Genomic landscape of transcriptionally active histone arginine methylation marks, H3R2me2s and H4R3me2a, relative to nucleosome depleted regions.

Protein arginine methyltransferase 1 (PRMT1) and the product of this enzyme (histone H4 asymmetrically dimethylated at Arg 3; H4R3me2a) are important in the establishment and maintenance of chicken and murine erythrocyte transcriptionally active chromatin. Silencing the expression of PRMT1 results in loss of acetylated histones H3 and H4 and methylated H3K4 and prevents erythropoiesis. Here, we show that H4R3me2a and the PRMT5-catalyzed histone H3 symmetrically dimethylated at Arg 2 (H3R2me2s) locate largely to introns of expressed genes and intergenic regions, with both marks co-localizing in the chicken polychromatic erythrocyte genome. H4R3me2a and H3R2me2s were associated with histone marks of active promoters and enhancers, as well as with the body of genes that have an atypical chromatin structure, with nucleosome depleted regions. H4R3me2a co-localized with acetylated H3K27. Previous studies have shown that PRMT1 was bound to CBP/p300, suggesting a role of PRMT1-mediated H4R3me2a in CBP/p300 recruitment and H3K27 acetylation. Moreover, PRMT1 might be a key enzyme affected when S-adenosyl methionine levels are reduced in metabolic disorders.