Over 2 million people currently receive treatment with dialysis or a kidney transplant throughout the world. Thus, developing a new strategy to treat chronic kidney diseases is significant from the perspective of a health economic and the prevention of cardiovascular death. The small GTPase Rho and its effector Rho-kinase (ROCK) are involved in the pathogenesis of diabetic nephropathy. In chronic kidney diseases including diabetic nephropathy, tubulointerstitial fibrosis is known to be highly associated with renal outcome. We have previously reported that ROCK inhibition prevented the progression of diabetic nephropathy in murine models. With regards to ROCK, there are two isoforms, which are ROCK1 and ROCK2. ROCK1 has been shown to be involved in the endocytosis of albumin in tubular epithelial cells via megalin/cubilin-dependent mechanism. However, the role of renal tubular ROCK2 remains to be elucidated. The aim of this study is to reveal the role of renal tubular ROCK2 in the pathogenesis of chronic kidney disease. To this end, we used a tubulointerstitial injury model known as folic acid-induced nephropathy (FAN). Importantly, ROCK2 was elevated at protein levels in FAN group compared with vehicle-treated group. We next generated tubular specific ROCK2 knockout mouse (TR2KO) by crossing Ksp-Cre mice with mice containing two loxP sites flanking in Exon 3 of ROCK2. In the Ksp-Cre transgenic mice, Cre recombinase has been demonstrated to be expressed in tubules, collecting ducts, and thick ascending limbs. Compared with vehicle-treated group, collagen deposition in the kidneys of FAN group was highly elevated as revealed by Masson’s trichrome staining. The increased collagen deposition was significantly improved in TR2KO. Our findings indicate that ROCK2 regulates the progression of tubulointerstitial fibrosis. ROCK2 may be a potential therapeutic target for the prevention of chronic kidney disease.

Disclosure

K.Sekiguchi: None. K.Matoba: None. S.Ohashi: None. E.Mitsuyoshi: None. Y.Nagai: None. Y.Takeda: None. R.Nishimura: Speaker's Bureau; Sanofi K.K., Medicure Inc., Boehringer Ingelheim Inc., Takeda Pharmaceutical Company Limited, Kissei Pharmaceutical Co., Ltd., Novartis Pharma K.K., Eli Lilly Japan K.K., Novo Nordisk, Merck & Co., Inc., Abbott Japan Co., Ltd., Astellas Pharma Inc., Teijin Pharma Limited, Taisho Pharmaceutical Holdings Co., Ltd., Ono Pharmaceutical Co., Ltd., AstraZeneca.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at http://www.diabetesjournals.org/content/license.