Department of Medicine, UCSD, San Deigo, CA, USA.
J Hypertens. 2012 Oct;30(10):1961-9. doi: 10.1097/HJH.0b013e328356b86a.
Cathepsin L (CTSL1) catalyzes the formation of peptides that influence blood pressure (BP). Naturally occurring genetic variation or targeted ablation of the Ctsl1 locus in mice yield cardiovascular pathology. Here, we searched for genetic variation across the human CTSL1 locus and probed its functional effects, especially in the proximal promoter.
Systematic polymorphism discovery by re-sequencing across CTSL1 in 81 patients uncovered 38 genetic variants, five of which were relatively common (MAF >5%), creating a single linkage disequilibrium block in multiple biogeographic ancestries. One of these five common variants lay in a functional domain of the gene: promoter C-171A (rs3118869), which disrupts a predicted xenobiotic response element (XRE; match C>A). In transfected CTSL1 promoter/luciferase reporter plasmids, C-171A allele influenced transcription (C>A, P = 3.36E-6), and transcription was also augmented by co-exposure to the aryl hydrocarbon receptor (AHR) complex (AHR:ARNT) in the presence of their ligand dioxin (P = 6.81E-8); allele (C vs. A) and AHR:ARNT/dioxin stimulus interacted to control gene expression (interaction P = 0.033). Endogenous Ctsl1, Ahr, and Arnt transcripts were present in chromaffin cells. Promoter functional C-171A genotype also predicted hypertension (P = 1.0E-3), SBP (P = 4.0E-4), and DBP (P = 3.0E-3), in an additive pattern for diploid genotypes (A/A > C/A > C/C) in 868 patients, and the results were extended by validation analysis into an independent population sample of 986 patients.
We conclude that common genetic variation in the proximal CTSL1 promoter, especially at position C-171A, is functional in cells, and alters transcription so as to explain the association of CTSL1 with BP in vivo. At the XRE, endogenous genetic variation plus exogenous aryl hydrocarbon stimulation interact to control CTSL1 gene expression. These results unveil a novel control point whereby heredity and environment can intersect to control a complex trait, and point to new transcriptional strategies for intervention into transmitter biosynthesis and its cardiovascular consequences.
组织蛋白酶 L (CTSL1) 催化形成影响血压 (BP) 的肽。在小鼠中，天然存在的遗传变异或靶向敲除 Ctsl1 基因座会导致心血管病理学。在这里，我们在人类 CTSL1 基因座上搜索遗传变异，并研究其功能影响，特别是在近端启动子。
通过对 81 名患者的 CTSL1 进行重新测序，系统地发现了 38 种遗传变异，其中 5 种是相对常见的（MAF>5%），在多种生物地理祖先中形成了一个单一的连锁不平衡块。这 5 种常见变异中的一种位于基因的功能域：启动子 C-171A（rs3118869），它破坏了一个预测的外源性反应元件 (XRE; 匹配 C>A)。在转染的 CTSL1 启动子/荧光素酶报告质粒中，C-171A 等位基因影响转录（C>A，P=3.36E-6），并且在存在其配体二恶英时，AHR 复合物（AHR:ARNT）也增强转录（P=6.81E-8）；等位基因（C 对 A）和 AHR:ARNT/二恶英刺激相互作用以控制基因表达（相互作用 P=0.033）。在嗜铬细胞中存在内源性 Ctsl1、Ahr 和 Arnt 转录本。启动子功能 C-171A 基因型也预测了 868 名患者的高血压（P=1.0E-3）、SBP（P=4.0E-4）和 DBP（P=3.0E-3），在二倍体基因型中呈加性模式（A/A>C/A>C/C），并且通过对 986 名患者的独立样本的验证分析扩展了结果。
我们的结论是，近端 CTSL1 启动子的常见遗传变异，特别是在位置 C-171A，在细胞中是功能性的，并且改变转录，从而解释 CTSL1 与体内 BP 的关联。在 XRE 处，内源性遗传变异加上外源性芳烃烃刺激相互作用以控制 CTSL1 基因表达。这些结果揭示了一个新的控制点，遗传和环境可以在这里相互作用以控制复杂性状，并为干预递质生物合成及其心血管后果的新转录策略指明了方向。
