Department of Nephrology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 400010, China.
Institute for Viral Hepatitis, Key Laboratory of Molecular Biology for Infectious Diseases, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, 400010, China.
PLoS One. 2016 Feb 11;11(2):e0148696. doi: 10.1371/journal.pone.0148696. eCollection 2016.
Transforming growth factor-β (TGF-β), via its receptors, induces epithelial-mesenchymal transition (EMT) and plays an important role in the development of renal tubulointersitial fibrosis. Angiotensin II type 2 receptor (AT2R), which mediates beneficial renal physiological functions, has received attention as a prospective therapeutic target for renoprotection. In this study, we investigated the effect and underlying mechanism of AT2R on the TGF-β receptor II (TGF-βRII) expression and function in human proximal tubular cells (HK-2). Here, we show that the AT2R agonist CGP42112A decreased TGF-βRII protein expression in a concentration- and time-dependent manner in HK-2 cells. The inhibitory effect of the AT2R on TGF-βRII expression was blocked by the AT2R antagonists PD123319 or PD123177. Stimulation with TGF-β1 enhanced EMT in HK-2 cells, which was prevented by pre-treatment with CGP42112A. One of mechanisms in this regulation is associated with the increased TGF-βRII degradation after activation of AT2R. Furthermore, laser confocal immunofluorescence microscopy showed that AT2R and TGF-βRII colocalized in HK-2 cells. AT2R and TGF-βRII coimmunoprecipitated and this interaction was increased after AT2R agonist stimulation for 30 min. The inhibitory effect of the AT2R on TGF-βRII expression was also blocked by the nitric oxide synthase inhibitor L-NAME, indicating that nitric oxide is involved in the signaling pathway. Taken together, our study indicates that the renal AT2R regulates TGF-βRII expression and function via the nitric oxide pathway, which may be important in the control of renal tubulointerstitial fibrosis.
转化生长因子-β（TGF-β）通过其受体诱导上皮-间充质转化（EMT），并在肾小管间质纤维化的发生发展中发挥重要作用。血管紧张素 II 型受体（AT2R）介导有益的肾脏生理功能，作为肾脏保护的潜在治疗靶点受到关注。在本研究中，我们研究了 AT2R 对人近端肾小管细胞（HK-2）中 TGF-β 受体 II（TGF-βRII）表达和功能的影响及其潜在机制。结果表明，AT2R 激动剂 CGP42112A 以浓度和时间依赖性方式降低 HK-2 细胞中 TGF-βRII 蛋白表达。AT2R 拮抗剂 PD123319 或 PD123177 阻断了 AT2R 对 TGF-βRII 表达的抑制作用。TGF-β1 刺激增强了 HK-2 细胞的 EMT，而 CGP42112A 预处理可预防这种作用。这种调节的机制之一与 AT2R 激活后 TGF-βRII 降解增加有关。此外，激光共聚焦免疫荧光显微镜显示 AT2R 和 TGF-βRII 在 HK-2 细胞中存在共定位。AT2R 和 TGF-βRII 共免疫沉淀，且这种相互作用在 AT2R 激动剂刺激 30 分钟后增加。一氧化氮合酶抑制剂 L-NAME 阻断了 AT2R 对 TGF-βRII 表达的抑制作用，表明一氧化氮参与了信号通路。综上所述，我们的研究表明，肾脏 AT2R 通过一氧化氮途径调节 TGF-βRII 的表达和功能，这可能对控制肾小管间质纤维化很重要。
