JUNCTIONAL COMPLEX DYSREGULATION DURING ISCHEMIC INJURY

缺血性肾组织损伤是导致死亡的重要因素。 以及患有多种肾脏疾病的患者的发病率。一个 缺血性损伤的主要后果是上皮细胞的丢失 通过大规模破坏肌动蛋白细胞骨架和 细胞-细胞连接复合体(粘连连接和紧密连接)。 连接络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。三磷酸腺苷耗竭作为一种体外模型 肾缺血。在这里，我们建议分析监管机制 在ATP耗尽过程中的紧密连接，并决定这些调节如何 这种机制可能会保护细胞免受损害或加速恢复。 实验将研究如何黏附连接(钙粘附素介导的细胞- 细胞黏附)调节紧密连接的组装和功能。我们 假设ATP耗尽导致紧密连接解体 粘结拆卸的后果。钙粘附素细胞黏附 将通过操纵来检查缺血期间的分子功能 上皮钙粘附素功能(表达显性负性钙粘附素) 细胞，以及对紧密连接组装和细胞极性的影响 接受化验。 通过粘着连接的信号过程也可以是 在ATP耗尽期间中断。在这方面要检验的一个主要假说 项目是Rho家族GTPase在上皮细胞中的功能是 肾缺血时抑制导致交界区中断 复合体。Rho家族GTP酶(Rho、Rac和CDC42)是 Ras基因超家族，并已被证明调节肌动蛋白细胞骨架 集合。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 这些信号系统也可能保护细胞免受缺血损伤。 我们的研究将为我们提供新的和基本的见解 在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.