Mechanisms of proteinuria induced by RhoA GTPases

RhoA GTPases 诱导蛋白尿的机制

• 批准号: 7929949
• 负责人: Robert Spurney
• 金额: --
• 依托单位: DURHAM VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7929949
• 关键词: Actins; Adhesions; Adverse effects; Affect; Americas; Apoptosis; Apoptotic; Applications Grants; Architecture; Biology; CDC42 gene; Cells; Cellular Morphology; Characteristics; Data; Development; Disease; Dominant-Negative Mutation; Doxycycline; Elements; Endocrine system; Epithelial Cells; Family; Family member; Foot Process; Genetic; Goals; Guanosine Triphosphate Phosphohydrolases; Inflammatory; Injury; Kidney; Kidney Diseases; Kidney Failure; Link; Literature; Mediating; Medical; Molecular; Monomeric GTP-Binding Proteins; Mutation; Nephrotic Syndrome; Pathogenesis; Pathway interactions; Phenotype; Physiological; Play; Process; Protein Isoforms; Proteins; Proteinuria; Renal function; Renal glomerular disease; Research Personnel; Role; Signal Pathway; Signal Transduction; Surface; System; Technology; Transgenes; Transgenic Mice; Transgenic Organisms; United States; base; cell motility; drug development; glomerular basement membrane; glomerular filtration; glomerular function; glomerulosclerosis; in vivo; insight; mutant; podocyte; polymerization; prevent; promoter; research study; response; rho; rho GTP-Binding Proteins; therapeutic target

DESCRIPTION (provided by applicant): Genetic studies have highlighted the importance of glomerular epithelial cells (podocytes) in glomerular biology. Several familial forms of nephrotic syndrome are caused by mutations in proteins expressed exclusively by glomerular podocytes. Their interdigitating foot processes cover the exterior surface of the glomerular basement membrane (GBM) and play a key role in maintaining the integrity of the glomerular filtration barrier. A growing literature suggests that this function may be regulated by small GTPases belonging to the Rho GTPase family. In this regard, RhoA may stabilize the glomerular architecture by promoting a podocyte phenotype that inhibits proteinuria and foot process (FP) effacement. In this scenario, some basal level of RhoA activity would be beneficial. In contrast, high levels of RhoA activity induced by inflammatory processes may cause podocyte injury, perhaps by inhibiting prosurvival pathways and, in turn, enhancing podocyte apoptosis. Because of the inability of the podocyte to effectively replicate postnatally, podocyte apoptosis may cause a decrease in the number of functional podocytes, which, accumulating evidence suggests, may be a final common pathway promoting glomerulosclerosis. Based on these observations, we hypothesized that inhibition of basal Rho activity is detrimental to glomerular filtration barrier function by destabilizing the glomerular architecture and promoting FP effacement and changes in glomerular permselectivity. In contrast, high levels of Rho activity also have adverse effects on glomerular function by causing podocyte depletion. To investigate these hypotheses, two specific aims are proposed. In specific aim #1, we will investigate the role of Rho-dependent signaling cascades in promoting podocyte injury by creating transgenic (TG) mice that express a constitutively activate RhoA GTPase specifically in glomerular podocytes using an inducible promoter system. We will then determine if Rho activation causes glomerular injury by enhancing podocyte apoptosis in vivo as well as determine the signaling pathways mediating the apoptotic effect. In specific aim #2, we will determine if basal Rho activity plays an important role in maintaining the integrity of the glomerular filtration barrier by expressing a dominant negative Rho GTPase in glomerular podocytes using TG technologies and determining if RhoA inhibition under basal conditions causes a change in the podocyte phenotype that promotes proteinuria. If the proposed experiments are successful, the studies will provide important insights into the role of Rho-dependent signaling cascades in regulating podocyte function. PUBLIC HEALTH RELEVANCE: Kidney disease is a significant and expensive medical problem affecting over 2.5 million people in the United States of America. The goal of this grant application is determine if multiple hormonal systems implicated in the pathogenesis of kidney disease activate a final common signaling pathway that promotes kidney damage. If the studies are successful, this signaling pathway would be an important therapeutic target for the development of drugs to prevent kidney failure.

描述（由申请人提供）： 遗传研究强调了肾小球上皮细胞（足细胞）在肾小球生物学中的重要性。肾病综合征的几种家族形式是由仅由肾小球足细胞表达的蛋白质突变引起的。它们的插入脚步过程覆盖了肾小球基底膜（GBM）的外表面，并在维持肾小球滤过屏障的完整性方面起着关键作用。越来越多的文献表明，该功能可能受属于Rho GTPase家族的小型GTP酶的调节。在这方面，RhoA可以通过促进抑制蛋白尿和脚步过程（FP）效率的足细胞表型来稳定肾小球结构。在这种情况下，某些基础RHOA活动水平将是有益的。相反，炎症过程引起的高水平的RHOA活性可能会导致足细胞损伤，这可能是通过抑制生存途径，进而增强了足细胞凋亡。由于足细胞无法在产后有效复制，因此足细胞凋亡可能会导致功能性足细胞数量减少，该功能性足细胞的数量累积，这表明，这可能是促进肾小球癌变症的最终常见途径。基于这些观察结果，我们假设抑制基底RHO活性是通过破坏肾小球结构并促进FP效率和肾小球允许允许允许渗透性的变化而对肾小球滤过屏障功能有害的。相反，高水平的RHO活性也通过引起足细胞耗竭对肾小球功能产生不利影响。为了研究这些假设，提出了两个具体的目标。在特定的目标＃1中，我们将通过创建转基因（TG）小鼠在促进足细胞损伤中的Rho依赖性信号级联反应的作用，该小鼠使用诱导启动子系统表达在肾小球足细胞中特异性地激活RhoA GTPase的作用。然后，我们将通过增强体内足细胞凋亡以及确定介导凋亡效应的信号通路来确定RHO激活是否会导致肾小球损伤。在特定的目标＃2中，我们将确定基础RHO活性是否在维持肾小球滤过屏障的完整性中是否起着重要作用，通过使用TG技术表达肾小球足细胞中的主要负Rho GTPase并确定在基础条件下在基础条件下是否在基础条件下导致podococyte型phactoria photuro的蛋白质的变化。如果提出的实验成功，研究将提供重要的见解，以了解Rho依赖性信号级联反应在调节足细胞功能中的作用。 公共卫生相关性： 肾脏疾病是一个重大且昂贵的医疗问题，影响了美国超过250万人。该赠款应用的目的是确定与肾脏疾病发病机理有关的多种激素系统是否激活了促进肾脏损害的最终常见信号通路。如果研究成功，则该信号通路将是预防肾衰竭的药物开发的重要治疗靶标。