Blesson Chellakkan S, Chinnathambi Vijayakumar, Hankins Gary D, Yallampalli Chandra, Sathishkumar Kunju
Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX 77030.
Division of Reproductive Endocrinology Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX 77555.
Hypertension. 2015 Mar;65(3):683-690. doi: 10.1161/HYPERTENSIONAHA.114.04521. Epub 2014 Dec 8.
Prenatal exposure to excess testosterone induces hyperandrogenism in adult females and predisposes them to hypertension. We tested whether androgens induce hypertension through transcriptional regulation and signaling of protein kinase C (PKC) in the mesenteric arteries. Pregnant Sprague-Dawley rats were injected with vehicle or testosterone propionate (0.5 mg/kg per day from gestation days 15 to 19, SC) and their 6-month-old adult female offspring were examined. Plasma testosterone levels (0.84±0.04 versus 0.42±0.09 ng/mL) and blood pressures (111.6±1.3 versus 104.5±2.4 mm Hg) were significantly higher in prenatal testosterone-exposed rats compared with controls. This was accompanied with enhanced expression of PKCδ mRNA (1.5-fold) and protein (1.7-fold) in the mesenteric arteries of prenatal testosterone-exposed rats. In addition, mesenteric artery contractile responses to PKC activator, phorbol-12,13-dibutyrate, was significantly greater in prenatal testosterone-exposed rats. Treatment with androgen receptor antagonist flutamide (10 mg/kg, SC, BID for 10 days) significantly attenuated hypertension, PKCδ expression, and the exaggerated vasoconstriction in prenatal testosterone-exposed rats. In vitro exposure of testosterone to cultured mesenteric artery smooth muscle cells dose dependently upregulated PKCδ expression. Analysis of PKCδ gene revealed a putative androgen responsive element in the promoter upstream to the transcription start site and an enhancer element in intron-1. Chromatin immunoprecipitation assays showed that androgen receptors bind to these elements in response to testosterone stimulation. Furthermore, luciferase reporter assays showed that the enhancer element is highly responsive to androgens and treatment with flutamide reverses reporter activity. Our studies identified a novel androgen-mediated mechanism for the control of PKCδ expression via transcriptional regulation that controls vasoconstriction and blood pressure.
孕期暴露于过量睾酮会导致成年雌性出现高雄激素血症，并使其易患高血压。我们测试了雄激素是否通过肠系膜动脉中蛋白激酶C（PKC）的转录调控和信号传导来诱发高血压。给怀孕的斯普拉格-道利大鼠注射溶剂或丙酸睾酮（从妊娠第15天至19天，皮下注射，每天0.5 mg/kg），并对其6个月大的成年雌性后代进行检查。与对照组相比，孕期暴露于睾酮的大鼠血浆睾酮水平（0.84±0.04对0.42±0.09 ng/mL）和血压（111.6±1.3对104.5±2.4 mmHg）显著更高。这伴随着孕期暴露于睾酮的大鼠肠系膜动脉中PKCδ mRNA（1.5倍）和蛋白（1.7倍）表达增强。此外，孕期暴露于睾酮的大鼠肠系膜动脉对PKC激活剂佛波醇-12,13-二丁酸酯的收缩反应显著更大。用雄激素受体拮抗剂氟他胺（10 mg/kg，皮下注射，每日两次，共10天）治疗可显著减轻孕期暴露于睾酮的大鼠的高血压、PKCδ表达及过度的血管收缩。在体外，将睾酮暴露于培养的肠系膜动脉平滑肌细胞，剂量依赖性地上调PKCδ表达。对PKCδ基因的分析显示，在转录起始位点上游的启动子中有一个假定的雄激素反应元件，在第1内含子中有一个增强子元件。染色质免疫沉淀试验表明，雄激素受体在睾酮刺激下与这些元件结合。此外，荧光素酶报告基因试验表明，增强子元件对雄激素高度敏感，用氟他胺处理可逆转报告基因活性。我们的研究确定了一种新的雄激素介导的机制，通过转录调控来控制PKCδ表达，进而控制血管收缩和血压。
