An Integrative Genomic Approach to APOL1-Associated Nephropathy.

描述(申请人提供)：与高加索人相比，非裔美国人中常见形式的肾脏疾病的发病率，包括归因于高血压的肾脏疾病的发病率明显更高。现在已知载脂蛋白L1基因(APOL1)变异频率的种族差异可以解释这些差异。APOL1风险变异在非裔美国人中出现的频率很高，因为一个拷贝可以保护非洲人免受导致非洲昏睡病的寄生虫的侵袭，这种寄生虫是一种潜在的致命疾病。大约10%的非裔美国人遗传了两份APOL1风险变异，使他们患肾脏疾病的风险增加了10倍。APOL1基因变异导致肾脏疾病的机制尚不清楚。这项应用旨在确定APOL1基因变异如何导致肾脏疾病，这些信息可能会产生更有效的治疗方法。现有的治疗方法，包括严格控制血压，结果令人失望。我们建议确定：(1)肾细胞中APOL1基因的变异是否直接导致细胞功能障碍而导致肾脏疾病，和/或(2)循环中APOL1蛋白(高密度脂蛋白结合或去脂)异常导致肾脏疾病。为了探索机制1，我们将检查具有和不具有APOL1风险变异的非裔美国人肾脏细胞的基因表达谱，以确定哪些基因和基因途径过度表达(上调)或低表达(下调)，这是基于细胞的APOL1特有的基因构成。为了探索机制2，将根据个体的遗传构成来检查循环中的APOL1蛋白与高密度脂蛋白的数量和结合模式。肾细胞将在体外暴露于正常和危险的APOL1蛋白，以确定危险变异蛋白是否对细胞有毒，以及这种毒性是如何表现出来的。在这些研究的基础上，可以对表达正常和变异的APOL1的转基因小鼠进行额外的分析，以评估APOL1蛋白的肾脏影响和体内代谢。我们还将尝试通过对周围的染色体区域进行深度测序来识别APOL1基因中未被检测到的肾脏疾病风险变异。这些实验可能确定APOL1基因变异导致非糖尿病肾病的机制，并帮助找到治疗这种对非裔美国人社区产生不成比例影响的毁灭性疾病的方法。

DESCRIPTION (provided by applicant): The incidence rates of common forms of kidney disease including that attributed to hypertension are significantly higher in African Americans, relative to Caucasians. Racial differences in the frequency of Apolipoprotein L1 gene (APOL1) variants are now known to account for these differences. APOL1 risk variants rose to high frequency in African Americans since one copy protects from the parasite that causes African sleeping sickness, a potentially fatal disease. Approximately 10% of African Americans inherit two copies of APOL1 risk variants, placing them at a ten-fold increased risk for kidney disease. The mechanism whereby APOL1 gene variants contribute to kidney disease is unknown. This application proposes to determine how APOL1 gene variants contribute to kidney disease, information likely to yield more effective therapies. Existing therapies including strict blood pressure control have had disappointing results. We propose to determine whether: (1) variation in the APOL1 gene in kidney cells directly leads to cell dysfunction with resultant kidney disease, and/or (2) abnormal circulating ApoL1 proteins (high density lipoprotein [HDL] bound or lipid-free) lead to kidney disease. To explore mechanism 1, gene expression profiles will be examined in kidney cells from African Americans with and without APOL1 risk variants to determine which genes and gene pathways are over expressed (turned up) or under expressed (turned down), based upon the APOL1- specific genetic make-up of the cells. To explore mechanism 2, the amount and binding patterns of circulating ApoL1 proteins to HDL will be examined based upon an individual's genetic make- up. Kidney cells will be exposed to normal and risk ApoL1 proteins in vitro to determine whether risk variant proteins are toxic to cells and how this toxicity manifests. Based on these studies, additional analyses may be conducted in transgenic mice expressing normal and variant APOL1 to assess renal effects and in vivo metabolism of ApoL1 proteins. We will also attempt to identify undetected kidney disease risk variants in the APOL1 gene by deeply sequencing the surrounding chromosomal region. These experiments are likely to determine the mechanisms whereby APOL1 gene variants lead to non-diabetic kidney disease and assist in finding a cure for this devastating disease disproportionately impacting the African American community.