Transient receptor potential canonical 6 knockdown ameliorated diabetic kidney disease by inhibiting nuclear factor of activated T cells 2 expression in glomerular mesangial cells

PURPOSE: Glomerular mesangial cell (GMC) dysfunction plays a vital role in the pathogenesis of diabetic kidney disease (DKD). Transient receptor potential canonical 6 (TRPC6) has been demonstrated to be involved in the development of DKD. However, the underlying mechanism remains unclear. The present study investigated the role of TRPC6 in GMC dysfunction and the related mechanism. METHODS: Diabetic rats and cultured GMCs were used in the experiment. The diabetic rat model was created by intraperitoneal injection of streptozotocin. Protein and mRNA levels were assessed by Western blotting and quantitative RT–PCR, respectively. Histological changes in the kidneys were observed by immunochemistry and hematoxylin and eosin. TRPC6 knockdown was achieved by adenovirus-mediated TRPC6 shRNA delivery in vivo and TRPC6 siRNA transfection in vitro. RESULTS: TRPC6 expression was increased in diabetic rat kidneys. Knockdown of TRPC6 attenuated diabetes-induced kidney functional deterioration. In addition, the increases in extracellular matrix components, including collagen IV, collagen I, and fibronectin production, as well as NFAT2 expression were also suppressed. In cultured GMCs, high glucose (25 mM, HG) treatment increased the expression of TRPC6. Knockdown of TRPC6 alleviated HG-induced increases in collagen IV, fibronectin, and NFAT2 expression. Knockdown of NFAT2 also inhibited the upregulation of proteins, including collagen IV and fibronectin, in HG-treated GMCs. CONCLUSION: These results demonstrate that inhibition of TRPC6/NFAT2 signaling attenuates GMC dysfunction and the development of DKD and suggest that pharmacological targeting of TRPC6/NFAT2 in GMCs may provide beneficial effects for DKD.