NSUN2-mediated GATM m5C methylation regulates creatine metabolism to drive mitochondrial fission and promote renal fibrosis.

Chronic kidney disease (CKD) is increasing globally, presenting a critical health challenge. Renal fibrosis, the main pathological feature of CKD, is poorly understood and lacks targeted therapies. Here, we reveal that 5-methylcytosine (m5C) RNA methylation, primarily mediated by methyltransferase NSUN2, is significantly upregulated in renal fibrosis. Reduction of m5C RNA methylation levels upon NSUN2 loss attenuates fibrosis responses in cells, and specific knockout of NSUN2 in renal tubular epithelial cells alleviates renal fibrosis in several disease models. Mechanistically, NSUN2 methylates and stabilizes glycine amidinetransferase (GATM) mRNA. GATM exacerbates mitochondrial fission not only by directly binding to Drp1 but also through its product creatine, collectively driving the progression of renal fibrosis. We subsequently identify an inhibitor of NSUN2 that mitigates the progression of renal fibrosis. Collectively, our study demonstrates that targeting NSUN2-mediated m5C methylation of GATM mRNA therapeutically offers a promising strategy to slow the progression of CKD.