SMYD5 catalyzes histone H3 lysine 36 trimethylation at promoters

SETD2 methylates histone H3K36me3 in gene bodies in mammalian cells. Here the authors show H3K36me3 is also enriched at the promoter regions, and that this methylation is carried out by SMYD5, which is recruited by RNA polymerase II. They furthermore show SMYD5 is elevated in liver cancer and is correlated with changes in gene expression. Histone marks, carriers of epigenetic information, regulate gene expression. In mammalian cells, H3K36me3 is mainly catalyzed by SETD2 at gene body regions. Here, we find that in addition to gene body regions, H3K36me3 is enriched at promoters in primary cells. Through screening, we identify SMYD5, which is recruited to chromatin by RNA polymerase II, as a methyltransferase catalyzing H3K36me3 at promoters. The enzymatic activity of SMYD5 is dependent on its C-terminal glutamic acid-rich domain. Overexpression of full-length Smyd5, but not the C-terminal domain-truncated Smyd5, restores H3K36me3 at promoters in Smyd5 knockout cells. Furthermore, elevated Smyd5 expression contributes to tumorigenesis in liver hepatocellular carcinoma. Together, our findings identify SMYD5 as the H3K36me3 methyltransferase at promoters that regulates gene expression, providing insights into the localization and function of H3K36me3.

Automated summary

SETD2 methylates histone H3K36me3 in gene bodies in mammalian cells. In this study, the authors demonstrate that H3K36me3 is also enriched at promoter regions and is catalyzed by SMYD5, recruited by RNA polymerase II. They further show that SMYD5 is elevated in liver cancer, with a correlation to changes in gene expression. These findings provide insights into the localization and function of H3K36me3.