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：
9284462
负责人：
Leslie A Bruggeman
金额：
$ 22.21万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-07-20 至 2017-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9284462
关键词：
AIDS-Associated Nephropathy APOL1 gene Address African African American American Animals Apolipoproteins Autophagocytosis Autophagosome Binding Biological Biology Biopsy Specimen Blood Cardiovascular Diseases Cell Culture Techniques Cell Line Cells Cessation of life Chromosomes, Human, Pair 22 Chronic Kidney Failure Code Complementary DNA Complex Data Development Diagnosis Disease Docking Electron Microscopy End stage renal failure Environmental Risk Factor Expenditure Experimental Designs FRAP1 gene Gene Expression Profile Genetic Epistasis 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 Location Lysosomes Maps Mediating Medicare Metabolic Methods Modeling Mus NPHS2 protein Normal tissue morphology Pathogenesis Pathology Pathway interactions Patients Pattern Phenotype Prevention Protein Biosynthesis Proteins Publishing Regulation Resistance Risk SNAP receptor Severities Signal Transduction Stress Study models Susceptibility Gene Testing Time Tissues Transgenic Mice Trypanosoma United States Variant Viral Viral Proteins Virus base diabetic disease diagnosis disease phenotype experimental study genetic association health disparity high risk population improved in vivo in vivo Model mouse model nef Protein nephrin non-diabetic novel overexpression particle pathogen podocyte promoter public health relevance response risk variant transgene expression uptake vector

项目摘要

DESCRIPTION (provided by applicant): Chronic kidney disease (CKD), like many complex disease phenotypes, reflects dependent interactions between genetic susceptibilities and environmental factors. APOL1 variants explain much of the excess risk of advanced non-diabetic CKD in patients of African ancestry. However, only some patients with risk genotypes develop kidney disease, suggesting that genetic epistasis or environmental stress is required to trigger variant APOL1-dependent kidney injury. To investigate how APOL1 variants result in CKD, we have focused 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-dependent suppression of core autophagy may cause diabetic glomerulopathy, a renal pathology not associated with APOL1 variants, we provide evidence that the genetic association of APOL1 with CKD results from APOL1- dependent regulation of distinct, selective autophagy pathways, which result in the destruction of pathogens. We hypothesize that APOL1 is an autophagic adaptor that tethers a docking SNARE (VAMP8) displayed on lysosomes to the autophagosomal protein LC3-II. The tethering function of APOL1 is activated by binding a triggering molecule, the HIV protein Nef, and results in the selective degradation of autophagosomes carrying HIV viral particles and proteins. Variant APOL1 proteins are functionally defective, permitting HIV to persist in the infected cell and continue synthesis of viral proteins including Nef. Nef blocks autophagic elimination of the virus and is critical for development of HIVAN. Our proposed experiments 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 are 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 and examine normal and variant APOL1 regulation of autophagy in cell lines and cultured podocytes. These studies can result in novel, mechanism-based therapies, improve health disparities in African American patients and identify novel mechanisms of human CKD.

描述（由申请人提供）：慢性肾病（CKD）与许多复杂的疾病表型一样，反映了遗传易感性和环境因素之间的依赖性相互作用。 APOL1 变异在很大程度上解释了非洲血统患者患晚期非糖尿病 CKD 的过高风险。然而，只有一些具有风险基因型的患者会发生肾脏疾病，这表明需要遗传上位或环境应激来触发变异的 APOL1 依赖性肾损伤。为了研究 APOL1 变异如何导致 CKD，我们重点关注 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 依赖性核心自噬抑制可能导致糖尿病肾小球病（一种与 APOL1 变异无关的肾脏病理学），但我们提供的证据表明，APOL1 与 CKD 的遗传关联源于 APOL1 依赖的对不同选择性自噬途径的调节，从而导致破坏病原体。我们假设 APOL1 是一种自噬接头，它将溶酶体上展示的对接 SNARE (VAMP8) 与自噬体蛋白 LC3-II 相连。 APOL1 的束缚功能通过结合触发分子 HIV 蛋白 Nef 来激活，并导致携带 HIV 病毒颗粒和蛋白的自噬体选择性降解。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，并继续合成包括 Nef 在内的病毒蛋白。 Nef 阻止病毒的自噬消除，对于 HIVAN 的发展至关重要。我们提出的实验解决了有关 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，并检查细胞系和培养足细胞中正常和变异的 APOL1 对自噬的调节。这些研究可以产生新颖的、基于机制的疗法，改善非裔美国患者的健康差异，并确定人类 CKD 的新机制。