding information:
  • NCRR NIH HHS - RR-00165(United States)
  • NIGMS NIH HHS - GM081084(United States)

[Anti-inflammatory effect of radix Angelicae sinensis].

  • Hu H
  • Zhongguo Zhong Yao Za Zhi
  • 1991 Nov 6

Literature context:


Abstract:

Radix Angelicae Sinensis (RAS) decoction can markedly inhibit acute and chronic inflammation caused by various phlogistic agents. Similar effects are equally seen in adrenalectomized rats. RAS can also suppress the biosynthesis or release of prostaglandin E2 in inflamed tissues induced by carrageenan, as well as significantly decrease the hemolytic activity of complement bypass, but shows no effect on the inflammation caused by histamine.

Funding information:
  • NHLBI NIH HHS - P01 HL095491(United States)