TRPC channels in proteinuric kidney disease

描述（由申请人提供）：典型瞬时受体电位通道6（TRPC 6）最近已被添加到越来越多的家族性蛋白尿肾病相关基因中，其特征在于肾病和最终肾衰竭。有趣的是，迄今为止已知的所有TRPC 6突变都是功能获得突变，这表明通过TRPC 6通道增加的Ca +2内流导致足细胞损伤。足细胞中TRPC通道调节的机制在很大程度上是未知的。此外，问题仍然是通过TRPC通道的Ca +2内流的增加是否发生在遗传性和获得性蛋白尿肾病中。我们的初步数据表明，TRPC 1和TRPC 5在肾小球足细胞中表达，在那里，像TRPC 6，他们本地化的足细胞足突，在附近的狭缝隔膜。我们在足细胞中的粘附测定和伤口测定表明通道到膜皱褶的显著易位，表明通道定位是受调节的过程。血管紧张素在表达AT1R的足细胞中诱导显著的钙瞬变，并且该钙内流的显著部分似乎是由TRPC通道介导的。足细胞膜片钳实验证实了TRPC样电流的存在。单通道记录表明，通道活性的调节通道易位到膜。当足细胞中的膜运输被药理学和分子技术破坏时，TRPC样电流大大减少，支持通道活性由通道易位到膜来调节的观点。基于我们的初步工作，我们假设TRPC 1和TRPC 5在足细胞中形成新的通道，其与TRPC 6一致，通过响应于通过血管紧张素1型受体的上游信号传导而调节Ca +2向质膜的易位来介导Ca +2内流。

DESCRIPTION (provided by applicant): The canonical transient receptor potential channel 6 (TRPC6) has been recently added to the growing number of genes involved in familial forms of proteinuric kidney disease, characterized by nephrosis and ultimate renal failure. Interestingly, all TRPC6 mutations known to date are gain of function mutations, suggesting that increased Ca+2 influx through TRPC6 channels leads to podocyte injury. The mechanisms for TRPC channel regulation in podocytes are largely unknown. Furthermore, the question remains whether an increase in Ca+2 influx through TRPC channels occurs in both genetic and acquired forms of proteinuric kidney disease. Our preliminary data suggest that TRPC1 and TRPC5 are expressed in glomerular podocytes, where, like TRPC6, they localize to podocyte foot processes, in the vicinity of slit diaphragms. Our adhesion assays and wound assays in podocytes demonstrate a striking translocation of channel to membrane ruffles, indicating that channel localization is a regulated process. Angiotensin induces prominent calcium transients in podocytes expressing the AT1R, and a significant portion of this calcium influx appears to be mediated by TRPC channels. Patch clamp experiments in podocytes confirm the presence of a TRPC-like current. Single channel recordings suggest that channel activity is regulated by channel translocation to the membrane. When membrane trafficking is disrupted by pharmacologic and molecular techniques in podocytes, the TRPC-like current is largely diminished, supporting the notion that channel activity is regulated by channel translocation to the membrane. Based on our preliminary work, we hypothesize that TRPC1 and TRPC5 form novel channels in podocytes, which, in concert with TRPC6, mediate Ca+2 influx by their regulated translocation to the plasma membrane in response to upstream signaling through the Angiotensin Type 1 Receptor.