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Ki67 antibody - Proliferation Marker

RRID:AB_443209

Antibody ID

AB_443209

Target Antigen

Ki67 antibody - Proliferation Marker rat, mouse, other mammalian, human, horse, human, mouse, rat, horse, indian muntjac

Proper Citation

(Abcam Cat# ab15580, RRID:AB_443209)

Clonality

polyclonal antibody

Comments

validation status unknown, seller recommendations provided in 2012: Immunocytochemistry; Immunohistochemistry - fixed; Immunohistochemistry - frozen; Flow Cytometry; Immunofluorescence; Immunohistochemistry; Western Blot; Flow Cyt, ICC, ICC/IF, IHC-FoFr, IHC-Fr, IHC-FrFl, IHC-P, WB; Rated by ISCC, Intestinal Stem Cell Consortium (check ratings https://iscc.coh.org/)

Host Organism

rabbit

Vendor

Abcam

Cat Num

ab15580

Publications that use this research resource

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)

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)

Brain Somatic Mutations in MTOR Disrupt Neuronal Ciliogenesis, Leading to Focal Cortical Dyslamination.

  • Park SM
  • Neuron
  • 2018 Jun 9

Literature context:


Abstract:

Focal malformations of cortical development (FMCDs), including focal cortical dysplasia (FCD) and hemimegalencephaly (HME), are major etiologies of pediatric intractable epilepsies exhibiting cortical dyslamination. Brain somatic mutations in MTOR have recently been identified as a major genetic cause of FMCDs. However, the molecular mechanism by which these mutations lead to cortical dyslamination remains poorly understood. Here, using patient tissue, genome-edited cells, and mouse models with brain somatic mutations in MTOR, we discovered that disruption of neuronal ciliogenesis by the mutations underlies cortical dyslamination in FMCDs. We found that abnormal accumulation of OFD1 at centriolar satellites due to perturbed autophagy was responsible for the defective neuronal ciliogenesis. Additionally, we found that disrupted neuronal ciliogenesis accounted for cortical dyslamination in FMCDs by compromising Wnt signals essential for neuronal polarization. Altogether, this study describes a molecular mechanism by which brain somatic mutations in MTOR contribute to the pathogenesis of cortical dyslamination in FMCDs.

Funding information:
  • NHLBI NIH HHS - HL073284(United States)

Ablation of the presynaptic organizer Bassoon in excitatory neurons retards dentate gyrus maturation and enhances learning performance.

  • Annamneedi A
  • Brain Struct Funct
  • 2018 Jun 18

Literature context:


Abstract:

Bassoon is a large scaffolding protein of the presynaptic active zone involved in the development of presynaptic terminals and in the regulation of neurotransmitter release at both excitatory and inhibitory brain synapses. Mice with constitutive ablation of the Bassoon (Bsn) gene display impaired presynaptic function, show sensory deficits and develop severe seizures. To specifically study the role of Bassoon at excitatory forebrain synapses and its relevance for control of behavior, we generated conditional knockout (Bsn cKO) mice by gene ablation through an Emx1 promoter-driven Cre recombinase. In these animals, we confirm selective loss of Bassoon from glutamatergic neurons of the forebrain. Behavioral assessment revealed that, in comparison to wild-type littermates, Bsn cKO mice display selectively enhanced contextual fear memory and increased novelty preference in a spatial discrimination/pattern separation task. These changes are accompanied by an augmentation of baseline synaptic transmission at medial perforant path to dentate gyrus (DG) synapses, as indicated by increased ratios of field excitatory postsynaptic potential slope to fiber volley amplitude. At the structural level, an increased complexity of apical dendrites of DG granule cells can be detected in Bsn cKO mice. In addition, alterations in the expression of cellular maturation markers and a lack of age-dependent decrease in excitability between juvenile and adult Bsn cKO mice are observed. Our data suggest that expression of Bassoon in excitatory forebrain neurons is required for the normal maturation of the DG and important for spatial and contextual memory.

Funding information:
  • Deutsche Forschungsgemeinschaft - CRC 779-Neurobiology of Motivated Behavior project A06()
  • Deutsche Forschungsgemeinschaft - CRC 779-Neurobiology of Motivated Behavior project B05()
  • Deutsche Forschungsgemeinschaft - CRC 779-Neurobiology of Motivated Behavior project B09()
  • Leibniz-Gemeinschaft - LGS SynaptoGenetics()
  • NIGMS NIH HHS - S06 GM061223-05A1(United States)

A Designed Peptide Targets Two Types of Modifications of p53 with Anti-cancer Activity.

  • Liang L
  • Cell Chem Biol
  • 2018 Jun 21

Literature context:


Abstract:

Many cancer-related proteins are controlled by composite post-translational modifications (PTMs), but prevalent strategies only target one type of modification. Here we describe a designed peptide that controls two types of modifications of the p53 tumor suppressor, based on the discovery of a protein complex that suppresses p53 (suppresome). We found that Morn3, a cancer-testis antigen, recruits different PTM enzymes, such as sirtuin deacetylase and ubiquitin ligase, to confer composite modifications on p53. The molecular functions of Morn3 were validated through in vivo assays and chemico-biological intervention. A rationally designed Morn3-targeting peptide (Morncide) successfully activated p53 and suppressed tumor growth. These findings shed light on the regulation of protein PTMs and present a strategy for targeting two modifications with one molecule.

Funding information:
  • NCI NIH HHS - K08 CA102545(United States)

BAI1 Suppresses Medulloblastoma Formation by Protecting p53 from Mdm2-Mediated Degradation.

  • Zhu D
  • Cancer Cell
  • 2018 Jun 11

Literature context:


Abstract:

Adhesion G protein-coupled receptors (ADGRs) encompass 33 human transmembrane proteins with long N termini involved in cell-cell and cell-matrix interactions. We show the ADGRB1 gene, which encodes Brain-specific angiogenesis inhibitor 1 (BAI1), is epigenetically silenced in medulloblastomas (MBs) through a methyl-CpG binding protein MBD2-dependent mechanism. Knockout of Adgrb1 in mice augments proliferation of cerebellar granule neuron precursors, and leads to accelerated tumor growth in the Ptch1+/- transgenic MB mouse model. BAI1 prevents Mdm2-mediated p53 polyubiquitination, and its loss substantially reduces p53 levels. Reactivation of BAI1/p53 signaling axis by a brain-permeable MBD2 pathway inhibitor suppresses MB growth in vivo. Altogether, our data define BAI1's physiological role in tumorigenesis and directly couple an ADGR to cancer formation.

Funding information:
  • Canadian Institutes of Health Research - ROP99020(Canada)
  • NCI NIH HHS - P20 CA151129()
  • NCI NIH HHS - P30 CA138292()
  • NCI NIH HHS - R01 CA086335()
  • NCI NIH HHS - R01 CA163722()
  • NINDS NIH HHS - P30 NS055077()
  • NINDS NIH HHS - R01 NS096236()

SOXF factors regulate murine satellite cell self-renewal and function through inhibition of β-catenin activity.

  • Alonso-Martin S
  • Elife
  • 2018 Jun 8

Literature context:


Abstract:

Muscle satellite cells are the primary source of stem cells for postnatal skeletal muscle growth and regeneration. Understanding genetic control of satellite cell formation, maintenance, and acquisition of their stem cell properties is on-going, and we have identified SOXF (SOX7, SOX17, SOX18) transcriptional factors as being induced during satellite cell specification. We demonstrate that SOXF factors regulate satellite cell quiescence, self-renewal and differentiation. Moreover, ablation of Sox17 in the muscle lineage impairs postnatal muscle growth and regeneration. We further determine that activities of SOX7, SOX17 and SOX18 overlap during muscle regeneration, with SOXF transcriptional activity requisite. Finally, we show that SOXF factors also control satellite cell expansion and renewal by directly inhibiting the output of β-catenin activity, including inhibition of Ccnd1 and Axin2. Together, our findings identify a key regulatory function of SoxF genes in muscle stem cells via direct transcriptional control and interaction with canonical Wnt/β-catenin signaling.

Funding information:
  • Agence Nationale de la Recherche - ANR 11 BSV2 017 02()
  • Agence Nationale de la Recherche - ANR-12-BSV1-0038-04()
  • Agence Nationale de la Recherche - ANR-13-BSV1-0011-02()
  • Agence Nationale de la Recherche - ANR-15-CE13-0011-01()
  • Agence Nationale de la Recherche - ANR-15-RHUS-0003()
  • Association Française contre les Myopathies - AFM 16050()
  • Association Française contre les Myopathies - AFM 17865()
  • Association Française contre les Myopathies - TRANSLAMUSCLE 19507()
  • Basque Community - BF106.177()
  • Biotechnology and Biological Sciences Research Council - BB/I017585/1(United Kingdom)
  • Deutsche Forschungsgemeinschaft - GK 1631()
  • Deutsche Forschungsgemeinschaft - KFO192 (Sp1152/8-1)()
  • European Union Sixth and Seventh Framework Program - MYORES and ENDOSTEM # 241440()
  • Fondation pour la Recherche Médicale - DEQ20130326526()
  • Fondation pour la Recherche Médicale - FDT20130928236()
  • FSH Society - 262948-2()
  • FSH Society and BIODESIGN - 262948-2()
  • Horizon 2020 Framework Programme - BIODESIGN (262948-2)()
  • Horizon 2020 Framework Programme - MYORES and ENDOSTEM # 241440()
  • Labex REVIVE - ANR-10-LABX-73()
  • Medical Research Council - MR/PO23215/1()
  • Muscular Dystrophy UK - RA3/3052()

Interleukin-6 Regulates Adult Neural Stem Cell Numbers during Normal and Abnormal Post-natal Development.

  • Storer MA
  • Stem Cell Reports
  • 2018 May 8

Literature context:


Abstract:

Circulating systemic factors can regulate adult neural stem cell (NSC) biology, but the identity of these circulating cues is still being defined. Here, we have focused on the cytokine interleukin-6 (IL-6), since increased circulating levels of IL-6 are associated with neural pathologies such as autism and bipolar disorder. We show that IL-6 promotes proliferation of post-natal murine forebrain NSCs and that, when the IL-6 receptor is inducibly knocked out in post-natal or adult neural precursors, this causes a long-term decrease in forebrain NSCs. Moreover, a transient circulating surge of IL-6 in perinatal or adult mice causes an acute increase in neural precursor proliferation followed by long-term depletion of adult NSC pools. Thus, IL-6 signaling is both necessary and sufficient for adult NSC self-renewal, and acute perturbations in circulating IL-6, as observed in many pathological situations, have long-lasting effects on the size of adult NSC pools.

Funding information:
  • NIGMS NIH HHS - GM61712(United States)

Region specific oligodendrocyte transcription factor expression in a model of neonatal hypoxic injury.

  • Affeldt BM
  • Int. J. Dev. Neurosci.
  • 2018 May 18

Literature context:


Abstract:

White matter injury (WMI) of prematurity is associated with a spectrum of neurological disorders ranging from mild cognitive and behavioral deficits to cerebral palsy. Translational studies have implicated impaired oligodendrocyte development after hypoxia as the primary cause of WMI, but the underlying mechanisms remain poorly understood. The goal of this study was to identify alterations in the expression of oligodendrocyte precursor cell transcription factors in a mouse model of transient mild global hypoxia. Postnatal day (P) 7 mouse pups were exposed to hypoxia (7.5% O2) for 60minutes. We compared oligodendrocyte differentiation and subsequent myelin formation between hypoxia and sham animals at P9, P14 and P28 by examining the expression of key transcription factor regulators of oligodendrocyte differentiation (Ascl1, Olig1, Olig2, and Nkx2.2), as well as APC, a mature oligodendrocyte marker, in the major white matter regions including the corpus callosum, external capsule and anterior commissure. We also examined the effect on myelin formation by examining two myelin specific protein constituents, myelin associated glycoprotein (MAG) and myelin basic protein (MBP), in white matter tracts and whole brain lysate respectively. We found that transient hypoxia at P7 altered the expression of Ascl1, Olig1 and Nkx2.2, resulting in delayed myelination in the external capsule. In addition, our study showed that oligodendrocyte progenitor cells specified several days prior to a hypoxic event are more susceptible to maturation arrest than those specified shortly prior to hypoxia. Our results suggest that alterations of Ascl1, Olig1 and Nkx2.2 underlie impaired oligodendrocyte differentiation and deficient myelination in WMI. These transcription factors are potential therapeutic targets for the treatment of WMI in preterm infants.

Myoepithelial Cells of Submucosal Glands Can Function as Reserve Stem Cells to Regenerate Airways after Injury.

  • Tata A
  • Cell Stem Cell
  • 2018 May 3

Literature context:


Abstract:

Cells demonstrate plasticity following injury, but the extent of this phenomenon and the cellular mechanisms involved remain underexplored. Using single-cell RNA sequencing (scRNA-seq) and lineage tracing, we uncover that myoepithelial cells (MECs) of the submucosal glands (SMGs) proliferate and migrate to repopulate the airway surface epithelium (SE) in multiple injury models. Specifically, SMG-derived cells display multipotency and contribute to basal and luminal cell types of the SMGs and SE. Ex vivo expanded MECs have the potential to repopulate and differentiate into SE cells when grafted onto denuded airway scaffolds. Significantly, we find that SMG-like cells appear on the SE of both extra- and intra-lobular airways of large animal lungs following severe injury. We find that the transcription factor SOX9 is necessary for MEC plasticity in airway regeneration. Because SMGs are abundant and present deep within airways, they may serve as a reserve cell source for enhancing human airway regeneration.

Funding information:
  • NHLBI NIH HHS - R00 HL127181()
  • NIDDK NIH HHS - DK59630(United States)
  • NIEHS NIH HHS - U01 ES017219()

Synaptotagmin 4 Regulates Pancreatic β Cell Maturation by Modulating the Ca2+ Sensitivity of Insulin Secretion Vesicles.

  • Huang C
  • Dev. Cell
  • 2018 May 7

Literature context:


Abstract:

Islet β cells from newborn mammals exhibit high basal insulin secretion and poor glucose-stimulated insulin secretion (GSIS). Here we show that β cells of newborns secrete more insulin than adults in response to similar intracellular Ca2+ concentrations, suggesting differences in the Ca2+ sensitivity of insulin secretion. Synaptotagmin 4 (Syt4), a non-Ca2+ binding paralog of the β cell Ca2+ sensor Syt7, increased by ∼8-fold during β cell maturation. Syt4 ablation increased basal insulin secretion and compromised GSIS. Precocious Syt4 expression repressed basal insulin secretion but also impaired islet morphogenesis and GSIS. Syt4 was localized on insulin granules and Syt4 levels inversely related to the number of readily releasable vesicles. Thus, transcriptional regulation of Syt4 affects insulin secretion; Syt4 expression is regulated in part by Myt transcription factors, which repress Syt4 transcription. Finally, human SYT4 regulated GSIS in EndoC-βH1 cells, a human β cell line. These findings reveal the role that altered Ca2+ sensing plays in regulating β cell maturation.

Funding information:
  • Cancer Research UK - 12183(United Kingdom)
  • NIDDK NIH HHS - R01 DK050203()
  • NIDDK NIH HHS - R01 DK090570()

Ablation of proliferating neural stem cells during early life is sufficient to reduce adult hippocampal neurogenesis.

  • Youssef M
  • Hippocampus
  • 2018 May 9

Literature context:


Abstract:

Environmental exposures during early life, but not during adolescence or adulthood, lead to persistent reductions in neurogenesis in the adult hippocampal dentate gyrus (DG). The mechanisms by which early life exposures lead to long-term deficits in neurogenesis remain unclear. Here, we investigated whether targeted ablation of dividing neural stem cells during early life is sufficient to produce long-term decreases in DG neurogenesis. Having previously found that the stem cell lineage is resistant to long-term effects of transient ablation of dividing stem cells during adolescence or adulthood (Kirshenbaum et al., 2014), we used a similar pharmacogenetic approach to target dividing neural stem cells for elimination during early life periods sensitive to environmental insults. We then assessed the Nestin stem cell lineage in adulthood. We found that the adult neural stem cell reservoir was depleted following ablation during the first postnatal week, when stem cells were highly proliferative, but not during the third postnatal week, when stem cells were more quiescent. Remarkably, ablating proliferating stem cells during either the first or third postnatal week led to reduced adult neurogenesis out of proportion to the changes in the stem cell pool, indicating a disruption of the stem cell function or niche following stem cell ablation in early life. These results highlight the first three postnatal weeks as a series of sensitive periods during which elimination of dividing stem cells leads to lasting alterations in adult DG neurogenesis and stem cell function. These findings contribute to our understanding of the relationship between DG development and adult neurogenesis, as well as suggest a possible mechanism by which early life experiences may lead to lasting deficits in adult hippocampal neurogenesis. This article is protected by copyright. All rights reserved.

Funding information:
  • Intramural NIH HHS - (United States)
  • NIMH NIH HHS - F30 MH111209()
  • NIMH NIH HHS - R01 MH091844()
  • NIMH NIH HHS - R56 MH106809()

Distinct timing of neurogenesis of ipsilateral and contralateral retinal ganglion cells.

  • Marcucci F
  • J. Comp. Neurol.
  • 2018 May 15

Literature context:


Abstract:

In higher vertebrates, the circuit formed by retinal ganglion cells (RGCs) projecting ipsilaterally (iRGCs) or contralaterally (cRGCs) to the brain permits binocular vision and depth perception. iRGCs and cRGCs differ in their position within the retina and in expression of transcription, guidance and activity-related factors. To parse whether these two populations also differ in the timing of their genesis, a feature of distinct neural subtypes and associated projections, we used newer birthdating methods and cell subtype specific markers to determine birthdate and cell cycle exit more precisely than previously. In the ventrotemporal (VT) retina, i- and cRGCs intermingle and neurogenesis in this zone lags behind RGC production in the rest of the retina where only cRGCs are positioned. In addition, within the VT retina, i- and cRGC populations are born at distinct times: neurogenesis of iRGCs surges at E13, and cRGCs arise as early as E14, not later in embryogenesis as reported. Moreover, in the ventral ciliary margin zone (CMZ), which contains progenitors that give rise to some iRGCs in ventral neural retina (Marcucci et al., 2016), cell cycle exit is slower than in other retinal regions in which progenitors give rise only to cRGCs. Further, when the cell cycle regulator Cyclin D2 is missing, cell cycle length in the CMZ is further reduced, mirroring the reduction of both i- and cRGCs in the Cyclin D2 mutant. These results strengthen the view that differential regulation of cell cycle dynamics at the progenitor level is associated with specific RGC fates and laterality of axonal projection. This article is protected by copyright. All rights reserved.

Funding information:
  • NIGMS NIH HHS - R01 GM61001(United States)

Morphogenesis and Compartmentalization of the Intestinal Crypt.

  • Sumigray KD
  • Dev. Cell
  • 2018 Apr 23

Literature context:


Abstract:

The adult mammalian intestine is composed of two connected structures, the absorptive villi and the crypts, which house progenitor cells. Mouse crypts develop postnatally and are the architectural unit of the stem cell niche, yet the pathways that drive their formation are not known. Here, we combine transcriptomic, quantitative morphometric, and genetic analyses to identify mechanisms of crypt development. We uncover the upregulation of a contractility gene network at the earliest stage of crypt formation, which drives myosin II-dependent apical constriction and invagination of the crypt progenitor cells. Subsequently, hinges form, compartmentalizing crypts from villi. Hinges contain basally constricted cells, and this cell shape change was inhibited by increased hemidesmosomal adhesion in Rac1 null mice. Loss of hinges resulted in reduced villar spacing, revealing an unexpected role for crypts in tissue architecture and physiology. These studies provide a framework for studying crypt morphogenesis and identify essential regulators of niche formation.

Funding information:
  • NCI NIH HHS - R01 CA113519(United States)

Evolution and cell-type specificity of human-specific genes preferentially expressed in progenitors of fetal neocortex.

  • Florio M
  • Elife
  • 2018 Mar 21

Literature context:


Abstract:

Understanding the molecular basis that underlies the expansion of the neocortex during primate, and notably human, evolution requires the identification of genes that are particularly active in the neural stem and progenitor cells of the developing neocortex. Here, we have used existing transcriptome datasets to carry out a comprehensive screen for protein-coding genes preferentially expressed in progenitors of fetal human neocortex. We show that 15 human-specific genes exhibit such expression, and many of them evolved distinct neural progenitor cell-type expression profiles and levels compared to their ancestral paralogs. Functional studies on one such gene, NOTCH2NL, demonstrate its ability to promote basal progenitor proliferation in mice. An additional 35 human genes with progenitor-enriched expression are shown to have orthologs only in primates. Our study provides a resource of genes that are promising candidates to exert specific, and novel, roles in neocortical development during primate, and notably human, evolution.

Funding information:
  • Deutsche Forschungsgemeinschaft - SFB655 A2()
  • European Research Council - 250197()
  • Medical Research Council - G0900901(United Kingdom)

Unveiling the Role of Ecto-5'-Nucleotidase/CD73 in Astrocyte Migration by Using Pharmacological Tools.

  • Adzic M
  • Front Pharmacol
  • 2018 Mar 17

Literature context:


Abstract:

CD73 is a bifunctional glycosylphosphatidylinositol (GPI)-anchored membrane protein which functions as ecto-5'-nucleotidase and a membrane receptor for extracellular matrix protein (ECM). A large body of evidence demonstrates a critical involvement of altered purine metabolism and particularly, increased expression of CD73 in a number of human disorders, including cancer and immunodeficiency. Massive up-regulation of CD73 was also found in reactive astrocytes in several experimental models of human neuropathologies. In all the pathological contexts studied so far, the increased expression of CD73 has been associated with the altered ability of cells to adhere and/or migrate. Thus, we hypothesized that increased expression of CD73 in reactive astrocytes has a role in the process of astrocyte adhesion and migration. In the present study, the involvement of CD73 in astrocyte migration was investigated in the scratch wound assay (SW), using primary astrocyte culture prepared from neonatal rat cortex. The cultures were treated with one of the following pharmacological inhibitors which preferentially target individual functions of CD73: (a) α,β-methylene ADP (APCP), which inhibits the catalytic activity of CD73 (b) polyclonal anti-CD73 antibodies, which bind to the internal epitope of CD73 molecule and mask their surface exposure and (c) small interfering CD73-RNA (siCD73), which silences the expression of CD73 gene. It was concluded that approaches that reduce surface expression of CD73 increase migration velocity and promote wound closure in the scratch wound assay, while inhibition of the enzyme activity by APCP induces redistribution of CD73 molecules at the cell surface, thus indirectly affecting cell adhesion and migration. Application of anti-CD73 antibodies induces a decrease in CD73 activity and membrane expression, through CD73 molecules shedding and their release to the culture media. In addition, all applied pharmacological inhibitors differentially affect other aspects of astrocyte function in vitro, including reduced cell proliferation, altered expression of adenosine receptors and increased expression of ERK1/2. Altogether these data imply that CD73 participates in cell adhesion/migration and transmits extracellular signals through interactions with ECM.

Funding information:
  • Howard Hughes Medical Institute - CA11867(United States)

Oligodendrocytes control potassium accumulation in white matter and seizure susceptibility.

  • Larson VA
  • Elife
  • 2018 Mar 29

Literature context:


Abstract:

The inwardly rectifying K+ channel Kir4.1 is broadly expressed by CNS glia and deficits in Kir4.1 lead to seizures and myelin vacuolization. However, the role of oligodendrocyte Kir4.1 channels in controlling myelination and K+ clearance in white matter has not been defined. Here, we show that selective deletion of Kir4.1 from oligodendrocyte progenitors (OPCs) or mature oligodendrocytes did not impair their development or disrupt the structure of myelin. However, mice lacking oligodendrocyte Kir4.1 channels exhibited profound functional impairments, including slower clearance of extracellular K+ and delayed recovery of axons from repetitive stimulation in white matter, as well as spontaneous seizures, a lower seizure threshold, and activity-dependent motor deficits. These results indicate that Kir4.1 channels in oligodendrocytes play an important role in extracellular K+ homeostasis in white matter, and that selective loss of this channel from oligodendrocytes is sufficient to impair K+ clearance and promote seizures.

Funding information:
  • National Institutes of Health - NS050274()
  • National Institutes of Health - NS051509()
  • National Institutes of Health - NS080153()
  • NCATS NIH HHS - UL1 TR000457(United States)

The Dietary Supplement Chondroitin-4-Sulfate Exhibits Oncogene-Specific Pro-tumor Effects on BRAF V600E Melanoma Cells.

  • Lin R
  • Mol. Cell
  • 2018 Mar 15

Literature context:


Abstract:

Dietary supplements such as vitamins and minerals are widely used in the hope of improving health but may have unidentified risks and side effects. In particular, a pathogenic link between dietary supplements and specific oncogenes remains unknown. Here we report that chondroitin-4-sulfate (CHSA), a natural glycosaminoglycan approved as a dietary supplement used for osteoarthritis, selectively promotes the tumor growth potential of BRAF V600E-expressing human melanoma cells in patient- and cell line-derived xenograft mice and confers resistance to BRAF inhibitors. Mechanistically, chondroitin sulfate glucuronyltransferase (CSGlcA-T) signals through its product CHSA to enhance casein kinase 2 (CK2)-PTEN binding and consequent phosphorylation and inhibition of PTEN, which requires CHSA chains and is essential to sustain AKT activation in BRAF V600E-expressing melanoma cells. However, this CHSA-dependent PTEN inhibition is dispensable in cancer cells expressing mutant NRAS or PI3KCA, which directly activate the PI3K-AKT pathway. These results suggest that dietary supplements may exhibit oncogene-dependent pro-tumor effects.

Funding information:
  • NCI NIH HHS - R01 CA140515()
  • NCI NIH HHS - R01 CA174786()
  • NCI NIH HHS - R01 CA183594()
  • Wellcome Trust - 090532(United Kingdom)

Basal Cells Show Increased Expression of Aromatase and Estrogen Receptor α in Prostate Epithelial Lesions of Male Aging Rats.

  • Morais-Santos M
  • Endocrinology
  • 2018 Feb 1

Literature context:


Abstract:

Besides androgens, estrogen signaling plays a key role in normal development and pathologies of the prostate. Irreversible synthesis of estrogens from androgens is catalyzed by aromatase. Interestingly, animals lacking aromatase do not develop cancer or prostatitis, whereas those with overexpression of aromatase and, consequently, high estrogen levels develop prostatitis and squamous metaplasia via estrogen receptor 1 (ERα). Even with this evidence, the aromatase expression in the prostate is controversial. Moreover, little is known about the occurrence of age-dependent variation of aromatase and its association with histopathological changes commonly found in advanced age, a knowledge gap that is addressed herein. For this purpose, the immunoexpression of aromatase was evaluated in the prostatic complex of young adult to senile Wistar rats. ERα was also investigated, to extend our understanding of estrogen responsiveness in the prostate. Moderate cytoplasmic immunoreactivity for aromatase was detected in the glandular epithelium. Eventually, some basal cells showed intense staining for aromatase. The expression pattern for aromatase appeared similar in the normal epithelium when young and senile rats were compared; this result was corroborated by Western blotting. Conversely, in senile rats, there was an increase in the frequency of basal cells intensely stained for aromatase, which appeared concentrated in areas of intraepithelial proliferation and prostatitis. These punctual areas also presented increased ERα positivity. Together, these findings suggest a plausible source for hormonal imbalance favoring estrogen production, which, by acting through ERα, may favor the development of prostatic lesions commonly found in advanced age.

The Polyploid State Plays a Tumor-Suppressive Role in the Liver.

  • Zhang S
  • Dev. Cell
  • 2018 Feb 26

Literature context:


Abstract:

Most cells in the liver are polyploid, but the functional role of polyploidy is unknown. Polyploidization occurs through cytokinesis failure and endoreduplication around the time of weaning. To interrogate polyploidy while avoiding irreversible manipulations of essential cell-cycle genes, we developed orthogonal mouse models to transiently and potently alter liver ploidy. Premature weaning, as well as knockdown of E2f8 or Anln, allowed us to toggle between diploid and polyploid states. While there was no detectable impact of ploidy alterations on liver function, metabolism, or regeneration, mice with more polyploid hepatocytes suppressed tumorigenesis and mice with more diploid hepatocytes accelerated tumorigenesis in mutagen- and high-fat-induced models. Mechanistically, the diploid state was more susceptible to Cas9-mediated tumor-suppressor loss but was similarly susceptible to MYC oncogene activation, indicating that polyploidy differentially protected the liver from distinct genomic aberrations. This suggests that polyploidy evolved in part to prevent malignant outcomes of liver injury.

Funding information:
  • Cancer Research UK - (United Kingdom)
  • NCI NIH HHS - R01 CA190525()

PTEN negatively regulates the cell lineage progression from NG2+ glial progenitor to oligodendrocyte via mTOR-independent signaling.

  • González-Fernández E
  • Elife
  • 2018 Feb 20

Literature context:


Abstract:

Oligodendrocytes (OLs), the myelin-forming CNS glia, are highly vulnerable to cellular stresses, and a severe myelin loss underlies numerous CNS disorders. Expedited OL regeneration may prevent further axonal damage and facilitate functional CNS repair. Although adult OL progenitors (OPCs) are the primary players for OL regeneration, targetable OPC-specific intracellular signaling mechanisms for facilitated OL regeneration remain elusive. Here, we report that OPC-targeted PTEN inactivation in the mouse, in contrast to OL-specific manipulations, markedly promotes OL differentiation and regeneration in the mature CNS. Unexpectedly, an additional deletion of mTOR did not reverse the enhanced OL development from PTEN-deficient OPCs. Instead, ablation of GSK3β, another downstream signaling molecule that is negatively regulated by PTEN-Akt, enhanced OL development. Our results suggest that PTEN persistently suppresses OL development in an mTOR-independent manner, and at least in part, via controlling GSK3β activity. OPC-targeted PTEN-GSK3β inactivation may benefit facilitated OL regeneration and myelin repair.

Funding information:
  • Ellison Medical Foundation - AG-NS-1101-13()
  • National Institute of Neurological Disorders and Stroke - R01NS07693()
  • National Institute of Neurological Disorders and Stroke - R01NS089586()
  • NIH HHS - DP2 OD006740(United States)
  • Shriners Hospitals for Children - 84298-PHI()
  • Shriners Hospitals for Children - 85500-PHI-14()
  • Shriners Hospitals for Children - 86600()

YAP/TAZ-Dependent Reprogramming of Colonic Epithelium Links ECM Remodeling to Tissue Regeneration.

  • Yui S
  • Cell Stem Cell
  • 2018 Jan 4

Literature context:


Abstract:

Tissue regeneration requires dynamic cellular adaptation to the wound environment. It is currently unclear how this is orchestrated at the cellular level and how cell fate is affected by severe tissue damage. Here we dissect cell fate transitions during colonic regeneration in a mouse dextran sulfate sodium (DSS) colitis model, and we demonstrate that the epithelium is transiently reprogrammed into a primitive state. This is characterized by de novo expression of fetal markers as well as suppression of markers for adult stem and differentiated cells. The fate change is orchestrated by remodeling the extracellular matrix (ECM), increased FAK/Src signaling, and ultimately YAP/TAZ activation. In a defined cell culture system recapitulating the extracellular matrix remodeling observed in vivo, we show that a collagen 3D matrix supplemented with Wnt ligands is sufficient to sustain endogenous YAP/TAZ and induce conversion of cell fate. This provides a simple model for tissue regeneration, implicating cellular reprogramming as an essential element.

Funding information:
  • NCI NIH HHS - R01 CA084197-11(United States)

CCPG1 Is a Non-canonical Autophagy Cargo Receptor Essential for ER-Phagy and Pancreatic ER Proteostasis.

  • Smith MD
  • Dev. Cell
  • 2018 Jan 22

Literature context:


Abstract:

Mechanisms of selective autophagy of the ER, known as ER-phagy, require molecular delineation, particularly in vivo. It is unclear how these events control ER proteostasis and cellular health. Here, we identify cell-cycle progression gene 1 (CCPG1), an ER-resident protein with no known physiological role, as a non-canonical cargo receptor that directly binds to core autophagy proteins via an LIR motif to mammalian ATG8 proteins and, independently and via a discrete motif, to FIP200. These interactions facilitate ER-phagy. The CCPG1 gene is inducible by the unfolded protein response and thus directly links ER stress to ER-phagy. In vivo, CCPG1 protects against ER luminal protein aggregation and consequent unfolded protein response hyperactivation and tissue injury of the exocrine pancreas. Thus, via identification of this autophagy protein, we describe an unexpected molecular mechanism of ER-phagy and provide evidence that this may be physiologically relevant in ER luminal proteostasis.

Funding information:
  • NICHD NIH HHS - T32 HD068256(United States)

Fiber-Mediated Nourishment of Gut Microbiota Protects against Diet-Induced Obesity by Restoring IL-22-Mediated Colonic Health.

  • Zou J
  • Cell Host Microbe
  • 2018 Jan 10

Literature context:


Abstract:

Dietary supplementation with fermentable fiber suppresses adiposity and the associated parameters of metabolic syndrome. Microbiota-generated fiber-derived short-chain fatty acids (SCFAs) and free fatty acid receptors including GPR43 are thought to mediate these effects. We find that while fermentable (inulin), but not insoluble (cellulose), fiber markedly protected mice against high-fat diet (HFD)-induced metabolic syndrome, the effect was not significantly impaired by either inhibiting SCFA production or genetic ablation of GPR43. Rather, HFD decimates gut microbiota, resulting in loss of enterocyte proliferation, leading to microbiota encroachment, low-grade inflammation (LGI), and metabolic syndrome. Enriching HFD with inulin restored microbiota loads, interleukin-22 (IL-22) production, enterocyte proliferation, and antimicrobial gene expression in a microbiota-dependent manner, as assessed by antibiotic and germ-free approaches. Inulin-induced IL-22 expression, which required innate lymphoid cells, prevented microbiota encroachment and protected against LGI and metabolic syndrome. Thus, fermentable fiber protects against metabolic syndrome by nourishing microbiota to restore IL-22-mediated enterocyte function.

Funding information:
  • NCI NIH HHS - CA111922(United States)

β2 Adrenergic-Neurotrophin Feedforward Loop Promotes Pancreatic Cancer.

  • Renz BW
  • Cancer Cell
  • 2018 Jan 8

Literature context:


Abstract:

Catecholamines stimulate epithelial proliferation, but the role of sympathetic nerve signaling in pancreatic ductal adenocarcinoma (PDAC) is poorly understood. Catecholamines promoted ADRB2-dependent PDAC development, nerve growth factor (NGF) secretion, and pancreatic nerve density. Pancreatic Ngf overexpression accelerated tumor development in LSL-Kras+/G12D;Pdx1-Cre (KC) mice. ADRB2 blockade together with gemcitabine reduced NGF expression and nerve density, and increased survival of LSL-Kras+/G12D;LSL-Trp53+/R172H;Pdx1-Cre (KPC) mice. Therapy with a Trk inhibitor together with gemcitabine also increased survival of KPC mice. Analysis of PDAC patient cohorts revealed a correlation between brain-derived neurotrophic factor (BDNF) expression, nerve density, and increased survival of patients on nonselective β-blockers. These findings suggest that catecholamines drive a feedforward loop, whereby upregulation of neurotrophins increases sympathetic innervation and local norepinephrine accumulation.

Funding information:
  • NCI NIH HHS - P30 CA013696()
  • NCI NIH HHS - R35 CA210088()
  • NCRR NIH HHS - S10 RR025686()
  • NIDDK NIH HHS - DK053904(United States)

Neuroprotective effects of quercetin 4'-O-β-d-diglucoside on human striatal precursor cells in nutrient deprivation condition.

  • Sarchielli E
  • Acta Histochem.
  • 2018 Jan 18

Literature context:


Abstract:

Several investigations have demonstrated neuroprotective effects of quercetin, a polyphenol widely present in nature, against neurotoxic chemicals, as well as in neuronal injury/neurodegenerative disease models. Most of these studies have been performed with quercetin aglycone and its metabolites, while scanty data are available on its glycosides. This study is aimed at investigating the neuroprotective effects of quercetin 3,4'-O-β-d-diglucoside (Q3,4'dG), isolated from the bulbs of the white cultivar (Allium cepa L.), using an in vitro model of human striatal precursor cells (HSPs), a primary culture isolated from the striatal primordium and previously characterized. To study the effect of Q3,4'dG on cell survival, HSPs were exposed to nutrient deprivation created by replacing culture medium with phosphate buffer saline (PBS). Our findings showed that Q3,4'dG treatment significantly promoted cell survival and strongly decreased apoptosis induced by nutrient deprivation, as evaluated by cell proliferation/death analyses. In addition, since the adhesive capacities of cells are essential for cell survival, the expression of some adhesion molecules, such as pancadherin and focal adhesion kinase, was evaluated. Interestingly, PBS exposure significantly decreased the expression of both molecules, while in the presence of Q3,4'dG this effect was prevented. This study provides evidence of a neuroprotective role exerted by Q3,4'dG and suggests its possible implication in sustaining neuronal survival for prevention and treatment of neurodegenerative disorders.

Funding information:
  • NHLBI NIH HHS - U01HL098166(United States)

Graded Elevation of c-Jun in Schwann Cells In Vivo: Gene Dosage Determines Effects on Development, Remyelination, Tumorigenesis, and Hypomyelination.

  • Fazal SV
  • J. Neurosci.
  • 2017 Dec 13

Literature context:


Abstract:

Schwann cell c-Jun is implicated in adaptive and maladaptive functions in peripheral nerves. In injured nerves, this transcription factor promotes the repair Schwann cell phenotype and regeneration and promotes Schwann-cell-mediated neurotrophic support in models of peripheral neuropathies. However, c-Jun is associated with tumor formation in some systems, potentially suppresses myelin genes, and has been implicated in demyelinating neuropathies. To clarify these issues and to determine how c-Jun levels determine its function, we have generated c-Jun OE/+ and c-Jun OE/OE mice with graded expression of c-Jun in Schwann cells and examined these lines during development, in adulthood, and after injury using RNA sequencing analysis, quantitative electron microscopic morphometry, Western blotting, and functional tests. Schwann cells are remarkably tolerant of elevated c-Jun because the nerves of c-Jun OE/+ mice, in which c-Jun is elevated ∼6-fold, are normal with the exception of modestly reduced myelin thickness. The stronger elevation of c-Jun in c-Jun OE/OE mice is, however, sufficient to induce significant hypomyelination pathology, implicating c-Jun as a potential player in demyelinating neuropathies. The tumor suppressor P19ARF is strongly activated in the nerves of these mice and, even in aged c-Jun OE/OE mice, there is no evidence of tumors. This is consistent with the fact that tumors do not form in injured nerves, although they contain proliferating Schwann cells with strikingly elevated c-Jun. Furthermore, in crushed nerves of c-Jun OE/+ mice, where c-Jun levels are overexpressed sufficiently to accelerate axonal regeneration, myelination and function are restored after injury.SIGNIFICANCE STATEMENT In injured and diseased nerves, the transcription factor c-Jun in Schwann cells is elevated and variously implicated in controlling beneficial or adverse functions, including trophic Schwann cell support for neurons, promotion of regeneration, tumorigenesis, and suppression of myelination. To analyze the functions of c-Jun, we have used transgenic mice with graded elevation of Schwann cell c-Jun. We show that high c-Jun elevation is a potential pathogenic mechanism because it inhibits myelination. Conversely, we did not find a link between c-Jun elevation and tumorigenesis. Modest c-Jun elevation, which is beneficial for regeneration, is well tolerated during Schwann cell development and in the adult and is compatible with restoration of myelination and nerve function after injury.

Canonical Wnt/β-Catenin Signaling Regulates Postnatal Mouse Epididymal Development But Does Not Affect Epithelial Cell Differentiation.

  • Kumar M
  • Endocrinology
  • 2017 Dec 1

Literature context:


Abstract:

The epithelial lining of the epididymis establishes an optimal environment in which spermatozoa acquire the ability to fertilize an oocyte. This highly specialized organ develops from a simple embryonic tube known as the Wolffian duct (WD). How the simple columnar epithelium of WD acquires the complex features of the adult epididymal epithelium is currently unclear. During these first few weeks after birth, the epididymal epithelium undergoes major changes and by 5 weeks consists of four different cell types. The main objective of this study was to evaluate potential roles of Wnt signaling during postnatal epididymal development and differentiation. To analyze the activity of Wnt signaling during postnatal development, we evaluated the epididymis of TCFGFP mice, a Wnt reporter mouse model. Wnt signaling activity as indicated by green fluorescent protein expression was detected in the whole epididymis of TCFGFP mice during the first 2 weeks of life but was localized only to the caput region by 5 weeks of age. Using a genetic cell lineage tracing approach, we showed that all four of the epididymal epithelial cell types originated from the simple columnar epithelium of WD. To delineate the functional significance of epithelial Wnt signaling in epididymal development and differentiation, we generated a mouse model in which β-catenin (Ctnnb1) was specifically ablated from the epididymal epithelium upon administration of doxycycline. Genetic suppression of epithelial Wnt/β-catenin signaling inhibited epididymal development by affecting cell proliferation but had no effect on epithelial cell differentiation.

Funding information:
  • NINDS NIH HHS - NS041218(United States)

Therapeutic Antibody Targeting Tumor- and Osteoblastic Niche-Derived Jagged1 Sensitizes Bone Metastasis to Chemotherapy.

  • Zheng H
  • Cancer Cell
  • 2017 Dec 11

Literature context:


Abstract:

Bone metastasis is a major health threat to breast cancer patients. Tumor-derived Jagged1 represents a central node in mediating tumor-stromal interactions that promote osteolytic bone metastasis. Here, we report the development of a highly effective fully human monoclonal antibody against Jagged1 (clone 15D11). In addition to its inhibitory effect on bone metastasis of Jagged1-expressing tumor cells, 15D11 dramatically sensitizes bone metastasis to chemotherapy, which induces Jagged1 expression in osteoblasts to provide a survival niche for cancer cells. We further confirm the bone metastasis-promoting function of osteoblast-derived Jagged1 using osteoblast-specific Jagged1 transgenic mouse model. These findings establish 15D11 as a potential therapeutic agent for the prevention or treatment of bone metastasis.

Funding information:
  • NCI NIH HHS - P30 CA072720()
  • NCI NIH HHS - R01 CA134519()
  • NCI NIH HHS - R01 CA141062()
  • NCI NIH HHS - R01 CA212410()
  • NIGMS NIH HHS - R29 GM053989(United States)

Molecular Anatomy of the Developing Human Retina.

  • Hoshino A
  • Dev. Cell
  • 2017 Dec 18

Literature context:


Abstract:

Clinical and genetic heterogeneity associated with retinal diseases makes stem-cell-based therapies an attractive strategy for personalized medicine. However, we have limited understanding of the timing of key events in the developing human retina, and in particular the factors critical for generating the unique architecture of the fovea and surrounding macula. Here we define three key epochs in the transcriptome dynamics of human retina from fetal day (D) 52 to 136. Coincident histological analyses confirmed the cellular basis of transcriptional changes and highlighted the dramatic acceleration of development in the fovea compared with peripheral retina. Human and mouse retinal transcriptomes show remarkable similarity in developmental stages, although morphogenesis was greatly expanded in humans. Integration of DNA accessibility data allowed us to reconstruct transcriptional networks controlling photoreceptor differentiation. Our studies provide insights into human retinal development and serve as a resource for molecular staging of human stem-cell-derived retinal organoids.

Funding information:
  • Intramural NIH HHS - ZIA EY000450-09()
  • Intramural NIH HHS - ZIA EY000474-08()
  • Intramural NIH HHS - ZIA EY000546-02()
  • NCI NIH HHS - P01CA40046(United States)
  • NEI NIH HHS - F32 EY025117()
  • NEI NIH HHS - Z01 EY000450()
  • NICHD NIH HHS - R24 HD000836()
  • NIGMS NIH HHS - P01 GM081619()

Tension-Dependent Stretching Activates ZO-1 to Control the Junctional Localization of Its Interactors.

  • Spadaro D
  • Curr. Biol.
  • 2017 Dec 18

Literature context:


Abstract:

Tensile forces regulate epithelial homeostasis, but the molecular mechanisms behind this regulation are poorly understood. Using structured illumination microscopy and proximity ligation assays, we show that the tight junction protein ZO-1 exists in stretched and folded conformations within epithelial cells, depending on actomyosin-generated force. We also show that ZO-1 and ZO-2 regulate the localization of the transcription factor DbpA and the tight junction membrane protein occludin in a manner that depends on the organization of the actin cytoskeleton, myosin-II activity, and substrate stiffness, resulting in modulation of gene expression, cell proliferation, barrier function, and cyst morphogenesis. Pull-down experiments show that interactions between N-terminal (ZPSG) and C-terminal domains of ZO-1 prevent binding of DbpA to the ZPSG, suggesting that force-dependent intra-molecular interactions regulate ZPSG binding to ligands within cells. In vivo and in vitro experiments also suggest that ZO-1 heterodimerization with ZO-2 promotes the stretched conformation and ZPSG interaction with ligands. Magnetic tweezers single-molecule experiments suggest that pN-scale tensions (∼2-4 pN) are sufficient to maintain the stretched conformation of ZO-1, while keeping its structured domains intact, and that 5-20 pN force is required to disrupt the interaction between the extreme C-terminal and the ZPSG domains of ZO-1. We propose that tensile forces regulate epithelial homeostasis by activating ZO proteins through stretching, to control the junctional recruitment and downstream signaling of their interactors.

Funding information:
  • NIAID NIH HHS - AI090166(United States)

mTORC1 Activation during Repeated Regeneration Impairs Somatic Stem Cell Maintenance.

  • Haller S
  • Cell Stem Cell
  • 2017 Dec 7

Literature context:


Abstract:

The balance between self-renewal and differentiation ensures long-term maintenance of stem cell (SC) pools in regenerating epithelial tissues. This balance is challenged during periods of high regenerative pressure and is often compromised in aged animals. Here, we show that target of rapamycin (TOR) signaling is a key regulator of SC loss during repeated regenerative episodes. In response to regenerative stimuli, SCs in the intestinal epithelium of the fly and in the tracheal epithelium of mice exhibit transient activation of TOR signaling. Although this activation is required for SCs to rapidly proliferate in response to damage, repeated rounds of damage lead to SC loss. Consistently, age-related SC loss in the mouse trachea and in muscle can be prevented by pharmacologic or genetic inhibition, respectively, of mammalian target of rapamycin complex 1 (mTORC1) signaling. These findings highlight an evolutionarily conserved role of TOR signaling in SC function and identify repeated rounds of mTORC1 activation as a driver of age-related SC decline.

Funding information:
  • BLRD VA - I01 BX002324()
  • NCRR NIH HHS - UL1 RR024989(United States)
  • NHLBI NIH HHS - R01 HL132996()
  • NIA NIH HHS - K99 AG041764()
  • NIA NIH HHS - P01 AG036695()
  • NIA NIH HHS - R00 AG041764()
  • NIA NIH HHS - R01 AG047497()
  • NIA NIH HHS - R01 AG047820()
  • NIA NIH HHS - R37 AG023806()
  • NIDDK NIH HHS - R01 DK100342()
  • NIDDK NIH HHS - R01 DK113144()

Arid1a Has Context-Dependent Oncogenic and Tumor Suppressor Functions in Liver Cancer.

  • Sun X
  • Cancer Cell
  • 2017 Nov 13

Literature context:


Abstract:

ARID1A, an SWI/SNF chromatin-remodeling gene, is commonly mutated in cancer and hypothesized to be tumor suppressive. In some hepatocellular carcinoma patients, ARID1A was highly expressed in primary tumors but not in metastatic lesions, suggesting that ARID1A can be lost after initiation. Mice with liver-specific homozygous or heterozygous Arid1a loss were resistant to tumor initiation while ARID1A overexpression accelerated initiation. In contrast, homozygous or heterozygous Arid1a loss in established tumors accelerated progression and metastasis. Mechanistically, gain of Arid1a function promoted initiation by increasing CYP450-mediated oxidative stress, while loss of Arid1a within tumors decreased chromatin accessibility and reduced transcription of genes associated with migration, invasion, and metastasis. In summary, ARID1A has context-dependent tumor-suppressive and oncogenic roles in cancer.

Long-Fiber Carbon Nanotubes Replicate Asbestos-Induced Mesothelioma with Disruption of the Tumor Suppressor Gene Cdkn2a (Ink4a/Arf).

  • Chernova T
  • Curr. Biol.
  • 2017 Nov 6

Literature context:


Abstract:

Mesothelioma is a fatal tumor of the pleura and is strongly associated with asbestos exposure. The molecular mechanisms underlying the long latency period of mesothelioma and driving carcinogenesis are unknown. Moreover, late diagnosis means that mesothelioma research is commonly focused on end-stage disease. Although disruption of the CDKN2A (INK4A/ARF) locus has been reported in end-stage disease, information is lacking on the status of this key tumor suppressor gene in pleural lesions preceding mesothelioma. Manufactured carbon nanotubes (CNTs) are similar to asbestos in terms of their fibrous shape and biopersistent properties and thus may pose an asbestos-like inhalation hazard. Here we show that instillation of either long CNTs or long asbestos fibers into the pleural cavity of mice induces mesothelioma that exhibits common key pro-oncogenic molecular events throughout the latency period of disease progression. Sustained activation of pro-oncogenic signaling pathways, increased proliferation, and oxidative DNA damage form a common molecular signature of long-CNT- and long-asbestos-fiber-induced pathology. We show that hypermethylation of p16/Ink4a and p19/Arf in CNT- and asbestos-induced inflammatory lesions precedes mesothelioma; this results in silencing of Cdkn2a (Ink4a/Arf) and loss of p16 and p19 protein, consistent with epigenetic alterations playing a gatekeeper role in cancer. In end-stage mesothelioma, silencing of p16/Ink4a is sustained and deletion of p19/Arf is detected, recapitulating human disease. This study addresses the long-standing question of which early molecular changes drive carcinogenesis during the long latency period of mesothelioma development and shows that CNT and asbestos pose a similar health hazard.

Extracellular ATP induces graded reactive response of astrocytes and strengthens their antioxidative defense in vitro.

  • Adzic M
  • J. Neurosci. Res.
  • 2017 Nov 16

Literature context:


Abstract:

It is widely accepted that adenosine triphosphate (ATP) acts as a universal danger-associated molecular pattern with several known mechanisms for immune cell activation. In the central nervous system, ATP activates microglia and astrocytes and induces a neuroinflammatory response. The aim of the present study was to describe responses of isolated astrocytes to increasing concentrations of ATP (5 µM to 1 mM), which were intended to mimic graded intensity of the extracellular stimulus. The results show that ATP induces graded activation response of astrocytes in terms of the cell proliferation, stellation, shape remodeling, and underlying actin and GFAP filament rearrangement, although the changes occurred without an apparent increase in GFAP and actin protein expression. On the other hand, ATP in the range of applied concentrations did not evoke IL-1β release from cultured astrocytes, nor did it modify the release from LPS and LPS+IFN-γ-primed astrocytes. ATP did not promote astrocyte migration in the wound-healing assay, nor did it increase production of reactive oxygen and nitrogen species and lipid peroxidation. Instead, ATP strengthened the antioxidative defense of astrocytes by inducing Cu/ZnSOD and MnSOD activities and by increasing their glutathione content. Our current results suggest that although ATP triggers several attributes of activated astrocytic phenotype with a magnitude that increases with the concentration, it is not sufficient to induce full-blown reactive phenotype of astrocytes in vitro. © 2016 Wiley Periodicals, Inc.

PGC-1α Promotes Breast Cancer Metastasis and Confers Bioenergetic Flexibility against Metabolic Drugs.

  • Andrzejewski S
  • Cell Metab.
  • 2017 Nov 7

Literature context:


Abstract:

Metabolic adaptations play a key role in fueling tumor growth. However, less is known regarding the metabolic changes that promote cancer progression to metastatic disease. Herein, we reveal that breast cancer cells that preferentially metastasize to the lung or bone display relatively high expression of PGC-1α compared with those that metastasize to the liver. PGC-1α promotes breast cancer cell migration and invasion in vitro and augments lung metastasis in vivo. Pro-metastatic capabilities of PGC-1α are linked to enhanced global bioenergetic capacity, facilitating the ability to cope with bioenergetic disruptors like biguanides. Indeed, biguanides fail to mitigate the PGC-1α-dependent lung metastatic phenotype and PGC-1α confers resistance to stepwise increases in metformin concentration. Overall, our results reveal that PGC-1α stimulates bioenergetic potential, which promotes breast cancer metastasis and facilitates adaptation to metabolic drugs.

Generation of Mouse and Human Organoid-Forming Intestinal Progenitor Cells by Direct Lineage Reprogramming.

  • Miura S
  • Cell Stem Cell
  • 2017 Oct 5

Literature context:


Abstract:

Intestinal organoids hold great promise as a valuable tool for studying and treating intestinal diseases. The currently available sources of human intestinal organoids, tissue fragments or pluripotent stem cells, involve invasive procedures or complex differentiation protocols, respectively. Here, we show that a set of four transcription factors, Hnf4α, Foxa3, Gata6, and Cdx2, can directly reprogram mouse fibroblasts to acquire the identity of fetal intestine-derived progenitor cells (FIPCs). These induced FIPCs (iFIPCs) form spherical organoids that develop into adult-type budding organoids containing cells with intestinal stem cell properties. The resulting stem cells produce all intestinal epithelial cell lineages and undergo self-renewing cell divisions. After transplantation, the induced spherical and budding organoids can reconstitute colonic and intestinal epithelia, respectively. The same combination of four defined transcription factors can also induce human iFIPCs. This alternative approach for producing intestinal organoids may well facilitate application for disease analysis and therapy development.

Microenvironment-Driven Shift of Cohesion/Detachment Balance within Tumors Induces a Switch toward Metastasis in Neuroblastoma.

  • Delloye-Bourgeois C
  • Cancer Cell
  • 2017 Oct 9

Literature context:


Abstract:

Neuroblastoma (NB) is a childhood cancer arising from sympatho-adrenal neural crest cells. Disseminated forms have high frequency of multiple tumoral foci whose etiology remains unknown; NB embryonic origin limits investigations in patients and current models. We developed an avian embryonic model driving human NB tumorigenesis in tissues homologous to patients. We found that aggressive NBs display a metastatic mode, secondary dissemination via peripheral nerves and aorta. Through tumor transcriptional profiling, we found that NB dissemination is induced by the shutdown of a pro-cohesion autocrine signal, SEMA3C, which constrains the tumoral mass. Lowering SEMA3C levels shifts the balance toward detachment, triggering NB cells to collectively evade the tumor. Together with patient cohort analysis, this identifies a microenvironment-driven pro-metastatic switch for NB.

Canonical WNT Signaling Regulates the Pituitary Organizer and Pituitary Gland Formation.

  • Osmundsen AM
  • Endocrinology
  • 2017 Oct 1

Literature context:


Abstract:

The pituitary organizer is a domain within the ventral diencephalon that expresses Bmp4, Fgf8, and Fgf10, which induce the formation of the pituitary precursor, Rathke's pouch, from the oral ectoderm. The WNT signaling pathway regulates this pituitary organizer such that loss of Wnt5a leads to an expansion of the pituitary organizer and an enlargement of Rathke's pouch. WNT signaling is classified into canonical signaling, which is mediated by β-CATENIN, and noncanonical signaling, which operates independently of β-CATENIN. WNT5A is typically classified as a noncanonical WNT; however, other WNT family members are expressed in the ventral diencephalon and nuclear localized β-CATENIN is observed in the ventral diencephalon. Therefore, we sought to determine whether canonical WNT signaling is necessary for regulation of pituitary organizer function. Using a conditional loss-of-function approach, we deleted β-catenin within the mouse ventral diencephalon. Mutant embryos have a smaller Rathke's pouch, resulting from a reduced pituitary organizer, especially Fgf8. This result suggests that canonical WNT signaling promotes pituitary organizer function, instead of inhibiting it. To test this hypothesis, we stimulated canonical WNT signaling in the ventral diencephalon using an inducible gain-of-function allele of β-catenin and found that stimulating canonical WNT signaling expands the domain of Fgf8 and results in a dysmorphic Rathke's pouch. These results demonstrate that canonical WNT signaling in the ventral diencephalon is necessary for proper expression of pituitary organizer genes and suggests that a balance of both canonical and noncanonical WNT signaling is necessary to ensure proper formation of Rathke's pouch.

YAP/TAZ and Hedgehog Coordinate Growth and Patterning in Gastrointestinal Mesenchyme.

  • Cotton JL
  • Dev. Cell
  • 2017 Oct 9

Literature context:


Abstract:

YAP/TAZ are the major mediators of mammalian Hippo signaling; however, their precise function in the gastrointestinal tract remains poorly understood. Here we dissect the distinct roles of YAP/TAZ in endodermal epithelium and mesenchyme and find that, although dispensable for gastrointestinal epithelial development and homeostasis, YAP/TAZ function as the critical molecular switch to coordinate growth and patterning in gut mesenchyme. Our genetic analyses reveal that Lats1/2 kinases suppress expansion of the primitive mesenchymal progenitors, where YAP activation also prevents induction of the smooth muscle lineage through transcriptional repression of Myocardin. During later development, zone-restricted downregulation of YAP/TAZ provides the positional cue and allows smooth muscle cell differentiation induced by Hedgehog signaling. Taken together, our studies identify the mesenchymal requirement of YAP/TAZ in the gastrointestinal tract and highlight the functional interplays between Hippo and Hedgehog signaling underlying temporal and spatial control of tissue growth and specification in developing gut.

Bortezomib Alone and in Combination With Salinosporamid A Induces Apoptosis and Promotes Pheochromocytoma Cell Death In Vitro and in Female Nude Mice.

  • Bullova P
  • Endocrinology
  • 2017 Oct 1

Literature context:


Abstract:

Proteasome inhibitors have been frequently used in treating hematologic and solid tumors. They are administered individually or in combination with other regimens, to prevent severe side effects and resistance development. Because they have been shown to be efficient and are pharmaceutically available, we tested the first Food and Drug Administration-approved proteasome inhibitor bortezomib alone and in combination with another proteasome inhibitor, salinosporamid A, in pheochromocytoma cells. Pheochromocytomas/Paragangliomas (PHEOs/PGLs) are neuroendocrine tumors for which no definite cure is yet available. Therefore, drugs with a wide spectrum of mechanisms of action are being tested to identify suitable candidates for PHEO/PGL treatment. In the current study, we show that bortezomib induces PHEO cell death via the apoptotic pathway in vitro and in vivo. The combination of bortezomib with salinosporamid A exhibits additive effect on these cells and inhibits proliferation, cell migration and invasion, and angiogenesis more potently than bortezomib alone. Altogether, we suggest these proteasome inhibitors, especially bortezomib, could be potentially tested in PHEO/PGL patients who might benefit from treatment with either the inhibitors alone or in combination with other treatment options.

Distinct Mesenchymal Lineages and Niches Promote Epithelial Self-Renewal and Myofibrogenesis in the Lung.

  • Zepp JA
  • Cell
  • 2017 Sep 7

Literature context:


Abstract:

The lung is an architecturally complex organ comprising a heterogeneous mixture of various epithelial and mesenchymal lineages. We use single-cell RNA sequencing and signaling lineage reporters to generate a spatial and transcriptional map of the lung mesenchyme. We find that each mesenchymal lineage has a distinct spatial address and transcriptional profile leading to unique niche regulatory functions. The mesenchymal alveolar niche cell is Wnt responsive, expresses Pdgfrα, and is critical for alveolar epithelial cell growth and self-renewal. In contrast, the Axin2+ myofibrogenic progenitor cell preferentially generates pathologically deleterious myofibroblasts after injury. Analysis of the secretome and receptome of the alveolar niche reveals functional pathways that mediate growth and self-renewal of alveolar type 2 progenitor cells, including IL-6/Stat3, Bmp, and Fgf signaling. These studies define the cellular and molecular framework of lung mesenchymal niches and reveal the functional importance of developmental pathways in promoting self-renewal versus a pathological response to tissue injury.

Prolonged sleep deprivation decreases cell proliferation and immature newborn neurons in both dorsal and ventral hippocampus of male rats.

  • Murata Y
  • Neurosci. Res.
  • 2017 Sep 4

Literature context:


Abstract:

Previous studies have indicated that sleep deprivation negatively affects hippocampal neurogenesis, which may explain the reason for the relation between sleep loss and depression. Increasing evidence indicates that the hippocampus is anatomically and functionally segregated along a dorsolateral (cognitive function)/ventromedial (control for mood and stress response) axis. Thus, the present study was conducted to elucidate regional differences in the adverse effects of sleep deprivation on hippocampal neurogenesis. Male Sprague-Dawley rats were subjected to sleep deprivation using the "platform on the water" method for 24- or 72-h. Quantification of hippocampal cell proliferation and immature newborn neurons was stereologically estimated using immunostaining with Ki-67 and doublecortin (DCX), respectively, by optical fractionator method. A consecutive three days of sleep deprivation significantly reduced the density of Ki-67- and DCX-immunopositive cells both in the dorsal and ventral hippocampal subgranular zone and the decrease in DCX-labeled cells was more pronounced in the ventral hippocampus than in dorsal region. Our results indicate that prolonged sleep deprivation decreases hippocampal cell proliferation and neurogenesis in both the dorsal and ventral dentate gyrus. Future studies will be needed to clarify the impact of sleep deprivation-induced decreases in hippocampal neurogenesis on the development of depression.

MicroRNAs Induce a Permissive Chromatin Environment that Enables Neuronal Subtype-Specific Reprogramming of Adult Human Fibroblasts.

  • Abernathy DG
  • Cell Stem Cell
  • 2017 Sep 7

Literature context:


Abstract:

Directed reprogramming of human fibroblasts into fully differentiated neurons requires massive changes in epigenetic and transcriptional states. Induction of a chromatin environment permissive for acquiring neuronal subtype identity is therefore a major barrier to fate conversion. Here we show that the brain-enriched miRNAs miR-9/9∗ and miR-124 (miR-9/9∗-124) trigger reconfiguration of chromatin accessibility, DNA methylation, and mRNA expression to induce a default neuronal state. miR-9/9∗-124-induced neurons (miNs) are functionally excitable and uncommitted toward specific subtypes but possess open chromatin at neuronal subtype-specific loci, suggesting that such identity can be imparted by additional lineage-specific transcription factors. Consistently, we show that ISL1 and LHX3 selectively drive conversion to a highly homogeneous population of human spinal cord motor neurons. This study shows that modular synergism between miRNAs and neuronal subtype-specific transcription factors can drive lineage-specific neuronal reprogramming, providing a general platform for high-efficiency generation of distinct subtypes of human neurons.

Funding information:
  • NCI NIH HHS - U01 CA200060()
  • NHGRI NIH HHS - R01 HG007175()
  • NHGRI NIH HHS - R01 HG007354()
  • NHGRI NIH HHS - U01 HG009391()
  • NIDA NIH HHS - R25 DA027995()
  • NIEHS NIH HHS - R01 ES024992()
  • NIEHS NIH HHS - U24 ES026699()

Mutant Mice With Calcium-Sensing Receptor Activation Have Hyperglycemia That Is Rectified by Calcilytic Therapy.

  • Babinsky VN
  • Endocrinology
  • 2017 Aug 1

Literature context:


Abstract:

The calcium-sensing receptor (CaSR) is a family C G-protein-coupled receptor that plays a pivotal role in extracellular calcium homeostasis. The CaSR is also highly expressed in pancreatic islet α- and β-cells that secrete glucagon and insulin, respectively. To determine whether the CaSR may influence systemic glucose homeostasis, we characterized a mouse model with a germline gain-of-function CaSR mutation, Leu723Gln, referred to as Nuclear flecks (Nuf). Heterozygous- (CasrNuf/+) and homozygous-affected (CasrNuf/Nuf) mice were shown to have hypocalcemia in association with impaired glucose tolerance and insulin secretion. Oral administration of a CaSR antagonist compound, known as a calcilytic, rectified the glucose intolerance and hypoinsulinemia of CasrNuf/+ mice and ameliorated glucose intolerance in CasrNuf/Nuf mice. Ex vivo studies showed CasrNuf/+ and CasrNuf/Nuf mice to have reduced pancreatic islet mass and β-cell proliferation. Electrophysiological analysis of isolated CasrNuf/Nuf islets showed CaSR activation to increase the basal electrical activity of β-cells independently of effects on the activity of the adenosine triphosphate (ATP)-sensitive K+ (KATP) channel. CasrNuf/Nuf mice also had impaired glucose-mediated suppression of glucagon secretion, which was associated with increased numbers of α-cells and a higher α-cell proliferation rate. Moreover, CasrNuf/Nuf islet electrophysiology demonstrated an impairment of α-cell membrane depolarization in association with attenuated α-cell basal KATP channel activity. These studies indicate that the CaSR activation impairs glucose tolerance by a combination of α- and β-cell defects and also influences pancreatic islet mass. Moreover, our findings highlight a potential application of targeted CaSR compounds for modulating glucose metabolism.

A comprehensive analysis of coregulator recruitment, androgen receptor function and gene expression in prostate cancer.

  • Liu S
  • Elife
  • 2017 Aug 18

Literature context:


Abstract:

Standard treatment for metastatic prostate cancer (CaP) prevents ligand-activation of androgen receptor (AR). Despite initial remission, CaP progresses while relying on AR. AR transcriptional output controls CaP behavior and is an alternative therapeutic target, but its molecular regulation is poorly understood. Here, we show that action of activated AR partitions into fractions that are controlled preferentially by different coregulators. In a 452-AR-target gene panel, each of 18 clinically relevant coregulators mediates androgen-responsiveness of 0-57% genes and acts as a coactivator or corepressor in a gene-specific manner. Selectivity in coregulator-dependent AR action is reflected in differential AR binding site composition and involvement with CaP biology and progression. Isolation of a novel transcriptional mechanism in which WDR77 unites the actions of AR and p53, the major genomic drivers of lethal CaP, to control cell cycle progression provides proof-of-principle for treatment via selective interference with AR action by exploiting AR dependence on coregulators.

Amplification of F-Actin Disassembly and Cellular Repulsion by Growth Factor Signaling.

  • Yoon J
  • Dev. Cell
  • 2017 Jul 24

Literature context:


Abstract:

Extracellular cues that regulate cellular shape, motility, and navigation are generally classified as growth promoting (i.e., growth factors/chemoattractants and attractive guidance cues) or growth preventing (i.e., repellents and inhibitors). Yet, these designations are often based on complex assays and undefined signaling pathways and thus may misrepresent direct roles of specific cues. Here, we find that a recognized growth-promoting signaling pathway amplifies the F-actin disassembly and repulsive effects of a growth-preventing pathway. Focusing on Semaphorin/Plexin repulsion, we identified an interaction between the F-actin-disassembly enzyme Mical and the Abl tyrosine kinase. Biochemical assays revealed Abl phosphorylates Mical to directly amplify Mical Redox-mediated F-actin disassembly. Genetic assays revealed that Abl allows growth factors and Semaphorin/Plexin repellents to combinatorially increase Mical-mediated F-actin disassembly, cellular remodeling, and repulsive axon guidance. Similar roles for Mical in growth factor/Abl-related cancer cell behaviors further revealed contexts in which characterized positive effectors of growth/guidance stimulate such negative cellular effects as F-actin disassembly/repulsion.

Funding information:
  • NIMH NIH HHS - R01 MH085923()

Local Cues Establish and Maintain Region-Specific Phenotypes of Basal Ganglia Microglia.

  • De Biase LM
  • Neuron
  • 2017 Jul 19

Literature context:


Abstract:

Microglia play critical roles in tissue homeostasis and can also modulate neuronal function and synaptic connectivity. In contrast to astrocytes and oligodendrocytes, which arise from multiple progenitor pools, microglia arise from yolk sac progenitors and are widely considered to be equivalent throughout the CNS. However, little is known about basic properties of deep brain microglia, such as those within the basal ganglia (BG). Here, we show that microglial anatomical features, lysosome content, membrane properties, and transcriptomes differ significantly across BG nuclei. Region-specific phenotypes of BG microglia emerged during the second postnatal week and were re-established following genetic or pharmacological microglial ablation and repopulation in the adult, indicating that local cues play an ongoing role in shaping microglial diversity. These findings demonstrate that microglia in the healthy brain exhibit a spectrum of distinct functional states and provide a critical foundation for defining microglial contributions to BG circuit function.

Persistent Expression of VCAM1 in Radial Glial Cells Is Required for the Embryonic Origin of Postnatal Neural Stem Cells.

  • Hu XL
  • Neuron
  • 2017 Jul 19

Literature context:


Abstract:

During development, neural stem cells (NSCs) undergo transitions from neuroepithelial cells to radial glial cells (RGCs), and later, a subpopulation of slowly dividing RGCs gives rise to the quiescent adult NSCs that populate the ventricular-subventricular zone (V-SVZ). Here we show that VCAM1, a transmembrane protein previously found in quiescent adult NSCs, is expressed by a subpopulation of embryonic RGCs, in a temporal and region-specific manner. Loss of VCAM1 reduced the number of active embryonic RGCs by stimulating their premature neuronal differentiation while preventing quiescence in the slowly dividing RGCs. This in turn diminished the embryonic origin of postnatal NSCs, resulting in loss of adult NSCs and defective V-SVZ regeneration. VCAM1 affects the NSC fate by signaling through its intracellular domain to regulate β-catenin signaling in a context-dependent manner. Our findings provide new insight on how stem cells in the embryo are preserved to meet the need for growth and regeneration.

Funding information:
  • NINDS NIH HHS - R37 NS019904(United States)

Interrupted Glucagon Signaling Reveals Hepatic α Cell Axis and Role for L-Glutamine in α Cell Proliferation.

  • Dean ED
  • Cell Metab.
  • 2017 Jun 6

Literature context:


Abstract:

Decreasing glucagon action lowers the blood glucose and may be useful therapeutically for diabetes. However, interrupted glucagon signaling leads to α cell proliferation. To identify postulated hepatic-derived circulating factor(s) responsible for α cell proliferation, we used transcriptomics/proteomics/metabolomics in three models of interrupted glucagon signaling and found that proliferation of mouse, zebrafish, and human α cells was mTOR and FoxP transcription factor dependent. Changes in hepatic amino acid (AA) catabolism gene expression predicted the observed increase in circulating AAs. Mimicking these AA levels stimulated α cell proliferation in a newly developed in vitro assay with L-glutamine being a critical AA. α cell expression of the AA transporter Slc38a5 was markedly increased in mice with interrupted glucagon signaling and played a role in α cell proliferation. These results indicate a hepatic α islet cell axis where glucagon regulates serum AA availability and AAs, especially L-glutamine, regulate α cell proliferation and mass via mTOR-dependent nutrient sensing.

Funding information:
  • BLRD VA - I01 BX000666()
  • BLRD VA - I01 BX002728()
  • NIDDK NIH HHS - P30 DK020593()
  • NIDDK NIH HHS - P60 DK020593()
  • NIDDK NIH HHS - R01 DK069603()
  • NIDDK NIH HHS - R01 DK094199()
  • NIDDK NIH HHS - R01 DK097829()
  • NIDDK NIH HHS - R21 DK066636()
  • NIDDK NIH HHS - R24 DK106755()
  • NIDDK NIH HHS - R33 DK066636()
  • NIDDK NIH HHS - T32 DK007563()
  • NIDDK NIH HHS - U01 DK072473()
  • NIDDK NIH HHS - U01 DK089538()
  • NIDDK NIH HHS - U01 DK089572()
  • NIDDK NIH HHS - UC4 DK104211()
  • NIDDK NIH HHS - UC4 DK108120()

A Role for Androgens in Epithelial Proliferation and Formation of Glands in the Mouse Uterus.

  • Simitsidellis I
  • Endocrinology
  • 2017 Jun 5

Literature context:


Abstract:

The endometrium consists of stromal and epithelial compartments (luminal and glandular) with distinct functions in the regulation of uterine homeostasis. Ovarian sex steroids, namely 17β-estradiol and progesterone, play essential roles in modulating uterine cell proliferation, stromal-epithelial cross-talk and differentiation in preparation for pregnancy. The effect of androgens on uterine function remains poorly understood. The current study investigated the effect of the non-aromatizable androgen dihydrotestosterone (DHT) on mouse endometrial function. Ovx female mice were given a single sc injection (short treatment) or 7 daily injections (long treatment) of vehicle alone (5% ethanol, 0.4% methylcellulose) or vehicle with the addition of 0.2 mg DHT (n=8/group) and a single injection of bromodeoxyuridine 2 hours prior to tissue recovery. Treatment with DHT increased uterine weight, the area of the endometrial compartment and immunoexpression of the androgen receptor in the luminal and glandular epithelium. Treatment-dependent proliferation of epithelial cells was identified by immunostaining for MKi67 and bromodeoxyuridine. Real-time PCR identified significant DHT-dependent changes in the concentrations of mRNAs encoded by genes implicated in the regulation of the cell cycle (Wee1, Ccnd1, Rb1) and stromal-epithelial interactions (Wnt4, Wnt5a, Wnt7a, Cdh1, Vcl, Igf1, Prl8, Prlr) as well as a striking effect on the number of endometrial glands. This study has revealed a novel role for androgens in regulating uterine function with an effect on the glandular compartment of the endometrium. This previously unrecognized role for androgens has implications for our understanding of the role of androgens in regulation of endometrial function and fertility in women.

Funding information:
  • NIDA NIH HHS - R21 DA041018(United States)

Aberrant TGF-β Signaling Drives Castration-Resistant Prostate Cancer in a Male Mouse Model of Prostate Tumorigenesis.

  • Pu H
  • Endocrinology
  • 2017 Jun 1

Literature context:


Abstract:

The androgen receptor (AR) plays a critical role as a driver of castration-resistant prostate cancer (CRPC). Our previous studies demonstrated that disruption of transforming growth factor-β (TGF-β) signaling via introduction of dominant-negative transforming growth factor-β type II receptor (DNTGFβRII) in the prostate epithelium of transgenic adenocarcinoma of the prostate mice accelerated tumor. This study investigated the consequences of disrupted TGF-β signaling on prostate tumor growth under conditions of castration-induced androgen deprivation in the preclinical model of DNTGFβRII. Our results indicate that in response to androgen deprivation therapy (ADT) the proliferative index in prostate tumors from DNTGFβRII mice was higher compared with prostate tumors from TGFβRII wild-type (WT) mice, whereas there was a reduced incidence of apoptosis in tumors from DNTGFβRII. Protein and gene expression profiling revealed that tumors from DNTGFβRII mice exhibit a strong nuclear AR localization among the prostate tumor epithelial cells and increased AR messenger RNA after ADT. In contrast, TGFβRII WT mice exhibited a marked loss in nuclear AR in prostate tumor acini (20 weeks), followed by a downregulation of AR and transmembrane protease serine 2 messenger RNA. There was a significant increase in nuclear AR and activity in prostate tumors from castrate DNTGFβRII compared with TGFβRII WT mice. Consequential to aberrant TGF-β signaling, ADT enhanced expression and nuclear localization of Smad4 and β-catenin. Our findings support that under castrate conditions, aberrant TGF-β signaling leads to AR activation and β-catenin nuclear localization, an adaptation mechanism contributing to emergence of CRPC. The work defines a potentially significant new targeting platform for overcoming therapeutic resistance in CRPC.

Funding information:
  • NIDDK NIH HHS - R01 DK083761()

SAF-A Regulates Interphase Chromosome Structure through Oligomerization with Chromatin-Associated RNAs.

  • Nozawa RS
  • Cell
  • 2017 Jun 15

Literature context:


Abstract:

Higher eukaryotic chromosomes are organized into topologically constrained functional domains; however, the molecular mechanisms required to sustain these complex interphase chromatin structures are unknown. A stable matrix underpinning nuclear organization was hypothesized, but the idea was abandoned as more dynamic models of chromatin behavior became prevalent. Here, we report that scaffold attachment factor A (SAF-A), originally identified as a structural nuclear protein, interacts with chromatin-associated RNAs (caRNAs) via its RGG domain to regulate human interphase chromatin structures in a transcription-dependent manner. Mechanistically, this is dependent on SAF-A's AAA+ ATPase domain, which mediates cycles of protein oligomerization with caRNAs, in response to ATP binding and hydrolysis. SAF-A oligomerization decompacts large-scale chromatin structure while SAF-A loss or monomerization promotes aberrant chromosome folding and accumulation of genome damage. Our results show that SAF-A and caRNAs form a dynamic, transcriptionally responsive chromatin mesh that organizes large-scale chromosome structures and protects the genome from instability.

Single-Cell RNA-Seq Analysis Maps Development of Human Germline Cells and Gonadal Niche Interactions.

  • Li L
  • Cell Stem Cell
  • 2017 Jun 1

Literature context:


Abstract:

Human fetal germ cells (FGCs) are precursors to sperm and eggs and are crucial for maintenance of the species. However, the developmental trajectories and heterogeneity of human FGCs remain largely unknown. Here we performed single-cell RNA-seq analysis of over 2,000 FGCs and their gonadal niche cells in female and male human embryos spanning several developmental stages. We found that female FGCs undergo four distinct sequential phases characterized by mitosis, retinoic acid signaling, meiotic prophase, and oogenesis. Male FGCs develop through stages of migration, mitosis, and cell-cycle arrest. Individual embryos of both sexes simultaneously contain several subpopulations, highlighting the asynchronous and heterogeneous nature of FGC development. Moreover, we observed reciprocal signaling interactions between FGCs and their gonadal niche cells, including activation of the bone morphogenic protein (BMP) and Notch signaling pathways. Our work provides key insights into the crucial features of human FGCs during their highly ordered mitotic, meiotic, and gametogenetic processes in vivo.

IL-22 Upregulates Epithelial Claudin-2 to Drive Diarrhea and Enteric Pathogen Clearance.

  • Tsai PY
  • Cell Host Microbe
  • 2017 Jun 14

Literature context:


Abstract:

Diarrhea is a host response to enteric pathogens, but its impact on pathogenesis remains poorly defined. By infecting mice with the attaching and effacing bacteria Citrobacter rodentium, we defined the mechanisms and contributions of diarrhea and intestinal barrier loss to host defense. Increased permeability occurred within 2 days of infection and coincided with IL-22-dependent upregulation of the epithelial tight junction protein claudin-2. Permeability increases were limited to small molecules, as expected for the paracellular water and Na+ channel formed by claudin-2. Relative to wild-type, claudin-2-deficient mice experienced severe disease, including increased mucosal colonization by C. rodentium, prolonged pathogen shedding, exaggerated cytokine responses, and greater tissue injury. Conversely, transgenic claudin-2 overexpression reduced disease severity. Chemically induced osmotic diarrhea reduced colitis severity and C. rodentium burden in claudin-2-deficient, but not transgenic, mice, demonstrating that claudin-2-mediated protection is the result of enhanced water efflux. Thus, IL-22-induced claudin-2 upregulation drives diarrhea and pathogen clearance.

Funding information:
  • NCRR NIH HHS - S10 RR025643()
  • NICHD NIH HHS - T32 HD007009()
  • NIDDK NIH HHS - F30 DK103511()
  • NIDDK NIH HHS - F32 DK009180()
  • NIDDK NIH HHS - K01 DK092381()
  • NIDDK NIH HHS - R01 DK061931()
  • NIDDK NIH HHS - R01 DK068271()
  • NIDDK NIH HHS - R24 DK099803()

Loss of Dnmt3a and Dnmt3b does not affect epidermal homeostasis but promotes squamous transformation through PPAR-γ.

  • Rinaldi L
  • Elife
  • 2017 Apr 20

Literature context:


Abstract:

The DNA methyltransferase Dnmt3a suppresses tumorigenesis in models of leukemia and lung cancer. Conversely, deregulation of Dnmt3b is thought to generally promote tumorigenesis. However, the role of Dnmt3a and Dnmt3b in many types of cancer remains undefined. Here, we show that Dnmt3a and Dnmt3b are dispensable for homeostasis of the murine epidermis. However, loss of Dnmt3a-but not Dnmt3b-increases the number of carcinogen-induced squamous tumors, without affecting tumor progression. Only upon combined deletion of Dnmt3a and Dnmt3b, squamous carcinomas become more aggressive and metastatic. Mechanistically, Dnmt3a promotes the expression of epidermal differentiation genes by interacting with their enhancers and inhibits the expression of lipid metabolism genes, including PPAR-γ, by directly methylating their promoters. Importantly, inhibition of PPAR-γ partially prevents the increase in tumorigenesis upon deletion of Dnmt3a. Altogether, we demonstrate that Dnmt3a and Dnmt3b protect the epidermis from tumorigenesis and that squamous carcinomas are sensitive to inhibition of PPAR-γ.

Funding information:
  • Worldwide Cancer Research - 10-0050()

Diazepam Binding Inhibitor Promotes Stem Cell Expansion Controlling Environment-Dependent Neurogenesis.

  • Dumitru I
  • Neuron
  • 2017 Apr 5

Literature context:


Abstract:

Plasticity of adult neurogenesis supports adaptation to environmental changes. The identification of molecular mediators that signal these changes to neural progenitors in the niche has remained elusive. Here we report that diazepam binding inhibitor (DBI) is crucial in supporting an adaptive mechanism in response to changes in the environment. We provide evidence that DBI is expressed in stem cells in all neurogenic niches of the postnatal brain. Focusing on the hippocampal subgranular zone (SGZ) and employing multiple genetic manipulations in vivo, we demonstrate that DBI regulates the balance between preserving the stem cell pool and neurogenesis. Specifically, DBI dampens GABA activity in stem cells, thereby sustaining the proproliferative effect of physical exercise and enriched environment. Our data lend credence to the notion that the modulatory effect of DBI constitutes a general mechanism that regulates postnatal neurogenesis.

Tridimensional Visualization and Analysis of Early Human Development.

  • Belle M
  • Cell
  • 2017 Mar 23

Literature context:


Abstract:

Generating a precise cellular and molecular cartography of the human embryo is essential to our understanding of the mechanisms of organogenesis in normal and pathological conditions. Here, we have combined whole-mount immunostaining, 3DISCO clearing, and light-sheet imaging to start building a 3D cellular map of the human development during the first trimester of gestation. We provide high-resolution 3D images of the developing peripheral nervous, muscular, vascular, cardiopulmonary, and urogenital systems. We found that the adult-like pattern of skin innervation is established before the end of the first trimester, showing important intra- and inter-individual variations in nerve branches. We also present evidence for a differential vascularization of the male and female genital tracts concomitant with sex determination. This work paves the way for a cellular and molecular reference atlas of human cells, which will be of paramount importance to understanding human development in health and disease. PAPERCLIP.

A Multi-step Transcriptional and Chromatin State Cascade Underlies Motor Neuron Programming from Embryonic Stem Cells.

  • Velasco S
  • Cell Stem Cell
  • 2017 Feb 2

Literature context:


Abstract:

Direct cell programming via overexpression of transcription factors (TFs) aims to control cell fate with the degree of precision needed for clinical applications. However, the regulatory steps involved in successful terminal cell fate programming remain obscure. We have investigated the underlying mechanisms by looking at gene expression, chromatin states, and TF binding during the uniquely efficient Ngn2, Isl1, and Lhx3 motor neuron programming pathway. Our analysis reveals a highly dynamic process in which Ngn2 and the Isl1/Lhx3 pair initially engage distinct regulatory regions. Subsequently, Isl1/Lhx3 binding shifts from one set of targets to another, controlling regulatory region activity and gene expression as cell differentiation progresses. Binding of Isl1/Lhx3 to later motor neuron enhancers depends on the Ebf and Onecut TFs, which are induced by Ngn2 during the programming process. Thus, motor neuron programming is the product of two initially independent transcriptional modules that converge with a feedforward transcriptional logic.

Funding information:
  • NINDS NIH HHS - NS-23805(United States)
  • NINDS NIH HHS - R01 NS081674(United States)

A Quiescent Bcl11b High Stem Cell Population Is Required for Maintenance of the Mammary Gland.

  • Cai S
  • Cell Stem Cell
  • 2017 Feb 2

Literature context:


Abstract:

Stem cells in many tissues sustain themselves by entering a quiescent state to avoid genomic insults and to prevent exhaustion caused by excessive proliferation. In the mammary gland, the identity and characteristics of quiescent epithelial stem cells are not clear. Here, we identify a quiescent mammary epithelial cell population expressing high levels of Bcl11b and located at the interface between luminal and basal cells. Bcl11bhigh cells are enriched for cells that can regenerate mammary glands in secondary transplants. Loss of Bcl11b leads to a Cdkn2a-dependent exhaustion of ductal epithelium and loss of epithelial cell regenerative capacity. Gain- and loss-of-function studies show that Bcl11b induces cells to enter the G0 phase of the cell cycle and become quiescent. Taken together, these results suggest that Bcl11b acts as a central intrinsic regulator of mammary epithelial stem cell quiescence and exhaustion and is necessary for long-term maintenance of the mammary gland.

Funding information:
  • NCI NIH HHS - P01 CA139490()
  • NCI NIH HHS - R01 CA100225()
  • NCI NIH HHS - U01 CA154209()

Differential Wnt signaling activity limits epithelial gland development to the anti-mesometrial side of the mouse uterus.

  • Goad J
  • Dev. Biol.
  • 2017 Feb 15

Literature context:


Abstract:

In mice, implantation always occurs towards the antimesometrial side of the uterus, while the placenta develops at the mesometrial side. What determines this particular orientation of the implanting blastocyst remains unclear. Uterine glands are critical for implantation and pregnancy. In this study, we showed that uterine gland development and active Wnt signaling activity is limited to the antimesometrial side of the uterus. Dkk2, a known antagonist of Wnt signaling, is only present at the mesometrial side of the uterus. Imaging of whole uterus, thick uterine sections (100-1000µm), and individual glands revealed that uterine glands are simple tubes with branches that are directly connected to the luminal epithelium and are only present towards the antimesometrial side of the uterus. By developing a unique mouse model targeting the uterine epithelium, we demonstrated that Wnt/β-catenin signaling is essential for prepubertal gland formation and normal implantation, but dispensable for postpartum gland development and regeneration. Our results for the first time have provided a probable explanation for the antimesometrial bias for implantation.

Time-Specific Effects of Spindle Positioning on Embryonic Progenitor Pool Composition and Adult Neural Stem Cell Seeding.

  • Falk S
  • Neuron
  • 2017 Feb 22

Literature context:


Abstract:

The developmental mechanisms regulating the number of adult neural stem cells (aNSCs) are largely unknown. Here we show that the cleavage plane orientation in murine embryonic radial glia cells (RGCs) regulates the number of aNSCs in the lateral ganglionic eminence (LGE). Randomizing spindle orientation in RGCs by overexpression of Insc or a dominant-negative form of Lgn (dnLgn) reduces the frequency of self-renewing asymmetric divisions while favoring symmetric divisions generating two SNPs. Importantly, these changes during embryonic development result in reduced seeding of aNSCs. Interestingly, no effects on aNSC numbers were observed when Insc was overexpressed in postnatal RGCs or aNSCs. These data suggest a new mechanism for controlling aNSC numbers and show that the role of spindle orientation during brain development is highly time and region dependent.

lncRNA Functional Networks in Oligodendrocytes Reveal Stage-Specific Myelination Control by an lncOL1/Suz12 Complex in the CNS.

  • He D
  • Neuron
  • 2017 Jan 18

Literature context:


Abstract:

Long noncoding RNAs (lncRNAs) are emerging as important regulators of cellular functions, but their roles in oligodendrocyte myelination remain undefined. Through de novo transcriptome reconstruction, we establish dynamic expression profiles of lncRNAs at different stages of oligodendrocyte development and uncover a cohort of stage-specific oligodendrocyte-restricted lncRNAs, including a conserved chromatin-associated lncOL1. Co-expression network analyses further define the association of distinct oligodendrocyte-expressing lncRNA clusters with protein-coding genes and predict lncRNA functions in oligodendrocyte myelination. Overexpression of lncOL1 promotes precocious oligodendrocyte differentiation in the developing brain, whereas genetic inactivation of lncOL1 causes defects in CNS myelination and remyelination following injury. Functional analyses illustrate that lncOL1 interacts with Suz12, a component of polycomb repressive complex 2, to promote oligodendrocyte maturation, in part, through Suz12-mediated repression of a differentiation inhibitory network that maintains the precursor state. Together, our findings reveal a key lncRNA epigenetic circuitry through interaction with chromatin-modifying complexes in control of CNS myelination and myelin repair.

Funding information:
  • NINDS NIH HHS - R01 NS072427()
  • NINDS NIH HHS - R01 NS075243()
  • NINDS NIH HHS - R37 NS096359()

Conditional Deletion of the L-Type Calcium Channel Cav1.2 in Oligodendrocyte Progenitor Cells Affects Postnatal Myelination in Mice.

  • Cheli VT
  • J. Neurosci.
  • 2016 Oct 19

Literature context:


Abstract:

To determine whether L-type voltage-operated Ca2+ channels (L-VOCCs) are required for oligodendrocyte progenitor cell (OPC) development, we generated an inducible conditional knock-out mouse in which the L-VOCC isoform Cav1.2 was postnatally deleted in NG2-positive OPCs. A significant hypomyelination was found in the brains of the Cav1.2 conditional knock-out (Cav1.2KO) mice specifically when the Cav1.2 deletion was induced in OPCs during the first 2 postnatal weeks. A decrease in myelin proteins expression was visible in several brain structures, including the corpus callosum, cortex, and striatum, and the corpus callosum of Cav1.2KO animals showed an important decrease in the percentage of myelinated axons and a substantial increase in the mean g-ratio of myelinated axons. The reduced myelination was accompanied by an important decline in the number of myelinating oligodendrocytes and in the rate of OPC proliferation. Furthermore, using a triple transgenic mouse in which all of the Cav1.2KO OPCs were tracked by a Cre reporter, we found that Cav1.2KO OPCs produce less mature oligodendrocytes than control cells. Finally, live-cell imaging in early postnatal brain slices revealed that the migration and proliferation of subventricular zone OPCs is decreased in the Cav1.2KO mice. These results indicate that the L-VOCC isoform Cav1.2 modulates oligodendrocyte development and suggest that Ca2+ influx mediated by L-VOCCs in OPCs is necessary for normal myelination. SIGNIFICANCE STATEMENT: Overall, it is clear that cells in the oligodendrocyte lineage exhibit remarkable plasticity with regard to the expression of Ca2+ channels and that perturbation of Ca2+ homeostasis likely plays an important role in the pathogenesis underlying demyelinating diseases. To determine whether voltage-gated Ca2+ entry is involved in oligodendrocyte maturation and myelination, we used a conditional knock-out mouse for voltage-operated Ca2+ channels in oligodendrocyte progenitor cells. Our results indicate that voltage-operated Ca2+ channels can modulate oligodendrocyte development in the postnatal brain and suggest that voltage-gated Ca2+ influx in oligodendroglial cells is critical for normal myelination. These findings could lead to novel approaches to intervene in neurodegenerative diseases in which myelin is lost or damaged.

Germline NLRP1 Mutations Cause Skin Inflammatory and Cancer Susceptibility Syndromes via Inflammasome Activation.

  • Zhong FL
  • Cell
  • 2016 Sep 22

Literature context:


Abstract:

Inflammasome complexes function as key innate immune effectors that trigger inflammation in response to pathogen- and danger-associated signals. Here, we report that germline mutations in the inflammasome sensor NLRP1 cause two overlapping skin disorders: multiple self-healing palmoplantar carcinoma (MSPC) and familial keratosis lichenoides chronica (FKLC). We find that NLRP1 is the most prominent inflammasome sensor in human skin, and all pathogenic NLRP1 mutations are gain-of-function alleles that predispose to inflammasome activation. Mechanistically, NLRP1 mutations lead to increased self-oligomerization by disrupting the PYD and LRR domains, which are essential in maintaining NLRP1 as an inactive monomer. Primary keratinocytes from patients experience spontaneous inflammasome activation and paracrine IL-1 signaling, which is sufficient to cause skin inflammation and epidermal hyperplasia. Our findings establish a group of non-fever inflammasome disorders, uncover an unexpected auto-inhibitory function for the pyrin domain, and provide the first genetic evidence linking NLRP1 to skin inflammatory syndromes and skin cancer predisposition.

Cell-Type-Specific Alternative Splicing Governs Cell Fate in the Developing Cerebral Cortex.

  • Zhang X
  • Cell
  • 2016 Aug 25

Literature context:


Abstract:

Alternative splicing is prevalent in the mammalian brain. To interrogate the functional role of alternative splicing in neural development, we analyzed purified neural progenitor cells (NPCs) and neurons from developing cerebral cortices, revealing hundreds of differentially spliced exons that preferentially alter key protein domains-especially in cytoskeletal proteins-and can harbor disease-causing mutations. We show that Ptbp1 and Rbfox proteins antagonistically govern the NPC-to-neuron transition by regulating neuron-specific exons. Whereas Ptbp1 maintains apical progenitors partly through suppressing a poison exon of Flna in NPCs, Rbfox proteins promote neuronal differentiation by switching Ninein from a centrosomal splice form in NPCs to a non-centrosomal isoform in neurons. We further uncover an intronic human mutation within a PTBP1-binding site that disrupts normal skipping of the FLNA poison exon in NPCs and causes a brain-specific malformation. Our study indicates that dynamic control of alternative splicing governs cell fate in cerebral cortical development.

Proneurotrophin-3 promotes cell cycle withdrawal of developing cerebellar granule cell progenitors via the p75 neurotrophin receptor.

  • Zanin JP
  • Elife
  • 2016 Jul 19

Literature context:


Abstract:

Cerebellar granule cell progenitors (GCP) proliferate extensively in the external granule layer (EGL) of the developing cerebellum prior to differentiating and migrating. Mechanisms that regulate the appropriate timing of cell cycle withdrawal of these neuronal progenitors during brain development are not well defined. The p75 neurotrophin receptor (p75(NTR)) is highly expressed in the proliferating GCPs, but is downregulated once the cells leave the cell cycle. This receptor has primarily been characterized as a death receptor for its ability to induce neuronal apoptosis following injury. Here we demonstrate a novel function for p75(NTR) in regulating proper cell cycle exit of neuronal progenitors in the developing rat and mouse EGL, which is stimulated by proNT3. In the absence of p75(NTR), GCPs continue to proliferate beyond their normal period, resulting in a larger cerebellum that persists into adulthood, with consequent motor deficits.

Funding information:
  • NIDCD NIH HHS - R01 DC00189.(United States)

A biofidelic 3D culture model to study the development of brain cellular systems.

  • Ren M
  • Sci Rep
  • 2016 Apr 26

Literature context:


Abstract:

Little is known about how cells assemble as systems during corticogenesis to generate collective functions. We built a neurobiology platform that consists of fetal rat cerebral cortical cells grown within 3D silk scaffolds (SF). Ivermectin (Ivm), a glycine receptor (GLR) agonist, was used to modulate cell resting membrane potential (Vmem) according to methods described in a previous work that implicated Ivm in the arrangement and connectivity of cortical cell assemblies. The cells developed into distinct populations of neuroglial stem/progenitor cells, mature neurons or epithelial-mesenchymal cells. Importantly, the synchronized electrical activity in the newly developed cortical assemblies could be recorded as local field potential (LFP) measurements. This study therefore describes the first example of the development of a biologically relevant cortical plate assembly outside of the body. This model provides i) a preclinical basis for engineering cerebral cortex tissue autografts and ii) a biofidelic 3D culture model for investigating biologically relevant processes during the functional development of cerebral cortical cellular systems.

Funding information:
  • Doris Duke Charitable Foundation - T32 AI007387(United States)

Thyroid Hormone Receptor α Plays an Essential Role in Male Skeletal Muscle Myoblast Proliferation, Differentiation, and Response to Injury.

  • Milanesi A
  • Endocrinology
  • 2016 Jan 31

Literature context:


Abstract:

Thyroid hormone plays an essential role in myogenesis, the process required for skeletal muscle development and repair, although the mechanisms have not been established. Skeletal muscle develops from the fusion of precursor myoblasts into myofibers. We have used the C2C12 skeletal muscle myoblast cell line, primary myoblasts, and mouse models of resistance to thyroid hormone (RTH) α and β, to determine the role of thyroid hormone in the regulation of myoblast differentiation. T3, which activates thyroid hormone receptor (TR) α and β, increased myoblast differentiation whereas GC1, a selective TRβ agonist, was minimally effective. Genetic approaches confirmed that TRα plays an important role in normal myoblast proliferation and differentiation and acts through the Wnt/β-catenin signaling pathway. Myoblasts with TRα knockdown, or derived from RTH-TRα PV (a frame-shift mutation) mice, displayed reduced proliferation and myogenic differentiation. Moreover, skeletal muscle from the TRα1PV mutant mouse had impaired in vivo regeneration after injury. RTH-TRβ PV mutant mouse model skeletal muscle and derived primary myoblasts did not have altered proliferation, myogenic differentiation, or response to injury when compared with control. In conclusion, TRα plays an essential role in myoblast homeostasis and provides a potential therapeutic target to enhance skeletal muscle regeneration.

Funding information:
  • NIDDK NIH HHS - R01 DK103723(United States)

Estrogen Receptor-β Up-Regulates IGF1R Expression and Activity to Inhibit Apoptosis and Increase Growth of Medulloblastoma.

  • Cookman CJ
  • Endocrinology
  • 2015 Jul 20

Literature context:


Abstract:

Medulloblastoma (Med) is the most common malignant brain tumor in children. The role of ESR2 [estrogen receptor (ER)-β] in promoting Med growth was comprehensively examined in three in vivo models and human cell lines. In a novel Med ERβ-null knockout model developed by crossing Esr2(-/-) mice with cerebellar granule cell precursor specific Ptch1 conditional knockout mice, the tumor growth rate was significantly decreased in males and females. The absence of Esr2 resulted in increased apoptosis, decreased B-cell lymphoma 2 (BCL2), and IGF-1 receptor (IGF1R) expression, and decreased levels of active MAPKs (ERK1/2) and protein kinase B (AKT). Treatment of Med in Ptch1(+/-) Trp53(-/-) mice with the antiestrogen chemotherapeutic drug Faslodex significantly increased symptom-free survival, which was associated with increased apoptosis and decreased BCL2 and IGF1R expression and signaling. Similar effects were also observed in nude mice bearing D283Med xenografts. In vitro studies in human D283Med cells metabolically stressed by glutamine withdrawal found that 17β-estradiol and the ERβ selective agonist 2,3-bis(4-hydroxyphenyl)-propionitrile dose dependently protected Med cells from caspase-3-dependent cell death. Those effects were associated with increased phosphorylation of IGF1R, long-term increases in ERK1/2 and AKT signaling, and increased expression of IGF-1, IGF1R, and BCL2. Results of pharmacological experiments revealed that the cytoprotective actions of estradiol were dependent on ERβ and IGF1R receptor tyrosine kinase activity and independent of ERα and G protein-coupled estrogen receptor 1 (G protein coupled receptor 30). The presented results demonstrate that estrogen promotes Med growth through ERβ-mediated increases in IGF1R expression and activity, which induce cytoprotective mechanisms that decrease apoptosis.

Funding information:
  • NIDCD NIH HHS - DC 00716(United States)

Non-Invasive In Vivo Imaging and Quantification of Tumor Growth and Metastasis in Rats Using Cells Expressing Far-Red Fluorescence Protein.

  • Christensen J
  • PLoS ONE
  • 2015 Jul 18

Literature context:


Abstract:

Non-invasive in vivo imaging is emerging as an important tool for basic and preclinical research. Near-infrared (NIR) fluorescence dyes and probes have been used for non-invasive optical imaging since in the NIR region absorption and auto fluorescence by body tissue is low, thus permitting for greater penetration depths and high signal to noise ratio. Currently, cell tracking systems rely on labeling cells prior to injection or administering probes targeting the cell population of choice right before imaging. These approaches do not enable imaging of tumor growth, as the cell label is diluted during cell division. In this study we have developed cell lines stably expressing the far-red fluorescence protein E2-Crimson, thus enabling continuous detection and quantification of tumor growth. In a xenograft rat model, we show that E2-Crimson expressing cells can be detected over a 5 week period using optical imaging. Fluorescence intensities correlated with tumor volume and weight and allowed for a reliable and robust quantification of the entire tumor compartment. Using a novel injection regime, the seeding of MDA-MB-231 breast cancer cells in the lungs in a rat model was established and verified.

Periostin induces pancreatic regeneration.

  • Smid JK
  • Endocrinology
  • 2015 Mar 21

Literature context:


Abstract:

We found that the secreted protein periostin (Postn) is highly induced after partial pancreatectomy in regenerating areas containing mesenchymal stroma and tubular complexes. Importantly, after partial pancreatectomy, Postn-deficient mice exhibit impaired mesenchymal formation and reduced regeneration specifically within the pancreatic β-cell compartment. Furthermore, Postn-deficient mice demonstrate an increased sensitivity to streptozotocin. Notably, injection of Postn directly into the pancreas stimulated proliferation of vimentin-expressing cells within 24 hours, and by 3 days, a mesenchymal stroma was present containing proliferating duct-like cells expressing the progenitor markers Ngn3 and Pdx1. Intraperitoneal injection of Postn resulted in increased numbers of islets and long-term glucoregulatory benefits with no adverse effects found in other tissues. Delivery of Postn throughout the pancreas via the common bile duct resulted in increased numbers of small insulin-expressing clusters and a significant improvement in glucose tolerance. Therefore, Postn is novel molecule capable of potentiating pancreatic β-cell regeneration.

Funding information:
  • NIDDK NIH HHS - R01 DK055758(United States)
  • NINDS NIH HHS - R01 NS073981(United States)

Mice lacking GD3 synthase display morphological abnormalities in the sciatic nerve and neuronal disturbances during peripheral nerve regeneration.

  • Ribeiro-Resende VT
  • PLoS ONE
  • 2014 Oct 21

Literature context:


Abstract:

The ganglioside 9-O-acetyl GD3 is overexpressed in peripheral nerves after lesioning, and its expression is correlated with axonal degeneration and regeneration in adult rodents. However, the biological roles of this ganglioside during the regenerative process are unclear. We used mice lacking GD3 synthase (Siat3a KO), an enzyme that converts GM3 to GD3, which can be further converted to 9-O-acetyl GD3. Morphological analyses of longitudinal and transverse sections of the sciatic nerve revealed significant differences in the transverse area and nerve thickness. The number of axons and the levels of myelin basic protein were significantly reduced in adult KO mice compared to wild-type (WT) mice. The G-ratio was increased in KO mice compared to WT mice based on quantification of thin transverse sections stained with toluidine blue. We found that neurite outgrowth was significantly reduced in the absence of GD3. However, addition of exogenous GD3 led to neurite growth after 3 days, similar to that in WT mice. To evaluate fiber regeneration after nerve lesioning, we compared the regenerated distance from the lesion site and found that this distance was one-fourth the length in KO mice compared to WT mice. KO mice in which GD3 was administered showed markedly improved regeneration compared to the control KO mice. In summary, we suggest that 9-O-acetyl GD3 plays biological roles in neuron-glia interactions, facilitating axonal growth and myelination induced by Schwann cells. Moreover, exogenous GD3 can be converted to 9-O-acetyl GD3 in mice lacking GD3 synthase, improving regeneration.

Funding information:
  • European Research Council - 261063(International)

Genetic control of ductal morphology, estrogen-induced ductal growth, and gene expression in female mouse mammary gland.

  • Wall EH
  • Endocrinology
  • 2014 Aug 19

Literature context:


Abstract:

The uterotropic response of the uterus to 17β-estradiol (E2) is genetically controlled, with marked variation observed depending on the mouse strain studied. Previous genetic studies from our laboratory using inbred mice that are high (C57BL6/J; B6) or low (C3H/HeJ; C3H) responders to E2 led to the identification of quantitative trait loci (QTL) associated with phenotypic variation in uterine growth and leukocyte infiltration. Like the uterus, phenotypic variation in the responsiveness of the mammary gland to E2 during both normal and pathologic conditions has been reported. In the current experiment, we utilized an E2-specific model of mammary ductal growth combined with a microarray approach to determine the degree to which genotype influences the responsiveness of the mammary gland to E2, including the associated transcriptional programs, in B6 and C3H mice. Our results reveal that E2-induced mammary ductal growth and ductal morphology are genetically controlled. In addition, we observed a paradoxical effect of mammary ductal growth in response to E2 compared with what has been reported for the uterus; B6 is a high responder for the uterus and was a low responder for mammary ductal growth, whereas the reverse was observed for C3H. In contrast, B6 was a high responder for mammary ductal side branching. The B6 phenotype was associated with increased mammary epithelial cell proliferation and apoptosis, and a distinct E2-induced transcriptional program. These findings lay the groundwork for future experiments designed to investigate the genes and mechanisms underlying phenotypic variation in tissue-specific sensitivity to systemic and environmental estrogens during various physiological and disease states.

Funding information:
  • NLM NIH HHS - T15LM07056(United States)

Prolactin activates ERα in the absence of ligand in female mammary development and carcinogenesis in vivo.

  • O'Leary KA
  • Endocrinology
  • 2013 Dec 25

Literature context:


Abstract:

Resistance of estrogen receptor positive (ERα+) breast cancers to antiestrogens is a major factor in the mortality of this disease. Although activation of ERα in the absence of ligand is hypothesized to contribute to this resistance, the potency of this mechanism in vivo is not clear. Epidemiologic studies have strongly linked prolactin (PRL) to both development of ERα+ breast cancer and resistance to endocrine therapies. Here we employed genetically modified mouse models to examine the ability of PRL and cross talk with TGFα to activate ERα, using a mutated ERα, ERα(G525L), which is refractory to endogenous estrogens. We demonstrate that PRL promotes pubertal ERα-dependent mammary ductal elongation and gene expression in the absence of estrogen, which are abrogated by the antiestrogen, ICI 182,780 (ICI). PRL and TGFα together reduce sensitivity to estrogen, and 30% of their combined stimulation of ductal proliferation is inhibited by ICI, implicating ligand-independent activation of ERα as a component of their interaction. However, PRL/TGFα-induced heterogeneous ERα+ tumors developed more rapidly in the presence of ICI and contained altered transcripts for surface markers associated with epithelial subpopulations and increased signal transducer and activator of transcription 5b expression. Together, these data support strong interactions between PRL and estrogen on multiple levels. Ligand-independent activation of ERα suggests that PRL may contribute to resistance to antiestrogen therapies. However, these studies also underscore ERα-mediated moderation of tumor phenotype. In light of the high expression of PRL receptors in ERα+ cancers, understanding the actions of PRL and cross talk with other oncogenic factors and ERα itself has important implications for therapeutic strategies.

Funding information:
  • NINDS NIH HHS - R01 NS074870(United States)

Postnatal expression of BRAFV600E does not induce thyroid cancer in mouse models of thyroid papillary carcinoma.

  • Shimamura M
  • Endocrinology
  • 2013 Nov 21

Literature context:


Abstract:

The mutant BRAF (BRAF(V600E)) is the most common genetic alteration in papillary thyroid carcinomas (PTCs). The oncogenicity of this mutation has been shown by some genetically engineered mouse models. However, in these mice, BRAF(V600E) is expressed in all the thyroid cells from the fetal periods, and suppresses thyroid function, thereby leading to TSH elevation, which by itself promotes thyroid tumorigenesis. To overcome these problems, we exploited 2 different approaches, both of which allowed temporally and spatially restricted expression of BRAF(V600E) in the thyroid glands. First, we generated conditional transgenic mice harboring the loxP-neo(R)-loxP-BRAF(V600E)-internal ribosome entry site-green fluorescent protein sequence [Tg(LNL-BRAF(V600E))]. The double transgenic mice (LNL-BRAF(V600E);TPO-Cre) were derived from a high expressor line of Tg(LNL-BRAF(V600E)) mice and TPO-Cre mice; the latter expresses Cre DNA recombinase under the control of thyroid-specific thyroid peroxidase (TPO) promoter and developed PTC-like lesions in early life under normal serum TSH levels due to mosaic recombination. In contrast, injection of adenovirus expressing Cre under the control of another thyroid-specific thyroglobulin (Tg) promoter (Ad-TgP-Cre) into the thyroids of LNL-BRAF(V600E) mice did not induce tumor formation despite detection of BRAF(V600E) and pERK in a small fraction of thyroid cells. Second, postnatal expression of BRAF(V600E) in a small number of thyroid cells was also achieved by injecting the lentivirus expressing loxP-green fluorescent protein-loxP-BRAF(V600E) into the thyroids of TPO-Cre mice; however, no tumor development was again observed. These results suggest that BRAF(V600E) does not appear to induce PTC-like lesions when expressed in a fraction of thyroid cells postnatally under normal TSH concentrations.

Funding information:
  • NIH HHS - DP5 OD017895(United States)

Close homologue of adhesion molecule L1 promotes survival of Purkinje and granule cells and granule cell migration during murine cerebellar development.

  • Jakovcevski I
  • J. Comp. Neurol.
  • 2009 Apr 10

Literature context:


Abstract:

Several L1-related adhesion molecules, expressed in a well-coordinated temporospatial pattern during development, are important for fine tuning of specific cerebellar circuitries. We tested the hypothesis that CHL1, the close homologue of L1, abundantly expressed in the developing and adult cerebellum, is also required for normal cerebellar histogenesis. We found that constitutive ablation of CHL1 in mice caused significant loss (20-23%) of Purkinje and granule cells in the mature 2-month-old cerebellum. The ratio of stellate/basket interneurons to Purkinje cells was abnormally high (+38%) in CHL1-deficient (CHL1-/-) mice compared with wild-type (CHL1+/+) littermates, but the gamma-aminobutyric acid (GABA)ergic synaptic inputs to Purkinje cell bodies and dendrites were normal, as were numbers of Golgi interneurons, microglia, astrocytes, and Bergmann glia. Purkinje cell loss occurred before the first postnatal week and was associated with enhanced apoptosis, presumably as a consequence of CHL1 deficiency in afferent axons. In contrast, generation of granule cells, as indicated by in vivo analyses of cell proliferation and death, was unaffected in 1-week-old CHL1-/- mice, but numbers of migrating granule cells in the molecular layer were increased. This increase was likely related to retarded cell migration because CHL1-/- granule cells migrated more slowly than CHL1+/+ cells in vitro, and Bergmann glial processes guiding migration in vivo expressed CHL1 in wild-type mice. Granule cell deficiency in adult CHL1-/- mice appeared to result from decreased precursor cell proliferation after the first postnatal week. Our results indicate that CHL1 promotes Purkinje and granule cell survival and granule cell migration during cerebellar development.

Funding information:
  • NICHD NIH HHS - P30 HD15052(United States)

Embryonic and postnatal development of microglial cells in the mouse retina.

  • Santos AM
  • J. Comp. Neurol.
  • 2008 Jan 10

Literature context:


Abstract:

Macrophage/microglial cells in the mouse retina during embryonic and postnatal development were studied by immunocytochemistry with Iba1, F4/80, anti-CD45, and anti-CD68 antibodies and by tomato lectin histochemistry. These cells were already present in the retina of embryos aged 11.5 days (E11.5) in association with cell death. At E12.5 some macrophage/microglial cells also appeared in peripheral regions of the retina with no apparent relationship with cell death. Immediately before birth microglial cells were present in the neuroblastic, inner plexiform (IPL), and ganglion cell (GCL) layers, and their distribution suggested that they entered the retina from the ciliary margin and the vitreous. The density of retinal microglial cells strongly decreased at birth, increased during the first postnatal week as a consequence of the entry of microglial precursors into the retina from the vitreous, and subsequently decreased owing to the cessation of microglial entry and the increase in retina size. The mature topographical distribution pattern of microglia emerged during postnatal development of the retina, apparently by radial migration of microglial cells from the vitreal surface in a vitreal-to-scleral direction. Whereas microglial cells were only seen in the GCL and IPL at birth, they progressively appeared in more scleral layers at increasing postnatal ages. Thus, microglial cells were present within all layers of the retina except the outer nuclear layer at the beginning of the second postnatal week. Once microglial cells reached their definitive location, they progressively ramified.

Funding information:
  • NEI NIH HHS - EY002520(United States)