RESUMO
Remyelination failure in diseases like multiple sclerosis (MS) was thought to involve suppressed maturation of oligodendrocyte precursors; however, oligodendrocytes are present in MS lesions yet lack myelin production. We found that oligodendrocytes in the lesions are epigenetically silenced. Developing a transgenic reporter labeling differentiated oligodendrocytes for phenotypic screening, we identified a small-molecule epigenetic-silencing-inhibitor (ESI1) that enhances myelin production and ensheathment. ESI1 promotes remyelination in animal models of demyelination and enables de novo myelinogenesis on regenerated CNS axons. ESI1 treatment lengthened myelin sheaths in human iPSC-derived organoids and augmented (re)myelination in aged mice while reversing age-related cognitive decline. Multi-omics revealed that ESI1 induces an active chromatin landscape that activates myelinogenic pathways and reprograms metabolism. Notably, ESI1 triggered nuclear condensate formation of master lipid-metabolic regulators SREBP1/2, concentrating transcriptional co-activators to drive lipid/cholesterol biosynthesis. Our study highlights the potential of targeting epigenetic silencing to enable CNS myelin regeneration in demyelinating diseases and aging.
Assuntos
Epigênese Genética , Bainha de Mielina , Oligodendroglia , Remielinização , Animais , Bainha de Mielina/metabolismo , Humanos , Camundongos , Remielinização/efeitos dos fármacos , Oligodendroglia/metabolismo , Sistema Nervoso Central/metabolismo , Camundongos Endogâmicos C57BL , Rejuvenescimento , Células-Tronco Pluripotentes Induzidas/metabolismo , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Organoides/metabolismo , Organoides/efeitos dos fármacos , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/genética , Diferenciação Celular/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/farmacologia , Masculino , Regeneração/efeitos dos fármacos , Esclerose Múltipla/metabolismo , Esclerose Múltipla/genética , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/patologiaRESUMO
Establishment of oligodendrocyte identity is crucial for subsequent events of myelination in the CNS. Here, we demonstrate that activation of ATP-dependent SWI/SNF chromatin-remodeling enzyme Smarca4/Brg1 at the differentiation onset is necessary and sufficient to initiate and promote oligodendrocyte lineage progression and maturation. Genome-wide multistage studies by ChIP-seq reveal that oligodendrocyte-lineage determination factor Olig2 functions as a prepatterning factor to direct Smarca4/Brg1 to oligodendrocyte-specific enhancers. Recruitment of Smarca4/Brg1 to distinct subsets of myelination regulatory genes is developmentally regulated. Functional analyses of Smarca4/Brg1 and Olig2 co-occupancy relative to chromatin epigenetic marking uncover stage-specific cis-regulatory elements that predict sets of transcriptional regulators controlling oligodendrocyte differentiation. Together, our results demonstrate that regulation of the functional specificity and activity of a Smarca4/Brg1-dependent chromatin-remodeling complex by Olig2, coupled with transcriptionally linked chromatin modifications, is critical to precisely initiate and establish the transcriptional program that promotes oligodendrocyte differentiation and subsequent myelination of the CNS.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular , Montagem e Desmontagem da Cromatina , Elementos Facilitadores Genéticos , Proteínas do Tecido Nervoso/metabolismo , Oligodendroglia/citologia , Animais , Encéfalo/citologia , Células Cultivadas , DNA Helicases/metabolismo , Regulação da Expressão Gênica , Camundongos , Camundongos Knockout , Proteínas Nucleares/metabolismo , Fator de Transcrição 2 de Oligodendrócitos , Oligodendroglia/metabolismo , Ratos , Medula Espinal/citologia , Fatores de Transcrição/metabolismoRESUMO
Medulloblastoma (MB) is the most common malignant childhood brain tumour1,2, yet the origin of the most aggressive subgroup-3 form remains elusive, impeding development of effective targeted treatments. Previous analyses of mouse cerebella3-5 have not fully defined the compositional heterogeneity of MBs. Here we undertook single-cell profiling of freshly isolated human fetal cerebella to establish a reference map delineating hierarchical cellular states in MBs. We identified a unique transitional cerebellar progenitor connecting neural stem cells to neuronal lineages in developing fetal cerebella. Intersectional analysis revealed that the transitional progenitors were enriched in aggressive MB subgroups, including group 3 and metastatic tumours. Single-cell multi-omics revealed underlying regulatory networks in the transitional progenitor populations, including transcriptional determinants HNRNPH1 and SOX11, which are correlated with clinical prognosis in group 3 MBs. Genomic and Hi-C profiling identified de novo long-range chromatin loops juxtaposing HNRNPH1/SOX11-targeted super-enhancers to cis-regulatory elements of MYC, an oncogenic driver for group 3 MBs. Targeting the transitional progenitor regulators inhibited MYC expression and MYC-driven group 3 MB growth. Our integrated single-cell atlases of human fetal cerebella and MBs show potential cell populations predisposed to transformation and regulatory circuitries underlying tumour cell states and oncogenesis, highlighting hitherto unrecognized transitional progenitor intermediates predictive of disease prognosis and potential therapeutic vulnerabilities.
Assuntos
Neoplasias Encefálicas , Transformação Celular Neoplásica , Feto , Meduloblastoma , Humanos , Neoplasias Encefálicas/patologia , Transformação Celular Neoplásica/patologia , Neoplasias Cerebelares/patologia , Cerebelo/citologia , Cerebelo/patologia , Feto/citologia , Feto/patologia , Meduloblastoma/patologia , Células-Tronco Neurais/citologia , Células-Tronco Neurais/patologia , PrognósticoRESUMO
Oligodendrocyte myelination and remyelination after injury are intricately regulated by various intrinsic and extrinsic factors, including transcriptional regulators. Among these, the zinc-finger protein ZFP488 is an oligodendrocyte-enriched transcriptional regulator that promotes oligodendrocyte differentiation in the developing neural tube and in oligodendroglial cell lines. However, the specific in vivo genetic requirements for ZFP488 during oligodendrocyte development and remyelination have not been defined. To address this gap, we generated a lineage-traceable ZFP488 knock-out mouse line, wherein a H2b-GFP reporter replaces the ZFP488-coding region. Using these mice of either sex, we examined the dynamics of ZFP488 expression from the endogenous promoter in the developing central nervous system (CNS). We observed a unique expression pattern in the oligodendrocyte lineage, with ZFP488 expression particularly enriched in differentiated oligodendrocytes. ZFP488 loss resulted in delayed myelination in the developing CNS and impaired remyelination after demyelinating injury in the brain. Integrated transcriptomic and genomic profiling further revealed that ZFP488 loss decreased expression of myelination-associated genes but not oligodendrocyte progenitor-associated genes, suggesting that ZFP488 serves as a positive regulator of myelination by regulating maturation programs. Thus, our genetic loss-of-function study revealed that ZFP488 regulates a stage-dependent differentiation program that controls the timing of CNS myelination and remyelination.Significance statement Precise timing of myelination is essential for efficient neural communication and is linked to the development of cognitive and motor skills as well as myelin repair after injury. ZFP488 is a transcriptional regulator enriched in oligodendrocytes, however its in vivo functions remain unclear. By generating ZFP488 loss-of-function mice, we demonstrated that ZFP488 is critical for the timing of myelination and remyelination and that its loss impaired the initial differentiation of oligodendrocytes but not their precursor formation and proliferation. Transcriptomic profiling showed that ZFP488 functions as a positive regulator of myelination by modulating oligodendrocyte maturation programs. Thus, our findings underscore the important role of ZFP488 in myelination and the potential of ZFP488 augmentation as an avenue to enhance oligodendrocyte regeneration.
RESUMO
Distinct neural stem cells (NSCs) reside in different regions of the subventricular zone (SVZ) and generate multiple olfactory bulb (OB) interneuron subtypes in the adult brain. However, the molecular mechanisms underlying such NSC heterogeneity remain largely unknown. Here, we show that the basic helix-loop-helix transcription factor Olig2 defines a subset of NSCs in the early postnatal and adult SVZ. Olig2-expressing NSCs exist broadly but are most enriched in the ventral SVZ along the dorsoventral axis complementary to dorsally enriched Gsx2-expressing NSCs. Comparisons of Olig2-expressing NSCs from early embryonic to adult stages using single cell transcriptomics reveal stepwise developmental changes in their cell cycle and metabolic properties. Genetic studies further show that cross-repression contributes to the mutually exclusive expression of Olig2 and Gsx2 in NSCs/progenitors during embryogenesis, but that their expression is regulated independently from each other in adult NSCs. Finally, lineage-tracing and conditional inactivation studies demonstrate that Olig2 plays an important role in the specification of OB interneuron subtypes. Altogether, our study demonstrates that Olig2 defines a unique subset of adult NSCs enriched in the ventral aspect of the adult SVZ.
Assuntos
Interneurônios/metabolismo , Ventrículos Laterais/crescimento & desenvolvimento , Ventrículos Laterais/metabolismo , Células-Tronco Neurais/metabolismo , Bulbo Olfatório/crescimento & desenvolvimento , Bulbo Olfatório/metabolismo , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Animais , Ciclo Celular/genética , Linhagem da Célula/genética , Células Cultivadas , Feminino , Técnicas de Inativação de Genes , Ventrículos Laterais/embriologia , Masculino , Camundongos , Camundongos Knockout , Neurogênese/genética , Bulbo Olfatório/embriologia , Fator de Transcrição 2 de Oligodendrócitos/genética , Transdução de Sinais/genética , Transcriptoma/genéticaRESUMO
Huntington's disease and juvenile-onset schizophrenia have long been regarded as distinct disorders. However, both manifest cell-intrinsic abnormalities in glial differentiation, with resultant astrocytic dysfunction and hypomyelination. To assess whether a common mechanism might underlie the similar glial pathology of these otherwise disparate conditions, we used comparative correlation network approaches to analyse RNA-sequencing data from human glial progenitor cells (hGPCs) produced from disease-derived pluripotent stem cells. We identified gene sets preserved between Huntington's disease and schizophrenia hGPCs yet distinct from normal controls that included 174 highly connected genes in the shared disease-associated network, focusing on genes involved in synaptic signalling. These synaptic genes were largely suppressed in both schizophrenia and Huntington's disease hGPCs, and gene regulatory network analysis identified a core set of upstream regulators of this network, of which OLIG2 and TCF7L2 were prominent. Among their downstream targets, ADGRL3, a modulator of glutamatergic synapses, was notably suppressed in both schizophrenia and Huntington's disease hGPCs. Chromatin immunoprecipitation sequencing confirmed that OLIG2 and TCF7L2 each bound to the regulatory region of ADGRL3, whose expression was then rescued by lentiviral overexpression of these transcription factors. These data suggest that the disease-associated suppression of OLIG2 and TCF7L2-dependent transcription of glutamate signalling regulators may impair glial receptivity to neuronal glutamate. The consequent loss of activity-dependent mobilization of hGPCs may yield deficient oligodendrocyte production, and hence the hypomyelination noted in these disorders, as well as the disrupted astrocytic differentiation and attendant synaptic dysfunction associated with each. Together, these data highlight the importance of convergent glial molecular pathology in both the pathogenesis and phenotypic similarities of two otherwise unrelated disorders, Huntington's disease and schizophrenia.
Assuntos
Doença de Huntington , Neuroglia , Esquizofrenia , Doença de Huntington/genética , Doença de Huntington/metabolismo , Doença de Huntington/patologia , Humanos , Esquizofrenia/genética , Esquizofrenia/metabolismo , Neuroglia/metabolismo , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Fator de Transcrição 2 de Oligodendrócitos/genética , Redes Reguladoras de Genes , Células-Tronco Pluripotentes/metabolismoRESUMO
Oligodendrocyte differentiation and myelination in the central nervous system are controlled and coordinated by a complex gene regulatory network that contains several transcription factors, including Zfp488 and Nkx2.2. Despite the proven role in oligodendrocyte differentiation little is known about the exact mode of Zfp488 and Nkx2.2 action, including their target genes. Here, we used overexpression of Zfp488 and Nkx2.2 in differentiating CG4 cells to identify aspects of the oligodendroglial expression profile that depend on these transcription factors. Although both transcription factors are primarily described as repressors, the detected changes argue for an additional function as activators. Among the genes activated by both Zfp488 and Nkx2.2 was the G protein-coupled receptor Gpr37 that is important during myelination. In agreement with a positive effect on Gpr37 expression, downregulation of the G protein-coupled receptor was observed in Zfp488- and in Nkx2.2-deficient oligodendrocytes in the mouse. We also identified several potential regulatory regions of the Gpr37 gene. Although Zfp488 and Nkx2.2 both bind to one of the regulatory regions downstream of the Gpr37 gene in vivo, none of the regulatory regions was activated by either transcription factor alone. Increased activation by Zfp488 or Nkx2.2 was only observed in the presence of Sox10, a transcription factor continuously present in oligodendroglial cells. Our results argue that both Zfp488 and Nkx2.2 also act as transcriptional activators during oligodendrocyte differentiation and cooperate with Sox10 to allow the expression of Gpr37 as a modulator of the myelination process.
Assuntos
Diferenciação Celular , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodomínio , Oligodendroglia , Receptores Acoplados a Proteínas G , Fatores de Transcrição SOXE , Fatores de Transcrição , Animais , Feminino , Masculino , Camundongos , Diferenciação Celular/fisiologia , Proteínas de Homeodomínio/metabolismo , Proteínas de Homeodomínio/genética , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética , Fatores de Transcrição SOXE/metabolismo , Fatores de Transcrição SOXE/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genéticaRESUMO
The mechanistic target of rapamycin (mTOR) is a central regulator of cell growth and an attractive anticancer target that integrates diverse signals to control cell proliferation. Previous studies using mTOR inhibitors have shown that mTOR targeting suppresses gene expression and cell proliferation. To date, however, mTOR-targeted therapies in cancer have seen limited efficacy, and one key issue is related to the development of evasive resistance. In this manuscript, through the use of a gene targeting mouse model, we have found that inducible deletion of mTOR in hematopoietic stem cells (HSCs) results in a loss of quiescence and increased proliferation. Adaptive to the mTOR loss, mTOR-/- HSCs increase chromatin accessibility and activate global gene expression, contrary to the effects of short-term inhibition by mTOR inhibitors. Mechanistically, such genomic changes are due to a rewiring and adaptive activation of the ERK/MNK/eIF4E signaling pathway that enhances the protein translation of RNA polymerase II, which in turn leads to increased c-Myc gene expression, allowing the HSCs to thrive despite the loss of a functional mTOR pathway. This adaptive mechanism can also be utilized by leukemia cells undergoing long-term mTOR inhibitor treatment to confer resistance to mTOR drug targeting. The resistance can be counteracted by MNK, CDK9, or c-Myc inhibition. These results provide insights into the physiological role of mTOR in mammalian stem cell regulation and implicate a mechanism of evasive resistance in the context of mTOR targeting.
Assuntos
Proliferação de Células/efeitos dos fármacos , Células-Tronco Hematopoéticas/metabolismo , Sirolimo/farmacologia , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/genética , Animais , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/genética , Cromatina/metabolismo , Sequenciamento de Cromatina por Imunoprecipitação , Quinase 9 Dependente de Ciclina/metabolismo , Fator de Iniciação 4E em Eucariotos/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Marcação de Genes , Genes myc/genética , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/genética , Camundongos , Camundongos Knockout , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , RNA Polimerase II/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
The oligodendrocyte (OL) lineage transcription factor Olig2 is expressed throughout oligodendroglial development and is essential for oligodendroglial progenitor specification and differentiation. It was previously reported that deletion of Olig2 enhanced the maturation and myelination of immature OLs and accelerated the remyelination process. However, by analyzing multiple Olig2 conditional KO mouse lines (male and female), we conclude that Olig2 has the opposite effect and is required for OL maturation and remyelination. We found that deletion of Olig2 in immature OLs driven by an immature OL-expressing Plp1 promoter resulted in defects in OL maturation and myelination, and did not enhance remyelination after demyelination. Similarly, Olig2 deletion during premyelinating stages in immature OLs using Mobp or Mog promoter-driven Cre lines also did not enhance OL maturation in the CNS. Further, we found that Olig2 was not required for myelin maintenance in mature OLs but was critical for remyelination after lysolecithin-induced demyelinating injury. Analysis of genomic occupancy in immature and mature OLs revealed that Olig2 targets the enhancers of key myelination-related genes for OL maturation from immature OLs. Together, by leveraging multiple immature OL-expressing Cre lines, these studies indicate that Olig2 is essential for differentiation and myelination of immature OLs and myelin repair. Our findings raise fundamental questions about the previously proposed role of Olig2 in opposing OL myelination and highlight the importance of using Cre-dependent reporter(s) for lineage tracing in studying cell state progression.SIGNIFICANCE STATEMENT Identification of the regulators that promote oligodendrocyte (OL) myelination and remyelination is important for promoting myelin repair in devastating demyelinating diseases. Olig2 is expressed throughout OL lineage development. Ablation of Olig2 was reported to induce maturation, myelination, and remyelination from immature OLs. However, lineage-mapping analysis of Olig2-ablated cells was not conducted. Here, by leveraging multiple immature OL-expressing Cre lines, we observed no evidence that Olig2 ablation promotes maturation or remyelination of immature OLs. Instead, we find that Olig2 is required for immature OL maturation, myelination, and myelin repair. These data raise fundamental questions about the proposed inhibitory role of Olig2 against OL maturation and remyelination. Our findings highlight the importance of validating genetic manipulation with cell lineage tracing in studying myelination.
Assuntos
Doenças Desmielinizantes , Remielinização , Animais , Feminino , Masculino , Camundongos , Diferenciação Celular , Doenças Desmielinizantes/metabolismo , Bainha de Mielina/metabolismo , Fator de Transcrição 2 de Oligodendrócitos/genética , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Oligodendroglia/metabolismo , Camundongos KnockoutRESUMO
The chromatin remodeler CHD8 represents a high-confidence risk factor in autism, a multistage progressive neurologic disorder, however the underlying stage-specific functions remain elusive. In this study, by analyzing Chd8 conditional knock-out mice (male and female), we find that CHD8 controls cortical neural stem/progenitor cell (NSC) proliferation and survival in a stage-dependent manner. Strikingly, inducible genetic deletion reveals that CHD8 is required for the production and fitness of transit-amplifying intermediate progenitors (IPCs) essential for upper-layer neuron expansion in the embryonic cortex. p53 loss of function partially rescues apoptosis and neurogenesis defects in the Chd8-deficient brain. Further, transcriptomic and epigenomic profiling indicates that CHD8 regulates the chromatin accessibility landscape to activate neurogenesis-promoting factors including TBR2, a key regulator of IPC neurogenesis, while repressing DNA damage- and p53-induced apoptotic programs. In the adult brain, CHD8 depletion impairs forebrain neurogenesis by impeding IPC differentiation from NSCs in both subventricular and subgranular zones; however, unlike in embryos, it does not affect NSC proliferation and survival. Treatment with an antidepressant approved by the Federal Drug Administration (FDA), fluoxetine, partially restores adult hippocampal neurogenesis in Chd8-ablated mice. Together, our multistage functional studies identify temporally specific roles for CHD8 in developmental and adult neurogenesis, pointing to a potential strategy to enhance neurogenesis in the CHD8-deficient brain.SIGNIFICANCE STATEMENT The role of the high-confidence autism gene CHD8 in neurogenesis remains incompletely understood. Here, we identify a stage-specific function of CHD8 in development of NSCs in developing and adult brains by conserved, yet spatiotemporally distinct, mechanisms. In embryonic cortex, CHD8 is critical for the proliferation, survival, and differentiation of both NSC and IPCs during cortical neurogenesis. In adult brain, CHD8 is required for IPC generation but not the proliferation and survival of adult NSCs. Treatment with FDA-approved antidepressant fluoxetine partially rescues the adult neurogenesis defects in CHD8 mutants. Thus, our findings help resolve CHD8 functions throughout life during embryonic and adult neurogenesis and point to a potential avenue to promote neurogenesis in CHD8 deficiency.
Assuntos
Transtorno Autístico , Cromatina , Proteínas de Ligação a DNA , Neurogênese , Animais , Feminino , Masculino , Camundongos , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fluoxetina , Hipocampo/metabolismo , Camundongos Knockout , Neurogênese/fisiologia , Proteína Supressora de Tumor p53 , ProsencéfaloRESUMO
The Chd8 gene encodes a member of the chromodomain helicase DNA-binding (CHD) family of SNF2H-like adenosine triphosphate (ATP)-dependent chromatin remodeler, the mutations of which define a subtype of autism spectrum disorders. Increasing evidence from recent studies indicates that ATP-dependent chromatin-remodeling genes are involved in the control of crucial gene-expression programs in hematopoietic stem/progenitor cell (HSPC) regulation. In this study, we identified CHD8 as a specific and essential regulator of normal hematopoiesis. Loss of Chd8 leads to severe anemia, pancytopenia, bone marrow failure, and engraftment failure related to a drastic depletion of HSPCs. CHD8 forms a complex with ATM and its deficiency increases chromatin accessibility and drives genomic instability in HSPCs causing an activation of ATM kinase that further stabilizes P53 protein by phosphorylation and leads to increased HSPC apoptosis. Deletion of P53 rescues the apoptotic defects of HSPCs and restores overall hematopoiesis in Chd8-/- mice. Our findings demonstrate that chromatin organization by CHD8 is uniquely necessary for the maintenance of hematopoiesis by integrating the ATM-P53-mediated survival of HSPCs.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Hematopoese , Células-Tronco Hematopoéticas/citologia , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Sobrevivência Celular , Células Cultivadas , Proteínas de Ligação a DNA/genética , Deleção de Genes , Células-Tronco Hematopoéticas/metabolismo , Camundongos , Pancitopenia/genética , Pancitopenia/metabolismo , Estabilidade ProteicaRESUMO
The repair and functional recovery of the nervous system is a highly regulated process that requires the coordination of many different components including the proper myelination of regenerated axons. Dysmyelination and remyelination failures after injury result in defective nerve conduction, impairing normal nervous system functions. There are many convergent regulatory networks and signaling mechanisms between development and regeneration. For instance, the regulatory mechanisms required for oligodendrocyte lineage progression could potentially play fundamental roles in myelin repair. In recent years, epigenetic chromatin modifications have been implicated in CNS myelination and functional nerve restoration. The pro-regenerative transcriptional program is likely silenced or repressed in adult neural cells including neurons and myelinating cells in the central and peripheral nervous systems limiting the capacity for repair after injury. In this review, we will discuss the roles of epigenetic mechanisms, including histone modifications, chromatin remodeling, and DNA methylation, in the maintenance and establishment of the myelination program during normal oligodendrocyte development and regeneration. We also discuss how these epigenetic processes impact myelination and axonal regeneration, and facilitate the improvement of current preclinical therapeutics for functional nerve regeneration in neurodegenerative disorders or after injury.
Assuntos
Cromatina/metabolismo , Epigenômica/métodos , Regeneração Nervosa/genética , Animais , HumanosRESUMO
Yap1 and its paralogue Taz largely control epithelial tissue growth. We have identified that hematopoietic stem cell (HSC) fitness response to stress depends on Yap1 and Taz. Deletion of Yap1 and Taz induces a loss of HSC quiescence, symmetric self-renewal ability, and renders HSC more vulnerable to serial myeloablative 5-fluorouracil treatment. This effect depends on the predominant cytosolic polarization of Yap1 through a PDZ domain-mediated interaction with the scaffold Scribble. Scribble and Yap1 coordinate to control cytoplasmic Cdc42 activity and HSC fate determination in vivo. Deletion of Scribble disrupts Yap1 copolarization with Cdc42 and decreases Cdc42 activity, resulting in increased self-renewing HSC with competitive reconstitution advantages. These data suggest that Scribble/Yap1 copolarization is indispensable for Cdc42-dependent activity on HSC asymmetric division and fate. The combined loss of Scribble, Yap1, and Taz results in transcriptional upregulation of Rac-specific guanine nucleotide exchange factors, Rac activation, and HSC fitness restoration. Scribble links Cdc42 and the cytosolic functions of the Hippo signaling cascade in HSC fate determination.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Diferenciação Celular/genética , Células-Tronco Hematopoéticas/metabolismo , Proteínas de Membrana/genética , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Biomarcadores , Proliferação de Células , Autorrenovação Celular , Células Cultivadas , Células-Tronco Hematopoéticas/citologia , Humanos , Proteínas de Membrana/metabolismo , Transdução de Sinais , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Proteínas de Sinalização YAP , Proteína cdc42 de Ligação ao GTP/genética , Proteína cdc42 de Ligação ao GTP/metabolismoRESUMO
Oligodendrocyte precursor cells (OPCs) constitute the main proliferative cells in the adult brain, and deregulation of OPC proliferation-differentiation balance results in either glioma formation or defective adaptive (re)myelination. OPC differentiation requires significant genetic reprogramming, implicating chromatin remodeling. Mounting evidence indicates that chromatin remodelers play important roles during normal development and their mutations are associated with neurodevelopmental defects, with CHD7 haploinsuficiency being the cause of CHARGE syndrome and CHD8 being one of the strongest autism spectrum disorder (ASD) high-risk-associated genes. Herein, we report on uncharacterized functions of the chromatin remodelers Chd7 and Chd8 in OPCs. Their OPC-chromatin binding profile, combined with transcriptome and chromatin accessibility analyses of Chd7-deleted OPCs, demonstrates that Chd7 protects nonproliferative OPCs from apoptosis by chromatin closing and transcriptional repression of p53 Furthermore, Chd7 controls OPC differentiation through chromatin opening and transcriptional activation of key regulators, including Sox10, Nkx2.2, and Gpr17 However, Chd7 is dispensable for oligodendrocyte stage progression, consistent with Chd8 compensatory function, as suggested by their common chromatin-binding profiles and genetic interaction. Finally, CHD7 and CHD8 bind in OPCs to a majority of ASD risk-associated genes, suggesting an implication of oligodendrocyte lineage cells in ASD neurological defects. Our results thus offer new avenues to understand and modulate the CHD7 and CHD8 functions in normal development and disease.
Assuntos
Montagem e Desmontagem da Cromatina , Proteínas de Ligação a DNA/metabolismo , Oligodendroglia/metabolismo , Células-Tronco/metabolismo , Animais , Transtorno do Espectro Autista/genética , Transtorno do Espectro Autista/metabolismo , Transtorno do Espectro Autista/patologia , Síndrome CHARGE/genética , Síndrome CHARGE/metabolismo , Síndrome CHARGE/patologia , Sobrevivência Celular , Proteínas de Ligação a DNA/genética , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodomínio , Camundongos , Camundongos Knockout , Proteínas Nucleares , Oligodendroglia/patologia , Células-Tronco/patologia , Fatores de TranscriçãoRESUMO
Brain regeneration and tumorigenesis are complex processes involving in changes in chromatin structure to regulate cellular states at the molecular and genomic level. The modulation of chromatin structure dynamics is critical for maintaining progenitor cell plasticity, growth and differentiation. Oligodendrocyte precursor cells (OPC) can be differentiated into mature oligodendrocytes, which produce myelin sheathes to permit saltatory nerve conduction. OPCs and their primitive progenitors such as pri-OPC or pre-OPC are highly adaptive and plastic during injury repair or brain tumor formation. Recent studies indicate that chromatin modifications and epigenetic homeostasis through histone modifying enzymes shape genomic regulatory landscape conducive to OPC fate specification, lineage differentiation, maintenance of myelin sheaths, as well as brain tumorigenesis. Thus, histone modifications can be convergent mechanisms in regulating OPC plasticity and malignant transformation. In this review, we will focus on the impact of histone modifying enzymes in modulating OPC plasticity during normal development, myelin regeneration and tumorigenesis.
Assuntos
Neoplasias Encefálicas/genética , Regeneração do Cérebro/genética , Carcinogênese/genética , Plasticidade Celular , Regulação Neoplásica da Expressão Gênica/genética , Células Precursoras de Oligodendrócitos , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Epigênese Genética , Histona Acetiltransferases/genética , Código das Histonas/genética , Histona Metiltransferases/genética , Humanos , Bainha de Mielina/metabolismo , Neuroglia , Complexo Repressor Polycomb 2/genéticaRESUMO
NG2 cells are a resident glial progenitor cell population that is uniformly distributed throughout the developing and mature mammalian CNS. Those in the postnatal CNS generate exclusively myelinating and non-myelinating oligodendrocytes and are thus equated with oligodendrocyte precursor cells. Prenatally, NG2 cells in the ventral gray matter of the forebrain generate protoplasmic astrocytes as well as oligodendrocytes. The fate conversion from NG2 cells into protoplasmic astrocytes is dependent on downregulation of the key oligodendrocyte transcription factor Olig2. We showed previously that constitutive deletion of Olig2 in NG2 cells converts NG2 cells in the neocortex into protoplasmic astrocytes at the expense of oligodendrocytes. In this study, we show that postnatal deletion of Olig2 caused NG2 cells in the neocortex but not in other gray matter regions to become protoplasmic astrocytes. However, NG2 cells in the neocortex became more resistant to astrocyte fate switch over the first 3 postnatal weeks. Fewer NG2 cells differentiated into astrocytes and did so with longer latency after Olig2 deletion at postnatal day 18 (P18) compared with deletion at P2. The high-mobility group transcription factor Sox10 was not downregulated for at least 1 month after Olig2 deletion at P18 despite an early transient upregulation of the astrocyte transcription factor NFIA. Furthermore, inhibiting cell proliferation in slice culture reduced astrocyte differentiation from Olig2-deleted perinatal NG2 cells, suggesting that cell division might facilitate nuclear reorganization needed for astrocyte transformation.SIGNIFICANCE STATEMENT NG2 cells are glial progenitor cells that retain a certain degree of lineage plasticity. In the normal postnatal neocortex, they generate mostly oligodendrocyte lineage cells. When the oligodendrocyte transcription factor Olig2 is deleted in NG2 cells in the neocortex, they switch their fate to protoplasmic astrocytes. However, the efficiency of the fate switch decreases with age over the first 3 postnatal weeks and is reduced when cell proliferation is inhibited. As the neocortex matures, sustained expression of the oligodendrocyte lineage-specific key transcription factor Sox10 becomes less dependent on Olig2. Together, our findings suggest a gradual stabilization of the oligodendrocyte lineage genes and loss of lineage plasticity during the first 3 weeks after birth, possibly due to nuclear reorganization.
Assuntos
Astrócitos/citologia , Diferenciação Celular/fisiologia , Células-Tronco Neurais/citologia , Neurogênese/fisiologia , Fator de Transcrição 2 de Oligodendrócitos/metabolismo , Animais , Linhagem da Célula , Camundongos , Camundongos Knockout , Neocórtex/citologia , Oligodendroglia/citologiaRESUMO
Bergmann glia facilitate granule neuron migration during development and maintain the cerebellar organization and functional integrity. At present, molecular control of Bergmann glia specification from cerebellar radial glia is not fully understood. In this report, we show that ZEB2 (aka, SIP1 or ZFHX1B), a Mowat-Wilson syndrome-associated transcriptional regulator, is highly expressed in Bergmann glia, but hardly detectable in astrocytes in the cerebellum. The mice lacking Zeb2 in cerebellar radial glia exhibit severe deficits in Bergmann glia specification, and develop cerebellar cortical lamination dysgenesis and locomotion defects. In developing Zeb2-mutant cerebella, inward migration of granule neuron progenitors is compromised, the proliferation of glial precursors is reduced, and radial glia fail to differentiate into Bergmann glia in the Purkinje cell layer. In contrast, Zeb2 ablation in granule neuron precursors or oligodendrocyte progenitors does not affect Bergmann glia formation, despite myelination deficits caused by Zeb2 mutation in the oligodendrocyte lineage. Transcriptome profiling identified that ZEB2 regulates a set of Bergmann glia-related genes and FGF, NOTCH, and TGFß/BMP signaling pathway components. Our data reveal that ZEB2 acts as an integral regulator of Bergmann glia formation ensuring maintenance of cerebellar integrity, suggesting that ZEB2 dysfunction in Bergmann gliogenesis might contribute to motor deficits in Mowat-Wilson syndrome.SIGNIFICANCE STATEMENT Bergmann glia are essential for proper cerebellar organization and functional circuitry, however, the molecular mechanisms that control the specification of Bergmann glia remain elusive. Here, we show that transcriptional factor ZEB2 is highly expressed in mature Bergmann glia, but not in cerebellar astrocytes. The mice lacking Zeb2 in cerebellar radial glia, but not oligodendrocyte progenitors or granular neuron progenitors, exhibit severe defects in Bergmann glia formation. The orderly radial scaffolding formed by Bergmann glial fibers critical for cerebellar lamination was not established in Zeb2 mutants, displaying motor behavior deficits. This finding demonstrates a previously unrecognized critical role for ZEB2 in Bergmann glia specification, and points to an important contribution of ZEB2 dysfunction to cerebellar motor disorders in Mowat-Wilson syndrome.
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Cerebelo/citologia , Cerebelo/crescimento & desenvolvimento , Neurogênese/genética , Neurogênese/fisiologia , Neuroglia/fisiologia , Homeobox 2 de Ligação a E-box com Dedos de Zinco/genética , Homeobox 2 de Ligação a E-box com Dedos de Zinco/fisiologia , Animais , Astrócitos/fisiologia , Contagem de Células , Cerebelo/fisiologia , Fácies , Perfilação da Expressão Gênica , Doença de Hirschsprung/genética , Deficiência Intelectual/genética , Locomoção/fisiologia , Camundongos , Camundongos Transgênicos , Microcefalia/genética , Células-Tronco Neurais/fisiologia , Oligodendroglia/fisiologia , Células de Purkinje/fisiologia , Transcriptoma/fisiologiaRESUMO
Recently, we identified biallelic mutations of SLC25A46 in patients with multiple neuropathies. Functional studies revealed that SLC25A46 may play an important role in mitochondrial dynamics by mediating mitochondrial fission. However, the cellular basis and pathogenic mechanism of the SLC25A46-related neuropathies are not fully understood. Thus, we generated a Slc25a46 knock-out mouse model. Mice lacking SLC25A46 displayed severe ataxia, mainly caused by degeneration of Purkinje cells. Increased numbers of small, unmyelinated and degenerated optic nerves as well as loss of retinal ganglion cells indicated optic atrophy. Compound muscle action potentials in peripheral nerves showed peripheral neuropathy associated with degeneration and demyelination in axons. Mutant cerebellar neurons have large mitochondria, which exhibit abnormal distribution and transport. Biochemically mutant mice showed impaired electron transport chain activity and accumulated autophagy markers. Our results suggest that loss of SLC25A46 causes degeneration in neurons by affecting mitochondrial dynamics and energy production.
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Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Proteínas de Transporte de Fosfato/genética , Proteínas de Transporte de Fosfato/metabolismo , Animais , Ataxia/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Dinâmica Mitocondrial/fisiologia , Mutação , Células Ganglionares da Retina/patologiaRESUMO
PURPOSE: Genetic diagnosis for children suffering from epilepsy has important implications for treatment, prognosis, and development of precision medicine strategies. METHODS: We performed exome sequencing (ES) or targeted sequencing on 733 children with epilepsy onset within the first year of life. We subgrouped our patients based on the onset age of seizure into neonatal and before 1 year (1-12 months), to compare the clinical and genetic features. RESULTS: The subgroups with different onset age of seizure showed different pathogenic variant spectrum, and the 1-year age group was more likely to have developmental delays than the neonate group (p = 0.000614). The diagnostic rate was 26.7% for targeted sequencing using a 2742-gene panel, and 42% for ES. We identified 12 genes, which covered 48.7% of diagnostic cases. Our data revealed that 41.9% of patients in the neonate group and 49.7% patients in the 1-year group had treatment options based on molecular diagnosis. CONCLUSION: The 12 most commonly implicated genes in this cohort and the genes with treatment options should be considered as part of the essential panel for early diagnosis of epilepsy onset, if large medical exome analyses or ES are not feasible as first-tier analysis. Genetic results are beginning to improve therapy by antiepileptic medication selections and precision medicine approaches.
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Epilepsia/genética , Povo Asiático/genética , China/epidemiologia , Estudos de Coortes , Eletroencefalografia , Epilepsia/diagnóstico , Epilepsia/epidemiologia , Exoma , Feminino , Testes Genéticos/métodos , Humanos , Lactente , Recém-Nascido , Masculino , Convulsões/genética , Sequenciamento do Exoma/métodosRESUMO
Hypoxic-ischemic encephalopathy (HIE) is a serious disease for neonates. However, present therapeutic strategies are not effective enough for treating HIE. Previous study showed that mesenchymal stem cells (MSCs) can exert neuroprotective effects for brain damage, but its mechanism remains elusive. Using in vitro coculture of rat cortical primary neurons and MSCs in HI conditions, we demonstrated that MSCs help increase brain derived neurotrophic factor (BDNF) and autophagy markers (LC3II and Beclin1) in the cultures and decrease cells death (lactate dehydrogenase levels). We demonstrated a similar mechanism using an in vivo rat model of HI in combination with MSCs transplantation. Using a behavioral study, we further showed that MSCs transplantation into the rat brain after HI injury can attenuate behavioral deficits. Finally, we found that the increase in BDNF and autophagy related factors after HI injury combined with MSCs transplantation can be reversed by anti-BDNF treatment and strengthen the point that the protective effects of BDNF work through inhibition of the mammalin target of rapamycin (mTOR) pathway. Collectively, we proposed that coculture/transplantation of MSCs after HI injury leads to increased BDNF expression and a subsequent reduction in mTOR pathway activation that results in increased autophagy and neuroprotection. This finding gives a hint to explore new strategies for treating neonates with HIE. Stem Cells 2018;36:1109-1121.