Genetic Determinants of Susceptibility to Kidney Disease in African Americans

描述（由申请人提供）：非洲裔美国人患终末期肾病 (ESRD) 的风险比欧洲裔美国人高 3 倍以上。这种不成比例的风险对于几乎所有形式的肾脏疾病来说都是显而易见的，但只有一小部分可以用社会经济地位和/或获得医疗保健的机会不佳来解释。最近的研究发现了编码 MYH9（一种非肌肉肌球蛋白重链）的基因的多态性，与非裔美国人 ESRD 的易感性相关，解释了可归因风险的一个重要组成部分。鉴定 MYH9 变异与 ESRD 风险之间的关联是一项重大突破。然而，由于这些变异不包括外显子或内含子：外显子连接序列的显着变化，因此主要的研究机会和科学知识差距是确定 MYH9 多态性与肾损伤发病机制之间的因果机制。由于 MYH9 是一种结构性细胞内蛋白，因此很难通过临床样本分析来研究其在肾脏疾病病理学中的作用。尽管如此，要将这种遗传关联的发现转化为对高危个体的改进预防和治疗，需要精确了解这些遗传变异影响肾脏疾病病程的机制。因此，我们建议生成小鼠品系，其中在不存在小鼠直向同源物的情况下，将人类 MYH9 单倍型插入小鼠基因组的同线性位置。这些细胞系将使用新颖且稳健的两步方法产生，其中在胚胎干（ES）细胞中切除小鼠基因座，其方式允许将类似的人类基因直接快速引入到删除的基因座中。我们开发这种方法的经验表明，插入的人类基因在小鼠体内保留了其关键的功能和调节特性。因此，这些动物模型的开发将为在精确控制的遗传和环境条件下研究人类 MHY9 单倍型体内的生理后果提供独特的机会，以便了解它们对肾损伤发展的贡献。我们组建了一支高素质的多学科团队，以确保这些小鼠品系的产生和初步表征能够在《恢复法》规定的两年时间内完成。这些动物模型将成为确定预防非裔美国人终末期肾病的新策略的有力工具。 公共卫生相关性：非裔美国人患终末期肾病 (ESRD) 的风险明显高于欧洲裔美国人。虽然人们已经认识到这种差异有一段时间了，但其原因尚不清楚。最近，两个小组独立确定了非裔美国人的 ESRD 风险与 MYH9 基因变异之间的关联。然而，目前尚不清楚该基因的变异如何导致肾脏疾病。在我们提出的研究中，我们计划培育出将人类 MYH9 变体插入小鼠基因组中的小鼠，在精确控制的遗传和环境条件下对它们进行研究，以了解它们对肾损伤发展的贡献。这些动物模型将成为确定预防非裔美国人终末期肾病的新策略的有力工具。

DESCRIPTION (provided by applicant): The risk for developing end-stage renal disease (ESRD) in African Americans is more than 3-fold higher than European Americans. This disproportionate risk is apparent for virtually all forms of kidney disease, but only a minor portion can be explained by socio-economic status and/or poor access to health care. Recent studies have identified polymorphisms in the gene encoding MYH9, a non-muscle myosin heavy chain that are associated with susceptibility to ESRD in African-Americans, explaining a substantial component of the attributable risk. Identification of this association between MYH9 variants and risk for ESRD is a major breakthrough. However, since these variants do not include significant changes in the sequence of exons or intron:exon junctions, the major research opportunity and scientific knowledge gap is to determine the causal mechanisms connecting MYH9 polymorphisms with the pathogenesis of kidney injury. Because MYH9 is a structural, intra-cellular protein, its role in the pathobiology of kidney disease will be difficult to study in patients through analysis of clinical samples. Nonetheless, translating the discovery of this genetic association into improved prevention and treatment for individuals at risk will require precise understanding of the mechanisms whereby these genetic variants influence the course of kidney disease. Accordingly, we propose to generate mouse lines in which human MYH9 haplotypes are inserted into the syntenic location of the mouse genome in the absence of the mouse orthologue. These lines will be generated using a novel and robust 2-step method wherein the mouse locus is excised in embryonic stem (ES) cells in a manner that allows rapid introduction of the analogous human gene directly into the deleted locus. Our experience in developing this method indicates that the inserted human gene retains its key functional and regulatory properties in the mouse. Thus, development of these animal models will provide a unique opportunity for studying the physiological consequences of human MHY9 haplotypes in vivo under precisely controlled genetic and environmental conditions in order to understand their contributions to the development of kidney injury. We have assembled a highly accomplished, multi-disciplinary team to ensure that the generation and initial characterization of these mouse lines can be completed within the two-year period specified by the Recovery Act. These animal models will be powerful tools for identifying new strategies for preventing ESRD in African Americans. PUBLIC HEALTH RELEVANCE: African Americans have a significantly greater risk of developing end-stage renal disease (ESRD) than European Americans. While this disparity has been recognized for some time, its cause was not known. Recently, two groups independently identified associations between risk for ESRD in African-Americans and variations in a gene called MYH9. However, it is not clear how the variation in this gene could lead to kidney disease. In the studies we are proposing, we plan to generate mice in which the human MYH9 variants are inserted into the mouse genome where they can be studied under precisely controlled genetic and environmental conditions in order to understand their contributions to the development of kidney injury. These animal models will be powerful tools for identifying new strategies for preventing ESRD in African Americans.