Cardiovascular Genetics Laboratory, Department of Biotechnology, Indian Institute of Technology Madras, Chennai, India.
PLoS One. 2011 Jan 31;6(1):e16661. doi: 10.1371/journal.pone.0016661.
3-Hydroxy-3-methylglutaryl-coenzyme A [HMG-CoA] reductase gene (Hmgcr) is a susceptibility gene for essential hypertension. Sequencing of the Hmgcr locus in genetically hypertensive BPH (blood pressure high), genetically hypotensive BPL (blood pressure low) and genetically normotensive BPN (blood pressure normal) mice yielded a number of single nucleotide polymorphisms (SNPs). BPH/BPL/BPN Hmgcr promoter-luciferase reporter constructs were generated and transfected into liver HepG2, ovarian CHO, kidney HEK-293 and neuronal N2A cells for functional characterization of the promoter SNPs. The BPH-Hmgcr promoter showed significantly less activity than the BPL-Hmgcr promoter under basal as well as nicotine/cholesterol-treated conditions. This finding was consistent with lower endogenous Hmgcr expression in liver and lower plasma cholesterol in BPH mice. Transfection experiments using 5'-promoter deletion constructs (strategically made to assess the functional significance of each promoter SNP) and computational analysis predicted lower binding affinities of transcription factors c-Fos, n-Myc and Max with the BPH-promoter as compared to the BPL-promoter. Corroboratively, the BPH promoter-luciferase reporter construct co-transfected with expression plasmids of these transcription factors displayed less pronounced augmentation of luciferase activity than the BPL construct, particularly at lower amounts of transcription factor plasmids. Electrophoretic mobility shift assays also showed diminished interactions of the BPH promoter with HepG2 nuclear proteins. Taken together, this study provides mechanistic basis for the differential Hmgcr expression in these mouse models of human essential hypertension and have implications for better understanding the role of this gene in regulation of blood pressure.
3-羟-3-甲基戊二酰基辅酶 A [HMG-CoA]还原酶基因（Hmgcr）是原发性高血压的易感基因。对遗传高血压的 BPH（血压高）、遗传低血压的 BPL（血压低）和遗传正常血压的 BPN（血压正常）小鼠的 Hmgcr 基因座进行测序，发现了一些单核苷酸多态性（SNPs）。构建了 BPH/BPL/BPN Hmgcr 启动子-荧光素酶报告基因构建体，并转染到肝 HepG2、卵巢 CHO、肾 HEK-293 和神经元 N2A 细胞中，以对启动子 SNPs 进行功能表征。在基础状态和尼古丁/胆固醇处理条件下，BPH-Hmgcr 启动子的活性明显低于 BPL-Hmgcr 启动子。这一发现与 BPH 小鼠肝脏中内源性 Hmgcr 表达较低和血浆胆固醇较低相一致。使用 5'-启动子缺失构建体（策略性地评估每个启动子 SNP 的功能意义）和计算分析进行的转染实验预测，与 BPL 启动子相比，转录因子 c-Fos、n-Myc 和 Max 与 BPH 启动子的结合亲和力较低。相应地，与 BPL 构建体相比，共转染这些转录因子表达质粒的 BPH 启动子-荧光素酶报告基因构建体显示出较低的荧光素酶活性增强，尤其是在转录因子质粒量较低时。电泳迁移率变动分析也表明，BPH 启动子与 HepG2 核蛋白的相互作用减少。总之，这项研究为这些人类原发性高血压小鼠模型中 Hmgcr 表达的差异提供了机制基础，并为更好地理解该基因在血压调节中的作用提供了依据。
