Ablation of Dicer from murine Schwann cells increases their proliferation while blocking myelination
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE22023 | GEO | 2010/12/01
SECONDARY ACCESSION(S): PRJNA127445
REPOSITORIES: GEO
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Project description:The myelin sheaths that surround the thick axons of the peripheral nervous system are produced by the highly specialized Schwann cells. Differentiation of Schwann cells and myelination occur in discrete steps. Each of these requires coordinated expression of specific proteins in a precise sequence, yet the regulatory mechanisms controlling protein expression during these events are incompletely understood. Here we report that Schwann cell-specific ablation of the enzyme Dicer1, which is required for the production of small non-coding regulatory microRNAs, fully arrests Schwann cell differentiation, resulting in early postnatal lethality. Dicer-/- Schwann cells had lost their ability to myelinate, yet were still capable of sorting axons. Both cell death and, paradoxically, proliferation of immature Schwann cells was vastly enhanced, suggesting that their terminal differentiation is triggered by growth-arresting regulatory microRNAs. Using microRNA microarrays, we identified 16 miRNAs that are upregulated upon myelination and whose expression is controlled by Dicer in Schwann cells. This set of microRNAs appears to drive Schwann cell differentiation and myelination of peripheral nerves, thereby fulfilling a crucial function for survival of the organism. Samples representing Schwann cell-specific ablation of the enzyme Dicer1 and wild type controls at developmental stages E17 and P4. Geometric mean-averaged data linked below as supplementary file.
2010-12-01 | E-GEOD-22023 | biostudies-arrayexpress
Project description:Myelination is essential for nervous system function. Schwann cells interact with neurons and with the basal lamina to sort and myelinate axons, using known receptors and signaling pathways. In contrast, the transcriptional control of axonal sorting and the role of mechano-transduction in myelination are largely unknown. Yap and Taz are effectors of the Hippo pathway that integrate chemical and mechanical signals in cells. Here, we describe a previously unknown role for the Hippo pathway in myelination. Using conditional mutagenesis in mice we show that Taz is required in Schwann cells for radial sorting and myelination. Yap is redundant with Taz as ablation of both Yap and Taz abolishes radial sorting. Yap/Taz regulate Schwann cell proliferation and transcription of basal lamina receptors, both necessary for proper radial sorting of axons, and subsequent myelination. These data link transcriptional effectors of the Hippo pathway and of mechanotransduction to myelin formation in Schwann cells.
2016-06-06 | GSE79115 | GEO
Project description:Schwann cells, expanded in number by exposure to growth factors in vitro, could be useful in nervous system repair. Our previous results suggest that long term exposure to heregulin and forskolin changes the functional properties of the human Schwann cells, including the ability to myelinate axons after transplantation. Here, we propose to determine the molecular changes in the Schwann cells that occur as a result of extended growth with mitogenic factors. We believe that the information obtained in these studies will provide clues about mechanisms underlying the already observed changes in function. This information will aid in the prediction of the safety and efficacy of neural repair approaches that use cultured, expanded Schwann cells. Finally this data may provide clues into the mechanisms underlying normal human Schwann cell function.,To use gene array analysis to compare gene expression profiles in early and late passage human Schwann cells exposed to the growth factors heregulin and forskolin.,Observed changes in the function of human Schwann cells, including their capacity for growth and differentiation, after prolonged exposure to heregulin and forskolin, are caused by changes in the gene expression profiles in these cells.
2007-06-22 | E-GEOD-4030 | biostudies-arrayexpress
Project description:The aim of our study is to determine the functions of histone deacetylases (HDACs) 1 and 2 in Schwann cells during postnatal development of the peripheral nervous system (PNS). Schwann cells are the myelinating glial cells of the PNS. At birth, mouse sciatic nerves mature in 2 subsequent phases: 1/ big caliber axons get sorted into a 1 to 1 relationship with Schwann cells, 2/ Schwann cells build a myelin sheath around sorted axons. In mice where both HDAC1 & HDAC2 have been specifically knocked out in Schwann cells, both phases are impaired. HDACs are chromatin remodeling enzymes, they can thus alter gene expression directly. We want to identify which genes controlled by HDAC1 and HDAC2 in Schwann cells are necessary for the maturation of sciatic nerves. Because HDAC1 and HDAC2 can compensate for each other loss to some extend, we will first analyze changes of gene expression in HDAC1/HDAC2 double KO animals. We expect to gain critical insights into the molecular mechanisms controlling Schwann cell differentiation and myelination. This knowledge is of key importance for the success of regenerative medicine in peripheral neuropathies, nerve tumors, and transplantation paradigms in non-regenerative CNS lesions and in large PNS injuries. 3 double knockout mutants for HDAC1 and HDAC2 and 3 control littermates were analyzed. Tissues analyzed: sciatic nerves of 2 day-old mouse pups
2011-02-25 | E-GEOD-27451 | biostudies-arrayexpress
Project description:DNA methylation is a key epigenetic regulator of mammalian embryogenesis and somatic cell differentiation. Using high-resolution genome-scale maps of methylation patterns, we show that the formation of myelin in the peripheral nervous system, proceeds with progressive DNA demethylation, which coincides with an upregulation of critical genes of the myelination process. More importantly, we found that, in addition to expression of DNA methyltransferases and demethylases, the levels of S-adenosylmethionine (SAMe), the principal biological methyl donor, could also play a critical role in regulating DNA methylation during myelination and in the pathogenesis of diabetic neuropathy. In summary, this study provides compelling evidence that SAMe levels need to be tightly controlled to prevent aberrant DNA methylation patterns, and together with recently published studies on the influence of SAMe on histone methylation in cancer and embryonic stem cell differentiation show that in diverse biological processes, the methylome, and consequently gene expression patterns, are critically dependent on levels of SAMe. Axonal myelination by Schwann cells in the peripheral nervous system is essential for rapid saltatory impulse conduction, and malformation or destruction of myelin sheaths can lead to severe motor and sensory disabilities (peripheral neuropathies). Using high-resolution genome-scale methylome maps, we found that DNA methylation could play a critical role in the generation of myelinated Schwann cells. This process was accompanied by a global DNA demethylation at most genomic elements. Notably, demethylation at gene-regulatory regions was associated with activation of critical myelination-specific genes. Furthermore, we found an aberrant DNA methylation pattern in a mouse model of diabetic neuropathy, which could be involved in the pathogenesis of the disease. Importantly, we found that these methylation patterns in both situations could be regulated by levels of S-adenosylmethionine (SAMe), the principal biological methyl donor. Together with recent studies on the influence of SAMe on histone methylation in diverse biological processes, we conclude that the methylation landscape of cells could be critically dependent on levels of SAMe. These provide a mechanistic link between metabolism and gene regulatory networks in normal and pathological situations. Sciatic nerves from post natal day 90 GNMT (wt and KO) mice of either sex were dissected and pooled together, 2 replicates per sample group.
2014-01-27 | E-GEOD-45701 | biostudies-arrayexpress
Project description:DNA methylation is a key epigenetic regulator of mammalian embryogenesis and somatic cell differentiation. Using high-resolution genome-scale maps of methylation patterns, we show that the formation of myelin in the peripheral nervous system, proceeds with progressive DNA demethylation, which coincides with an upregulation of critical genes of the myelination process. More importantly, we found that, in addition to expression of DNA methyltransferases and demethylases, the levels of S-adenosylmethionine (SAMe), the principal biological methyl donor, could also play a critical role in regulating DNA methylation during myelination and in the pathogenesis of diabetic neuropathy. In summary, this study provides compelling evidence that SAMe levels need to be tightly controlled to prevent aberrant DNA methylation patterns, and together with recently published studies on the influence of SAMe on histone methylation in cancer and embryonic stem cell differentiation show that in diverse biological processes, the methylome, and consequently gene expression patterns, are critically dependent on levels of SAMe. Axonal myelination by Schwann cells in the peripheral nervous system is essential for rapid saltatory impulse conduction, and malformation or destruction of myelin sheaths can lead to severe motor and sensory disabilities (peripheral neuropathies). Using high-resolution genome-scale methylome maps, we found that DNA methylation could play a critical role in the generation of myelinated Schwann cells. This process was accompanied by a global DNA demethylation at most genomic elements. Notably, demethylation at gene-regulatory regions was associated with activation of critical myelination-specific genes. Furthermore, we found an aberrant DNA methylation pattern in a mouse model of diabetic neuropathy, which could be involved in the pathogenesis of the disease. Importantly, we found that these methylation patterns in both situations could be regulated by levels of S-adenosylmethionine (SAMe), the principal biological methyl donor. Together with recent studies on the influence of SAMe on histone methylation in diverse biological processes, we conclude that the methylation landscape of cells could be critically dependent on levels of SAMe. These provide a mechanistic link between metabolism and gene regulatory networks in normal and pathological situations. Sciatic nerves from C57Bl6J mice of either sex, were dissected and pooled together at different developmental stages, 3 replicates per sample group.
2014-01-27 | E-GEOD-45700 | biostudies-arrayexpress
Project description:We have established functions of the stimulus dependent MAPKs, ERK1/2 and ERK5 in DRG, motor neuron, and Schwann cell development. Surprisingly, many aspects of early DRG and motor neuron development were found to be ERK1/2 independent and Erk5 deletion had no obvious effect on embryonic PNS. In contrast, Erk1/2 deletion in developing neural crest resulted in peripheral nerves that were devoid of Schwann cell progenitors, and deletion of Erk1/2 in Schwann cell precursors caused disrupted differentiation and marked hypomyelination of axons. The Schwann cell phenotypes are similar to those reported in neuregulin-1 and ErbB mutant mice and neuregulin effects could not be elicited in glial precursors lacking Erk1/2. ERK/MAPK regulation of myelination was specific to Schwann cells, as deletion in oligodendrocyte precursors did not impair myelin formation, but reduced precursor proliferation. Our data suggest a tight linkage between developmental functions of ERK/MAPK signaling and biological actions of specific RTK-activating factors. Microarray analysis on RNA extracts derived from E12.5 Erk1/2CKO(Wnt1) and wildtype DRGs
2010-10-16 | E-GEOD-24730 | biostudies-arrayexpress
Project description:Cells need to integrate chemical and physical signals into transcriptional programs. In the peripheral nerves, axonal caliber selection by specialized Schwann cells, is critical for developmental myelination. However, only mechanisms through which Schwann cells sense chemical signals are well characterized. We identify ACtin-Like protein 6a (ACTL6a), a component of the SWI/SNF chromatin remodeling complex, as critical for axonal caliber recognition and developmental myelination. ACTL6a is expressed in the developing nerve and, when activated by contact with axons or nanofibers of specific caliber, it promotes the eviction of repressive histone marks thereby enhancing the transcriptional program of myelination. Mutant mice with Schwann cells lacking ACTL6a display aberrant recognition of axonal caliber, resulting in defective radial sorting and lower levels of transcripts regulating myelination of developing nerves. We suggest that developing peripheral nerves require an ACTL6a-dependent integration of physical and chemical signals in Schwann cells to release of repressive histone modifications and promote myelination.
2022-03-08 | GSE179340 | GEO
Project description:Chromatin organization is critical for cell growth, differentiation, and disease development, however, its functions in peripheral myelination and myelin repair remain elusive. Here we observed a global diminution of chromatin accessibility during Schwann cell differentiation and demonstrated that the chromatin organizer CCCTC-binding factor (CTCF) is critical for Schwann cell myelination and myelin regeneration after nerve injury. Inhibition of Ctcf or its deletion blocked Schwann cell differentiation at the pre-myelinating stage, whereas overexpression of CTCF promoted the myelination program. CTCF establishes the chromatin interaction loop between promoters and regulatory elements to promote expression of key pro-myelinogenic factors such as EGR2. In addition, CTCF interacts with SUZ12, a component of polycomb-repressive-complex 2, to repress expression of immature Schwann cell-associated regulators including HES1, RSPO2, and CALCA. Together, our findings reveal the dual role of CTCF-dependent chromatin organization in promoting myelinogenic programs and recruiting chromatin-repressive complexes to block differentiation inhibitors to control peripheral myelination and myelin repair.
2020-06-22 | GSE138117 | GEO
Project description:The aim of our study is to determine the functions of histone deacetylases (HDACs) 1 and 2 in Schwann cells during postnatal development of the peripheral nervous system (PNS). Schwann cells are the myelinating glial cells of the PNS. At birth, mouse sciatic nerves mature in 2 subsequent phases: 1/ big caliber axons get sorted into a 1 to 1 relationship with Schwann cells, 2/ Schwann cells build a myelin sheath around sorted axons. In mice where both HDAC1 & HDAC2 have been specifically knocked out in Schwann cells, both phases are impaired. HDACs are chromatin remodeling enzymes, they can thus alter gene expression directly. We want to identify which genes controlled by HDAC1 and HDAC2 in Schwann cells are necessary for the maturation of sciatic nerves. Because HDAC1 and HDAC2 can compensate for each other loss to some extend, we will first analyze changes of gene expression in HDAC1/HDAC2 double KO animals. We expect to gain critical insights into the molecular mechanisms controlling Schwann cell differentiation and myelination. This knowledge is of key importance for the success of regenerative medicine in peripheral neuropathies, nerve tumors, and transplantation paradigms in non-regenerative CNS lesions and in large PNS injuries.
2011-02-25 | GSE27451 | GEO