386-P: ROCK1 Regulation of AMPK in the Development of Diabetic Nephropathy

Rho-associated, coiled-coil-containing protein kinase (ROCK) is activated in the diabetic kidney. Studies over the past decade have illuminated ROCK signaling as an essential pathway in the pathogenesis of diabetic nephropathy. Accumulating evidence shows that renal dysfunction among patient with diabetes is associated with abnormal fatty acid oxidation in the kidney. However, the interaction of ROCK and fatty acid oxidation in diabetic kidneys remains unclear. Extracellular flux analyzer demonstrated that deficiency of ROCK1, one of the ROCK isoforms, improves TGF-β-induced mitochondrial dysfunction in primary cultured mesangial cells. ROCK1 deficiency rescued TGF-β-induced downregulation of fatty acid oxidation mediators such as peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) , and carnitine palmitoyltransferase 1A (CPT1A) . An investigation of mechanisms underlying this observation revealed activated ROCK1 axis through the phosphorylation of AMPK and increased expression of PGC-1α. Fluorescence histochemistry showed that ROCK1 deficiency suppresses ROS production induced by mitochondrial damage due to abnormal fatty acid metabolism. Consistent with this result, compared to wild-type mice, ROCK1 knockout mice exhibited reduced albuminuria and histological abnormalities along with the recovery of impaired fatty acid utilization and mitochondrial fragmentation. Furthermore, RNA-seq showed that ROCK1 deficiency in mesangial cells significantly altered the expression of genes involved in metabolic pathway. These observations indicate that ROCK1 is a key player in the development of diabetic renal injury. ROCK1 may be a potential therapeutic target for the treatment of diabetic nephropathy.