DOT1L-AF10-mediated H3K79me3 promotes NF-kB p65-dependent inflammatory activation in endothelial cells

DOT1L-catalyzed H3K79 methylation is a hallmark of actively transcribed genes and has been extensively studied in developmental and disease contexts. While DOT1L inhibition has emerged as a promising therapeutic strategy in cancer, its role in pro-atherogenic endothelial inflammation remains unclear. To investigate this, we utilized an in vivo partial carotid artery ligation model and observed increased DOT1L expression and H3K79me3 level. Consistently, in vitro studies employing a 3D-printed human coronary artery model and TNF- stimulation corroborated these results, showing elevated DOT1L expression and H3K79me3 deposition, while levels of H3K79me and me2 remained unchanged. Further analyses identified key DOT1L-containing complex (DotCom) components, AF10 and AF9 (upregulated) and AF17 (downregulated), as contributors to the enhanced H3K79me3 landscape. CUT&RUN sequencing showed prominent H3K79me3 enrichment at the RELA (NF-{kappa}B p65) promoter, corresponding with increased NF-{kappa}B p65 expression and activation. Notably, inhibition/knockdown of the methyltransferase DOT1L or overexpression of the demethylase FBXL10 significantly reduced H3K79me3 levels, thereby suppressing NF-{kappa}B p65 expression and attenuating endothelial inflammation, independent of canonical NF-{kappa}B p65 activation. These findings establish DOT1L-mediated H3K79me3 as a crucial epigenetic regulator of endothelial inflammation, highlighting a potential therapeutic avenue for mitigating NF-{kappa}B p65-driven pro-atherogenic endothelial dysfunction.