m6A methyltransferase METTL3 contributes to sympathetic hyperactivity post-MI via promoting TRAF6-dependent mitochondrial ROS production

• Published in: Free radical biology & medicine Vol. 209; no. Pt 2; pp. 342 - 354
• Main Authors: Yang, Peijin, Wang, Yu, Ge, Weili, Jing, Yanyan, Hu, Hesheng, Yin, Jie, Xue, Mei, Wang, Ye, Li, Xiaolu, Li, Xinran, Shi, Yugen, Tan, Jiayu, Li, Yan, Yan, Suhua
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.11.2023
• Subjects: Animals; m6A; Methyltransferases - genetics; Methyltransferases - metabolism; METTL3; Mitochondria - metabolism; Myocardial infarction; Myocardial Infarction - metabolism; PVN; Rats; Reactive Oxygen Species - metabolism; Sympathetic hyperactivity; TNF Receptor-Associated Factor 6 - genetics; TNF Receptor-Associated Factor 6 - metabolism; TRAF6/ECSIT pathway; Myocardial infarction; PVN; m6A; Sympathetic hyperactivity; TRAF6/ECSIT pathway; METTL3
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2023.10.392

N6-methyladenosine (m6A) is the most prevalent post-translational modification in eukaryotic mRNA. Recently, m6A editing modified by methyltransferase-like enzyme 3 (METTL3), the core m6A methyltransferase, has been demonstrated to be involved in cardiac sympathetic hyperactivity. This study aimed to clarify the effects and underlying mechanisms of METTL3 in the paraventricular nucleus (PVN) in mediating sympathetic activity following myocardial infarction (MI). We established rat MI models by left anterior descending coronary artery ligation. m6A quantification was performed.The expression of METTL3 and its downstream gene, tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), were determined. The functional role of METTL3 in sympathetic hyperactivity and electrical conduction stability were verified by assessing renal sympathetic nerve activity (RSNA), norepinephrine (NE) levels, and programmed electrical stimulation. Rescue experiments were also conducted. The mechanism by which m6A is involved in mitochondrial reactive oxygen species (mROS) production, mediated by TRAF6/ECSIT pathway, was explored in lipopolysaccharide (LPS) treated primary microglial cells. METTL3 was predominantly localized in the microglia and significantly increased within the PVN at 3 days post-MI. Inhibition of METTL3 decreased m6A levels, TRAF6 expression, and mROS production; downregulated sympathoexcitation, indicated by attenuated NE concentration and RSNA; decreased the incidence of ventricular tachycardia or fibrillation; and improved cardiac function. Mechanistically, downregulation of METTL3 prevented TRAF6 translocation to the mitochondria in the microglia and subsequent TRAF6/ECSIT pathway activation, resulting in decreased mROS production. This study demonstrates that METTL3-mediated m6A modification promotes sympathetic hyperactivity through TRAF6/ECSIT pathway and mitochondrial oxidative stress in the PVN, thereby leading to ventricular arrhythmias post-MI. The schematic of the hypothesis demonstrating the critical role and mechanism of m6A editing regulated by methyltransferase METTL3 on sympathetic hyperactivity within the PVN post-MI. [Display omitted] •METTL3-mediated m6A in the PVN was involved in sympathetic hyperactivity by TRAF6/ECSIT pathway and mROS production post-MI.•METTL3 was predominantly located in microglia, regulated m6A levels, increased expression of downstream molecules TRAF6, ECSIT and mitochondrial ROS, improved cardiac function post-MI.•Inhibition of METTL3 partly decreased TRAF6 translocation to the mitochondria, TRAF6/ECSIT pathway activation and oxidative stress in microglia.