Molecular Mechanism of APOL1 Associated Kidney Disease

APOL1相关肾脏疾病的分子机制

• 批准号: 8791547
• 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 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8791547
• 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; 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50万美国人患有末期肾脏疾病（ESRD）。非洲裔美国人的ESRD比欧洲人高4-5倍。最近，我们表明，仅在非洲近代人的个体中，载脂蛋白1（Apol1）基因中的编码序列变体解释了这种健康差异很大一部分。现在已经通过多项其他研究证实了这一点。 APOL1变体对不同类型的肾脏疾病有重大影响，包括高血压相关的ESRD，局灶性节段性肾小球硬化和与HIV相关的肾病。具有两个变异APOL1等位基因的个体具有7-30倍的肾脏疾病风险。 350万非裔美国人可能患有高风险APOL1基因型。没有两个变体等位基因的非裔美国人的风险很小。目前，关于肾脏中APOL1或其ROL的生物学知之甚少。 APOL1在对锥虫的抗性中具有明确的作用，而G1和G2变体似乎在非洲很普遍，因为它们赋予了引起非洲睡眠疾病的锥虫形式的保护。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，以了解肾脏疾病风险中这种巨大差异的生物学机制。 Apol1是一个仅BH3域的BCL2家庭成员，表明在凋亡中可能起作用。我们在卵母细胞中的最初实验使我们相信该途径可能是与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体APOL1生物学，以了解导致肾脏疾病的机制。 2。检查apol1对足细胞凋亡的特定影响：我们假设Apol1风险变体通过N末端中的BH3域促进足细胞凋亡，并且肾脏风险变体增强了Apol1的促进性效应。我们将在不同APOL1基因型的培养足细胞和使用APOL1构建体转染足细胞的培养足细胞中检验这一假设，该假设旨在探测潜在的凋亡机制。 3。使用斑马鱼模型研究体内APOL1介导的肾脏损伤：我们将使用斑马鱼来了解APOL1变体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性并引起肾小球病理，并且野生型APOL1可以逆转由G1引起的病理表型。我们将使用无处不在和组织特异性启动子检查整个生物体中异源APOL1表达的影响。我们将定义导致疾病和防止G1介导的损伤的野生型域的风险变异域。我们还将定义体内apol1的野生型，G1和G2形式之间的特定相互作用。最后，我们将研究Apol1变体在促进或预防肾小球细胞凋亡中的作用。