Kidney disease mechanisms associated with human genetic variation

与人类遗传变异相关的肾脏疾病机制

基本信息

批准号：
8548032
负责人：
Leslie A Bruggeman
金额：
$ 19.8万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-09-30 至 2014-07-19
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8548032
关键词：
AIDS-Associated Nephropathy Accounting Address African African American Alleles American Animals Apolipoproteins Autophagocytosis Binding Biological Biopsy Specimen Blood Cardiovascular Diseases Cell Culture Techniques Cell Line Cessation of life Chromosomes, Human, Pair 22 Chronic Kidney Failure Code Complex Data Development Diabetic Nephropathy Diagnosis Disease Docking Electron Microscopy End stage renal failure Endosomes Environmental Risk Factor Expenditure Experimental Designs Gene Expression Profile Genes Genetic Predisposition to Disease Genetic Variation Genotype Goals HIV HIV Infections HIV-1 Haplotypes Healthcare Home environment Homeostasis Human Human Genetics Immunofluorescence Immunologic In Situ In Situ Hybridization In Vitro Infection Infection prevention Injury Kidney Kidney Diseases Kidney Failure Knowledge Label Location Maps Mediating Medicare Metabolic Methods Minority Modeling Mus NPHS2 protein Normal tissue morphology Outcome Pathogenesis Pathology Pathway interactions Patients Pattern Phenotype Population Prevention therapy Protein Biosynthesis Proteins Publishing Resistance Risk SNAP receptor Severities Signal Transduction Stratification Stress Supporting Cell Susceptibility Gene Testing Time Tissues Transgenes Transgenic Mice Trypanosoma United States Variant Viral base disease diagnosis gene interaction high risk improved in vivo in vivo Model mouse model nef Protein non-diabetic novel overexpression particle pathogen podocyte promoter research study response trait transgene expression uptake

项目摘要

DESCRIPTION (provided by applicant): Chronic kidney disease (CKD), like many complex disease traits, manifests from dependent interactions between genetic susceptibilities and environmental factors. The recently described APOL1 risk alleles associated with CKD and African Ancestry is one example, where only a portion of genetically-susceptible patients develop kidney disease, suggesting a second hit or stress is required to trigger variant APOL1- dependent kidney injury. To investigate the mechanism of APOL1 variants in CKD, we have chosen to focus on HIV-associated nephropathy (HIVAN), the disease most robustly associated with APOL1 risk haplotypes and clearly dependent on an environmental factor, HIV-1 infection. Our preliminary data demonstrate APOL1 is expressed in the podocyte, and APOL1 overexpression activates autophagy. Although mTor-induced core autophagy pathways have been implicated in the glomerular injury of diabetic nephropathy -- a renal pathology not associated with APOL1 variants -- we have evidence that selective autophagy pathways involving destruction of pathogens may be uniquely regulated by APOL1. We hypothesize that APOL1 functions as an autophagocytic adaptor by binding to both a docking SNARE (VAMP8) displayed on endosomes and to the autophagosomal protein LC3-II. The autophagocytic adaptor function of APOL1 is activated by binding a triggering molecule, such as the HIV protein Nef after infection, and results in the selective degradation of VAMP8-labeled endosomal cargo including viral particles and proteins. Variant APOL1 proteins are functionally defective, permitting HIV to persist in the infected cell, and supporting the new synthesis of Nef, the HIV protein critical for development of HIVAN. Our proposed experiments will address three unanswered and novel questions regarding APOL1 function in CKD. Is APOL1 synthesized in situ in kidney and what is its subcellular home? Does circulating or renal-expressed variant APOL1 mediate kidney disease? Does dysregulation of autophagy pathways activated in response to specific environmental stresses result in kidney disease in patients with APOL1 risk genotypes? These questions will be addressed with the following Specific Aims: 1. Determine APOL1 expression and intracellular location in normal kidney, and determine if APOL1 localization varies with risk genotype and/or disease diagnosis; 2. Generate in vivo models for the study of APOL1 function; 3. Characterize protein interactions between APOL1 with VAMP8 and the HIV protein Nef. Examine the effect of normal and variant APOL1 expression on autophagy in cell lines and cultured podocytes. Focusing on the unique pathways though which APOL1 regulates autophagy will most likely result in novel, mechanism-based therapies. Determining how APOL1 variation is associated with human kidney diseases will provide a unique opportunity to understand pathways causing common chronic kidney disease and use of that knowledge can be exploited to develop new strategies for therapy, prevention and risk stratification.

描述（由申请人提供）：慢性肾病（CKD）与许多复杂的疾病特征一样，是由遗传易感性和环境因素之间的依赖性相互作用表现出来的。最近描述的与 CKD 和非洲血统相关的 APOL1 风险等位基因就是一个例子，其中只有一部分遗传易感患者会患上肾脏疾病，这表明需要第二次打击或压力才能触发变异的 APOL1 依赖性肾损伤。为了研究 APOL1 变异在 CKD 中的作用机制，我们选择关注 HIV 相关肾病 (HIVAN)，这种疾病与 APOL1 风险单倍型密切相关，并且明显依赖于环境因素 HIV-1 感染。我们的初步数据表明 APOL1 在足细胞中表达，并且 APOL1 过度表达会激活自噬。尽管 mTor 诱导的核心自噬途径与糖尿病肾病（一种与 APOL1 变异无关的肾脏病理学）的肾小球损伤有关，但我们有证据表明，涉及破坏病原体的选择性自噬途径可能受到 APOL1 的独特调节。我们假设 APOL1 通过与内体上展示的对接 SNARE (VAMP8) 和自噬体蛋白 LC3-II 结合而发挥自噬细胞接头的作用。 APOL1 的自噬细胞接头功能通过结合触发分子（例如感染后的 HIV 蛋白 Nef）而被激活，并导致 VAMP8 标记的内体货物（包括病毒颗粒和蛋白质）选择性降解。变体 APOL1 蛋白存在功能缺陷，使得 HIV 能够在受感染的细胞中持续存在，并支持 Nef 的新合成，Nef 是 HIV 蛋白，对于 HIVAN 的发展至关重要。我们提出的实验将解决有关 CKD 中 APOL1 功能的三个尚未解答的新问题。 APOL1 是在肾脏中原位合成的吗？它的亚细胞归属是什么？循环或肾脏表达的 APOL1 变异是否介导肾脏疾病？针对特定环境压力而激活的自噬途径失调是否会导致 APOL1 风险基因型患者出现肾脏疾病？这些问题将通过以下具体目标得到解决： 1. 确定 APOL1 在正常肾脏中的表达和细胞内位置，并确定 APOL1 定位是否随风险基因型和/或疾病诊断而变化； 2. 生成APOL1功能研究的体内模型； 3. 表征 APOL1 与 VAMP8 和 HIV 蛋白 Nef 之间的蛋白质相互作用。检查正常和变异 APOL1 表达对细胞系和培养足细胞自噬的影响。关注 APOL1 调节自噬的独特途径很可能会产生新颖的、基于机制的疗法。确定 APOL1 变异如何与人类肾脏疾病相关，将为了解导致常见慢性肾脏疾病的途径提供独特的机会，并且可以利用这些知识来制定治疗、预防和风险分层的新策略。