Diabetic kidney disease (DKD) is a major microvascular complication of diabetes. The glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide exerts renoprotective effects beyond glucose control; however, the underlying mechanisms remain incompletely understood. The protective effects and mechanisms of liraglutide were investigated using in vitro (HK-2 cells under glucolipotoxic conditions) and in vivo (DKD rat) models. Key molecular and functional assessments included the evaluation of oxidative stress, apoptosis, mitochondrial function (dynamics (MFN1, MFN2, FIS1, and DRP1), mitophagy (PINK1, PARKIN, LC3II/I, and P62), and ultrastructure), and histone acetylation (H3K9/14/18/27ac). The critical role of the NQO1/SIRT3 pathway was validated using pharmacological inhibition and genetic silencing (shRNA/AAV). Both in vitro and in vivo, a multifaceted injury phenotype, including oxidative stress, apoptosis, mitochondrial dysfunction, and histone hyperacetylation, was induced, accompanied by downregulation of the NQO1/SIRT3 pathway. Disruption of this pathway further exacerbated these injuries. Conversely, liraglutide treatment effectively counteracted this phenotype, improving metabolic parameters (blood glucose, blood insulin, and blood lipids), renal function (blood urea nitrogen, serum creatinine, and urine albumin-to-creatinine ratio) and histopathology. Liraglutide attenuated oxidative stress and apoptosis, restored mitochondrial function and mitophagy, and reduced histone hyperacetylation. These protective effects were consistently associated with the restoration of NQO1/SIRT3 expression. Genetic or pharmacological disruption of the NQO1/SIRT3 axis significantly attenuated the efficacy of liraglutide, and combined inhibition completely abolished its effects. Our findings demonstrate that liraglutide attenuates DKD by activating the NQO1/SIRT3 pathway, which coordinates the enhancement of mitochondrial function and the restoration of epigenetic homeostasis. This study revealed that the NQO1/SIRT3 pathway is a critical mechanistic mediator of the renoprotective effect of liraglutide.
