TRPC6 mediates high glucose-induced mitochondrial fission through activation of CDK5 in cultured human podocytes

Abstract

Mitochondrial abnormalities contribute to the development of diabetic nephropathy (DN). However, the precise mechanisms of mitochondrial dysfunction in DN remain unclear. Transient receptor potential canonical channel-6 (TRPC6), a non-selective cation channel permeable to Ca2+, has been shown to regulate mitochondrial dynamics. This study was therefore aimed to explore the regulatory role and mechanisms of TRPC6 in high glucose (HG)-induced mitochondrial dysfunction in podocytes. Here we found that TRPC6 expression and TRPC6-induced Ca2+ influx were increased in HG-treated podocytes. Furthermore, the TRPC6 inhibitor and TRPC6 siRNA ameliorated mitochondrial dysfunction and apoptosis in HG-treated podocytes. BAPTA-AM, an intracellular calcium chelating agent, attenuated mitochondrial fission under HG conditions as well. Then, we found the activity of calpain and cyclin-dependent kinase 5 (CDK5) was markedly enhanced in HG-treated podocytes, which can be blocked by pretreatment with the TRPC6 inhibitor. Calpain-1 inhibition by calpeptin or by calpain-1 siRNA transfection not only attenuated HG-induced mitochondrial fission but also reduced the activity of CDK5. Additionally, the CDK5 inhibitor and its siRNA decreased mitochondrial fragmentation in HG-treated podocytes. Collectively, we revealed the essential role of TRPC6 in regulating HG-induced mitochondrial fission and apoptosis through the calpain-1/CDK5 pathway in human podocytes, which may provide new insights into the pathogenesis of DN.

miR‐4645‐3p attenuates podocyte injury and mitochondrial dysfunction in diabetic kidney disease by targeting Cdk5

“…In kidney, Cdk5 regulates the differentiation, proliferation, and morphology of podocytes and plays an important role in maintaining the normal structure and function of podocytes 12 . In diabetes, hyperglycemia, TGF‐β1, and endoplasmic reticulum stress could overactivate Cdk5 and lead to podocyte injury and apoptosis 13–15 . Although many studies have shown that hyperactivated Cdk5 is associated with the podocyte injury in DKD, the exact mechanism still needs to be clarified.…”

“…12 In diabetes, hyperglycemia, TGF-β1, and endoplasmic reticulum stress could overactivate Cdk5 and lead to podocyte injury and apoptosis. [13][14][15] Although many studies have shown that hyperactivated Cdk5 is associated with the podocyte injury in DKD, the exact mechanism still needs to be clarified.…”