The INO80 chromatin remodeling complex regulates histone H2A.Z mobility and the G1-S transition in oligodendrocyte precursors

Chromatin remodelling complexes (CRCs) participate in oligodendrocyte (OL) differentiation, survival and maintenance. We asked whether CRCs also control proliferation of OL precursors (OPs) - focusing on the INO80 complex, which is known to regulate proliferation of a variety of other cell types during development and disease. CRISPR/Cas9-mediated inactivation of Ino80 in vitro, or Cre-mediated deletion in vivo, slowed the OP cell cycle substantially by prolonging G1, without inducing OL differentiation. RNAseq analysis revealed that E2F target genes were dysregulated in OPs from INO80-deficient mice, but correlated RNAseq and ATAC-seq uncovered no general correlation beween gene expression and altered nucleosome positioning at transcription start sites. Fluorescence photobleaching experiments in cultured OPs demonstrated that histone H2A.Z mobility increased following loss of INO80, suggesting that INO80 regulates the cell cycle machinery in OPs through H2A.Z/ H2A exchange. We also present evidence that INO80 associates with OLIG2, a master regulator of OL development.