Project description:In the central nervous system, oligodendrocytes encase axons with myelin, a highly organized multilayered membrane structure. Myelin allows the rapid propagation of action potentials along the axons, while also supporting their mantainance metabolically. Fatty acids are basic building blocks for both glyco- and phospholipids, key constituents of cell membranes. Moreover, fatty acids can modify proteins via palmitoylation and activate transcriptional networks, e.g. through the PPARs transcription factors. Due to the high demand of membrane oligodendrocytes face to produce myelin, we hypothesized that they strongly rely upon fatty acid synthesis rather than mostly on their intake from the dietary pool. We tested this hypothesis by deleting the enzyme Fatty Acid Synthase specifically from neonatal oligodendrocyte progenitor cells, in vivo in C57Bl/6 olig2Cre FASN floxed mice. We addressed the consequences of this depletion on oligodendrocytes differentation and myelination potential in the central nervous system. In particular, we analyzed by RNA-seq how lack of FASN affected the transcriptome of optic nerves dissected from P14 mutant (olig2Cre FASN lox/lox) versus control (FASN lox/lox) mice.
Project description:We performed genome-wide profiling of Tcf7l2 occupancy during oligodendrocyte differentiation and identified the key enzymes involved in cholesterol metabolism and essential for CNS myelination. Examination of Tcf7l2 chIP-seq in oligodendrocyte progenitor cell and 2 differentiation oligodendrocytes.
Project description:We used RNA sequencing to examine the transcriptional changes in differentiated oligodendrocytes, oligodendrocyte precursor cells, astroctytes, and microglia after blocking exocytosis from oligodendrocyte-lineage cells
Project description:Myelination of neuronal axons is essential for nervous system development. Myelination requires dramatic cytoskeletal dynamics in oligodendrocytes, but how actin is regulated during myelination is poorly understood. We recently identified serum response factor (SRF)—a transcription factor known to regulate expression of actin and actin regulators in other cell types—as a critical driver of myelination in the aged brain. Yet, a major gap remains in understanding the fundamental role of SRF in oligodendrocyte lineage cells. Here we show that SRF is required cell autonomously in oligodendrocytes for myelination during development. Combining ChIP-seq with RNA-seq identifies SRF-target genes in OPCs and oligodendrocytes that include actin and other key cytoskeletal genes. Accordingly, SRF knockout oligodendrocytes exhibit dramatically reduced actin filament levels early in differentiation, consistent with its role in actin-dependent myelin sheath initiation. Together, our findings identify SRF as a transcriptional regulator that controls the expression of cytoskeletal genes required in oligodendrocytes for myelination. This study identifies a novel pathway regulating oligodendrocyte biology with high relevance to brain development, aging, and disease.
Project description:Myelination of neuronal axons is essential for nervous system development. Myelination requires dramatic cytoskeletal dynamics in oligodendrocytes, but how actin is regulated during myelination is poorly understood. We recently identified serum response factor (SRF)—a transcription factor known to regulate expression of actin and actin regulators in other cell types—as a critical driver of myelination in the aged brain. Yet, a major gap remains in understanding the fundamental role of SRF in oligodendrocyte lineage cells. Here we show that SRF is required cell autonomously in oligodendrocytes for myelination during development. Combining ChIP-seq with RNA-seq identifies SRF-target genes in OPCs and oligodendrocytes that include actin and other key cytoskeletal genes. Accordingly, SRF knockout oligodendrocytes exhibit dramatically reduced actin filament levels early in differentiation, consistent with its role in actin-dependent myelin sheath initiation. Together, our findings identify SRF as a transcriptional regulator that controls the expression of cytoskeletal genes required in oligodendrocytes for myelination. This study identifies a novel pathway regulating oligodendrocyte biology with high relevance to brain development, aging, and disease.
Project description:Myelination of neuronal axons is essential for nervous system development. Myelination requires dramatic cytoskeletal dynamics in oligodendrocytes, but how actin is regulated during myelination is poorly understood. We recently identified serum response factor (SRF)—a transcription factor known to regulate expression of actin and actin regulators in other cell types—as a critical driver of myelination in the aged brain. Yet, a major gap remains in understanding the fundamental role of SRF in oligodendrocyte lineage cells. Here we show that SRF is required cell autonomously in oligodendrocytes for myelination during development. Combining ChIP-seq with RNA-seq identifies SRF-target genes in OPCs and oligodendrocytes that include actin and other key cytoskeletal genes. Accordingly, SRF knockout oligodendrocytes exhibit dramatically reduced actin filament levels early in differentiation, consistent with its role in actin-dependent myelin sheath initiation. Together, our findings identify SRF as a transcriptional regulator that controls the expression of cytoskeletal genes required in oligodendrocytes for myelination. This study identifies a novel pathway regulating oligodendrocyte biology with high relevance to brain development, aging, and disease.
Project description:Citrullination, the deimination of arginine residues into citrulline, has been implicated in the aetiology of several diseases. In multiple sclerosis (MS), citrullination is thought to be a major driver of pathology, through hypercitrullination and destabilization of myelin. As such, inhibition of citrullination has been suggested as a therapeutical strategy for MS. Here we show that citrullination by peptidylarginine deiminase 2 (PADI2) is in contrast required for normal oligodendrocyte differentiation, myelination and motor function. We identify several targets for PADI2, including not only myelin-related proteins, but also several chromatin-associated proteins, implicating PADI2 in epigenetic regulation. Accordingly, we observe that PADI2 inhibition and its knockdown affect chromatin accessibility and prevent the upregulation of genes involved in oligodendrocyte differentiation. Moreover, mice lacking PADI2, display motoric dysfunction and a decreased number of myelinated axons in the corpus callosum. Our study demonstrates that citrullination is required for oligodendrocyte lineage progression and myelination and thus its targeted activation in the oligodendrocyte lineage might be beneficial in the context of remyelination in diseases as MS.
Project description:We performed genome-wide profiling of Tcf7l2 occupancy during oligodendrocyte differentiation and identified the key enzymes involved in cholesterol metabolism and essential for CNS myelination.
Project description:Oligodendrocytes are responsible for myelin formation and axonal trophic support in the vertebrate CNS. While a number of factors have been discovered that regulate oligodendrocyte lineage progression, the exact molecular mechanisms involved in this process remain unclear. Emerging studies have shown that N6-methyladenosine (m6A), the most common internal RNA modification of mammalian mRNA, plays a critical role in various developmental processes. In this study, we demonstrate that oligodendrocyte lineage progression is accompanied by changes in m6A modification on numerous transcripts. In vivo conditional inactivation in oligodendrocyte lineage cells of an essential m6A writer component, METTL14, results in decreased oligodendrocyte numbers and CNS hypomyelination, although oligodendrocyte precursor cell (OPC) numbers are normal. In vitro Mettl14 ablation disrupts post-mitotic oligodendrocyte maturation. In addition, Mettl14 ablation has distinct effects on OPC and oligodendrocyte transcriptomes. Together, our findings indicate that dynamic RNA methylation plays a critical regulatory role in oligodendrocyte development and CNS myelination.