Molecular Mechanism of APOL1 Associated Kidney Disease

APOL1相关肾脏疾病的分子机制

• 批准号: 9011946
• 负责人: SETH Leo ALPER
• 金额: $ 43.5万
• 依托单位: BETH ISRAEL DEACONESS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-03 至 2018-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9011946
• 关键词: AIDS-Associated Nephropathy; Accounting; Africa; African; African American; African Trypanosomiasis; Alleles; American; Amino Acid Sequence; Anabolism; Apolipoproteins; Apoptosis; Apoptotic; BH3 Domain; Biological; Biology; Caring; Cell membrane; Cell physiology; Cells; Cellular biology; Code; Disease; Embryo; End stage renal failure; Endocytosis; Epidemic; European; Family member; Focal Segmental Glomerulosclerosis; Frequencies; Functional disorder; Genes; Genotype; Goals; Human; Hypertension; Individual; Injury; Ion Channel; Ions; Kidney; Kidney Diseases; Kidney Failure; Lead; Mediating; Modeling; Molecular; Oocytes; Organelles; Organism; Pathologic; Pathology; Pathway interactions; Peptide Sequence Determination; Permeability; Phenotype; Physiological; Primates; Property; Public Health; Recombinants; Reporting; Resistance; Risk; Role; Structure; System; Testing; Tissues; Trypanosoma; Variant; Whole Organism; Zebrafish; base; design and construction; disorder risk; genetic variant; health disparity; high risk; improved; in vivo; minority health; podocyte; prevent; promoter; public health relevance; racial health disparity; research study; risk variant; trafficking

DESCRIPTION (provided by applicant): More than 500,000 Americans suffer from end-stage renal disease (ESRD). African Americans develop ESRD at rates 4-5 fold higher than European Americans. Recently we showed that coding sequence variants in the ApolipoproteinL1 (ApoL1) gene, present only in individuals with recent African ancestry, explain a very large proportion of this health disparity. This has now been confirmed by multiple additional studies. ApoL1 variants have a major impact on different types of kidney disease including hypertension-associated ESRD, focal segmental glomerulosclerosis, and HIV-associated nephropathy. Individuals with two variant ApoL1 alleles have a 7-30 fold increased risk for kidney disease. 3.5 million African Americans likely have the high risk ApoL1 genotype. African Americans without two variant alleles have minimal excess risk. At present, little is known about the biology of ApoL1 or its rol in the kidney. ApoL1 has a defined role in resistance to trypanosomes, and the G1 and G2 variants appear to have become common in Africa because they confer protection against the forms of trypanosomes that cause African Sleeping Sickness. Here, our goal is to elucidate the function of ApoL1 and its role in causing human kidney disease in order to understand the biological mechanisms underlying this large disparity in kidney disease risk. ApoL1 is a Bcl2 family member with a BH3-only domain, suggesting a possible role in apoptosis. Our initial experiments in oocytes lead us to believe that this pathway may be an important mechanism of glomerular injury in ApoL1-associated disease. We propose to: 1. Define the cell biology and cell physiology of ApoL1: We will define the basic cellular biology of ApoL1 including biosynthesis, trafficking, ion channel properties, endocytosis, and effects on organellar structure and function. We will compare wild type and renal risk variant ApoL1 biology to understand the mechanisms that lead to kidney disease. 2. Examine specific effects of ApoL1 on apoptosis in podocytes: We hypothesize that ApoL1 risk variants promote podocyte apoptosis via a BH3 domain in the N- terminus and that the renal risk variants enhance ApoL1's pro-apoptotic effects. We will test this hypothesis both in cultured podocytes of different ApoL1 genotypes and by transfecting podocytes with ApoL1 constructs designed to probe the underlying apoptotic mechanisms. 3. Use a zebrafish model to study ApoL1- mediated renal injury in vivo: We will use zebrafish to understand how ApoL1 variants promote glomerular injury. We have demonstrated that the G1 risk variant increases embryonic lethality and causes glomerular pathology, and that wild type ApoL1 can reverse the pathologic phenotype caused by G1. We will examine the effects of heterologous ApoL1 expression in a whole organism using ubiquitous and tissue-specific promoters. We will define the risk variant domains that cause disease and the wild type domains that prevent G1-mediated injury. We will also define the specific interactions between the wild-type, G1, and G2 forms of ApoL1 in vivo. Lastly, we will examine the role of ApoL1 variants in promoting or preventing apoptosis of glomerular cells.

描述（由申请人提供）：超过 500,000 名美国人患有终末期肾病 (ESRD)。非裔美国人患 ESRD 的比率比欧洲裔美国人高 4-5 倍。最近，我们发现载脂蛋白 L1 (ApoL1) 基因中的编码序列变异仅存在于最近有非洲血统的个体中，这在很大程度上解释了这种健康差异。现在这一点已被多项其他研究证实。 ApoL1 变异对不同类型的肾脏疾病有重大影响，包括高血压相关的 ESRD、局灶节段性肾小球硬化症和 HIV 相关肾病。具有两个 ApoL1 等位基因变异的个体患肾脏疾病的风险增加 7-30 倍。 350 万非裔美国人可能具有高风险 ApoL1 基因型。没有两个变异等位基因的非裔美国人的超额风险很小。目前，人们对 ApoL1 的生物学或其在肾脏中的作用知之甚少。 ApoL1 在抵抗锥虫方面具有明确的作用，G1 和 G2 变体似乎在非洲很常见，因为它们可以针对引起非洲昏睡病的锥虫形式提供保护。在这里，我们的目标是阐明 ApoL1 的功能及其在引起人类肾脏疾病中的作用，以便了解肾脏疾病风险巨大差异背后的生物学机制。 ApoL1 是 Bcl2 家族成员，具有仅 BH3 结构域，表明可能在细胞凋亡中发挥作用。我们在卵母细胞中的初步实验使我们相信该途径可能是 ApoL1 相关疾病中肾小球损伤的重要机制。我们建议： 1. 定义 ApoL1 的细胞生物学和细胞生理学：我们将定义 ApoL1 的基本细胞生物学，包括生物合成、运输、离子通道特性、内吞作用以及对细胞器结构的影响 和功能。我们将比较野生型和肾脏风险变异 ApoL1 的生物学特性，以了解导致肾脏疾病的机制。 2.检查ApoL1对足细胞凋亡的具体影响：我们假设ApoL1风险变异通过N末端的BH3结构域促进足细胞凋亡，并且肾脏风险变异增强ApoL1的促凋亡作用。我们将在不同 ApoL1 基因型的培养足细胞中以及通过用旨在探测潜在细胞凋亡机制的 ApoL1 构建体转染足细胞来测试这一假设。 3. 使用斑马鱼模型研究 ApoL1 介导的体内肾损伤：我们将使用斑马鱼来了解 ApoL1 变异如何促进肾小球损伤。我们已经证明G1风险变异会增加胚胎致死率并引起肾小球病理，而野生型ApoL1可以逆转G1引起的病理表型。我们将使用普遍存在的组织特异性启动子来检查异源 ApoL1 表达在整个生物体中的影响。我们将定义导致疾病的风险变异结构域和预防 G1 介导的损伤的野生型结构域。我们还将定义体内 ApoL1 野生型、G1 和 G2 形式之间的特定相互作用。最后，我们将研究 ApoL1 变异在促进或预防肾小球细胞凋亡中的作用。