RhoGDI: yin and yang of RhoGTPases cycle

RhoGDI：RhoGTPases 循环的阴和阳

• 批准号: 8372066
• 负责人: Celine DerMardirossian
• 金额: $ 36.01万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-26 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8372066
• 关键词: Actins; Adaptor Signaling Protein; Adult; Affect; Area; Binding; Biochemical; Biological; Biology; Biosensor; Cell physiology; Cells; Cessation of life; Complex; Country; Coupled; Cytoskeleton; Cytosol; DNA Sequence Rearrangement; Defect; Development; Disease; Dissociation; Event; Exhibits; Filtration; Foot Process; Functional disorder; Future; GTP Binding; Goals; Growth; Guanine; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Image; Injury; Intercellular Junctions; Kidney; Kidney Diseases; Kidney Failure; Knockout Mice; Lead; Life; Link; Membrane; Microfilaments; Microscopy; Molecular; Names; Outcome; Outcome Study; Physiological; Physiology; Play; Process; Proteins; Proteinuria; Public Health; Regulation; Renal function; Research; Research Project Grants; Role; Signal Transduction; Structure; System; Testing; Therapeutic; Time; Tissues; Tyrosine Phosphorylation; Yin-Yang; base; cell type; glomerular filtration; improved; in vivo; inhibitor/antagonist; injury and repair; insight; interdisciplinary approach; kidney cell; kidney epithelial cell; nephrin; novel; podocyte; polymerization; receptor; rhoB p20 GDI; slit diaphragm

DESCRIPTION (provided by applicant): Kidney disease, a major public health concern in the US and worldwide, is mainly caused by pathological changes in the precise regulation of glomerulus podocyte, the primary filtration unit in the kidney. Dysfunction of podocyte proteins including nephrin leads to renal disease owing to foot processes (FP) retraction, disruption of the filtration barrier and rearrangement of the actin cytoskeleton. However, the mechanisms linking nephrin activation to actin cytoskeleton reorganization are ill understood. The goal of this research project is to identify podocyte proteins involved in the molecular mechanisms controlling the regulation of GTPase, key regulators of the cytoskeletal, activity in space and time during FP development. GTPases act as molecular switches cycling between inactive (GDP-bound) and active (GTP-bound) forms. Several levels of regulation tightly control their activation state and accessibility. GDIs (Guanin Dissociation Inhibitors) function to inhibit GTPase activities. Activation through exchange of GDP for GTP is catalyzed by GEFs (Guanine Exchange Factors) and promotes downstream signaling; GAPs (Guanine- Activating Proteins) accelerate the intrinsic GTPase activity to inactivate the protein and terminate the signal. Given the key roles played by the cytoskeleton in renal podocyte function, the regulation of GTPase activity by GDI, GEFs and GAPs constitute critical points in the regulation of renal cytoskeletal dynamics. Dysregulation of such GTPase cycling can lead to pathological disease states in many cells/tissues. This is particular true in kidney, as evidenced by the dramatic defects in kidney structure and physiology that occur in the GDI knockout mouse, finally leading to death due to renal failure. We hypothesize that nephrin is at the apex of a hierarchy defining compartment identity through the recruitment of GTPases and their regulators. To test our hypothesis, we will pursue the following Aims: Aim1. We will investigate the molecular mechanisms by which a new podocyte GDI binding partner controls GTPase-GDI complexes and its effects on actin cytoskeleton dynamics during nephrin activation. Aim2. We have identified a new binding partner for nephrin that can regulate the inactivation of GTPases. Therefore, we will elucidate by which mechanisms this GAP regulate FP elongation. Aim3: We will determine the spatio-temporal regulation of GTPase-GDI complexes during nephrin stimulation. To this end, we will use a novel and unique live cell GTPase-GDI complex biosensor in in vivo imaging studies, coupled with computational multiplexing analyses. These studies will lead to a greater understanding of how these important components of renal function are controlled, ultimately guiding to unique and increasingly selective therapeutic approaches to intervene in nephritic disorders. PUBLIC HEALTH RELEVANCE: Kidney disease, highly prevalent worldwide, is often caused by a pathological change in the glomerulus, the filtration unit of the kidney. This application will elucidate the molecular mechanisms that govern the glomerulus function and will serve for the future development of novel targets for renal therapy.

描述（由申请人提供）： 肾脏疾病是美国和世界范围内的一个主要公共卫生问题，主要是由肾小球足细胞（肾脏中的主要过滤单位）的精确调节中的病理变化引起的。包括nephrin在内的足细胞蛋白功能障碍导致足突（FP）回缩、滤过屏障破坏和肌动蛋白重排 细胞骨架然而，连接nephrin激活肌动蛋白细胞骨架重组的机制还不清楚。本研究项目的目标是鉴定参与控制GTdR调节的分子机制的足细胞蛋白，GTdR是FP发育过程中细胞骨架的关键调节因子，在空间和时间上的活性。 GTPases充当在非活性（GDP结合）和活性（GDP结合）形式之间循环的分子开关。几个层次的调节严格控制其激活状态和可访问性。GDIs（Guanin Dissociation Inhibitors）抑制GT3活性。通过将GDP交换为GTP的活化由GEF（鸟嘌呤交换因子）催化并促进下游信号传导; GAP（鸟嘌呤活化蛋白）加速内在的GTP酶活性以使蛋白质变性并终止信号。考虑到细胞骨架在肾足细胞功能中所起的关键作用，通过GDI、GEF和GAP对GTdR活性的调节构成了肾细胞骨架动力学调节中的关键点。这种GT3循环的失调可导致许多细胞/组织中的病理性疾病状态。这在肾脏中尤其如此，如在GDI敲除小鼠中发生的肾脏结构和生理学的显著缺陷所证明的，最终导致由于肾衰竭而死亡。 我们假设，nephrin是在一个层次结构的顶点，通过招募GTP酶和他们的监管机构定义车厢的身份。为了验证我们的假设，我们将追求以下目标：目标1。我们将研究一种新的足细胞GDI结合伴侣控制GTP酶-GDI复合物的分子机制及其在nephrin激活过程中对肌动蛋白细胞骨架动力学的影响。目标2。我们已经确定了一个新的结合伙伴nephrin，可以调节失活的GTP酶。因此，我们将阐明该GAP调节FP延伸的机制。目的3：我们将确定在nephrin刺激过程中GTP酶-GDI复合物的时空调节。为此，我们将使用一种新的和独特的活细胞GTP酶-GDI复合物生物传感器在体内成像研究，再加上计算多路复用分析。 这些研究将使人们更好地了解这些重要的肾功能成分是如何控制的，最终指导独特的和越来越有选择性的治疗方法来干预肾病。 公共卫生相关性： 肾脏疾病在世界范围内高度流行，通常由肾小球（肾脏的过滤单位）的病理变化引起。本申请将阐明控制肾小球功能的分子机制，并将为未来开发肾脏治疗的新靶点提供服务。