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

基本信息

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
项目类别：
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

项目摘要

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：蛋白尿肾病的发病率正在增加，全世界有超过 5 亿例病例。在过去的二十年里，人们已经清楚的是，称为足细胞的特殊肾细胞可以调节无论病因如何，肾脏过滤都会受到各种形式的蛋白尿疾病的损害。尽管如此，保护足细胞和减缓慢性肾病进展的靶向有效疗法是完全缺乏。之前，我们报道过小 GTPase Rap1 调节基本通过在非活性 GDP 结合形式和活性 GTP 结合形式之间循环来调节足细胞中的生物过程。我们证明足细胞 Rap1 激活状态受许多上游因素控制，包括正值和负值共同控制 GTP 和 GDP 绑定形式的比例。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因子的作用由其中几个基因的突变引起，包括新发现的功能获得性突变 Rap1 负调节因子 Rap1GAP。这些突变中的每一个都有一个共同点，即它们会导致相对足细胞 Rap1-GTP 的消耗。在当前的提案中，我们表明足细胞 Rap1-GTP 的水平在包括糖尿病肾病（DKD）在内的人类肾小球疾病中，这种现象也有所减少。通过遗传或药理学提高足细胞 Rap1 激活水平可保护足细胞短期损伤模型。通过针对足细胞特异性上游 Rap1 调控途径，我们开发新型 Rap1 激动剂化合物，可激活足细胞中的 Rap1，但不能激活其他细胞类型。这种方法允许足细胞特异性药理学 Rap1 激活并避免潜在的全身毒性。当前资助的目标是探索 Rap1 的治疗潜力足细胞疾病（包括 DKD）的激动剂。我们通过三个具体目标来实现这一目标： i) 测试增强足细胞 Rap1 激活是否会利用新型药物减轻慢性肾小球损伤可诱导的足细胞特异性组成型活性 Rap1 转基因小鼠。 ii) 表征肾小球表达双错义 Rap1GAP 的新型 Rap1GAP 敲入小鼠模型的表型人类疾病相关变异，然后利用两种新型小鼠模型来阐明特定的 Rap1 建立足细胞损伤敏感性与保护作用的下游效应器。 iii) 综合足细胞靶向 Rap1 激动剂化合物并筛选其拯救足细胞损伤的能力转基因 Rap1-GTP 缺陷斑马鱼。先导化合物的功效将在小鼠中进行测试肾脏疾病模型，包括 DKD。我们目前的先导化合物 BT-529，Rap1-Rap1GAP 相互作用拮抗剂，诱导足细胞中的 Rap1 激活，但不激活其他肾细胞，并且显着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针对肾脏疾病的新足细胞靶向疗法。