Nephrin is critical for the action of insulin on human glomerular podocytes
Nephrin is critical for the action of insulin on human glomerular podocytes
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DOI：
10.2337/db06-0693
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发表时间：
2007-04-01
期刊：
影响因子：
7.7
通讯作者：
Saleem, Moin A.
中科院分区：
文献类型：
--
作者：
Coward, Richard J. M.;Welsh, Gavin I.;Saleem, Moin A.
蛋白尿和终末期肾衰竭的主要原因是继发于胰岛素产生或细胞作用的异常，包括糖尿病和高胰岛素代谢综合征。人肾小球足细胞是维持肾脏滤过屏障和预防蛋白尿的关键细胞。我们最近发现，这种细胞对葡萄糖摄取具有胰岛素敏感性，其动力学与肌肉细胞相似。我们现在表明足细胞蛋白肾素在这个过程中是必不可少的。有条件永生化的足细胞来自两名不同的肾素突变患者（天然人肾素突变模型），对胰岛素无反应。在野生型足细胞中用siRNA敲低肾素可以消除胰岛素反应，而稳定转染肾素缺陷足细胞可以恢复它们的胰岛素反应。在机制上，我们发现肾素允许富含GLUT1和glut4的囊泡与该细胞的膜融合。此外，我们在体外和体外（利用酵母-2杂交和共免疫沉淀研究）表明，nephrin的COOH与囊泡SNARE蛋白VAMP2相互作用。这项工作证明了先前未被怀疑的肾素在足细胞的囊泡对接和胰岛素反应中的作用。
The leading causes of albuminuria and end-stage renal failure are secondary to abnormalities in the production or cellular action of insulin, including diabetes and hyperinsulinemic metabolic syndrome. The human glomerular podocyte is a critical cell for maintaining the filtration barrier of the kidney and preventing albuminuria. We have recently shown this cell to be insulin sensitive with respect to glucose uptake, with kinetics similar to muscle cells. We now show that the podocyte protein nephrin is essential for this process. Conditionally immortalized podocytes from two different patients with nephrin mutations (natural human nephrin mutant models) were unresponsive to insulin. Knocking nephrin down with siRNA in wild-type podocytes abrogated the insulin response, and stable nephrin transfection of nephrin-deficient podocytes rescued their insulin response. Mechanistically, we show that nephrin allows the GLUT1- and GLUT4-rich vesicles to fuse with the membrane of this cell. Furthermore, we show that the COOH of nephrin interacts with the vesicular SNARE protein VAMP2 in vitro and ex vivo (using yeast-2 hybrid and coimmunoprecipitation studies). This work demonstrates a previously unsuspected role of nephrin in vesicular docking and insulin responsiveness of podocytes.