Sun Guang-Ping, Kohno Masakazu, Guo Peng, Nagai Yukiko, Miyata Kayoko, Fan Yu-Yan, Kimura Shoji, Kiyomoto Hideyasu, Ohmori Koji, Li De-Tian, Abe Youichi, Nishiyama Akira
Department of CardioRenal and Cerebrovascular Medicine, Kagawa University Medical School, Kagawa, Japan.
J Am Soc Nephrol. 2006 Aug;17(8):2193-201. doi: 10.1681/ASN.2005121375. Epub 2006 Jun 21.
Recent studies have suggested a role for aldosterone in the pathogenesis of renal injury. This study investigated the potential contributions of Rho-kinase and TGF-beta pathways to aldosterone-induced renal injury. Rats were uninephrectomized and then treated for 5 wk with 1% NaCl in a drinking solution and one of the following: Vehicle (2% ethanol, subcutaneously; n = 9); aldosterone (0.75 microg/h, subcutaneously; n = 9); or aldosterone + fasudil, a specific Rho-kinase inhibitor (10 mg/kg per d, subcutaneously; n = 8). Phosphorylation of myosin phosphate target subunit-1 (MYPT1) and Smad2/3 in renal cortical tissue was measured by Western blotting with anti-phospho MYPT1 and Smad2/3 antibodies, respectively. Rats that received aldosterone infusion exhibited hypertension and severe renal injury characterized by proteinuria, glomerular sclerosis, and tubulointerstitial fibrosis with increases in alpha-smooth muscle actin staining and numbers of monocytes/macrophages in the interstitium. Renal cortical mRNA levels of types I and III collagen, TGF-beta, connective tissue growth factor, and monocyte chemoattractant protein-1 as well as Smad2/3 phosphorylation were significantly increased in rats that received aldosterone infusion. All of these changes were associated with an increase in renal tissue MYPT1 phosphorylation. Treatment with fasudil did not alter BP but significantly ameliorated proteinuria and renal injury in rats that received aldosterone infusion. Furthermore, fasudil prevented MYPT1 phosphorylation and markedly decreased alpha-smooth muscle actin staining, numbers of monocytes/macrophages, mRNA levels of types I and III collagen, TGF-beta, connective tissue growth factor and monocyte chemoattractant protein-1, and Smad2/3 activity in renal cortical tissues. These results provide evidence, for the first time, that Rho-kinase is substantially involved in aldosterone-induced renal injury through activation of a TGF-beta-dependent pathway.
近期研究表明醛固酮在肾损伤发病机制中起作用。本研究调查了Rho激酶和转化生长因子-β（TGF-β）信号通路在醛固酮诱导的肾损伤中的潜在作用。将大鼠进行单侧肾切除，然后在饮用溶液中用1%氯化钠处理5周，并给予以下处理之一：溶剂（2%乙醇，皮下注射；n = 9）；醛固酮（0.75微克/小时，皮下注射；n = 9）；或醛固酮+法舒地尔（一种特异性Rho激酶抑制剂，10毫克/千克/天，皮下注射；n = 8）。分别用抗磷酸化肌球蛋白磷酸酶靶亚基-1（MYPT1）和Smad2/3抗体通过蛋白质印迹法检测肾皮质组织中MYPT1和Smad2/3的磷酸化情况。接受醛固酮输注的大鼠出现高血压和严重肾损伤，表现为蛋白尿、肾小球硬化和肾小管间质纤维化，同时α-平滑肌肌动蛋白染色增加以及间质中单核细胞/巨噬细胞数量增多。接受醛固酮输注的大鼠肾皮质中I型和III型胶原、TGF-β、结缔组织生长因子和单核细胞趋化蛋白-1的mRNA水平以及Smad2/3磷酸化均显著增加。所有这些变化均与肾组织MYPT1磷酸化增加有关。法舒地尔治疗未改变血压，但显著改善了接受醛固酮输注大鼠的蛋白尿和肾损伤。此外，法舒地尔可防止MYPT1磷酸化，并显著降低α-平滑肌肌动蛋白染色、单核细胞/巨噬细胞数量、I型和III型胶原、TGF-β、结缔组织生长因子和单核细胞趋化蛋白-1的mRNA水平以及肾皮质组织中Smad2/3的活性。这些结果首次证明，Rho激酶通过激活TGF-β依赖性信号通路，在很大程度上参与了醛固酮诱导的肾损伤。
