PAD2-mediated citrullination contributes to efficient oligodendrocyte differentiation and myelination

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. ATAC-seq of siPadi2 and control differentiating oli-neu. 3 n's for scrambled siRNA and siRNA targeting Padi2 exon2 in differentiating oli-neu, performed ATAC-seq according to Buenrostro et al 2013. H3K27ac ChIP-seq of proliferating and differentiating oli-neu.