Rho GTPases and Actin Cytoskeletal Function in Renal Ischemia

肾缺血中的 Rho GTP 酶和肌动蛋白细胞骨架功能

• 批准号: 8069200
• 负责人: Simon J. Atkinson
• 金额: $ 31.54万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8069200
• 关键词: Actins; Acute Kidney Failure; Address; Adenovirus Vector; Affect; Animal Model; Animals; Award; Biochemical; Biological Assay; Blood flow; Cell Culture Techniques; Cell Polarity; Cell Survival; Cell physiology; Cells; Cellular Morphology; Cellular Stress; Clinical; Complex; Cytoskeletal Modeling; Cytoskeleton; Data; Depressed mood; Endothelial Cells; Epithelial Cells; Fluorescence Microscopy; Functional disorder; Goals; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; In Vitro; Injury; Ischemia; Kidney; Life; Link; Maintenance; Measurement; Measures; Mediating; Metabolic; Morbidity - disease rate; Outcome; Pathway interactions; Patient Care; Patients; Pharmaceutical Preparations; Pharmacotherapy; Phosphorylation Site; Phosphotransferases; Photons; Play; Proteins; RNA Interference; Recovery; Regulation; Relative (related person); Renal function; Role; Signal Pathway; Signal Transduction; Sirolimus; Structure; TSC1 gene; TSC1/2 gene; TSC2 gene; Testing; Translating; Tubular formation; adenylate kinase; cell injury; human FRAP1 protein; in vivo; in vivo Model; injury and repair; insight; kidney cell; monomer; mortality; mutant; novel; polymerization; renal ischemia; rho; rho GTP-Binding Proteins; sensor; success; therapy design

DESCRIPTION (provided by applicant): The persistence of ischemic acute renal failure as a major cause of morbidity and mortality in hospitalized patients and the relative lack of improvement in outcomes for these patients challenges us the better understand the cellular mechanisms underlying this injury. Disruption of the actin cytoskeletal organization that normally underpins the structure and function of proximal tubule epithelial cells is well-established as an early and critical aspect of injury, with direct consequences for renal function and cell survival. In the previous years of this award we have shown that Rho GTPases play critical roles that may mediate the cytoskeletal alterations observed with ischemia. Moreover, we showed that activities of RhoA, Rac1 and Cdc42 are sensitive to ATP depletion, but that the activity of each protein is differentially affected by depletion. We proposed that alterations in Rho GTPase activity and consequent cytoskeletal disruption are the result of signaling through the AMPK-TSC1/2 pathway resulting in inactivation of the type II (rapamycin insensitive) mTor complex 2, which has recently been shown to regulate the cytoskeleton through Rho GTPases or via novel mTOR independent pathways downstream of TSC1/2. We propose studies to test and elucidate our proposed mechanism using complementary studies in cell culture and in animal models of renal ischemia. We propose four specific aims to address our central hypothesis: 1) Investigate the activation of AMPK by ATP depletion in vitro and ischemia in vivo; 2) Investigate the role of TSC1/2 and Rheb GTPase signaling on Rho GTPase activity and cytoskeletal organization in vitro and in vivo; 3) Determine the effect of AMPK activation on the type II mTOR complex; 4) Determine the effect of altered AMPK, TSC1/2, Rheb and mTOR signaling on actin cytoskeletal organization and proximal tubule cell function in animal models of ischemic renal injury. These studies will determine the key mechanism linking energy depletion to cytoskeletal alterations, and afford an opportunity to identify targets for novel therapies. Narrative Ischemia (loss of blood flow) is a major cause of acute kidney failure. Currently there is a poor understanding of the way that kidney cells respond to ischemia, which makes it difficult to design therapies or drugs. The studies proposed will test a possible mechanism leading to cell injury that could be a target for drug therapy.

描述(由申请人提供)： 缺血性急性肾功能衰竭的持续性是住院患者发病率和死亡率的主要原因，这些患者的预后相对缺乏改善，这向我们提出了更好地理解这种损伤的细胞机制的挑战。肌动蛋白细胞骨架组织的破坏通常是近端小管上皮细胞结构和功能的基础，已被公认为是损伤的早期和关键方面，直接影响肾功能和细胞生存。在该奖项的前几年，我们已经证明Rho GTP酶在可能调节缺血时观察到的细胞骨架变化的过程中发挥关键作用。此外，我们还发现RhoA、rac1和CDC42的活性对ATP耗竭很敏感，但每种蛋白的活性受耗竭的影响不同。我们认为，Rho GTPase活性的改变和随之而来的细胞骨架破坏是通过AMPK-TSC1/2途径的信号导致II型(雷帕霉素不敏感)mTOR复合体2失活的结果，最近发现该复合体通过Rho GTP酶或TSC1/2下游的新的mTOR独立途径调节细胞骨架。我们建议通过细胞培养和肾脏缺血动物模型的补充研究来测试和阐明我们提出的机制。我们提出了四个特定的目标来解决我们的中心假设：1)研究ATP耗竭和体内缺血对AMPK的激活；2)研究TSC1/2和Rheb GTPase信号在体内外Rho GTP酶活性和细胞骨架组织中的作用；3)确定AMPK激活对II型mTOR复合体的影响；4)确定AMPK、TSC1/2、Rheb和mTOR信号的改变对缺血肾损伤动物模型肌动蛋白细胞骨架组织和近端小管细胞功能的影响。这些研究将确定将能量耗竭与细胞骨架改变联系起来的关键机制，并为确定新疗法的靶点提供机会。 叙述性 缺血(血流丧失)是急性肾功能衰竭的主要原因。目前，人们对肾脏细胞对缺血的反应方式知之甚少，这使得设计治疗或药物变得困难。拟议中的研究将测试导致细胞损伤的可能机制，这可能是药物治疗的目标。