Vascular Rho-kinase Signaling in Angiotensin II hyperten

高血压中外周阻力增加可能是由于血管收缩引起的，血管收缩是由促进血管肌细胞内收缩蛋白活化的信号转导增强引起的。本研究将扩展我们对高血压小鼠血管平滑肌中RhoA/Rho激酶信号系统的理解。该研究将以工作假设为指导，即血管紧张素II诱导的高血压中血管反应性增强通过两步机制发生，以增加RhoA/Rho激酶系统的功能活性：1）在血压升高的早期阶段， 血管紧张素II刺激超氧化物的产生，导致表皮生长因子受体（EGFR）的反式激活，随后刺激RhoA/Rho-激酶引起血管收缩;以及2）在血压升高的建立阶段期间，血管紧张素II增加血浆和组织中的白细胞介素-6（IL-6），导致JAK/STAT活化和RhoA/Rho-1的组分的表达增加。激酶级联和维持血管收缩。本工作假设将通过三个具体目标进行检验：1）检验以下假设：在血管紧张素II诱导的高血压的血压升高的早期阶段，八肽通过受体的超氧化物激活来刺激RhoA/Rho激酶信号传导 表皮生长因子（EGFR）; 2）检验在血管紧张素II诱导的高血压的维持期，八肽和IL-6通过激活JAK/STAT增加RhoA/Rho-激酶信号传导途径组分的表达的假设;和3）检验RhoA/Rho-激酶信号传导增强与血管紧张素II诱导的高血压中血压本身无关的假设。通过输注血管紧张素II使小鼠高血压，并使用遥测技术测量血压。在高血压过程的起始和维持阶段期间，将杀死小鼠，分离血管并进行RhoA/Rho激酶的功能和生化分析。 JAK/STAT信号转导通路。将测量超氧阴离子和IL-6水平。用于评价信号传导途径贡献的技术包括：1）离体动脉收缩行为的等距记录和灌注肠系膜和后肢中升压活性的测量; 2）评价信号传导级联的组分的药理学干预; 3）评价血管肌细胞（受保护后肢）的压力依赖性活化;和4）蛋白质表达的测量。在补充策略中，将使用IL-6敲除小鼠来评估这一作用。 血管紧张素II信号转导中的细胞因子。我们预测，在血管肌细胞，血管紧张素II和IL-6将导致增加的活动的调节蛋白，影响收缩活动。

Increased peripheral resistance in hypertension may be caused by a vasoconstriction resulting from enhanced transduction of signals promoting contractile protein activation within the vascular myocyte. This research proposal will extend our understanding of the RhoA/Rho-kinase signaling system in vascular smooth muscle from hypertensive mice. The research will be guided by the working hypothesis that augmented vascular reactivity in angiotensin II-induced hypertension occurs by a two-step mechanism to increase the functional activity of the RhoA/Rho-kinase system: 1) during the early phase of blood pressure elevation, angiotensin II stimulates superoxide production leading to transactivation of the epidermal growth factor receptor (EGFR) and subsequent stimulation of RhoA/Rho-kinase to cause vasoconstriction; and 2) during the established phase of blood pressure elevation, angiotensin II increases interleukin-6 (IL-6) in plasma and tissue leading to JAK/STAT activation and increased expression of components of the RhoA/Rho-kinase cascade and maintained vasoconstriction. This working hypothesis will be tested by three specific aims: 1) to test the hypothesis that during the early phase of blood pressure elevation in angiotensin II-induced hypertension, the octapeptide stimulates RhoA/Rho-kinase signaling via superoxide activation of the receptor for epidermal growth factor (EGFR); 2) to test the hypothesis that during the maintained phase of angiotensin II-induced hypertension, the octapeptide and IL-6 increase expression of components of the RhoA/Rho-kinase signaling pathway via activation of JAK/STAT; and 3) to test the hypothesis that augmented RhoA/Rho-kinase signaling is not related to blood pressure per se in angiotensin II-induce hypertension. Mice will be made hypertensive by infusion of angiotensin II and blood pressure will be measured using telemetry. During the initiation and maintenance phases of the hypertensive process, the mice will be killed and blood vessels will be isolated and subjected to functional and biochemical analyses of the RhoA/Rho-kinase and JAK/STAT signal transduction pathways. Superoxide anion and IL-6 levels will be measured. The techniques used to evaluate the contribution of the signaling pathways include: 1) isometric recording of contractile behavior of isolated arteries and measures of pressor activity in perfused mesentery and hindquarters; 2) pharmacological interventions to evaluate components of the signaling cascades; 3) evaluation of pressure-dependent activation of vascular myocytes (protected hindlimb); and 4) measures of protein expression. In a complementary strategy, IL-6 knock-out mice will be used to evaluate the role of this cytokine in the transduction of the angiotensin II signal. We predict that, in vascular myocytes, angiotensin II and IL-6 will lead to an increased activity of regulatory proteins that influence contractile activity.