Tet1-mediated Epigenetic Programming Regulates Calcium Homeostasis and Stage-specific CNS Myelination and Regeneration

DNA hydroxymethylation by epigenetic modifiers TET dioxygenases is critical for gene transcription in various biological processes, however, its role in oligodendrocyte maturation and functions remain elusive. Here, we found that mice lacking Tet1 in the oligodendrocyte lineage exhibited hypomyelination in the CNS in the juvenile stage, leading to defects in action potential propagation, motor coordination, anxiety-like behavior and spatial memory capacities. Although the myelin deficiency recovered in adulthood, remyelination after cuprizone-induced demyelination was compromised in Tet1cKO mice. By integrating transcriptome and DNA methylation profiles, we identified a cohort of genes that were differentially regulated by Tet1 and hyperhydroxymethylation, including the genes associated with Ca2+ transportation. Tet1-deficient OPCs exhibited a reduction in [Ca2+] oscillations, while the agonists of calcium internal stores rescued the differentiation defect of Tet1-deficient OPCs. Thus, our results suggest that stage-specific Tet1-mediated epigenetic programming in oligodendrocytes maintain Ca2+ homeostasis for differentiation and regulate neuronal activities and myelin repair. Control and Tet1 mutant samples.