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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)：慢性肾脏病(CKD)，像许多复杂的疾病特征一样，表现为遗传易感性和环境因素之间的相互作用。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，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应激才能触发变异的APOL1依赖性肾脏损伤。为了研究AOL1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风险单倍型最相关，并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，APOL1的过度表达激活了自噬。虽然mTOR诱导的核心自噬通路与糖尿病肾病的肾小球损伤有关，但我们有证据表明，涉及破坏病原体的选择性自噬通路可能是由APOL1唯一调控的。我们假设APOL1通过与显示在内体上的对接陷阱(VAMP8)和自噬蛋白LC3-II结合而发挥自噬细胞适配器的功能。APOL1的自噬适配器功能是通过感染后与一个触发分子(如HIV蛋白Nef)结合而激活的，并导致VAMP8标记的内体货物包括病毒颗粒和蛋白质的选择性降解。变异的APOL1蛋白具有功能缺陷，允许HIV在感染细胞中持续存在，并支持Nef的新合成，Nef是HIV蛋白质，对HIVAN的发展至关重要。我们提出的实验将解决三个关于CKD中APOL1功能的悬而未决的新问题。APOL1是在肾脏中原位合成的吗？它的亚细胞家园是什么？循环或肾脏表达的APOL1变异体是否参与了肾脏疾病？对特定环境应激反应激活的自噬通路的失调是否会导致APOL1风险基因型患者的肾脏疾病？这些问题的解决具有以下特定的目的：1.确定APOL1在正常肾脏中的表达和细胞内定位，并确定APOL1的定位是否因危险基因和/或疾病诊断而异；2.建立体内模型以研究APOL1的功能；3.表征APOL1与VAMP8和HIV蛋白Nef之间的蛋白质相互作用。检测正常和变异的APOL1表达对细胞系和培养的足细胞自噬的影响。关注APOL1调节自噬的独特途径很可能会导致新的、基于机制的疗法。确定APOL1变异如何与人类肾脏疾病相关联将提供一个独特的机会，以了解导致常见慢性肾脏疾病的途径，并利用这些知识来开发新的治疗、预防和风险分层策略。