Systematic perturbations of SETD2, NSD1, NSD2, NSD3 and ASH1L reveal their distinct contributions to H3K36 methylation

Methylation of histone 3 lysine 36 (H3K36me) has emerged as an essential epigenetic component for the faithful regulation of gene expression. Despite its importance in development, disease, and cancer, how the molecular agents collectively shape the genome-wide deposition of H3K36me is unclear. Here, we use mouse mesenchymal stem cells to comprehensively perturb the components of the H3K36me deposition machinery and infer the activities of the five most prominent players: SETD2, NSD1, NSD2, NSD3, and ASH1L. We find that H3K36me2 is the most abundant of the three methylation states and that it is predominantly deposited at intergenic regions by NSD1, and in part by NSD2. In contrast, H3K36me1/3 are most abundant within exons and are positively correlated with gene expression. We demonstrate that while SETD2 is responsible for depositing most H3K36me3, it also deposits H3K36me2 within transcribed genes. Additionally, loss of SETD2 results in an increase of exonic H3K36me1, suggesting that other H3K36 methyltransferases may prime gene bodies with lower methylation states ahead of transcription. Through a reductive approach, we uncover the distribution patterns of NSD3- and ASH1L-catalyzed H3K36me2. While NSD1/2 establish broad intergenic H3K36me2 domains, NSD3 deposits H3K36me2 peaks centered on active promoter and enhancer regions. Meanwhile, the activity of ASH1L is restricted to regulatory elements of developmentally relevant genes, and our analyses implicate PBX2 as a potential recruitment factor. Overall, our study provides new insights into the regulation of H3K36me and helps to consolidate the wealth of previous observations in the context of structured analyses.