501-P: ROCK2 Activation Accelerates Podocyte Injury in Diabetic Kidney Disease

Podocyte apoptosis is a key pathological finding in the progression of diabetic kidney disease. Here we demonstrate that Rho-kinase (ROCK) mediates transforming growth factor β (TGF-β)-induced podocyte apoptosis. Mechanistically, ROCK regulates Notch ligand induction via the extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK) but not Smad pathways. Consistently, the ROCK inhibitor fasudil suppressed albuminuria and the urinary excretion of nephrin in type 2 diabetic db/db mice and attenuated podocyte apoptosis. The expression of Notch ligand and apoptosis markers such as Bax and cyclin-dependent kinase inhibitor 1A (CDKN1A) was decreased in podocytes derived from fasudil-treated db/db mice. In order to elucidate the isoform-specific roles of ROCK, we knocked down ROCK1 and ROCK2 separately using siRNA duplexes. Importantly, Notch ligand expression was specifically regulated by ROCK2 but not ROCK1. In renal tissue, ROCK2 was expressed mainly in nucleus of glomerular cells, tubules, and vascular walls in wild type mice. Podocyte colocalization was revealed by immunofluorescence of ROCK2 and nephrin, indicating the involvement of ROCK2 in diabetic podocytopathy. The present study provides evidence that ROCK plays a key role in podocyte apoptosis. ROCK2 may be an attractive therapeutic target for diabetic kidney disease. Disclosure K. Matoba: Research Support; Self; Daiichi Sankyo Company, Limited, Novo Nordisk Inc., Sanofi, Shionogi & Co., Ltd., Takeda Pharmaceutical Company Limited. D. Kawanami: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. Y. Takeda: None. Y. Nagai: None. K. Utsunomiya: None. Funding Japan Society for the Promotion of Science; Uehara Memorial Foundation; Japan Diabetes Society; Ichiro Kanehara Foundation; MSD Life Science Foundation; Yokoyama Foundation