RESUMEN
In oligodendrocytes of the vertebrate central nervous system a complex network of transcriptional regulators is required to ensure correct and timely myelination of neuronal axons. Here we identify Zfp276, the only mammalian ZAD-domain containing zinc finger protein, as a transcriptional regulator of oligodendrocyte differentiation and central myelination downstream of Sox10. In the central nervous system, Zfp276 is exclusively expressed in mature oligodendrocytes. Oligodendroglial deletion of Zfp276 led to strongly reduced expression of myelin genes in the early postnatal mouse spinal cord. Retroviral overexpression of Zfp276 in cultured oligodendrocyte precursor cells induced precocious expression of maturation markers and myelin genes, further supporting its role in oligodendroglial differentiation. On the molecular level, Zfp276 directly binds to and represses Sox10-dependent gene regulatory regions of immaturity factors and functionally interacts with the transcriptional repressor Zeb2 to enable fast transition of oligodendrocytes to the myelinating stage.
Asunto(s)
Oligodendroglía , Médula Espinal/citología , Factores de Transcripción , Animales , Diferenciación Celular , Ratones , Vaina de Mielina/fisiología , Neurogénesis , Oligodendroglía/citología , Oligodendroglía/metabolismo , Médula Espinal/metabolismo , Células Madre , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
The HMG-domain containing transcription factor Sox10 plays a crucial role in regulating Schwann cell survival and differentiation and is expressed throughout the entire Schwann cell lineage. While its importance in peripheral myelination is well established, little is known about its role in the early stages of Schwann cell development. In a search for direct target genes of Sox10 in Schwann cell precursors, the transcriptional co-repressor Tle4 was identified. At least two regions upstream of the Tle4 gene appear involved in mediating the Sox10-dependent activation. Once induced, Tle4 works in tandem with the bHLH transcriptional repressor Hes1 and exerts a dual inhibitory effect on Sox10 by preventing the Sox10 protein from transcriptionally activating maturation genes and by suppressing Sox10 expression through known enhancers of the gene. This mechanism establishes a regulatory barrier that prevents premature activation of factors involved in differentiation and myelin formation by Sox10 in immature Schwann cells. The identification of Tle4 as a critical downstream target of Sox10 sheds light on the gene regulatory network in the early phases of Schwann cell development. It unravels an elaborate regulatory circuitry that fine-tunes the timing and extent of Schwann cell differentiation and myelin gene expression.
Asunto(s)
Diferenciación Celular , Proteínas de Unión al ADN , Factores de Transcripción SOXE , Células de Schwann , Animales , Humanos , Ratones , Ratas , Diferenciación Celular/genética , Proteínas Co-Represoras/metabolismo , Proteínas Co-Represoras/genética , Retroalimentación Fisiológica , Regulación de la Expresión Génica , Vaina de Mielina/metabolismo , Células de Schwann/metabolismo , Células de Schwann/citología , Factores de Transcripción SOXE/metabolismo , Factores de Transcripción SOXE/genética , Factor de Transcripción HES-1/metabolismo , Factor de Transcripción HES-1/genética , Proteínas de Unión al ADN/metabolismoRESUMEN
The high-mobility-group domain-containing transcription factor Sox9 confers glial competence to neuroepithelial precursors in the developing central nervous system and is an important determinant of astroglial and oligodendroglial specification. In oligodendroglial cells, it remains expressed in oligodendrocyte progenitor cells (OPCs) of the developing nervous system, but is shut off in differentiating oligodendrocytes as well as in OPCs that persist in the adult nervous system. To better understand the role of Sox9 in OPCs, we generated mouse models that allowed oligodendroglial expression of a Sox9 transgene during development or in the adult. With transgene expression beginning in the last trimester of pregnancy, the number of OPCs increased dramatically, followed by comparable gains in the number of pre-myelinating and myelinating oligodendrocytes as assessed by marker gene expression. This argues that Sox9 boosts oligodendrogenesis during ontogenetic development at all stages, including terminal oligodendrocyte differentiation. When Sox9 transgene expression started in the adult, many transgene-expressing OPCs failed to maintain their progenitor cell identity and instead converted into myelinating oligodendrocytes. As infrequent and inefficient differentiation of adult OPCs is one of the main obstacles to effective remyelination in demyelinating diseases such as Multiple Sclerosis, increased Sox9 levels in adult OPCs may substantially increase their remyelination capacity.
Asunto(s)
Esclerosis Múltiple , Oligodendroglía , Ratones , Animales , Oligodendroglía/metabolismo , Diferenciación Celular/fisiología , Neuroglía/metabolismo , Esclerosis Múltiple/metabolismo , Células Madre/metabolismo , Vaina de Mielina/metabolismoRESUMEN
Differentiating oligodendrocytes generate myelin to ensure rapid saltatory conduction in the vertebrate central nervous system. Although oligodendroglial differentiation and myelination are accompanied by dramatic chromatin reorganizations, previously studied chromatin remodelers had only limited direct effects on the process. To study the functional significance of chromatin changes for myelination and identify relevant remodelers, we deleted Ep400, the central ATP-hydrolyzing subunit of the TIP60/EP400 complex, at defined times of mouse oligodendrocyte development. Whereas Ep400-deficient oligodendrocyte precursors develop normally, terminal differentiation and myelination are dramatically impaired. Mechanistically, Ep400 interacts with transcription factor Sox10, binds to regulatory regions of the Myrf gene and is required to induce this central transcriptional regulator of the myelination program. In addition to reduced and aberrant myelin formation, oligodendrocytes exhibit increased DNA damage and apoptosis so that numbers never reach wildtype levels during the short lifespan of Ep400-deficient mice. Ep400 deletion in already mature oligodendrocytes remains phenotypically inapparent arguing that Ep400 is dispensable for myelin maintenance. Given its essential function in myelin formation, modulation of Ep400 activity may be beneficial in conditions such as multiple sclerosis where this process is compromised.
Asunto(s)
ADN Helicasas/fisiología , Proteínas de Unión al ADN/fisiología , Vaina de Mielina/fisiología , Oligodendroglía/citología , Médula Espinal/citología , Animales , Encéfalo/citología , Encéfalo/embriología , Encéfalo/crecimiento & desarrollo , Encéfalo/metabolismo , Diferenciación Celular , Supervivencia Celular , Células Cultivadas , ADN Helicasas/genética , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Redes Reguladoras de Genes , Células HEK293 , Humanos , Ratones Transgénicos , Vaina de Mielina/ultraestructura , Oligodendroglía/metabolismo , Ratas , Ratas Wistar , Médula Espinal/embriología , Médula Espinal/crecimiento & desarrollo , Médula Espinal/metabolismoRESUMEN
Oligodendrocytes (OLs) facilitate information processing in the vertebrate central nervous system via axonal ensheathment. The structure and dynamics of the regulatory network that mediates oligodendrogenesis are poorly understood. We employed bioinformatics and meta-analysis of high-throughput datasets to reconstruct a regulatory network underpinning OL differentiation. From this network, we identified families of feedforward loops comprising the transcription factors (TFs) Olig2, Sox10, and Tcf7l2 and their targets. Among the targets, we found eight other TFs related to OL differentiation, suggesting a hierarchical architecture in which some TFs (Olig2, Sox10, and Tcf7l2) regulate via feedforward loops the expression of others (Sox2, Sox6, Sox11, Nkx2-2, Nkx6-2, Hes5, Myt1, and Myrf). Model simulations with a kinetic model reproduced the mechanisms of OL differentiation only when in the model, Sox10-mediated repression of Tcf7l2 by miR-338/miR-155 was introduced, a prediction confirmed in genetic functional experiments. Additional model simulations suggested that OLs from dorsal regions emerge through BMP/Sox9 signaling.
Asunto(s)
Diferenciación Celular/fisiología , Redes Reguladoras de Genes , Modelos Biológicos , Dinámicas no Lineales , Oligodendroglía/fisiología , Animales , Simulación por Computador , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodominio , Humanos , Ratones , MicroARNs/genética , MicroARNs/metabolismo , Proteínas Nucleares , Factores de TranscripciónRESUMEN
In the central nervous system, oligodendrocytes wrap axons with myelin sheaths, which is essential for rapid transfer of electric signals and their trophic support. In oligodendroglia, transcription factors of the Sox protein family are pivotal regulators of a variety of developmental processes. These include specification, proliferation, and migration of oligodendrocyte precursor cells as well as terminal differentiation to mature myelinating oligodendrocytes. Sox proteins are further affected in demyelinating diseases and are involved in remyelination following damage of the central nervous system. Here we summarize and discuss latest findings on transcriptional regulation of Sox proteins, their function, target genes, and interaction with other transcription factors and chromatin remodelers in oligodendroglia with physiological and pathophysiological relevance.
Asunto(s)
Vaina de Mielina/metabolismo , Oligodendroglía/metabolismo , Factores de Transcripción SOX/metabolismo , Animales , Ensamble y Desensamble de Cromatina , Enfermedades Desmielinizantes/genética , Enfermedades Desmielinizantes/metabolismo , Regulación de la Expresión Génica , Humanos , Vaina de Mielina/genética , Oligodendroglía/citología , Factores de Transcripción SOX/genéticaRESUMEN
The high-mobility-group domain containing SoxC transcription factors Sox4 and Sox11 are expressed and required in the vertebrate central nervous system in neuronal precursors and neuroblasts. To identify genes that are widely regulated by SoxC proteins during vertebrate neurogenesis we generated expression profiles from developing mouse brain and chicken neural tube with reduced SoxC expression and found the transcription factor prospero homeobox protein 1 (Prox1) strongly down-regulated under both conditions. This led us to hypothesize that Prox1 expression depends on SoxC proteins in the developing central nervous system of mouse and chicken. By combining luciferase reporter assays and over-expression in the chicken neural tube with in vivo and in vitro binding studies, we identify the Prox1 gene promoter and two upstream enhancers at -44 kb and -40 kb relative to the transcription start as regulatory regions that are bound and activated by SoxC proteins. This argues that Prox1 is a direct target gene of SoxC proteins during neurogenesis. Electroporations in the chicken neural tube furthermore show that Prox1 activates a subset of SoxC target genes, whereas it has no effects on others. We propose that the transcriptional control of Prox1 by SoxC proteins may ensure coupling of two types of transcription factors that are both required during early neurogenesis, but have at least in part distinct functions. Open Data: Materials are available on https://cos.io/our-services/open-science-badges/ https://osf.io/93n6m/.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas de Homeodominio/metabolismo , Células-Madre Neurales/fisiología , Neurogénesis/fisiología , Prosencéfalo/citología , Factores de Transcripción SOXC/metabolismo , Proteínas Supresoras de Tumor/metabolismo , Animales , Embrión de Pollo , Inmunoprecipitación de Cromatina , Biología Computacional , Ensayo de Cambio de Movilidad Electroforética , Electroporación , Embrión de Mamíferos , Ontología de Genes , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Proteínas de Homeodominio/genética , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Tubo Neural/citología , Tubo Neural/metabolismo , Factores del Dominio POU/genética , Factores del Dominio POU/metabolismo , Prosencéfalo/embriología , Prosencéfalo/crecimiento & desarrollo , Prosencéfalo/metabolismo , Factores de Transcripción SOXC/genética , Tubulina (Proteína)/metabolismo , Proteínas Supresoras de Tumor/genéticaRESUMEN
Oligodendrocytes are the myelinating glia of the central nervous system and ensure rapid saltatory conduction. Shortage or loss of these cells leads to severe malfunctions as observed in human leukodystrophies and multiple sclerosis, and their replenishment by reprogramming or cell conversion strategies is an important research aim. Using a transgenic approach we increased levels of the transcription factor Sox10 throughout the mouse embryo and thereby prompted Fabp7-positive glial cells in dorsal root ganglia of the peripheral nervous system to convert into cells with oligodendrocyte characteristics including myelin gene expression. These rarely studied and poorly characterized satellite glia did not go through a classic oligodendrocyte precursor cell stage. Instead, Sox10 directly induced key elements of the regulatory network of differentiating oligodendrocytes, including Olig2, Olig1, Nkx2.2 and Myrf. An upstream enhancer mediated the direct induction of the Olig2 gene. Unlike Sox10, Olig2 was not capable of generating oligodendrocyte-like cells in dorsal root ganglia. Our findings provide proof-of-concept that Sox10 can convert conducive cells into oligodendrocyte-like cells in vivo and delineates options for future therapeutic strategies.
Asunto(s)
Diferenciación Celular/genética , Sistema Nervioso Central/metabolismo , Esclerosis Múltiple/genética , Factores de Transcripción SOXE/genética , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Sistema Nervioso Central/patología , Embrión de Mamíferos , Proteína de Unión a los Ácidos Grasos 7 , Proteínas de Unión a Ácidos Grasos/genética , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodominio/genética , Humanos , Ratones , Esclerosis Múltiple/patología , Proteínas del Tejido Nervioso/genética , Neuroglía , Proteínas Nucleares , Factor de Transcripción 2 de los Oligodendrocitos , Oligodendroglía/metabolismo , Factores de Transcripción SOXE/metabolismo , Médula Espinal/metabolismo , Médula Espinal/patología , Factores de Transcripción/genética , Proteínas de Pez CebraRESUMEN
During development of myelin-forming oligodendrocytes in the central nervous system the two closely related transcription factors Sox9 and Sox10 play essential roles that are partly shared and partly unique. Whereas Sox9 primarily functions during oligodendroglial specification, Sox10 is uniquely required to induce terminal differentiation and myelination. During this process, Sox10 protein levels rise substantially. As this coincides with a reciprocal decrease in Sox9, we postulated that Sox10 influences Sox9 amounts in differentiating oligodendrocytes. Here we show that Sox9 levels are indeed inversely coupled to Sox10 levels such that Sox10 deletion in oligodendroglial cells evokes a reciprocal increase in Sox9. We furthermore provide evidence that this coupling involves upregulation of microRNAs miR335 and miR338 as direct transcriptional targets of Sox10. The two microRNAs in turn recognize the 3'-UTR of Sox9 mRNA and may thereby reduce Sox9 protein levels posttranscriptionally in oligodendroglial cells. Such a mechanism may enable oligodendroglial cells to adapt the ratio of both related Sox proteins in a manner required for successful lineage progression and differentiation. Mathematical modeling furthermore shows that the identified regulatory circuit has the potential to convert a transient stimulus into an irreversible switch of cellular properties and may thus contribute to terminal differentiation of oligodendrocytes.
Asunto(s)
Regulación de la Expresión Génica/genética , MicroARNs/metabolismo , Oligodendroglía/metabolismo , Factor de Transcripción SOX9/metabolismo , Factores de Transcripción SOXE/metabolismo , Animales , Animales Recién Nacidos , Encéfalo/citología , Células Cultivadas , Proteína Ácida Fibrilar de la Glía/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Modelos Moleculares , Modelos Teóricos , Proteína Básica de Mielina/metabolismo , Factor de Transcripción 2 de los Oligodendrocitos/metabolismo , Ratas , Factores de Transcripción SOXE/genética , Factores de Transcripción/metabolismo , TransfecciónRESUMEN
Oligodendrocytes and Schwann cells are the myelinating glia of the vertebrate nervous system and by generation of myelin sheaths allow rapid saltatory conduction. Previous in vitro work had pointed to a role of the zinc finger containing specificity proteins Sp1 and Sp3 as major regulators of glial differentiation and myelination. Here, we asked whether such a role is also evident in vivo using mice with specific deletions of Sp1 or Sp3 in myelinating glia. We also studied glia-specific conditional Sp2- and constitutive Sp4-deficient mice to include all related glutamine-rich Sp factors into our analysis. Surprisingly, we did not detect developmental Schwann cell abnormalities in any of the mutant mice. Oligodendrocyte development and differentiation was also not fundamentally affected as oligodendrocytes were present in all mouse mutants and retained their ability to differentiate and initiate myelin gene expression. The most severe defect we observed was a 50% reduction in Mbp- and proteolipid protein 1 (Plp1)-positive differentiating oligodendrocytes in Sp2 mutants at birth. Unexpectedly, glial development appeared undisturbed even in the joint absence of Sp1 and Sp3. We conclude that Sp2 has a minor effect on the differentiation of myelinating glia, and that glutamine-rich Sp proteins are not essential regulators of the process.
Asunto(s)
Diferenciación Celular/fisiología , Glutamina/metabolismo , Vaina de Mielina/metabolismo , Neuroglía/metabolismo , Oligodendroglía/metabolismo , Factor de Transcripción Sp2/metabolismo , Animales , Células Cultivadas , Regulación del Desarrollo de la Expresión Génica/fisiología , Proteína Básica de Mielina/metabolismo , Ratas , Células de Schwann/efectos de los fármacos , Células de Schwann/metabolismoRESUMEN
Neural precursor cells of the ventricular zone give rise to all neurons and glia of the central nervous system and rely for maintenance of their precursor characteristics on the closely related SoxB1 transcription factors Sox1, Sox2 and Sox3. We show in mouse spinal cord that, whereas SoxB1 proteins are usually downregulated upon neuronal specification, they continue to be expressed in glial precursors. In the oligodendrocyte lineage, Sox2 and Sox3 remain present into the early phases of terminal differentiation. Surprisingly, their deletion does not alter precursor characteristics but interferes with proper differentiation. Although a direct influence on myelin gene expression may be part of their function, we provide evidence for another mode of action. SoxB1 proteins promote oligodendrocyte differentiation in part by negatively controlling miR145 and thereby preventing this microRNA from inhibiting several pro-differentiation factors. This study presents one of the few cases in which SoxB1 proteins, including the stem cell factor Sox2, are associated with differentiation rather than precursor functions.
Asunto(s)
MicroARNs/genética , Oligodendroglía/metabolismo , Factor de Transcripción SOX9/metabolismo , Factores de Transcripción SOXB1/metabolismo , Animales , Diferenciación Celular , Línea Celular , Regulación del Desarrollo de la Expresión Génica , Células HEK293 , Humanos , Ratones , Células-Madre Neurales , Neurogénesis , Neuroglía/citología , Neuroglía/metabolismo , Regiones Promotoras Genéticas , Ratas , Factor de Transcripción SOX9/biosíntesis , Médula Espinal/citología , Médula Espinal/embriología , Médula Espinal/metabolismoRESUMEN
INTRODUCTION: Congenital hypomyelinating neuropathy (CHN) is a rare congenital neuropathy that presents in the neonatal period and has been linked previously to mutations in several genes associated with myelination. A recent study has linked 4 homozygous frameshift mutations in the contactin-associated protein 1 (CNTNAP1) gene with this condition. METHODS: We report a neonate with CHN who was found to have absent sensory nerve and compound muscle action potentials and hypomyelination on nerve biopsy. RESULTS: On whole exome sequencing, we identified a novel CNTNAP1 homozygous missense mutation (p.Arg388Pro) in the proband, and both parents were carriers. Molecular modeling suggests that this variant disrupts a ß-strand to cause an unstable structure and likely significant changes in protein function. CONCLUSIONS: This report links a missense CNTNAP1 variant to the disease phenotype previously associated only with frameshift mutations. Muscle Nerve 55: 761-765, 2017.
Asunto(s)
Moléculas de Adhesión Celular Neuronal/genética , Enfermedad de Charcot-Marie-Tooth/genética , Mutación Missense , Potenciales de Acción/fisiología , Enfermedad de Charcot-Marie-Tooth/fisiopatología , Electromiografía , Resultado Fatal , Humanos , Recién Nacido , Masculino , Neuronas Motoras/fisiología , Conducción Nerviosa/fisiologíaRESUMEN
Myelinating Schwann cells in the vertebrate peripheral nervous system rely on Brg1 (Smarca4) for terminal differentiation. Brg1 serves as central ATP-hydrolyzing subunit of the chromatin remodelling BAF complexes and is recruited during myelination as part of these complexes by the transcription factor Sox10 in Schwann cells. Here, we analyzed the role of Brg1 during development of myelinating oligodendrocytes in the CNS of the mouse. Following Brg1 deletion in oligodendrocyte precursors, these cells showed normal survival, proliferation, and migration. A mild but significant reduction in the number of oligodendrocytes with myelin gene expression in the absence of Brg1 points to a contribution to oligodendroglial differentiation but also shows that the role of Brg1 is much less prominent than during Schwann cell differentiation. Additionally, we failed to obtain evidence for a genetic interaction between Brg1 and Sox10 comparable with the one in Schwann cells. This argues that similarities exist between the regulatory networks and mechanisms in both types of myelinating glia but that the exact mode of action and the relevance of functional interactions differ, pointing to a surprising degree of variability in the control of myelination.
Asunto(s)
Diferenciación Celular/fisiología , Ensamble y Desensamble de Cromatina/fisiología , ADN Helicasas/deficiencia , Proteínas Nucleares/deficiencia , Oligodendroglía/fisiología , Factores de Transcripción/deficiencia , Animales , Células Cultivadas , ADN Helicasas/genética , Femenino , Masculino , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas Nucleares/genética , Factores de Transcripción/genéticaRESUMEN
Differentiation of oligodendrocytes and myelin production in the vertebrate central nervous system require highly concerted changes in gene expression. The transcription factors Sox10 and Myrf are both central to this process and jointly regulate expression of myelin genes. Here we show that Sox10 and Myrf also cooperate in the activation of the gene coding for the dual specificity protein phosphatase Dusp15 (also known as VHY) during this process. Activation is mediated by the Dusp15 promoter, which is also sufficient to drive oligodendroglial gene expression in vivo. It contains both a functional Sox10 and a functional Myrf binding site. Whereas Sox10 binds as a monomer, Myrf binds as a trimer. Available data furthermore indicate that cooperative activation is not a function of facilitated binding, but occurs at a later step of the activation process. shRNA-mediated knockdown of Dusp15 reduced expression of early and late differentiation markers in CG4 and primary oligodendroglial cells, whereas Dusp15 overexpression increased it transiently. This argues that Dusp15 is not only a joint target of Sox10 and Myrf in oligodendrocytes but may also mediate some of their effects during oligodendrocyte differentiation and myelin formation. GLIA 2016;64:2120-2132.
Asunto(s)
Fosfatasas de Especificidad Dual/metabolismo , Vaina de Mielina/metabolismo , Oligodendroglía/metabolismo , Factores de Transcripción SOXE/metabolismo , Factores de Transcripción/metabolismo , Factores de Edad , Animales , Animales Recién Nacidos , Encéfalo/citología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/fisiología , Células Cultivadas , Fosfatasas de Especificidad Dual/genética , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Ratones , Proteína Básica de Mielina/genética , Proteína Básica de Mielina/metabolismo , Regiones Promotoras Genéticas/genética , ARN Mensajero/metabolismo , Ratas , Factores de Transcripción SOXE/genética , Factores de Transcripción/genética , TransfecciónRESUMEN
Several transcription factors are essential for terminal differentiation of myelinating glia, among them the high-mobility-group-domain-containing protein Sox10. To better understand how these factors exert their effects and shape glial expression programs, we identified and characterized a physical and functional link between Sox10 and the Med12 subunit of the Mediator complex that serves as a conserved multiprotein interphase between transcription factors and the general transcription machinery. We found that Sox10 bound with two of its conserved domains to the C-terminal region of Med12 and its close relative, Med12-like. In contrast to Med12-like, substantial amounts of Med12 were detected in both Schwann cells and oligodendrocytes. Its conditional glia-specific deletion in mice led to terminal differentiation defects that were highly reminiscent of those obtained after Sox10 deletion. In support of a functional cooperation, both proteins were jointly required for Krox20 induction and were physically associated with the critical regulatory region of the Krox20 gene in myelinating Schwann cells. We conclude that Sox10 functions during terminal differentiation of myelinating glia, at least in part by Med12-dependent recruitment of the Mediator complex.
Asunto(s)
Diferenciación Celular/fisiología , Complejo Mediador/fisiología , Oligodendroglía/citología , Factores de Transcripción SOXE/fisiología , Células de Schwann/citología , Animales , Diferenciación Celular/genética , Línea Celular , Proteína 2 de la Respuesta de Crecimiento Precoz/biosíntesis , Femenino , Regulación del Desarrollo de la Expresión Génica/genética , Humanos , Masculino , Complejo Mediador/genética , Ratones , Ratones Transgénicos , Vaina de Mielina/genética , Vaina de Mielina/metabolismo , Oligodendroglía/metabolismo , Unión Proteica/genética , Unión Proteica/fisiología , Factores de Transcripción SOXE/genética , Células de Schwann/metabolismoRESUMEN
The transcription factor Sox10 is an important determinant of oligodendroglial identity and influences oligodendroglial development and characteristics at various stages. Starting from RNA-seq data, we here show that the expression of several voltage-gated ion channels with known expression and important function in oligodendroglial cells depends upon Sox10. These include the Nav1.1, Cav2.2, Kv1.1, and Kir4.1 channels. For each of the four encoding genes, we found at least one regulatory region that is activated by Sox10 in vitro and at the same time bound by Sox10 in vivo. Cell-specific deletion of Sox10 in oligodendroglial cells furthermore led to a strong downregulation of all four ion channels in a mouse model and thus in vivo. Our study provides a clear functional link between voltage-gated ion channels and the transcriptional regulatory network in oligodendroglial cells. Furthermore, our study argues that Sox10 exerts at least some of its functions in oligodendrocyte progenitor cells, in myelinating oligodendrocytes, or throughout lineage development via these ion channels. By doing so, we present one way in which oligodendroglial development and properties can be linked to neuronal activity to ensure crosstalk between cell types during the development and function of the central nervous system.
Asunto(s)
Oligodendroglía , Factores de Transcripción SOXE , Factores de Transcripción SOXE/metabolismo , Factores de Transcripción SOXE/genética , Animales , Oligodendroglía/metabolismo , Oligodendroglía/citología , Ratones , Canales Iónicos/metabolismo , Canales Iónicos/genética , Transcripción Genética , Regulación del Desarrollo de la Expresión Génica , Diferenciación Celular/genética , HumanosRESUMEN
Schwann cells are the main glial cell type in the PNS. They develop along nerves during embryogenesis and rely on the HMG domain containing Sox10 transcription factor for specification, lineage progression, and terminal differentiation. Sox10 deletion in immature Schwann cells caused peripheral nerve defects in mice that were not restricted to this glial cell type, although expression in the nerve and gene loss were. Formation of the perineurium as the protecting sheath was, for instance, heavily compromised. This resembled the defect observed after loss of Desert hedgehog (Dhh) in mice. Here we show that Sox10 activates Dhh expression in Schwann cells via an enhancer that is located in intron 1 of the Dhh gene. Sox10 binds this enhancer in monomeric form via several sites. Mutation of these sites abolishes both Schwann-cell-specific activity and Sox10 responsiveness in vitro and in transgenic mouse embryos. This argues that Sox10 activates Dhh expression by direct binding to the enhancer and by increasing Dhh levels promotes formation of the perineurial sheath. This represents the first mechanism for a non-cell-autonomous function of Sox10 during peripheral nerve development.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/fisiología , Proteínas Hedgehog/metabolismo , Sistema Nervioso Periférico/embriología , Factores de Transcripción SOXE/metabolismo , Animales , Línea Celular Transformada , Inmunoprecipitación de Cromatina , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Exones/genética , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Hedgehog/genética , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación/genética , Sistema Nervioso Periférico/citología , Sistema Nervioso Periférico/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Unión Proteica/genética , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Factores de Transcripción SOXE/genética , Células de Schwann/metabolismo , TransfecciónRESUMEN
The HMG-domain transcription factor Sox10 is expressed throughout oligodendrocyte development and is an important component of the transcriptional regulatory network in these myelin-forming CNS glia. Of the known Sox10 regulatory regions, only the evolutionary conserved U2 enhancer in the distal 5'-flank of the Sox10 gene exhibits oligodendroglial activity. We found that U2 was active in oligodendrocyte precursors, but not in mature oligodendrocytes. U2 activity also did not mediate the initial Sox10 induction after specification arguing that Sox10 expression during oligodendroglial development depends on the activity of multiple regulatory regions. The oligodendroglial bHLH transcription factor Olig2, but not the closely related Olig1 efficiently activated the U2 enhancer. Olig2 bound U2 directly at several sites including a highly conserved one in the U2 core. Inactivation of this site abolished the oligodendroglial activity of U2 in vivo. In contrast to Olig2, the homeodomain transcription factor Nkx6.2 repressed U2 activity. Repression may involve recruitment of Nkx6.2 to U2 and inactivation of Olig2 and other activators by protein-protein interactions. Considering the selective expression of Nkx6.2 at the time of specification and in differentiated oligodendrocytes, Nkx6.2 may be involved in limiting U2 activity to the precursor stage during oligodendrocyte development.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Elementos de Facilitación Genéticos , Células-Madre Neurales/metabolismo , Oligodendroglía/metabolismo , Factores de Transcripción SOXE/genética , Animales , Secuencia de Bases , Sitios de Unión , Línea Celular Tumoral , Secuencia Conservada , Evolución Molecular , Células HEK293 , Proteínas de Homeodominio/metabolismo , Humanos , Ratones , Ratones Transgénicos , Ratas , Proteínas Represoras/metabolismo , Médula Espinal/citología , Médula Espinal/embriología , Médula Espinal/crecimiento & desarrollo , Factores de Transcripción/metabolismoRESUMEN
Corynebacterium glutamicum has two different Amt-type proteins. While AmtB has a low substrate affinity and is not saturable up to 3 mM methylammonium, AmtA has a high substrate affinity and mediates saturable, membrane potential-dependent transport, resulting in a high steady-state accumulation of methylammonium, even in the absence of metabolic trapping.
Asunto(s)
Proteínas Bacterianas/fisiología , Proteínas de Transporte de Catión/fisiología , Corynebacterium glutamicum/metabolismo , Compuestos de Amonio Cuaternario/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Transporte Biológico , Proteínas de Transporte de Catión/genética , Proteínas de Transporte de Catión/metabolismo , Cromatografía en Capa Delgada , Corynebacterium glutamicum/genética , Concentración de Iones de Hidrógeno , Cinética , Metilaminas/metabolismo , Metilaminas/farmacocinética , Mutación , Compuestos de Amonio Cuaternario/farmacocinética , Especificidad por SustratoRESUMEN
Oligodendrocytes produce myelin for rapid transmission and saltatory conduction of action potentials in the vertebrate central nervous system. Activation of the myelination program requires several transcription factors including Sox10, Olig2, and Nkx2.2. Functional interactions among them are poorly understood and important components of the regulatory network are still unknown. Here, we identify Nfat proteins as Sox10 targets and regulators of oligodendroglial differentiation in rodents and humans. Overall levels and nuclear fraction increase during differentiation. Inhibition of Nfat activity impedes oligodendrocyte differentiation in vitro and in vivo. On a molecular level, Nfat proteins cooperate with Sox10 to relieve reciprocal repression of Olig2 and Nkx2.2 as precondition for oligodendroglial differentiation and myelination. As Nfat activity depends on calcium-dependent activation of calcineurin signaling, regulatory network and oligodendroglial differentiation become sensitive to calcium signals. NFAT proteins are also detected in human oligodendrocytes, downregulated in active multiple sclerosis lesions and thus likely relevant in demyelinating disease.