Renal Division, Department of Medicine, Federal University of São Paulo, Rua Pedro de Toledo, 781, São Paulo, SP, 04023-900, Brazil.
Mol Cell Biochem. 2018 Nov;448(1-2):265-274. doi: 10.1007/s11010-018-3331-y. Epub 2018 Feb 17.
Biological effects of angiotensin II (AngII) such as regulation of AngII target genes may be triggered by interaction of AngII with intracellular AngII receptor types 1 and 2 (AT and AT), defined as intracrine response. The aim of this study was to examine the presence of AT and AT receptors in nuclear membrane of human mesangial cells (HMCs) and evaluate the possible biological effects mediated by intracellular AT through an intracrine mechanism. Subcellular distribution of AT and AT was evaluated by immunofluorescence and by western blot in isolated nuclear extract. Endogenous intracellular synthesis of AngII was stimulated by high glucose (HG). Effects of HG were analyzed in the presence of candesartan, which prevents AngII internalization. Both receptors were found in nuclear membrane. Fluorescein isothiocyanate (FITC)-labeled AngII added to isolated nuclei produced a fluorescence that was reduced in the presence of losartan or PD-123319 and quenched in the presence of both inhibitors simultaneously. HG induced overexpression of fibronectin and increased cell proliferation in the presence of candesartan, indicating an intracrine action of AngII induced by HG. Results showed the presence of nuclear receptors in HMCs that can be activated by AngII through an intracrine response independent of cytoplasmic membrane AngII receptors.
血管紧张素 II（AngII）的生物学效应，如 AngII 靶基因的调节，可能是通过 AngII 与细胞内 AngII 受体类型 1 和 2（AT 和 AT）相互作用触发的，这种作用被定义为细胞内反应。本研究旨在研究人肾小球系膜细胞（HMC）核膜中是否存在 AT 和 AT 受体，并通过细胞内机制评估细胞内 AT 介导的可能的生物学效应。通过免疫荧光和分离的核提取物中的 Western blot 评估 AT 和 AT 的亚细胞分布。高葡萄糖（HG）刺激内源性细胞内 AngII 的合成。在坎地沙坦存在的情况下分析 HG 的作用，坎地沙坦可防止 AngII 内化。两种受体均存在于核膜中。荧光素异硫氰酸酯（FITC）标记的 AngII 加入分离的核中产生荧光，在洛沙坦或 PD-123319 存在下减少，在两种抑制剂同时存在下猝灭。HG 诱导纤维连接蛋白的过度表达，并在坎地沙坦存在下增加细胞增殖，表明 HG 诱导的 AngII 具有细胞内作用。结果表明，HMC 中存在核受体，这些受体可通过细胞内反应被 AngII 激活，而无需细胞质膜 AngII 受体。
