Dissecting the genetics of the Metabolic Syndrome on Chromosome 17 of the LH rat

描述(申请人提供)：包括肥胖、血脂异常、胰岛素抵抗和高血压在内的一系列疾病被称为代谢综合征，是心血管疾病的主要危险因素。它的发病率继续上升，部分原因是肥胖症的流行增加。里昂高血压(L H)大鼠是一种强大的近亲交配模型，用于解剖人类代谢综合征的遗传贡献，这些综合征具有高体重、高胆固醇、高甘油三酯和高胰岛素/葡萄糖比率，以及盐敏性高血压。有趣的是，同时选自同一SD菌落的里昂正常血压(LN)对照株，在遗传上与LH型非常相似(85%)，但表型非常不同。在LN×LN杂交中定位到大鼠染色体(RNO)17上的3个数量性状基因座(QTL)和RNO17、2、13上的3个血压QTL。我们假设LH17号染色体上有影响代谢综合征所有主要性状的基因，RNO17上的QTL和RNO17、2、13之间存在QTL互作。为了鉴定这些基因中的至少一个，我们提出了一种结合传统的位置克隆，在电子作图中，以及QTL(表型和基因表达)定位，以确定导致代谢综合征的原因基因和途径。我们将：1：验证LN和LN品系中RNO17的QTL区域。黄体生成素和层粘连蛋白菌株的遗传相似性使得快速产生和鉴定出共生的黄体黄体-17LN菌株和同源亚株。这些菌株将被用来缩小QTL区域，并确定哪些表型是由于多个QTL、相互作用的QTL或一个QTL内单个基因的多效性效应造成的。2：研究反式作用单倍型和顺式作用单倍型在代谢综合征潜在特征上的相互作用。我们将在LN和LN之间进行F2杂交，以确定RNO17、2和13上的QTL与导致我们在LH中观察到的表型的调控网络之间的相互作用。将通过表型、SNP基因分型和基因表达谱结合表型(P)QTL和表达(E)QTL定位对后代进行综合研究。3.通过SNP精细定位和同源大鼠实验验证，对RNO17基因进行QTL定位。对于每个候选区域，我们将通过额外的SNP分型来精细定位单倍型，以缩小和定义最小的QTL间隔。所有的遗传变异将在这些最小的区域确定，以确定候选基因和序列变体。这些区域将在基因中得到实验验证。4：通过大鼠转基因救援法验证功能变异。对于在上述目标中发现的功能序列变异证据最强的候选，我们将开发一只转基因大鼠，将LN等位基因导入LH大鼠或将LH等位基因导入LH17LN。

DESCRIPTION (provided by applicant): The collection of maladies including obesity, dyslipidemia, insulin resistance and hypertension is referred to as the metabolic syndrome and is a major risk factor for cardiovascular disease. Its incidence continues to rise, in part as a result of the epidemic increase in obesity. The Lyon Hypertensive (LH) rat is a powerful inbred model for dissecting the genetic contributions of the human metabolic syndrome, with high body weight, cholesterol, triglycerides, and insulin/glucose ratios, and salt-sensitive hypertension. Interestingly, the Lyon normotensive (LN) control strain, concurrently selected from the same SD colony, is genetically quite similar (85%) to the LH, but phenotypically very distinct. Genetic linkage mapping in an LH x LN intercross identified 3 clusters of Quantitative Traits Loci (QTL) on rat chromosome (RNO) 17 for multiple features of the metabolic syndrome in the LH rat and 3 QTL for blood pressure on RNO17, 2, and 13. We hypothesize that the LH chromosome 17 has genes contributing to all major traits of the metabolic syndrome, and that there are QTL interactions between QTL on RNO 17 and between RNO 17, 2, and 13. To identify at least one of these genes, we propose a combined traditional positional cloning, in silico mapping, and QTL (phenotype and gene expression) mapping to identify causal genes and pathways leading to the metabolic syndrome. We will: 1: Validate the QTL regions for RNO17 in the LH and LN strains. The close genetic identity of the LH and LN strains allows for rapid generation and characterization of a consomic LH-17LN strain and congenic substrains. These strains will be used to narrow the QTL regions and to determine which phenotypes are due to multiple QTL, interacting QTL, or pleiotropic effects of a single gene within a QTL. 2: Investigate interactions between trans-acting and cis-acting haplotypes on traits underlying the metabolic syndrome. We will perform an F2 intercross between LH and LN to determine the interactions between QTL on RNO17, 2, and 13, and regulatory networks causing the phenotypes we observe in the LH. The offspring will be comprehensively studied by phenotyping, SNP genotyping, and gene expression profiling for combined phenotype (p) QTL and expression (e) QTL mapping. 3: Refine the QTL on RNO17 through SNP fine-mapping and experimental validation in congenic rats. For each candidate region, we will fine-map the haplotypes by additional SNP typing to narrow and define minimal QTL intervals. All genetic variation will be determined in these minimal regions to identify candidate genes and sequence variants. These regions will be experimentally validated in the congenics. 4: Validate functional variants through rat transgenic rescue. For the strongest candidate with evidence of functional sequence variants identified in the above aims, we will develop a transgenic rat, either introducing the LN allele into the LH rat or the LH allele into the LH-17LN.