JUNCTIONAL COMPLEX DYSREGULATION DURING ISCHEMIC INJURY

缺血性肾组织损伤是导致死亡的重要因素 以及患有多种肾病的患者的发病率。 一 缺血性损伤的主要后果是上皮细胞的损失 极性通过大规模破坏肌动蛋白细胞骨架， 细胞-细胞连接复合体（粘附连接和紧密连接）。 连接复合物是维持极化离子所必需的 运输系统，受体和酶分布所需的 正常的肾功能 ATP耗尽可作为体外模型， 肾缺血 在这里，我们建议分析调节机制， ATP耗竭过程中的紧密连接，并确定这些调节 这些机制可以保护细胞免受损伤或加速恢复。 实验将研究粘附连接（钙粘蛋白介导的细胞- 细胞粘附）调节紧密连接组装和功能。 我们 假设ATP耗竭导致紧密连接解体， 粘附连接解体的结果。 钙粘蛋白细胞粘附 将通过操作来检查缺血期间的分子功能。 上皮细胞中钙粘蛋白功能（表达显性负性钙粘蛋白） 细胞，以及对紧密连接组装和细胞极性的影响将 进行分析。 通过粘附连接的信号传导过程也可能是 在ATP耗竭期间被破坏。 一个有待检验的主要假设是 Rho家族GT3在上皮细胞中的功能是 在肾缺血期间抑制，导致连接破坏 配合物 Rho家族GTP酶（Rho、Rac和Cdc 42）是GTPases家族的成员。 Ras基因超家族，并已被证明调节肌动蛋白细胞骨架 组装件. 初步证据表明，Rho家族GTP酶控制 上皮细胞中的细胞-细胞连接复合体组装。 激活 这些信号系统也可以保护细胞免受缺血性损伤。 我们的研究将提供新的和基本的见解， 在局部缺血期间被破坏的调节机制。

Ischemic renal tissue damage is a significant factor in the mortality and morbidity of patients suffering from numerous renal disorders. A primary consequence of ischemic injury is the loss of epithelial cell polarity through large-scale disruption of the actin cytoskeleton and cell-cell junctional complexes (adherens junctions and tight junctions). Junctional complexes are necessary for maintenance of polarized ion transport systems, receptors and enzyme distributions required for proper kidney function. ATP-depletion serves as an in vitro model for renal ischemia. Here we propose to analyze mechanisms that regulate tight junctions during ATP-depletion, and determine how these regulatory mechanisms may protect cells from damage or accelerate recovery. Experiments will examine how adherens junctions (cadherin-mediated cell- cell adhesion) regulate tight junction assembly and function. We hypothesize that ATP-depletion causes tight junction disassembly as a consequence of adherens junction disassembly. Cadherin cell adhesion molecule function during ischemia will be examined by manipulating cadherin function (expressing dominant negative cadherins) in epithelial cells, and effects on tight junction assembly and on cell polarity will be assayed. Signaling processes leading through the adherens junction may also be disrupted during ATP-depletion. A major hypothesis to be tested in this project is that Rho-family GTPase functions in epithelial cells are inhibited during renal ischemia leading to disruption of junctional complexes. Rho-family GTPases (Rho, Rac, and Cdc42) are members of the Ras gene superfamily, and have been shown to regulate actin cytoskeleton assembly. Preliminary evidence suggests that Rho-family GTPases control cell-cell junctional complex assembly in epithelial cells. Activation of these signaling systems may also protect cells from ischemic injury. Our studies will provide new and fundamental insight into critical regulatory mechanisms that are disrupted during ischemia.