Genetic Determinants of Vasorelaxation to beta-Agonist

描述（由申请人提供）： 对β受体激动剂的钝性血管舒张反应与高血压的发病机制有关。 血管扩张反应也因种族而异，遗传基础尚不清楚。 该提案的总体目标是确定血管扩张剂对β受体激动剂反应变异性的遗传变异。 在具体目标1中，我们将检验以下假设：高血压中对β-激动剂的静脉舒张反应缺陷与一氧化氮引起的内皮介导的静脉舒张减少相关，以及编码β-激动剂如β-肾上腺素能受体（例如，β 2-AR）和受体后信号传导（例如，鸟嘌呤核苷酸结合（G）蛋白Gs α和G蛋白偶联受体激酶BARK），合成β-激动剂肾上腺素的酶（例如，苯乙醇胺N-甲基转移酶，PNMT）和β-激动剂效应物（例如，内皮一氧化氮合成，eNOS）是对β-激动剂的静脉舒张反应的基础并预测其。 单核苷酸多态性（SNP）将通过对候选基因座进行重新测序和基因分型来确定。将根据SNP和/或单倍型（给定染色体上的SNP阵列）在血压正常者和高血压者之间比较对β-激动剂异丙肾上腺素（ISO）的局部手静脉反应。 迄今为止的初步数据表明，高血压患者的静脉舒张反应受损，并与内皮NO产生功能障碍有关，并发现β 2-AR单倍型和PNMT启动子区域的常见SNP（-353G/A）与血压调节相关。 在具体目标2中，我们将检验以下假设：β 2-AR的等位基因变异是淋巴细胞对β激动剂反应的基础，以及与对ISO的静脉扩张反应相关的等位基因变异影响离体和体外基因功能。 将分离淋巴细胞，并测定其对ISO的反应（例如，密度、敏感性和脱敏）将根据个体β 2-AR SNP（例如，Arg 16 Gly和G1 n27 G1 u）和/或单倍型。 我们将关联显著的等位基因变体（例如，在PNMT启动子处的-353 G/A）与用于体内基因功能的生物标志物（例如PNMT酶活性和血浆肾上腺素水平）进行比较，并且将分离或产生这些遗传变体，然后评估它们对培养细胞中的蛋白质表达和功能的影响。 本研究应确定不仅导致高血压发生而且导致β受体激动剂和β受体拮抗剂药效学个体间差异的遗传因素。

DESCRIPTION (provided by applicant): Blunted vasodilator responses to beta agonist have been implicated in the pathogenesis of hypertension. The vasodilator responses also vary by race, and the genetic basis is not clear. The overall goal of this proposal is to determine genetic variants that underlie the variability in vasodilator response to beta-agonists. In Specific Aim 1, we will test the hypotheses that defective venodilatory response to beta-agonists in hypertension is associated with reduced endothelium-mediated venodilation by nitric oxide, and that allelic variants at gene loci encoding the targets of beta-agonists such as beta-adrenergic receptors (e.g., beta2-AR) and post-receptor signaling (e.g., guanine-nucleotide-binding (G) protein Gs alpha and G-protein-coupled receptor kinases BARK), the enzymes for the synthesis of the beta-agonist epinephrine (e.g., Phenylethanolamine N-methyltransferase, PNMT), and of the beta-agonist effector (e.g., endothelial nitric oxide synthesis, eNOS) underlie and predict the venodilatory response to beta-agonists. Single nucleotide polymorphisms (SNPs) will be determined by resequencing and genotyping the candidate gene loci. The local hand venous response to beta-agonist isoproterenol (ISO) will be compared between normotensives and hypertensives and according to SNPs and/or haplotypes (the array of SNPs at a given chromosome). The preliminary data to date demonstrated that the venodilatory response in hypertension was impaired and related to dysfunction in endothelial NO production, and found that Beta2-AR haplotypes and a common SNP at PNMT promoter region (-353G/A) were associated with blood pressure regulation. In Specific Aim 2, we will test the hypotheses that allelic variants at beta2-AR underlie the lymphocyte response to beta-agonists, and that allelic variant associated with venodilatory response to ISO affect gene function ex vivo and in vitro. Lymphocytes will be isolated and their responses to ISO (e.g., density, sensitivity, and desensitization) will be measured according to individual Beta2-AR SNPs (e.g., Arg16GIy and G1n27G1u) and/or haplotypes. We will correlate the significant allelic variants (e.g., -353 G/A at PNMT promoter) with the biomarkers for the function of genes in vivo such as PNMT enzymatic activity and plasma epinephrine levels, and will isolate or generate these genetic variants and then assess their impact on protein expression and function in cultured cells. This study should define the genetic factors that contribute not only to the development of hypertension but also to the inter-individual variations in pharmacodynamics for both beta-agonists and beta-antagonists.