METTL3/YTHDF1-mediated mA modification stabilizes USP12 to deubiquitinate FOXO3 and promote apoptosis in sepsis-induced myocardial dysfunction.

Sepsis-induced myocardial dysfunction (SIMD) is a life-threatening complication primarily driven by inflammation, yet its molecular mechanisms remain unclear. In this study, we identified significant upregulation of the mA methyltransferase METTL3 (methyltransferase-like 3), the mA reader protein YTHDF1 (YTH N6-methyladenosine RNA binding protein 1), as well as increased expression levels of USP12 (ubiquitin-specific peptidase 12), FOXO3 (forkhead box O3), and key molecules in the intrinsic apoptotic pathway, PUMA (p53 upregulated modulator of apoptosis) and BAX (Bcl-2-associated X), through proteomic profiling in an LPS (Lipopolysaccharide)-induced SIMD mouse model. In vitro and in vivo experiments demonstrated that METTL3 and YTHDF1 regulated USP12 mRNA expression and stability through mA modification. Elevated USP12 interacted with FOXO3, preventing its ubiquitin-mediated degradation, which enhanced FOXO3 binding to the PUMA promoter, leading to upregulation of PUMA. PUMA upregulation initiated the intrinsic apoptotic pathway, activating downstream BAX, Apaf1 (apoptotic protease-activating factor 1), and Caspases, ultimately driving SIMD. Inhibition of METTL3 (with STM2457), YTHDF1 (with Ebselen), or PUMA (with CLZ-8) significantly suppressed intrinsic apoptosis and alleviated SIMD symptoms. These findings underscore the critical role of METTL3/YTHDF1-dependent mA modification in modulating the USP12-FOXO3-PUMA-BAX-Apaf1-Caspases signaling axis in SIMD, and suggest that targeting this pathway may offer a potential therapeutic strategy for SIMD.