Heskol, A. | Search bioRxiv

bioRxiv2020

A primed immune transcriptional program is activated in oligodendroglia in multiple sclerosis

Multiple sclerosis (MS) is a disease characterized by a targeted immune attack on myelin in the central nervous system (CNS). We have previously shown that oligodendrocytes (OLs), myelin producing cells in the CNS, and their precursors (OPCs), ac-quire disease-specific transcriptional states in MS 1,2. To under-stand how these alternative transcriptional programs are acti-vated in disease, we performed single-cell assay for transposase accessible chromatin using sequencing (scATAC-seq) on the OL lineage in the experimental autoimmune encephalomyeli-tis (EAE) mouse model of MS. We identified regulatory regions with increased accessibility in oligodendroglia (OLG) in EAE, some of which in the proximity of immune genes. A similar re-modeling of chromatin accessibility was observed upon treat-ment of postnatal OPCs with interferon-gamma (IFN{gamma}), but not with dexamethasone. These changes in accessibility were not exclusive to distal enhancers, but also occurred at promoter re-gions, suggesting a role for promoters in mediating cell-state transitions. Notably, we found that a subset of immune genes al-ready exhibited chromatin accessibility in OPCs ex vivo and in vivo, suggesting a primed chromatin state in OLG compatible with rapid transitions to an immune-competent state. Several primed genes presented bivalency of H3K4me3 and H3K27me3 at promoters in OPCs, with loss of H3K27me3 upon IFN{gamma} treatment. Inhibition of JMJD3/Kdm6b, mediating removal of H3K27me3, led to the inability to activate these genes upon IFN{gamma} treatment. Importantly, OLGs from the adult human brain showed chromatin accessibility at immune gene loci, par-ticularly at MHC-I pathway genes. A subset of single-nucleotide polymorphisms (SNPs) associated with MS susceptibility over-lapped with these primed regulatory regions in OLG from both mouse and human CNS. Our data suggest that susceptibility for MS may involve activation of immune gene programs in OLG. These programs are under tight control at the chromatin level in OLG and may therefore constitute novel targets for immunological-based therapies for MS.

neuroscience↗

bioRxiv2018

PADI2-mediated citrullination is required for 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 therapeutic strategy for MS. Here, in contrast, we show citrullination by peptidylarginine deiminase 2 (PADI2) is required for normal oligodendrocyte differentiation, myelination and motor function. We identify several targets for PADI2, including myelin-related proteins and 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 oligodendrocyte differentiation genes. Moreover, mice lacking PADI2, display motor dysfunction and decreased number of myelinated axons in the corpus callosum. We conclude that citrullination is required for oligodendrocyte lineage progression and myelination and suggest its targeted activation in the oligodendrocyte lineage might be beneficial in the context of remyelination.

neuroscience↗

bioRxiv2017

STRT-seq-2i: dual-index 5′ single cell and nucleus RNA-seq on an addressable microwell array

Single-cell RNA-seq has become routine for discovering cell types and revealing cellular diversity, but currently no high-throughput platform has been used successfully on archived human brain samples. We present STRT-seq-2i, an addressable 9600-microwell array platform, combining sampling by limiting dilution or FACS, with imaging and high throughput at competitive cost. We applied the platform to fresh single mouse cortical cells and to frozen post-mortem human cortical nuclei, matching the performance of a previous lower-throughput platform.

molecular biology↗