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: 7899725
• 负责人: Simon J. Atkinson
• 金额: $ 31.86万
• 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/7899725
• 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; Figs - dietary; Fluorescence Microscopy; Functional disorder; Goals; 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）： 缺血性急性肾衰竭的持续存在是住院患者发病率和死亡率的主要原因，这些患者的结局相对缺乏改善，这使我们更好地了解这种损伤的细胞机制。肌动蛋白细胞骨架组织的破坏，通常支持近端小管上皮细胞的结构和功能是公认的损伤的早期和关键方面，与肾功能和细胞存活的直接后果。在该奖项的前几年，我们已经表明，Rho GTP酶发挥关键作用，可能介导缺血观察到的细胞骨架改变。此外，我们发现，活性的RhoA，Rac 1和Cdc 42是敏感的ATP耗竭，但每个蛋白质的活性是不同的影响耗尽。我们提出Rho GTPases活性的改变和随后的细胞骨架破坏是通过AMPK-TSC 1/2途径的信号传导导致II型（雷帕霉素不敏感）mTor复合物2失活的结果，该复合物2最近已被证明通过Rho GTPases或通过TSC 1/2下游的新型mTOR独立途径调节细胞骨架。我们提出的研究，以测试和阐明我们提出的机制，在细胞培养和肾缺血的动物模型的补充研究。我们提出了四个具体的目标来解决我们的中心假设：1）研究AMPK在体外ATP耗竭和体内缺血中的激活; 2）研究TSC 1/2和Rheb GT3信号在体外和体内对Rho GT3活性和细胞骨架组织的作用; 3）确定AMPK激活对II型mTOR复合物的影响; 4）在缺血性肾损伤的动物模型中确定改变的AMPK、TSC 1/2、Rheb和mTOR信号传导对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消耗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。 叙事 缺血（血流损失）是急性肾衰竭的主要原因。目前，人们对肾细胞对缺血的反应方式了解甚少，这使得设计治疗或药物变得困难。这些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。