GENETIC MODIFIERS IN ANGIOTENSIN RECEPTOR-DEFICIENCY

肾素-血管紧张素系统(RAS)是血压和体液平衡的关键调节因子。在不同的人群中，RAS在高血压和终末器官损伤发病机制中的相对作用可能有很大的差异。我们推测，其中一些变异可能是由调节RAS在健康和疾病中的功能的遗传因素解释的；这些因素可能涉及编码RAS组分的基因或RAS之外的其他基因。在我们的初步研究中，我们已经确定了通过靶向破坏AT1a血管紧张素受体基因(Agtr1a)来显著改变小鼠肾脏结构的遗传修饰物。这些研究的目的是利用这个小鼠模型，通过以下特定目的来定位和表征这些自然产生的RAS的遗传修饰物：特殊目的#1：利用交叉杂交和反向杂交来确定修饰基因座对AT1a受体缺陷患者肾血管表型的影响。在我们的初步研究中，我们发现近交系C57BL/6或129/J背景的AT1a受体缺陷小鼠具有严重的肾脏表型，而F1(C57BL/6x129)AT1a受体缺陷小鼠的肾脏正常。我们将对亲本品系进行F1杂交和回交，并分析后代是否存在肾血管病变，以进一步表征这些遗传修饰物。在大量动物中对这一表型的准确定义将是特定目标2中提出的定位研究成功的关键。特定目标2：在AT1A受体缺陷小鼠中定位和识别肾血管病变的修饰基因。在仔细分析回交和杂交后代的表型后，我们将获得基因组DNA，并利用亲本(C57BL/6和129)之间的多态标记进行基因组微卫星分析。根据这次全基因组扫描的结果，我们将使用连锁分析来定位这些基因座。然后，我们将使用系统的方法来缩小连锁间隔，试图通过位置克隆和候选基因分析来分离修饰基因。这些研究为识别对RAS的生理学有显著修饰作用的新基因提供了可能性。将使用的实验方法的组合为Le博士提供了一个出色的培训工具。通过这些研究过程，她应该会熟练掌握一系列分子基因技术，这些技术应该会为她的职业生涯奠定基础。

The renin-angiotensin system (RAS) is a key regulator of blood pressure and fluid homeostasis. Within different human populations, the relative contribution of the RAS to the pathogenesis of hypertension and end- organ injury may vary widely. We hypothesize that some of this variation may be explained by genetic factors that modulate the functions of the RAS in health and disease; these factors may involve genes encoding the RAS components or other genes outside of the RAS. In our preliminary studies, we have identified genetic modifiers that dramatically alter kidney structure of mice with targeted disruption of the AT1A angiotensin receptor gene (Agtr1a). The objective of these studies is to use this mouse model to localize and characterize these naturally occurring genetic modifiers of the RAS through the following specific aims: Specific Aim #1: To define the influence of modifier loci on renal vascular phenotype in AT1A receptor-deficiency using inter-crosses and back crosses. In our preliminary studies, we have found that AT1A receptor-deficiency on inbred C57BL/6 or 129/J backgrounds has a severe renal phenotype, while kidneys are normal in F1(C57BL/6 x 129) AT1A receptor-deficient mice. We will perform F1 inter-crosses along with back crosses to the parental strains and analyze the progeny for the presence or absence of renal vascular lesions to further characterize these genetic modifiers. Precise definition of this phenotype in a large number of animals will be critical to the success of the mapping studies proposed in Specific Aim 2. Specific Aim #2: Mapping and identification of the modifying loci for renal vascular lesions in AT1A receptor-deficient mice. After a careful analysis of phenotype of progeny from back crosses and intercrosses, we will obtain genomic DNA and perform genomic micro-satellite analysis using markers that are polymorphic between the parental (C57BL/6 and 129) strains. Based on the results of this genome- wide scan, we will use linkage analysis to map the loci. Then, we will use a systematic approach to narrow the linkage intervals to attempt to isolate the modifier genes by positional cloning and candidate gene analysis. These studies provide the potential for identifying novel genes that have significant modifying effects on the physiology of the RAS. The combination of experimental methods that will be utilized provides an outstanding training vehicle for Dr. Le. Through the course of these studies, she should become fluent in a range of molecular genetic techniques that should provide a foundation for her career.