Canagliflozin ameliorates diabetic podocyte damage via enriching mitochondria-associated endoplasmic reticulum...

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have renoprotective properties in diabetic kidney disease (DKD) that extend beyond blood glucose-lowering effects; however, the underlying mechanism remains unclear. Recent studies suggest that the altered homeostasis of mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) was closely associated with the progression of DKD. In the current study, we investigated the effects of canagliflozin on diabetic podocyte injury and MAM formation in db/db mice and high glucose-induced podocytes. Eight weeks of canagliflozin treatment (30 mg/kg/day) decreased body weight and blood glucose level, and urinary albumin excretion of diabetic mice. Diabetes-associated renal histopathological changes and podocyte injury of db/db mice were also obviously improved by canagliflozin. In addition, a significant decrease in the MAM area and an increase in the fragmented mitochondria were observed in the podocytes of diabetic kidneys, while canagliflozin enhanced MAM formation and decreased fragmented mitochondria. Furthermore, canagliflozin-treated diabetic mice presented with amelioration of mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and apoptosis. Interestingly, no significant difference was observed after insulin treatment, although its glucose-lowering effect was comparable to that of canagliflozin. In vitro, canagliflozin reversed HG-induced MAM disruption, fragmented mitochondria, podocyte injury, mitochondrial dysfunction, ER stress, and apoptosis in podocytes. However, the above beneficial effects of canagliflozin on podocytes were offset by co-overexpression of FATE1, an uncoupler of MAM, under HG conditions. Taken together, these findings indicate that canagliflozin improves diabetic podocyte injury via modulating MAM structure and function.