The small GTPase Rho and its effector, Rho-kinase (ROCK), are implicated in the fundamental cellular processes (e.g., cell adhesion, migration). Studies over the past decade have illuminated ROCK as an important regulator of diabetic kidney disease. We previously demonstrated elevated renal ROCK activity in both type 1 and type 2 diabetic murine models. In an attempt to elucidate the roles of the activated ROCK, we provided evidence that ROCK inhibition attenuates an increase of urinary albumin excretion, glomerular sclerosis, and podocyte loss in rodents. Mechanistically, ROCK regulates inflammatory events as well as hypoxia-induced fibrotic reactions. However, specific roles of ROCK isoforms, ROCK1 and ROCK2, in diabetic kidneys remain unclear. In the present study, we first investigated the renal distribution of ROCK1 and ROCK2 using wild type mice and human kidneys obtained at necropsy. The immunohistochemical analysis detected both isoforms in glomeruli, tubules, and vessel walls. Whereas ROCK1 was mainly expressed in the cytoplasm, ROCK2 was accumulated in the nucleus of these cells. Double staining with anti-nephrin antibody showed co-localization of ROCK2 with nephrin, indicating distinctive roles of ROCK2 in the glomerular podocyte. In order to elucidate the role of podocyte ROCK2, we next evaluated gene expression levels of ROCK2 in high-fat diet-fed mice and patients with diabetic kidney disease. In both mice and patients, ROCK2 was increased in the setting of diabetes compared to healthy subjects. Of note, glomerular ROCK2 mRNA levels were positively correlated with the increase of urinary albumin excretion in mice. When considered alongside our previous observations, the current work highlights the importance of ROCK2 in diabetic podocytopathy.
K. Matoba: Research Support; Self; Sanofi K.K., Takeda Pharmaceutical Company Limited. Y. Takeda: None. Y. Nagai: None. T. Akamine: None. Y. Kanazawa: None. D. Kawanami: None. K. Utsunomiya: None. R. Nishimura: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. Speaker’s Bureau; Self; Abbott, AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly Japan K.K., Medtronic, Merck & Co., Inc., Novo Nordisk Inc., Sanofi K.K., Takeda Pharmaceutical Company Limited.
Japan Society for the Promotion of Science (18K15985)