Morin enhances the renoprotective effects of Empagliflozin in diabetic kidney disease via targeting ATF6-DAPK1 signaling

Context: Diabetic kidney disease (DKD) is a major complication of diabetes mellitus, driven by hyperglycemia-induced oxidative stress, ER stress, and mitochondrial apoptosis. Objective: This study examined the protective effects of Morin against hyperglycemia-induced renal tubular injury, alone or in combination with the SGLT2 inhibitor Empagliflozin, with emphasis on the ATF6-DAPK1 axis. Materials & methods: HK2 cells were exposed to high glucose with or without Morin and/or Empagliflozin. Cellular stress, mitochondrial function, and apoptosis were assessed. Morin-DAPK1 binding was examined via molecular docking, surface plasmon resonance (SPR), and cell thermal shift assay (CETSA). db/db mice received vehicle, Empagliflozin, Morin, or their combination for 14 weeks, followed by renal histological, biochemical, and metabolic evaluations. Results: Morin reduced ROS accumulation, ER stress (p-PERK, p-eIF2α, CHOP, cleaved ATF6), mitochondrial dysfunction, and apoptosis in HK2 cells. It suppressed DAPK1 mRNA expression via ATF6 inhibition and directly bound DAPK1 (Kd = 1.61 µM), disrupting its interaction with pro-apoptotic BAK/BIK. Empagliflozin indirectly downregulated DAPK1 through ER stress relief. Combination therapy synergistically reduced oxidative stress, preserved mitochondrial membrane potential, and prevented apoptosis. In db/db mice, both compounds improved renal structure, lowered blood glucose, reduced UACR, and inhibited kidney stress markers, with greater improvements in the combination group, which also alleviated hepatic steatosis. Discussion and Conclusion: Morin exhibits renoprotective effects against high glucose-induced cellular stress and diabetic kidney disease, at least partially via DAPK1 targeting. Co-administration with Empagliflozin enhances these effects, supporting its potential as an adjunct therapy for hyperglycemia-induced kidney injury.