Kidney disease mechanisms associated with human genetic variation

与人类遗传变异相关的肾脏疾病机制

• 批准号: 9653298
• 负责人: Leslie A Bruggeman
• 金额: $ 23.69万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-20 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9653298
• 关键词: Kidney; disease; mechanisms; associated; human

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）：慢性肾脏病（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。APOL 1变异解释了非洲血统患者中晚期非糖尿病CKD的大部分过度风险。然而，只有一些具有风险基因型的患者发生肾脏疾病，这表明遗传上位性或环境应激是触发变异APOL 1依赖性肾损伤所必需的。为了研究APOL 1变异如何导致CKD，我们关注了HIV相关肾病（HIVAN），这种疾病与APOL 1风险单倍型最密切相关，并且明显依赖于环境因素HIV-1感染。我们的初步数据表明APOL 1在足细胞中表达，APOL 1过表达激活自噬。虽然mTOR依赖性抑制核心自噬可能导致糖尿病肾小球病，一种与APOL 1变异体无关的肾脏病理学，但我们提供的证据表明，APOL 1与CKD的遗传相关性来自APOL 1依赖性调节不同的选择性自噬途径，从而导致病原体的破坏。我们假设APOL 1是一个自噬适配器，它将溶酶体上展示的对接陷阱（VAMP 8）与自噬体蛋白LC 3-II连接。APOL 1的束缚功能通过结合触发分子HIV蛋白Nef而被激活，并导致携带HIV病毒颗粒和蛋白的自噬体的选择性降解。APOL 1蛋白的变异在功能上是有缺陷的，这使得HIV能够在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阻断病毒的自噬消除，对HIVAN的发展至关重要。我们提出的实验解决了关于APOL 1在CKD中功能的三个未回答的新问题。APOL 1是在肾脏原位合成的吗？它的亚细胞家在哪里？循环或肾脏表达的APOL 1变体是否介导肾脏疾病？特异性环境应激激活的自噬通路失调是否会导致APOL 1风险基因型患者的肾脏疾病？这些问题的解决有以下具体目标：1。确定APOL 1在正常肾脏中的表达和细胞内定位，并确定APOL 1定位是否随风险基因型和/或疾病诊断而变化; 2.建立APOL 1功能研究的体内模型; 3.表征APOL 1与VAMP 8和HIV蛋白Nef之间的蛋白质相互作用，并检查细胞系和培养的足细胞中正常和变异的APOL 1对自噬的调节。这些研究可以产生新的、基于机制的疗法，改善非裔美国人患者的健康差异，并确定人类CKD的新机制。

项目成果

APOL1 and Preeclampsia: Intriguing Links, Uncertain Causality, Troubling Implications.

APOL1 和先兆子痫：有趣的联系、不确定的因果关系、令人不安的影响。

• DOI: 10.1053/j.ajkd.2021.01.013
• 发表时间: 2021
• 期刊: American journal of kidney diseases : the official journal of the National Kidney Foundation
• 作者: Sedor,JohnR;Bruggeman,LeslieA;O'Toole,JohnF
• 通讯作者: O'Toole,JohnF