ROLES OF THE PROXIMAL TUBLE RENIN ANGIOTENSIN SYSTEM

各种生理研究提供了令人信服的证据，表明 血管紧张素II（angiotensin II，Ang II）在肾近端血管紧张素受体（renal proliferation factor，RRF）的表达中起重要作用。 曲小管 生物化学和分子生物学技术 允许鉴定肾素、血管紧张素原（ang-n）和 血管紧张素转换酶（ACE）蛋白和mRNA在肾脏内。 几条证据表明，肾内的一个主要部位 肾素血管紧张素系统（RAS）是近端小管（PT）。 内 PT、ang-n和ACE mRNA是合成的，而肾素更可能是 重新吸收 由于PT内也存在血管紧张素受体， 内源性局部Ang II的产生，在体内有一个完整的PT。 此外，有说服力的数据支持的概念，一个完整的RAS 在近端小管内的各种小管中起着重要的作用， 功能包括钠和水的重吸收，蛋白质加工， 也许还有细胞肥大 本课题旨在研究植物生长因子的调控和功能， 近曲小管（PT）肾素血管紧张素系统（RAS）利用PT细胞， 文化 大量的信息支持了这样一个概念，即近端 肾小管RAS支持自分泌、旁分泌和内分泌功能。 可用的已建立的PT样细胞系，如OK细胞， 与体内PT细胞类似;培养中的原代PT细胞已证明 难以生长和传代，并且还快速去分化。 因此，开发新的方法来研究PT细胞的原代培养， 伴随建立转化的、永生化的PT细胞系，或 从转基因动物中克隆的细胞系将对 进一步研究PT RAS。 因此，我们的目标是：1。推导函数 通过开发永生化PT细胞系和研究 细胞和亚细胞的RAS组分的调节和定位， 这些细胞与原代培养物相比; 2.为了研究自分泌和 PTRAS的旁分泌作用机制，假设局部PT 血管紧张素原为肾小管血管紧张素提供局部底物， PT ACE具有多种功能; 3.调查的影响 通过（a）将PT细胞与产生肾素的 细胞，（B）将PT细胞暴露于已添加有肾素的培养基 和（c）通过将肾素转染到永生化PT细胞中。 因此 本申请试图检查 在细胞和亚细胞水平上的PT RAS。 我们预计这些数据 获得将是新颖的，并有影响的方式，PT RAS参与肾脏和心血管稳态。

A variety of physiological studies provides compelling evidence that angiotensin II (Ang II) has important actions in the renal proximal convoluted tubule. Biochemical and molecular biologic techniques have permitted the identification of renin, angiotensinogen (ang-n), and angiotensin converting enzyme (ACE) proteins and mRNAs within the kidney. Several lines of evidence suggest that a major site of the intrarenal renin angiotensin system (RAS) is the proximal tubule (PT). Within the PT, ang-n and ACE mRNAs are synthesized, whereas renin is more likely reabsorbed. As there are also angiotensin receptors within PT as well as endogenous local Ang II production, there is in vivo a complete PT. Furthermore, persuasive data support the concept that a complete RAS within the proximal tubule plays important roles in a variety of tubular functions including sodium and water reabsorption, protein processing, and, perhaps, cellular hypertrophy. The present project is designed to study regulation and function of the proximal tubule (PT) renin angiotensin system (RAS) utilizing PT cells in culture. Much information lends support to the concept that the proximal tubular RAS subserves autocrine, paracrine, and intracrine functions. Available established PT-like cell lines such as OK cells are not truly analogous to PT cells in vivo; primary PT cells in culture have proven difficult to grow and passage, and also de-dedifferentiate rapidly. Thus, developing new ways to study PT cells in primary culture and concomitantly establishing transformed, immortalized PT cell lines or cell lines cloned from transgenic animals would be of great benefit to further study of the PT RAS. Thus, our aims are: 1. To deduce functions of the PT RAS by developing immortalized PT cell lines and studying cellular and subcellular regulation and localization of RAS components in these cells compared to primary cultures; 2. To study the autocrine and paracrine mechanisms of action of the PT RAS, hypothesizing that local PT angiotensinogen provides-local substrate for tubular angiotensins and that PT ACE subserves multiple functions; 3. To investigate the effects of renin on PT cells by (a) co-culture of PT cells with renin-producing cells, (b) exposure of PT cells to media into which renin has been added and (c) by transfecting renin into immortalized PT cells. Thus, the present application seeks to examine the regulation and functions of the PT RAS on a cellular and subcellular level. We anticipate that the data obtained will be novel and have implications for the ways in which the PT RAS is involved in both renal and cardiovascular homeostasis.