Define roles of JMJD1B in mediating histone demethylation and gene expression

The arginine or lysine methylation status of histones dynamically changes during many essential cellular processes, particularly during embryonic and hematopoietic stem cell development. The enzymes demethylate methyllysine residues have been well defined, but the enzymes demethylate the methylarginine residues during different cellular processes are unknown. In current study, we demonstrate that JMJD1B is a lysine demethylase for H3K9me2 and an arginine demethylase for H4R3me2s. To reveal the biological significance of JMJD1B as an arginine demethylase, we isolate hematopoietic stem/progenitor cells (HSPC) from wild-type and JMJD1B knockout (JKO) bone marrow. We then conduct ChIP-seq on H4R3me2s and H3K9me2 histone markers and perform RNA-seq to determine the global gene expression profiles. We have observed global demethylation of H4R3me2s at the gene body but not the intergenic regions in hematopoietic stem/progenitor cells. H4R3me2s demethylation at the gene body region is directly correlated with gene expression in these cells. Furthermore, knockout of JMJD1B causes defects in removing the H4R3me2s epigenetic marker, leading to down-regulation of genes important for blood cells differentiation and development. Altogether, our current study demonstrates that arginine demethylases exist in cellular systems and that JMJD1B demethylates H4R3me2s for proper epigenetic programming during development. For each genetic background, a pool of HSPCs and BMCs from four biological replicates are collected and analyzed by ChIP-seq. HSPCs from two biological replicates are analyzed by RNA-seq. For ChIP-seq, the input and/or ChIP histone H4 is used as control.