Genetics of Renal End Organ Damage in Hypertension

描述（由申请人提供）：摘要在美国，终末期肾病的发病率正在惊人地增加，其中高血压和糖尿病是主要原因。目前，有2560万人处于肾脏疾病的早期阶段（1至3期），虽然严格控制血压和葡萄糖水平可能会减缓，但这不会阻止这些患者肾功能的进行性下降。因此，了解高血压引起的肾脏疾病的遗传基础是相当大的兴趣。在确定家族性肾病（肾病综合征）的遗传原因方面取得了重大进展。然而，没有发现遗传变异与常见形式的肾脏疾病有因果关系。我们的目标是更好地理解在Dahl盐敏感（S）大鼠中观察到的高血压诱导的肾病的遗传基础，该大鼠表现出显著的蛋白尿和局灶节段性肾小球硬化（FSGS）。蛋白尿和肾损伤的初步遗传分析是使用来自S。该研究确定了10个与肾损伤（通过蛋白尿测量）和/或功能相关的基因组区域。在2号染色体上开发的同源菌株表现出显着较少的蛋白尿和FSGS。该建议将评估位于大鼠2号染色体上一个小区域的遗传变异在S大鼠中观察到的进行性FSGS和蛋白尿中起重要作用的假设。根据同源菌株分析，致病位点已缩小到<1.2 Mbs，包含27个基因。然而，跨物种比较，基于自交系的SNP分析，全面的编码序列和基因表达分析令人信服地确定了4个基因，为进一步研究。本研究的主要目的是：（1）对S和small同源系大鼠的血压和肾脏血流动力学（包括肾血流量、肾小球毛细血管压力和肾小球通透性）进行时间研究;（2）对大鼠2号染色体上缩小到小区域的基因进行全面的基因表达、蛋白质印迹分析、测序和单倍型分析;和（3）使用基于细胞的方法和全动物方法评价鉴定的等位基因变体的功能意义。总之，该提案将确定并优先考虑与高血压诱导的肾脏疾病的Dahl S模型中的蛋白尿和FSGS相关的基因，并为功能研究，基因验证以及最终在人类人群中的研究提供基础。公共卫生相关性：项目叙述高血压是终末期肾病（ESRD）的主要促成因素。从1991年到2004年，接受透析或移植治疗的终末期肾病患者人数增加了一倍多，从209，000人增加到472，000人。在未来20年，预计ESRD患者人数将增加到200多万。此外，经济影响是巨大的，给医疗保险系统（耗资201亿美元，占医疗保险总支出的7%）和私人保险部门（估计为121亿美元）带来负担。不幸的现实是，治疗选择有限，只能减缓疾病的进展。这项工作的重点是确定Dahl盐敏感（S）大鼠易患高血压诱导的肾脏疾病的基因。先前使用S大鼠进行的遗传分析确定了几个与肾脏疾病相关的染色体区域。特别是，大鼠2号染色体上的一个区域被发现在S大鼠中观察到的肾损伤中起重要作用。在多项研究中，人类染色体1 q21上的同源区域也与肾脏疾病有关。这强调了在大鼠中鉴定该基因的重要性，因为这些发现可能很容易应用于人类肾脏疾病。总之，本提案的目标是利用人类疾病的啮齿动物模型和先进的遗传技术来加速鉴定与肾脏疾病有关的基因。从这项研究中获得的知识的应用将有助于更好地了解疾病的方式和原因，并最终在肾衰竭之前提供更早，更有效的治疗方法。

DESCRIPTION (provided by applicant): Abstract There is an alarming increase in the incidence of end-stage renal disease in the Unites States, with hypertension and diabetes being the major cause. Currently, 25.6 million people are in the early phase of kidney disease (stage 1 to 3) and while strict control of blood pressure and glucose levels may slow, it will not prevent the progressive decline of renal function in these patients. Therefore, understanding the genetic basis of hypertension-induced renal disease is of considerable interest. Significant progress has been made to identify the genetic causes of familial forms of renal disease (nephrotic syndrome). However, no genetic variants have been found to be causally linked to common forms of renal disease. It is our goal to develop a better understanding of the genetic basis of hypertension-induced renal disease observed in the Dahl salt- sensitive (S) rat, which exhibits significant proteinuria and focal segmental glomerulosclerosis (FSGS). An initial genetic analysis for proteinuria and renal injury was performed using a population derived from the S. The study identified ten genomic regions linked to renal damage (measured by proteinuria) and/or function. A congenic strain developed on chromosome 2 exhibited significantly less proteinuria and FSGS. This proposal will evaluate the hypothesis that genetic variant(s) located to a small region on rat chromosome 2 play a significant role in the progressive FSGS and proteinuria observed in the S rat. Based on congenic strain analysis, the causative locus has been narrowed to <1.2 Mbs containing 27 genes. However, cross-species comparative, inbred-based SNP analysis, comprehensive coding sequence and gene expression analysis has convincingly identified 4 genes for further study. The aims of the proposed study are: (1) to perform temporal studies of blood pressure and renal hemodynamics, including renal blood flow, glomerular capillary pressure, and glomerular permeability in the S and small congenic strain; (2) to perform comprehensive gene expression, western blot analysis, sequencing, and haplotype analysis for genes narrowed to the small region on rat chromosome 2; and (3) to evaluate the functional significance of identified allelic variants using cell- based and whole-animal approaches. In summary, this proposal will identify and prioritize gene(s) linked to proteinuria and FSGS in the Dahl S model of hypertension-induced renal disease and provide a basis for functional studies, gene validation, and eventually study in human-based populations. PUBLIC HEALTH RELEVANCE: Project Narrative High blood pressure is major contributor to end-stage renal disease (ESRD). The number of ESRD patients treated by either dialysis or transplantation has more than doubled in the period from 1991 to 2004 from 209,000 to 472,000. In the next 20 years, the numbers of ESRD patients are expected to increase to over 2 million. Additionally, the economic impact is substantial, burdening the Medicare system (costing $20.1 billion or 7% percent of total Medicare expenditures), and the private insurance sector (estimated at $12.1 billion). The unfortunate reality is that treatment options are limited and only slow the progression of the disease. The focus of the proposed work is to identify genes that predispose the Dahl salt-sensitive (S) rat to develop hypertension-induced kidney disease. Previous genetic analysis using the S rat identified several chromosomal regions linked to kidney disease. In particular, a region on rat chromosome 2 was found to play a significant role in the kidney injury observed in the S rat. The homologous region on human chromosome 1q21 has also been linked to kidney disease in multiple studies. This underlies the importance in identifying the gene in the rat because the findings may be readily applied to human kidney disease. In summary, it is the goal of this proposal to utilize a rodent model of human disease and advanced genetic techniques to expedite the identification of a gene involved in kidney disease. The application of knowledge gained from this research will contribute to a better understanding of the how and why of the disease and ultimately provide earlier and more effective treatments of the disease before kidney failure is reached.