X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

VECTASHIELD Mounting Medium with DAPI antibody

RRID:AB_2336790

Male and Female Mice Exhibit Divergent Responses of the Cortical Vasculature to Traumatic Brain Injury.

  • Jullienne A
  • J. Neurotrauma
  • 2018 Jul 15

Literature context:


Abstract:

We previously reported that traumatic brain injuries (TBI) alter the cerebrovasculature near the injury site in rats, followed by revascularization over a 2-week period. Here, we tested our hypothesis that male and female adult mice have differential cerebrovascular responses following a moderate controlled cortical impact (CCI). Using in vivo magnetic resonance imaging (MRI), a new technique called vessel painting, and immunohistochemistry, we found no differences between males and females in lesion volume, neurodegeneration, blood-brain barrier (BBB) alteration, and microglia activation. However, females exhibited more astrocytic hypertrophy and heme-oxygenase-1 (HO-1) induction at 1 day post-injury (dpi), whereas males presented with increased endothelial activation and expression of β-catenin, shown to be involved in angiogenesis. At 7 dpi, we observed an increase in the number of vessels and an enhancement in vessel complexity in the injured cortex of males compared with females. Cerebrovasculature recovers differently after CCI, suggesting biological sex should be considered when designing new therapeutic agents.

Funding information:
  • NICHD NIH HHS - R01HD041462(United States)

Activation of GPR55 increases neural stem cell proliferation and promotes early adult hippocampal neurogenesis.

  • Hill JD
  • Br. J. Pharmacol.
  • 2018 Jun 11

Literature context:


Abstract:

BACKGROUND AND PURPOSE: The cannabinoid system exerts functional regulation of neural stem cell (NSC) proliferation and adult neurogenesis, yet not all effects of cannabinoid-like compounds seen can be attributed to the cannabinoid 1 (CB1 ) or CB2 receptor. The recently de-orphaned GPR55 has been shown to be activated by numerous cannabinoid ligands suggesting that GPR55 is a third cannabinoid receptor. Here, we examined the role of GPR55 activation in NSC proliferation and early adult neurogenesis. EXPERIMENTAL APPROACH: The effects of GPR55 agonists (LPI, O-1602, ML184) on human (h) NSC proliferation in vitro were assessed by flow cytometry. Human NSC differentiation was determined by flow cytometry, qPCR and immunohistochemistry. Immature neuron formation in the hippocampus of C57BL/6 and GPR55-/- mice was evaluated by immunohistochemistry. KEY RESULTS: Activation of GPR55 significantly increased proliferation rates of hNSCs in vitro. These effects were attenuated by ML193, a selective GPR55 antagonist. ML184 significantly promoted neuronal differentiation in vitro while ML193 reduced differentiation rates as compared to vehicle treatment. Continuous administration of O-1602 into the hippocampus via a cannula connected to an osmotic pump resulted in increased Ki67+ cells within the dentate gyrus. O-1602 increased immature neuron generation, as assessed by DCX+ and BrdU+ cells, as compared to vehicle-treated animals. GPR55-/- animals displayed reduced rates of proliferation and neurogenesis within the hippocampus while O-1602 had no effect as compared to vehicle controls. CONCLUSIONS AND IMPLICATIONS: Together, these findings suggest GPR55 activation as a novel target and strategy to regulate NSC proliferation and adult neurogenesis.

Funding information:
  • NCI NIH HHS - CA 100707-12(United States)

Functional Consequences of Synapse Remodeling Following Astrocyte-Specific Regulation of Ephrin-B1 in the Adult Hippocampus.

  • Koeppen J
  • J. Neurosci.
  • 2018 Jun 20

Literature context:


Abstract:

Astrocyte-derived factors can control synapse formation and functions, making astrocytes an attractive target for regulating neuronal circuits and associated behaviors. Abnormal astrocyte-neuronal interactions are also implicated in neurodevelopmental disorders and neurodegenerative diseases associated with impaired learning and memory. However, little is known about astrocyte-mediated mechanisms that regulate learning and memory. Here, we propose astrocytic ephrin-B1 as a regulator of synaptogenesis in adult hippocampus and mouse learning behaviors. We found that astrocyte-specific ablation of ephrin-B1 in male mice triggers an increase in the density of immature dendritic spines and excitatory synaptic sites in the adult CA1 hippocampus. However, the prevalence of immature dendritic spines is associated with decreased evoked postsynaptic firing responses in CA1 pyramidal neurons, suggesting impaired maturation of these newly formed and potentially silent synapses or increased excitatory drive on the inhibitory neurons resulting in the overall decreased postsynaptic firing. Nevertheless, astrocyte-specific ephrin-B1 knock-out male mice exhibit normal acquisition of fear memory but enhanced contextual fear memory recall. In contrast, overexpression of astrocytic ephrin-B1 in the adult CA1 hippocampus leads to the loss of dendritic spines, reduced excitatory input, and impaired contextual memory retention. Our results suggest that astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and mediate excitatory synapse elimination through its interactions with neuronal EphB receptors. Indeed, a deletion of neuronal EphB receptors impairs the ability of astrocytes expressing functional ephrin-B1 to engulf synaptosomes in vitro Our findings demonstrate that astrocytic ephrin-B1 regulates long-term contextual memory by restricting new synapse formation in the adult hippocampus.SIGNIFICANCE STATEMENT These studies address a gap in our knowledge of astrocyte-mediated regulation of learning and memory by unveiling a new role for ephrin-B1 in astrocytes and elucidating new mechanisms by which astrocytes regulate learning. Our studies explore the mechanisms underlying astrocyte regulation of hippocampal circuit remodeling during learning using new genetic tools that target ephrin-B signaling in astrocytes in vivo On a subcellular level, astrocytic ephrin-B1 may compete with neuronal ephrin-B1 and trigger astrocyte-mediated elimination of EphB receptor-containing synapses. Given the role EphB receptors play in neurodevelopmental disorders and neurodegenerative diseases, these findings establish a foundation for future studies of astrocyte-mediated synaptogenesis in clinically relevant conditions that can help to guide the development of clinical applications for a variety of neurological disorders.

Funding information:
  • NCI NIH HHS - P01CA142106(United States)

Plasma Membrane Localization of Apoptotic Caspases for Non-apoptotic Functions.

  • Amcheslavsky A
  • Dev. Cell
  • 2018 May 21

Literature context:


Abstract:

Caspases are best characterized for their function in apoptosis. However, they also have non-apoptotic functions such as apoptosis-induced proliferation (AiP), where caspases release mitogens for compensatory proliferation independently of their apoptotic role. Here, we report that the unconventional myosin, Myo1D, which is known for its involvement in left/right development, is an important mediator of AiP in Drosophila. Mechanistically, Myo1D translocates the initiator caspase Dronc to the basal side of the plasma membrane of epithelial cells where Dronc promotes the activation of the NADPH-oxidase Duox for reactive oxygen species generation and AiP in a non-apoptotic manner. We propose that the basal side of the plasma membrane constitutes a non-apoptotic compartment for caspases. Finally, Myo1D promotes tumor growth and invasiveness of the neoplastic scrib RasV12 model. Together, we identified a new function of Myo1D for AiP and tumorigenesis, and reveal a mechanism by which cells sequester apoptotic caspases in a non-apoptotic compartment at the plasma membrane.

Funding information:
  • NIGMS NIH HHS - R01 GM107789()
  • NIGMS NIH HHS - R35 GM118330()
  • NINDS NIH HHS - R01 NS26115(United States)

Reciprocal Circuits Linking the Prefrontal Cortex with Dorsal and Ventral Thalamic Nuclei.

  • Collins DP
  • Neuron
  • 2018 Apr 18

Literature context:


Abstract:

Reciprocal interactions between the prefrontal cortex (PFC) and thalamus play a critical role in cognition, but the underlying circuits remain poorly understood. Here we use optogenetics to dissect the specificity and dynamics of cortico-thalamo-cortical networks in the mouse brain. We find that cortico-thalamic (CT) neurons in prelimbic PFC project to both mediodorsal (MD) and ventromedial (VM) thalamus, where layer 5 and 6 inputs activate thalamo-cortical (TC) neurons with distinct temporal profiles. We show that TC neurons in MD and VM in turn make distinct connections in PFC, with MD preferentially and strongly activating layer 2/3 cortico-cortical (CC) neurons. Finally, we assess local connections from superficial CC to deep CT neurons, which link thalamo-cortical and cortico-thalamic networks within the PFC. Together our findings indicate that PFC strongly drives neurons in the thalamus, whereas MD and VM indirectly influence reciprocally connected neurons in the PFC, providing a mechanistic understanding of these circuits.

Funding information:
  • NIAID NIH HHS - R01 AI088106-01(United States)

Cell-Type-Specific Shank2 Deletion in Mice Leads to Differential Synaptic and Behavioral Phenotypes.

  • Kim R
  • J. Neurosci.
  • 2018 Apr 25

Literature context:


Abstract:

Shank2 is an excitatory postsynaptic scaffolding protein implicated in synaptic regulation and psychiatric disorders including autism spectrum disorders. Conventional Shank2-mutant (Shank2-/-) mice display several autistic-like behaviors, including social deficits, repetitive behaviors, hyperactivity, and anxiety-like behaviors. However, cell-type-specific contributions to these behaviors have remained largely unclear. Here, we deleted Shank2 in specific cell types and found that male mice lacking Shank2 in excitatory neurons (CaMKII-Cre;Shank2fl/fl) show social interaction deficits and mild social communication deficits, hyperactivity, and anxiety-like behaviors. In particular, male mice lacking Shank2 in GABAergic inhibitory neurons (Viaat-Cre;Shank2fl/fl) display social communication deficits, repetitive self-grooming, and mild hyperactivity. These behavioral changes were associated with distinct changes in hippocampal and striatal synaptic transmission in the two mouse lines. These results indicate that cell-type-specific deletions of Shank2 in mice lead to differential synaptic and behavioral abnormalities.SIGNIFICANCE STATEMENT Shank2 is an abundant excitatory postsynaptic scaffolding protein implicated in the regulation of excitatory synapses and diverse psychiatric disorders including autism spectrum disorders. Previous studies have reported in vivo functions of Shank2 mainly using global Shank2-null mice, but it remains largely unclear how individual cell types contribute to Shank2-dependent regulation of neuronal synapses and behaviors. Here, we have characterized conditional Shank2-mutant mice carrying the Shank2 deletion in excitatory and inhibitory neurons. These mouse lines display distinct alterations of synaptic transmission in the hippocampus and striatum that are associated with differential behavioral abnormalities in social, repetitive, locomotor, and anxiety-like domains.

Funding information:
  • NIEHS NIH HHS - P42ES013660(United States)

Sub-topographic maps for regionally enhanced analysis of visual space in the mouse retina.

  • El-Danaf RN
  • J. Comp. Neurol.
  • 2018 Apr 20

Literature context:


Abstract:

In many species, neurons are unevenly distributed across the retina, leading to nonuniform analysis of specific visual features at certain locations in visual space. In recent years, the mouse has emerged as a premiere model for probing visual system function, development and disease. Thus, achieving a detailed understanding of mouse visual circuit architecture is of paramount importance. The general belief is that mice possess a relatively even topographic distribution of retinal ganglion cells (RGCs)- the output neurons of the eye. However, mouse RGCs include ∼30 subtypes; each responds best to a specific feature in the visual scene and conveys that information to central targets. Given the crucial role of RGCs and the prominence of the mouse as a model, we asked how different RGC subtypes are distributed across the retina. We targeted and filled individual fluorescently tagged RGC subtypes from across the retinal surface and evaluated the dendritic arbor extent and soma size of each cell according to its specific retinotopic position. Three prominent RGC subtypes: On-Off direction selective RGCs, object-motion-sensitive RGCs, and a specialized subclass of non-image-forming RGCs each had marked topographic variations in their dendritic arbor sizes. Moreover, the pattern of variation was distinct for each RGC subtype. Thus, there is increasing evidence that the mouse retina encodes visual space in a region-specific manner. As a consequence, some visual features are sampled far more densely at certain retinal locations than others. These findings have implications for central visual processing, perception and behavior in this prominent model species. This article is protected by copyright. All rights reserved.

Funding information:
  • NIAID NIH HHS - AI073641(United States)

Ultra-Slow Single-Vessel BOLD and CBV-Based fMRI Spatiotemporal Dynamics and Their Correlation with Neuronal Intracellular Calcium Signals.

  • He Y
  • Neuron
  • 2018 Feb 21

Literature context:


Abstract:

Functional MRI has been used to map brain activity and functional connectivity based on the strength and temporal coherence of neurovascular-coupled hemodynamic signals. Here, single-vessel fMRI reveals vessel-specific correlation patterns in both rodents and humans. In anesthetized rats, fluctuations in the vessel-specific fMRI signal are correlated with the intracellular calcium signal measured in neighboring neurons. Further, the blood-oxygen-level-dependent (BOLD) signal from individual venules and the cerebral-blood-volume signal from individual arterioles show correlations at ultra-slow (<0.1 Hz), anesthetic-modulated rhythms. These data support a model that links neuronal activity to intrinsic oscillations in the cerebral vasculature, with a spatial correlation length of ∼2 mm for arterioles. In complementary data from awake human subjects, the BOLD signal is spatially correlated among sulcus veins and specified intracortical veins of the visual cortex at similar ultra-slow rhythms. These data support the use of fMRI to resolve functional connectivity at the level of single vessels.

Funding information:
  • NIMH NIH HHS - 5P50MH086383-04(United States)

Chromatin Modification and Global Transcriptional Silencing in the Oocyte Mediated by the mRNA Decay Activator ZFP36L2.

  • Dumdie JN
  • Dev. Cell
  • 2018 Feb 5

Literature context:


Abstract:

Global transcriptional silencing is a highly conserved mechanism central to the oocyte-to-embryo transition. We report the unexpected discovery that global transcriptional silencing in oocytes depends on an mRNA decay activator. Oocyte-specific loss of ZFP36L2 an RNA-binding protein that promotes AU-rich element-dependent mRNA decay prevents global transcriptional silencing and causes oocyte maturation and fertilization defects, as well as complete female infertility in the mouse. Single-cell RNA sequencing revealed that ZFP36L2 downregulates mRNAs encoding transcription and chromatin modification regulators, including a large group of mRNAs for histone demethylases targeting H3K4 and H3K9, which we show are bound and degraded by ZFP36L2. Oocytes lacking Zfp36l2 fail to accumulate histone methylation at H3K4 and H3K9, marks associated with the transcriptionally silent, developmentally competent oocyte state. Our results uncover a ZFP36L2-dependent mRNA decay mechanism that acts as a developmental switch during oocyte growth, triggering wide-spread shifts in chromatin modification and global transcription.

Funding information:
  • NICHD NIH HHS - K12 HD001259()
  • NIGMS NIH HHS - R35 GM118069()
  • NIMH NIH HHS - R33MH083521(United States)

Quiescent Tissue Stem Cells Evade Immune Surveillance.

  • Agudo J
  • Immunity
  • 2018 Feb 20

Literature context:


Abstract:

Stem cells are critical for the maintenance of many tissues, but whether their integrity is maintained in the face of immunity is unclear. Here we found that cycling epithelial stem cells, including Lgr5+ intestinal stem cells, as well as ovary and mammary stem cells, were eliminated by activated T cells, but quiescent stem cells in the hair follicle and muscle were resistant to T cell killing. Immune evasion was an intrinsic property of the quiescent stem cells resulting from systemic downregulation of the antigen presentation machinery, including MHC class I and TAP proteins, and is mediated by the transactivator NLRC5. This process was reversed upon stem cell entry into the cell cycle. These studies identify a link between stem cell quiescence, antigen presentation, and immune evasion. As cancer-initiating cells can derive from stem cells, these findings may help explain how the earliest cancer cells evade immune surveillance.

Funding information:
  • NCI NIH HHS - R21 CA152536-01A1(United States)
  • NIAID NIH HHS - R01 AI104848()
  • NIAID NIH HHS - R01 AI113221()
  • NIH HHS - R21 OD020185()

BAD and KATP channels regulate neuron excitability and epileptiform activity.

  • Martínez-François JR
  • Elife
  • 2018 Jan 25

Literature context:


Abstract:

Brain metabolism can profoundly influence neuronal excitability. Mice with genetic deletion or alteration of Bad (BCL-2 agonist of cell death) exhibit altered brain-cell fuel metabolism, accompanied by resistance to acutely induced epileptic seizures; this seizure protection is mediated by ATP-sensitive potassium (KATP) channels. Here we investigated the effect of BAD manipulation on KATP channel activity and excitability in acute brain slices. We found that BAD's influence on neuronal KATP channels was cell-autonomous and directly affected dentate granule neuron (DGN) excitability. To investigate the role of neuronal KATP channels in the anticonvulsant effects of BAD, we imaged calcium during picrotoxin-induced epileptiform activity in entorhinal-hippocampal slices. BAD knockout reduced epileptiform activity, and this effect was lost upon knockout or pharmacological inhibition of KATP channels. Targeted BAD knockout in DGNs alone was sufficient for the antiseizure effect in slices, consistent with a 'dentate gate' function that is reinforced by increased KATP channel activity.

Funding information:
  • European Molecular Biology Organization - 473-2016()
  • Intramural NIH HHS - (United States)
  • NEI NIH HHS - P30 EY012196()
  • NIH HHS - DP1 EB016985()
  • NIH HHS - R01 NS055031()
  • NIH HHS - R01 NS083844()
  • NINDS NIH HHS - P30 NS072030()
  • NINDS NIH HHS - R01 NS055031()
  • NINDS NIH HHS - R01 NS083844()

Intra-arterial transplantation of human bone marrow mesenchymal stem cells (hBMMSCs) improves behavioral deficits and alters gene expression in rodent stroke model.

  • Vibhuti
  • J. Neurochem.
  • 2017 Dec 20

Literature context:


Abstract:

Stroke is a multi-factorial polygenic disease and is a major cause of death and adult disability. Administration of bone marrow stem cells protects ischemic rat brain by facilitating recovery of neurological functions. But the molecular mechanism of stem cells action and their effect on gene expression is not well explored. In this study, we have transplanted 1 × 106 human bone marrow mesenchymal stem cells (hBMMSCs) in middle cerebral artery occluded (MCAo) adult male Wistar rats through intracarotid artery route at 24 h after surgery. Motor behavioral tests (rotarod and open field) were performed to assess the changes in motor functions at day 0 and day1, 4, 8 and 14. The expression of studied genes at mRNA and protein level was quantified by using Q-PCR and western blotting, respectively. Further, we have assessed the methylation pattern of promoter of these genes by using methylation-specific PCR. Data were analyzed statistically and correlated. A significant improvement in behavioral deficits was observed in stem cells treated group after 14th day post stroke. Significantly (p < 0.05) increased mRNA and protein levels of brain derived neurotrophic factor and ANP genes in hBMMSCs treated group along with decrease in methylation level at their promoter was observed. On the other hand, significantly decreased mRNA and protein level of TSP1 and WNK1 in hBMMSCs treated group was observed. In conclusion, hBMMSCs administration significantly improves the behavioral deficits by improving motor and locomotor coordination. The promoter of TSP1 and WNK1 genes was found to be hyper-methylated in hBMMSCs group resulting in their decreased expression while the promoter of ANP and brain derived neurotrophic factor was found to be hypo-methylated. This study might shed a light on how hBMMSCs affect the gene expression by modulating methylation status.

A General Strategy for Discovery of Inhibitors and Activators of RING and U-box E3 Ligases with Ubiquitin Variants.

  • Gabrielsen M
  • Mol. Cell
  • 2017 Oct 19

Literature context:


Abstract:

RING and U-box E3 ubiquitin ligases regulate diverse eukaryotic processes and have been implicated in numerous diseases, but targeting these enzymes remains a major challenge. We report the development of three ubiquitin variants (UbVs), each binding selectively to the RING or U-box domain of a distinct E3 ligase: monomeric UBE4B, phosphorylated active CBL, or dimeric XIAP. Structural and biochemical analyses revealed that UbVs specifically inhibited the activity of UBE4B or phosphorylated CBL by blocking the E2∼Ub binding site. Surprisingly, the UbV selective for dimeric XIAP formed a dimer to stimulate E3 activity by stabilizing the closed E2∼Ub conformation. We further verified the inhibitory and stimulatory functions of UbVs in cells. Our work provides a general strategy to inhibit or activate RING/U-box E3 ligases and provides a resource for the research community to modulate these enzymes.

Axonal Type III Nrg1 Controls Glutamate Synapse Formation and GluA2 Trafficking in Hippocampal-Accumbens Connections.

  • Zhong C
  • eNeuro
  • 2017 Oct 30

Literature context:


Abstract:

Altered neuregulin 1 (Nrg1)/ErbB signaling and glutamatergic hypofunction have been implicated in the pathophysiology of schizophrenia. Here, we employed gene chimeric ventral hippocampus (vHipp)-nucleus accumbens (nAcc) coculture from mouse, electrophysiology, immunocytochemistry, FM1-43 vesicle fusion, and electron microscopy techniques to examine the pre- and postsynaptic mechanisms of genetic deficits in Nrg1/ErbB signaling-induced glutamatergic dysfunctions. Reduced presynaptic type III Nrg1 expression along vHipp axons decreases the number of glutamate synapses and impairs GluA2 trafficking in the postsynaptic nAcc neurons, resulting in decreased frequency and amplitude of miniature EPSCs (mEPSCs). Reduced expression of axonal type III Nrg1 along vHipp projections also decreases functional synaptic vesicle (SV) clustering and vesicular trafficking to presynaptic vHipp axonal terminals. These findings suggest that Nrg1/ErbB signaling modulate glutamatergic transmission via both pre- and postsynaptic mechanisms.

Funding information:
  • NINDS NIH HHS - R01 NS022061()

Modulation of occluding junctions alters the hematopoietic niche to trigger immune activation.

  • Khadilkar RJ
  • Elife
  • 2017 Aug 25

Literature context:


Abstract:

Stem cells are regulated by signals from their microenvironment, or niche. During Drosophila hematopoiesis, a niche regulates prohemocytes to control hemocyte production. Immune challenges activate cell-signalling to initiate the cellular and innate immune response. Specifically, certain immune challenges stimulate the niche to produce signals that induce prohemocyte differentiation. However, the mechanisms that promote prohemocyte differentiation subsequent to immune challenges are poorly understood. Here we show that bacterial infection induces the cellular immune response by modulating occluding-junctions at the hematopoietic niche. Occluding-junctions form a permeability barrier that regulates the accessibility of prohemocytes to niche derived signals. The immune response triggered by infection causes barrier breakdown, altering the prohemocyte microenvironment to induce immune cell production. Moreover, genetically induced barrier ablation provides protection against infection by activating the immune response. Our results reveal a novel role for occluding-junctions in regulating niche-hematopoietic progenitor signalling and link this mechanism to immune cell production following infection.

Oriented clonal cell dynamics enables accurate growth and shaping of vertebrate cartilage.

  • Kaucka M
  • Elife
  • 2017 Apr 17

Literature context:


Abstract:

Cartilaginous structures are at the core of embryo growth and shaping before the bone forms. Here we report a novel principle of vertebrate cartilage growth that is based on introducing transversally-oriented clones into pre-existing cartilage. This mechanism of growth uncouples the lateral expansion of curved cartilaginous sheets from the control of cartilage thickness, a process which might be the evolutionary mechanism underlying adaptations of facial shape. In rod-shaped cartilage structures (Meckel, ribs and skeletal elements in developing limbs), the transverse integration of clonal columns determines the well-defined diameter and resulting rod-like morphology. We were able to alter cartilage shape by experimentally manipulating clonal geometries. Using in silico modeling, we discovered that anisotropic proliferation might explain cartilage bending and groove formation at the macro-scale.

Funding information:
  • NIBIB NIH HHS - R01 EB014877()

WGA-Alexa Conjugates for Axonal Tracing.

  • Levy SL
  • Curr Protoc Neurosci
  • 2017 Apr 10

Literature context:


Abstract:

Anatomical labeling approaches are essential for understanding brain organization. Among these approaches are various methods of performing tract tracing. However, a major hurdle to overcome when marking neurons in vivo is visibility. Poor visibility makes it challenging to image a desired neuronal pathway so that it can be easily differentiated from a closely neighboring pathway. As a result, it becomes impossible to analyze individual projections or their connections. The tracer that is chosen for a given purpose has a major influence on the quality of the tracing. Here, we describe the wheat germ agglutinin (WGA) tracer conjugated to Alexa fluorophores for reliable high-resolution tracing of central nervous system projections. Using the mouse cerebellum as a model system, we implement WGA-Alexa tracing for marking and mapping neural circuits that control motor function. We also show its utility for marking localized regions of the cerebellum after performing single-unit extracellular recordings in vivo. © 2017 by John Wiley & Sons, Inc.

Funding information:
  • NCRR NIH HHS - C06 RR029965()
  • NICHD NIH HHS - U54 HD083092()
  • NINDS NIH HHS - F31 NS092264()
  • NINDS NIH HHS - R01 NS089664()
  • Wellcome Trust - 093956(United Kingdom)

Progression of Pro23His Retinopathy in a Miniature Swine Model of Retinitis Pigmentosa.

  • Scott PA
  • Transl Vis Sci Technol
  • 2017 Mar 21

Literature context:


Abstract:

PURPOSE: We characterize the progression of retinopathy in Filial 1 (F1) progeny of a transgenic (Tg) founder miniswine exhibiting severe Pro23His (P23H) retinopathy. METHODS: The F1 TgP23H miniswine progeny were created by crossing TgP23H founder miniswine 53-1 with wild type (WT) inbred miniature swine. Scotopic (rod-driven) and photopic (cone-driven) retinal functions were evaluated in F1 TgP23H and WT littermates using full field electroretinograms (ffERGs) at 1, 2, 3, 6, 9, 12, and 18 months of age, as well as the Tg founder miniswine at 6 years of age. Miniswine were euthanized and their retinas processed for morphologic evaluation at the light and electron microscopic level. Retinal morphology of a 36-month-old Tg miniswine also was examined. RESULTS: Wild type littermates reached mature scotopic and photopic retinal function by 3 months, while TgP23H miniswine showed abnormal scotopic ffERGs at the earliest time point, 1 month, and depressed photopic ffERGs after 2 months. Rod and cone photoreceptors (PR) exhibited morphologic abnormalities and dropout from the outer nuclear layer at 1 month, with only a monolayer of cone PR somata remaining after 2 months. The retinas showed progressive neural remodeling of the outer retina that included dendritic retraction of rod bipolar cells and glial seal formation by Müller cells. The TgP23H founder miniswine showed cone PR with relatively intact morphology exclusive to the area centralis. CONCLUSIONS: The F1 Tg miniswine and the TgP23H founder miniswine exhibit similar retinopathy. TRANSLATIONAL RELEVANCE: TgP23H miniswine are a useful large-eye model to study pathogenesis and preservation cone PRs in humans with retinitis pigmentosa.

Funding information:
  • NIH HHS - U42 OD011140()

DNA-PKcs, ATM, and ATR Interplay Maintains Genome Integrity during Neurogenesis.

  • Enriquez-Rios V
  • J. Neurosci.
  • 2017 Jan 25

Literature context:


Abstract:

The DNA damage response (DDR) orchestrates a network of cellular processes that integrates cell-cycle control and DNA repair or apoptosis, which serves to maintain genome stability. DNA-PKcs (the catalytic subunit of the DNA-dependent kinase, encoded by PRKDC), ATM (ataxia telangiectasia, mutated), and ATR (ATM and Rad3-related) are related PI3K-like protein kinases and central regulators of the DDR. Defects in these kinases have been linked to neurodegenerative or neurodevelopmental syndromes. In all cases, the key neuroprotective function of these kinases is uncertain. It also remains unclear how interactions between the three DNA damage-responsive kinases coordinate genome stability, particularly in a physiological context. Here, we used a genetic approach to identify the neural function of DNA-PKcs and the interplay between ATM and ATR during neurogenesis. We found that DNA-PKcs loss in the mouse sensitized neuronal progenitors to apoptosis after ionizing radiation because of excessive DNA damage. DNA-PKcs was also required to prevent endogenous DNA damage accumulation throughout the adult brain. In contrast, ATR coordinated the DDR during neurogenesis to direct apoptosis in cycling neural progenitors, whereas ATM regulated apoptosis in both proliferative and noncycling cells. We also found that ATR controls a DNA damage-induced G2/M checkpoint in cortical progenitors, independent of ATM and DNA-PKcs. These nonoverlapping roles were further confirmed via sustained murine embryonic or cortical development after all three kinases were simultaneously inactivated. Thus, our results illustrate how DNA-PKcs, ATM, and ATR have unique and essential roles during the DDR, collectively ensuring comprehensive genome maintenance in the nervous system. SIGNIFICANCE STATEMENT: The DNA damage response (DDR) is essential for prevention of a broad spectrum of different human neurologic diseases. However, a detailed understanding of the DDR at a physiological level is lacking. In contrast to many in vitro cellular studies, here we demonstrate independent biological roles for the DDR kinases DNA-PKcs, ATM, and ATR during neurogenesis. We show that DNA-PKcs is central to DNA repair in nonproliferating cells, and restricts DNA damage accumulation, whereas ATR controls damage-induced G2 checkpoint control and apoptosis in proliferating cells. Conversely, ATM is critical for controlling apoptosis in immature noncycling neural cells after DNA damage. These data demonstrate functionally distinct, but cooperative, roles for each kinase in preserving genome stability in the nervous system.

Funding information:
  • NCI NIH HHS - P01 CA096832()
  • NCI NIH HHS - P30 CA021765()
  • NIA NIH HHS - R01 AG027376()
  • NINDS NIH HHS - R01 NS037956()
  • NINDS NIH HHS - R56 NS037956()

Reduction of Nuak1 Decreases Tau and Reverses Phenotypes in a Tauopathy Mouse Model.

  • Lasagna-Reeves CA
  • Neuron
  • 2016 Oct 19

Literature context:


Abstract:

Many neurodegenerative proteinopathies share a common pathogenic mechanism: the abnormal accumulation of disease-related proteins. As growing evidence indicates that reducing the steady-state levels of disease-causing proteins mitigates neurodegeneration in animal models, we developed a strategy to screen for genes that decrease the levels of tau, whose accumulation contributes to the pathology of both Alzheimer disease (AD) and progressive supranuclear palsy (PSP). Integrating parallel cell-based and Drosophila genetic screens, we discovered that tau levels are regulated by Nuak1, an AMPK-related kinase. Nuak1 stabilizes tau by phosphorylation specifically at Ser356. Inhibition of Nuak1 in fruit flies suppressed neurodegeneration in tau-expressing Drosophila, and Nuak1 haploinsufficiency rescued the phenotypes of a tauopathy mouse model. These results demonstrate that decreasing total tau levels is a valid strategy for mitigating tau-related neurodegeneration and reveal Nuak1 to be a novel therapeutic entry point for tauopathies.