ANGIOTENSIN II INDUCED GROWTH OF VASCULAR SMOOTH MUSCLE

该提案将验证A-II （A-II）在血管发育过程中控制平滑肌细胞（SMC）生长和分化/成熟以及调节成年动物SMC收缩质量以应对工作量增加的适应性变化方面发挥重要作用的假设。这一假设将通过解决以下三个具体目标来验证。目的1将确定A-II在发育过程中血管SMC的分化和成熟中的作用。研究将包括确定敲除血管紧张素原、血管紧张素AT2受体或AT1受体（1a和1b单独或联合）是否与血管发育过程中SMC分化标志物的表达改变、胚胎血管收缩特性的改变（与a . Somlyo）和/或SMC分化标记基因的转录有关(通过将敲除动物与一些新的SM α -肌动蛋白、SM22alpha、和SM MHC LacZ方正线之前在我们的实验室中发现)。研究还将包括对嵌合小鼠的分析，以确定缺乏AT1或AT2受体的细胞是否存在SMC分化/成熟缺陷。目的2将确定分子机制，即收缩激动剂如A-II刺激SMC分化标记基因在体内的表达。研究将包括确定同源结构域蛋白MHOX在SM α -肌动蛋白启动子的顺式元件中的作用，该启动子先前被证明是培养SMC中A-II反应性所必需的。目的3还将确定A-II刺激rRNA转录增加的机制，以及这如何有助于调节收缩质量。研究将包括：a)确定调节rRNA转录因子上游结合因子（UBF）活性的磷酸化位点；b)鉴定在器官培养的完整血管制剂中调节UBF磷酸化增加的激酶（与A. Somlyo合作）。A-II和其他收缩激动剂在血管发育过程中调节SMC生长、分化和成熟的机制，以及血管对高血压的生理和病理反应。

This proposal will test the hypothesis that A-II (A-II) plays an important role in control of smooth muscle cell (SMC) growth and differentiation/maturation during vascular development, as well as in mediating adaptive changes in the contractile mass of SMC in adult animals in response to increases in work load. This hypothesis will be tested by addressing the following three specific aims. Aim 1 will be to determine the role of A-II in differentiation and maturation of vascular SMC during development. Studies will include determining whether knockout of the angiotensinogen, the angiotensin AT2 receptor, or the AT1 receptors (1a and 1b alone and in combination) is associated with alterations in expression of SMC differentiation markers during vascular development, changes in contractile properties of embryonic blood vessels (with A. Somlyo), and/or transcription of SMC differentiation marker genes (assessed by crossing knockout animals with a number of novel SM alpha-actin, SM22alpha, and SM MHC LacZ founder lines previously characterized in our lab). Studies will also include analysis of chimeric mice to determine cells lacking AT1 or AT2 receptors show defective SMC differentiation/maturation. Aim 2 will be to determine the molecular mechanisms whereby contractile agonists such as A-II stimulate expression of SMC differentiation marker genes in vivo. Studies will include determination of the role of the homeodomain protein MHOX in cis elements of the SM alpha-actin promoter previously shown to be required for A-II responsiveness in cultured SMC. Aim 3 also will be to determine mechanisms whereby A-II stimulates increased rRNA transcription, and how this contributes to regulation of contractile mass. Studies will include: a) determining phosphorylation sites that regulate the activity of the rRNA transcription factor upstream binding factor (UBF); b) identifying kinases that regulated increased phosphorylation of UBF in intact vessel preparations in organ culture (with A. Somlyo). The mechanisms whereby A-II and other contractile agonists regulate SMC growth, differentiation, and maturation in vivo during vascular development, as well as in physiological and pathological responses of blood vessels to high blood pressure.