METTL3 drives heart failure by regulating Spp1 and Fos m6A modification in myocardial infarction

Abstract While m6A modification has been reported in myocardial infarction (MI), the detailed mechanism by which METTL3 regulates the progression of the disease has not yet been elucidated, and it remains unclear why m6A modification increases after MI. Through MeRIP-seq and extensive bioinformatics analysis, the target genes SPP1 and FOS with the most significant m6A modification and differential expression in MI were screened. We successfully constructed heart specific Mettl3 knockout mice (Mettl3CKO) to verify that METTL3 promotes the deterioration of cardiac function after MI. We performed complementary molecular methods to assess protein quantity and interactions to identify mechanisms regulating this response. We manipulated select molecular pathways using both genetic and pharmacological methods to validate these mechanisms. Here, we showed that METTL3 exerted methyltransferase activity-dependent functions in gene regulation in MI, and a significant transcription factor HuR assisted the function of METTL3. and demonstrated that METTL3 was critical for the promotion of heart failure after MI. More specifically, METTL3 directly interacted with HuR through its nuclear localization domain in the cell nucleus under normoxia condition. When hypoxia developed, METTL3 separated from HuR and deposited m6A into 5’UTR of Spp1 and Fos mRNA to maintain their stability. In contrast, HuR bound to the ARE domain of 3’UTR of Spp1 and Fos mRNA to take them to the cytosol, maintaining their stability. Moreover, HIF-1α directly interacted with the HRE domain of Mettl3 to promote its transcription, and HuR bound to the ARE domain of 3’UTR of Mettl3 mRNA to maintain its stability to promote following translation. Collectively, our studies revealed previously unappreciated functions of METTL3 with the help of HuR, and a direct target of HIF-1α under normoxia condition, which together contribute to its essential function in MI, suggesting therapeutic potential for targeting the METTL3/HuR/Spp1(Fos) mRNA axis.