Myelin insulation as a risk factor for axonal degeneration in autoimmune demyelinating disease
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE222063 | GEO | 2023/05/02
REPOSITORIES: GEO
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Project description:Two percent of all patients with X-linked intellectual disability (XLID) exhibit loss-of-function mutations in the palmitoylating enzyme, ZDHHC91,2. One of the main anatomical deficits observed in these patients is a decrease in corpus callosum volume and a disruption of white matter integrity. We demonstrated that ablation of Zdhhc9 in mice substantially impairs the maturation of ligodendrocytes, resulting in fewer mature, myelinating oligodendrocytes, higher numbers of oligodendrocyte progenitor cells and a decrease in the density of myelinated axons. Ultrastructural analysis of the remaining myelinated axons in the corpus callosum revealed further disruptions in myelin integrity. RNA sequencing and proteomic analyses revealed a concomitant decrease in the expression of genes and proteins involved in lipid metabolism, cholesterol synthesis and myelin compaction. These results reveal a previously underappreciated and fundamental role for ZDHHC9 and protein palmitoylation in regulating oligodendrocyte differentiation and myelinogenesis and provide mechanistic insights into the deficits observed in white matter volume in patients with mutations in ZDHHC9.
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Project description:Rapid nerve conduction in the CNS is facilitated by the insulation of axons with myelin, a specialized oligodendroglial compartment distant from the cell body. Myelin is turned over and adapted throughout life; however, the molecular and cellular basis of myelin dynamics is not well understood. Hypothesizing that only a fraction of all myelin-related mRNAs has been identified so far, we subjected myelin biochemically purified from mouse brains at various ages to RNA sequencing. We find a surprisingly large pool of transcripts abundant and/or enriched in myelin. Furthermore, a comprehensive analysis showed that the myelin transcriptome is closely related to the myelin proteome but clearly distinct from the transcriptomes of oligodendrocytes and brain tissues, suggesting that the incorporation of mRNAs into the myelin compartment is highly selective. The mRNA-pool in myelin displays maturation-dependent dynamic changes of composition, abundance, and functional associations; however ageing-dependent changes after 6 months of age were minor. We suggest that this transcript pool provides a basis for the local modulation of myelin turnover and adaptation, i.e. in the individual internode. A light-weight membrane fraction enriched for myelin was purified from mouse brains as described previously (Jahn et al., Neuromethods, 2013). For RNA-Seq, RNA was isolated from myelin of mice from indicated ages.
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Project description:Rapid nerve conduction in the CNS is facilitated by the insulation of axons with myelin, a specialized oligodendroglial compartment distant from the cell body. Myelin is turned over and adapted throughout life; however, the molecular and cellular basis of myelin dynamics is not well understood. Hypothesizing that only a fraction of all myelin-related mRNAs has been identified so far, we subjected myelin biochemically purified from mouse brains at various ages to RNA sequencing. We find a surprisingly large pool of transcripts abundant and/or enriched in myelin. By bioinformatic comparison, the myelin transcriptome is closely related to the myelin proteome but clearly distinct from the transcriptomes of oligodendrocytes and brain tissues, suggesting that the incorporation of mRNAs into the myelin compartment is highly selective. The mRNA-pool in myelin displays maturation-dependent dynamic changes of composition, abundance, and functional associations; however ageing-dependent changes after 6 months of age were minor. We suggest that this transcript pool provides a basis for the local modulation of myelin turnover and adaptation, i.e. in the individual internode.
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Project description:Rapid nerve conduction in the CNS is facilitated by the insulation of axons with myelin, a specialized oligodendroglial compartment distant from the cell body. Myelin is turned over and adapted throughout life; however, the molecular and cellular basis of myelin dynamics is not well understood. Hypothesizing that only a fraction of all myelin-related mRNAs has been identified so far, we subjected myelin biochemically purified from mouse brains at various ages to RNA sequencing. We find a surprisingly large pool of transcripts abundant and/or enriched in myelin. Furthermore, a comprehensive analysis showed that the myelin transcriptome is closely related to the myelin proteome but clearly distinct from the transcriptomes of oligodendrocytes and brain tissues, suggesting that the incorporation of mRNAs into the myelin compartment is highly selective. The mRNA-pool in myelin displays maturation-dependent dynamic changes of composition, abundance, and functional associations; however ageing-dependent changes after 6 months of age were minor. We suggest that this transcript pool provides a basis for the local modulation of myelin turnover and adaptation, i.e. in the individual internode.
2016-06-24 | GSE78151 | GEO
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Project description:Failure of oligodendrocytes to remyelinate underlies diseases such as multiple sclerosis (MS). We found that epigenetic silencing prevents oligodendrocytes from producing myelin sheaths in demyelinating MS lesions. Here, we developed a transgenic reporter system to identify a small-molecule epigenetic modulator that stimulates oligodendrocyte maturation and myelin ensheathment in vitro. This compound promoted remyelination in animal models of MS and myelination of regenerated axons and increased myelin sheath lengths in human iPSC-derived organoids. Multi-omics analyses revealed that the compound induced an enhancer/super-enhancer landscape that upregulates crucial myelinogenesis-associated pathways, including RRAS2-AKT signaling, driving actin depolymerization necessary for myelin ensheathment. Strikingly, the compound also induced phase-separated nuclear condensates of SREBP1/2, which concentrate transcriptional co-activators to drive lipid and cholesterol biosynthesis. Silencing expression of a potential target of the small molecule, HDAC3, facilitated robust myelination and remyelination. Our findings suggest that small-molecule-modulated epigenome rejuvenation relieves epigenetic silencing barriers and promotes myelin repair.
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