Methyltransferase METTL1 regulates MSC mRNA stability via m7G modification in acute pancreatitis.

Acute pancreatitis (AP) is a serious inflammatory disease with significant morbidity, yet its underlying molecular mechanisms remain incompletely understood. This study reveals a novel epitranscriptomic pathway in AP pathogenesis centered on METTL1-mediated N7-methylguanosine (m7G) RNA modification. We found that METTL1 expression and global m7G levels were significantly elevated in serum from AP patients, pancreatic tissues of sodium taurocholate-induced AP mice, and in vitro models of LPS-polarized macrophages and STC-injured pancreatic acinar cells. Through integrated multi-omics analysis combining m7G methylome mapping and transcriptome profiling, we identified Musculin (MSC) as a key target whose mRNA stability is enhanced by METTL1-mediated m7G modification. Functional experiments demonstrated that MSC upregulation activates TNF signaling through phosphorylation of NF-κB, JNK, and MAPK proteins, thereby promoting macrophage M1 polarization and pancreatic acinar cell injury. The pathological significance of this pathway was confirmed in vivo, where pancreas-targeted knockdown of Mettl1 significantly attenuated AP severity. Furthermore, mechanistic studies using a catalytic-dead METTL1 mutant established that both the methyltransferase activity of METTL1 and subsequent TNF signaling activation are essential for driving inflammatory responses. Our findings delineate a previously unrecognized METTL1-m7G-MSC-TNF signaling axis that promotes AP progression, highlighting the therapeutic potential of targeting METTL1-mediated epitranscriptomic modification in inflammatory diseases.