Podocyte-specific Rap1 agonism for treatment of glomerular disease

足细胞特异性 Rap1 激动剂治疗肾小球疾病

• 批准号: 10588172
• 负责人: Lewis Kaufman
• 金额: $ 61.83万
• 依托单位: ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10588172
• 关键词: Agonist; Binding; Biological Process; Cell Culture Techniques; Chemicals; Chronic; Chronic Kidney Failure; Clinical; Congenital Nephrotic Syndrome; Diabetic Nephropathy; Disease; Disease Progression; Etiology; Family; Filtration; Focal and Segmental Glomerulosclerosis; GTP Binding; GTPase-Activating Proteins; Genes; Goals; Grant; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Guanosine Triphosphate Phosphohydrolases; Homeostasis; Human; Incidence; Inherited; Injury; Kidney; Kidney Diseases; Knock-in Mouse; Lead; Mediating; Modeling; Monomeric GTP-Binding Proteins; Mus; Mutation; Nature; Nephrotic Syndrome; Pathogenesis; Pathway interactions; Phenotype; Play; Predisposition; Process; RAPGEF2 gene; Regulatory Element; Regulatory Pathway; Renal glomerular disease; Reporting; Role; Signal Transduction; Testing; Therapeutic; Therapeutic Index; Transgenic Mice; Transgenic Organisms; Variant; Workplace; Zebrafish; antagonist; autosome; cell type; effective therapy; gain of function; gain of function mutation; gene therapy; genetic regulatory protein; human disease; inhibitor; injured; kidney cell; loss of function; mouse model; novel; novel therapeutic intervention; pharmacologic; podocyte; systemic toxicity; targeted treatment; therapeutic evaluation

Project Summary/Abstract: The incidence of proteinuric kidney diseases are increasing with well over 500 million cases worldwide. Over the last two decades, it has become clear that specialized kidney cells, called podocytes, regulate kidney filtration and are injured in all forms of proteinuric diseases regardless of etiology. Despite this, targeted effective therapies that protect podocytes and slow chronic kidney disease progression are completely lacking. Previously, we reported that the small GTPase Rap1 regulates fundamental biological processes in podocytes by cycling between inactive GDP-bound and active GTP-bound forms. We demonstrate that the podocyte Rap1 activation state is controlled by many upstream factors, both positive and negative, that converge to control the ratio of GTP- and GDP-bound forms. The essential role of these upstream regulators is emphasized by the presence of human familial nephrotic syndrome caused by mutations to several of these genes, including newly identified gain of function mutations in the negative Rap1 regulator, Rap1GAP. Each of these mutations has in common that they cause relative depletion of podocyte Rap1-GTP. In the current proposal, we show that levels of podocyte Rap1-GTP are also diminished in human glomerular diseases including in diabetic kidney disease (DKD). Augmenting levels of podocyte Rap1 activation genetically or pharmacologically protects podocytes in short term injury models. By targeting podocyte-specific upstream Rap1 regulatory pathways, we are developing novel Rap1 agonist compounds that activate Rap1 in podocytes, but not in other cell types. Such an approach allows for podocyte-specific pharmacological Rap1 activation and avoids potential systemic toxicities. The goals of the current grant are to explore the therapeutic potential of Rap1 agonists in podocyte diseases including in DKD. We accomplish this via three specific aims: i) Test whether enhanced podocyte Rap1 activation will mitigate chronic glomerular injury utilizing novel inducible podocyte-specific constitutively active Rap1 transgenic mice. ii) Characterize the glomerular phenotype of a novel Rap1GAP knock-in mouse model that expresses a double missense Rap1GAP human disease-associated variant and then utilize both novel mouse models to elucidate specific Rap1 downstream effectors that establish podocyte injury susceptibility versus protection. iii) Synthesize podocyte-targeted Rap1 agonist compounds and screen their ability to rescue podocyte injury in transgenic Rap1-GTP deficient zebrafish. The efficacy of lead compounds will be tested in mouse models of kidney disease including in DKD. Our current lead compound, BT-529, a Rap1-Rap1GAP interaction antagonist, induces Rap1 activation in podocytes but not in other kidney cells and dramatically protects cultured podocytes from injury. Overall, this work sets the stage for urgently needed new podocyte-targeted therapies for kidney diseases.

项目摘要/摘要： 蛋白尿肾脏疾病的发病率正在增加，全球超过5亿例病例。 在过去的二十年中，很明显，专门的肾细胞（称为足细胞）调节 肾脏过滤，在各种形式的蛋白尿疾病中受伤，无论病因如何尽管如此， 保护足细胞和缓慢慢性肾脏疾病进展的有效疗法是 完全缺乏。以前，我们报道了小的GTPase RAP1调节基本 通过在不活跃的GDP结合和活跃的GTP结合形式之间循环的足细胞中的生物过程。 我们证明了Podocyte Rap1激活状态受许多上游因素控制，两者都 积极和负面，将其融合到控制GTP和GDP结合形式的比率。必不可少的 人类家族性肾病综合征的存在强调了这些上游调节剂的作用 由对这些基因中的几个突变引起的，包括新确定的功能突变的增益 负RAP1调节器Rap1gap。这些突变中的每一个共同使它们引起相对 足细胞RAP1-GTP的耗竭。在当前的建议中，我们显示了Podocyte Rap1-GTP的水平 在包括糖尿病肾脏疾病（DKD）在内的人肾小球疾病中也会减少。 增强遗传上的Podocyte Rap1激活水平 短期伤害模型。通过靶向Podocyte特异性上游RAP1调节途径，我们是 开发新型的Rap1激动剂化合物，可激活足细胞中的Rap1，但没有在其他细胞类型中激活Rap1。 这样的方法允许Podocyte特异性的药理学RAP1激活，并避免潜在 全身毒性。当前赠款的目标是探索RAP1的治疗潜力 足细胞疾病中的激动剂，包括DKD。我们通过三个特定目标来完成此操作：i）测试 增强的足细胞RAP1激活是否会减轻利用新颖的慢性肾小球损伤 可诱导的足细胞特异性活性RAP1转基因小鼠。 ii）表征肾小球 一种新型Rap1Gap敲入鼠标模型的表型，该模型表达了双人物RAP1GAP 与人类疾病相关的变体，然后利用两个新型小鼠模型阐明特定的RAP1 建立足细胞损伤易感性与保护的下游效应子。 iii）合成 靶向Podocyte的Rap1激动剂化合物，并筛选其挽救足细胞损伤的能力 转基因RAP1-GTP缺乏斑马鱼。铅化合物的功效将在鼠标中测试 包括DKD在内的肾脏疾病模型。我们目前的铅化合物BT-529，Rap1-rap1gap 相互作用拮抗剂，在足细胞中诱导RAP1激活，但没有在其他肾细胞和 急剧保护培养的足细胞免受损伤。总体而言，这项工作为迫切需要的舞台奠定了基础 针对肾脏疾病的新型足细胞靶向疗法。