GATM-mediated creatine synthesis alleviates acute kidney injury by promoting lipophagy in renal tubular epithelial cells

Abstract Background Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid decline in renal function. Accumulating studies demonstrate that injury to renal tubular epithelial cells (RTECs) is central to the onset and progression of AKI, as well as a key driver of the transition from AKI to chronic kidney disease (CKD). Glycine amidinotransferase (GATM) is the rate-limiting enzyme in creatine synthesis, but its role in AKI remains unknown. This study therefore investigates the regulatory role and molecular mechanism of GATM in AKI. Methods GATM expression was assessed in single-cell datasets, AKI mouse models, and patient biopsies. GATM-knockout and adeno-associated virus-mediated overexpression mice were used to evaluate its functional role in vivo, alongside in vitro studies in HK-2 cells and primary RTECs. Mechanistic investigations integrated experiments on transcriptomic sequencing, lipophagy, and regulation of creatine synthesis. Upstream regulation was explored via m6A dot blot and siRNA-mediated knockdown, with a focus on the METTL14/YTHDF2-GATM axis. Results GATM was significantly downregulated in RTECs across AKI models and patients, with expression correlating positively with renal function. GATM knockout exacerbated AKI, whereas overexpression ameliorated injury and attenuated progression to CKD. Mechanistically, GATM overexpression promoted lipophagy via enhanced creatine synthesis, and these effects were reversed by autophagy inhibitor 3-methyladenine (3-MA) or creatine synthesis blockade. Upstream, METTL14/YTHDF2-mediated m6A methylation contributed to GATM downregulation, and their knockdown restored GATM expression and alleviated renal injury in AKI. Conclusion Our findings suggest that GATM may play a protective role in AKI, potentially through promoting lipophagy via creatine synthesis. Its downregulation via METTL14/YTHDF2-mediated m6A methylation may contribute to tubular injury. The METTL14/YTHDF2-GATM axis may represent a promising candidate for further therapeutic exploration in AKI.