Histone methyltransferase DOT1L mediates the TGF-β1/Smad3 signaling pathway through epigenetic modification of SYK in myocardial infarction

Myocardial infarction (MI) represents the most critical condition in coronary artery disease, and the fibrotic process, detrimental to optimal recovery, often sustains. In the present work, we assessed whether suppression of disruptor of telomeric silencing 1-like (DOT1L) could alleviate fibrosis in vivo and cardiac fibroblast (CFS) proliferation in vitro, and elucidated the possible mechanism involved in these events. After left coronary artery ligation, we found that the MI mice exhibited a decrease in cardiac function, along with evident MI and myocardial fibrosis. In addition, AngII increased CFS viability and migration, and enhanced the expression of fibrotic proteins. Inhibition of DOT1L ameliorated proliferation and fibrosis in CFS. Furthermore, DOT1L promoted the expression of spleen tyrosine kinase (SYK) by increasing the H3K79me2 modification of the SYK promoter. SYK upregulation reversed the inhibitory effect of DOT1L knockdown on CFS proliferation and fibrosis by activating the TGF-β1/Smad3 signaling. SYK also mitigated the ameliorative effect of DOT1L knockdown on myocardial injury and fibrosis caused by MI in vivo. In conclusion, these data indicated that DOT1L depletion might be a promising therapeutic target for fibrosis in MI.