Abstract

Cellular senescence plays a contributory role in the development and progression of diabetic kidney disease (DKD). Melatonin shows potent anti-senescent and anti-inflammatory effects, with demonstrated benefits in DKD. Delineation of the mechanisms through which melatonin delays cellular senescence to ameliorate the progression of DKD will enhance our understanding and ability to treat the disease. Therefore, to elucidate the effects and underlying mechanisms of melatonin, we established streptozotocin (STZ)-induced diabetic mouse models and high glucose (HG)-stimulated human renal cortical proximal tubule epithelial (HK-2) cell models. Cellular senescence was assessed by western blotting, quantitative real-time PCR (qPCR), and β-galactosidase (SA-β-gal) staining. Renal histopathological injury was evaluated by hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining, along with renal function measurements. The results showed that melatonin administration significantly improved renal function and attenuated histopathological damage in diabetic mice. Furthermore, melatonin effectively reduced the levels of cellular senescence marker proteins (p53, p21, p16 INK4A , and γ-H2AX), decreased the SA-β-gal positive staining area, and suppressed senescence-associated secretory phenotype (SASP) expression. Mechanistically, melatonin potently inhibited the upregulation of key proteins in the Wnt/β-catenin signaling pathway, including Wnt3a, β-catenin, p-GSK-3β, c-Myc, and Cyclin-D1, with an efficacy comparable to that of the Wnt inhibitor XAV-939. Notably, experiments in HK-2 cells further demonstrated that treatment with the Wnt/β-catenin activator BML-284 abrogated the protective effects of melatonin. Overall, these findings demonstrate that melatonin suppresses cellular senescence in DKD by inhibiting the Wnt/β-catenin pathway.