Project description:Hereditary Motor and Sensory Neuropathies (HMSN) are the most common inherited peripheral neuropathies and comprise a group of genetically heterogeneous diseases. We study the genetic defects causing three demyelinating disorders: HMSN1A, HMSN-LOM and congenital cateracts facial dysmophism neuropathy (CCFDN) syndrome, which are caused by mutations in PMP22, NDRG1 and CTDP1, respectively. The function and patho-mechanisms of these genes is still unknown. To identify effects downstream of the mutations, thereby possibly involved in the disease process, we used Serial expression of gene expression (SAGE) and microarray analysis. We analyzed human Schwann cell lines from three normal subjects, one HMSN-LOM patient, two HMSN-1A patients and two CCFDN patients and compared our data to a recent dataset of human Schwann cells (4 normal subjects passage 1 vs. 3, GDS1869/GSE4030 M.B. Bunge, 2006). We excluded genes that were not consistently regulated between biological and technical replicates and genes that were found to be influenced by passage number (p<0.05). Comparing expression profiles of demyelinating neuropathies with different mutations we identified: 1. expression signatures specific for each genotype. 2. Genes commonly (dys)regulated in all screened neuropathies. Interestingly, these include genes that play a role in reorganization of sodium channels in central and peripheral nerves (S100A10, CD90), or extracellular matrix remodeling (e.g. TGFBI, SERPINE1, THBS1). We also found high up-regulation of genes involved in Schwann cell lineage and in particular, genes that are associated with an immature or pre-myelinating Schwann cell phenotype (i.e. Sox2, Sox10, COL18A1, TFAP2A, Pax3, CDH19). Our study shows that many genes, possibly contributing to nerve pathology can be identified by this approach. Experiment Overall Design: Experimental design: in total 12 (two-color) arrays were run. All neuropathy samples were in duplicate (technical replicates). Two CCFDN and two HMSN1A patients were also analyzed as biological replicates. Three healthy subjects were included from which one was in duplicate. All samples (Cy3) were compared to a common reference pool (Cy5) which consisted of a mix of all samples.

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.

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.

Project description:The core component of the class III phosphatidylinositol 3-kinase complex, Beclin 1, takes part in different protein networks, thus switching its role from inducing autophagy to regulating autophagosomal maturation and endosomal trafficking. While assessed in neurons, astrocytes and microglia, its role was far less investigated in myelinating glia, including Schwann cells (SCs), responsible for peripheral nerve myelination. Remarkably, the dysregulation in endosomal trafficking is emerging as a pathophysiological mechanism underlying peripheral neuropathies, such as demyelinating Charcot-Marie-Tooth diseases. By knocking out Beclin 1 in SCs we here generated a novel mouse model (Becn1 cKO), developing a severe and progressive neuropathy, accompanied by involuntary tremors, body weight loss and premature death. Ultrastructural analysis revealed abated myelination and SCs displaying enlarged cytoplasm with progressive accumulation of intracellular vesicles. Transcriptomic and histological analysis from sciatic nerves of 10-day and 2-month-old mice revealed pro-mitotic gene deregulation and increased SCs proliferation at both stages with axonal loss and increased immune infiltration in adults, well reflecting the progressive motor and sensory functional impairment that characterizes Becn1 cKO mice, compared to controls. Our study establishes a further step in understanding key mechanisms in SC development and points to Beclin 1 and its regulated pathways as targets for demyelinating CMT forms. A novel conditional gene knockout was generated to investigate the role that Beclin 1 exerts in Schwann cells and in myelination. The newly generated mouse line resulted in a model for severe and progressive peripheral neuropathy. Together with defective myelination, we described radial sorting defects, motor and sensory neuron impairments, immune infiltrate in adults and a huge transcripts deregulation. The emerged deregulated signalling pathways highlighted how Beclin 1 is able to coordinate integrated signaling pathways essential for Schwann cell maturation and nerve development and homeostasis.

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.

			Action	DRS
	SRR17830073.fastq.gz	Fastqsanger.gz
	SRR17830074.fastq.gz	Fastqsanger.gz
	SRR17830075.fastq.gz	Fastqsanger.gz
	SRR17830076.fastq.gz	Fastqsanger.gz
	SRR23873592_1.fastq.gz	Fastqsanger.gz

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Deriving Schwann Cells from hPSCs Enable Disease Modeling and Drug Discovery for Diabetic Peripheral Neuropathy

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