ANGIOTENSIN II INDUCED GROWTH OF VASCULAR SMOOTH MUSCLE

该方案将验证A-II(A-II)在血管发育过程中控制SMC的生长和分化/成熟，以及在成年动物中介导SMC收缩质量随工作负荷增加而发生适应性变化的假设。这一假设将通过解决以下三个具体目标来检验。目的1确定A-II在血管SMC发育过程中的分化和成熟中的作用。研究将包括确定血管紧张素原、血管紧张素AT2受体或AT1受体(单独和联合使用1a和1b)的敲除是否与血管发育过程中SMC分化标记物表达的变化、胚胎血管收缩特性的改变和/或SMC分化标记物基因的转录(通过将一些新的SMα-肌动蛋白、SM22pha和SM MHC LacZ创建者系与本实验室以前描述的SMα-肌动蛋白、SM22pha和SM MHC LacZ建立系杂交来评估)相关。研究还将包括对嵌合小鼠的分析，以确定缺乏AT1或AT2受体的细胞显示SMC分化/成熟有缺陷。目的2确定A-II等收缩激动剂在体内刺激SMC分化标志物基因表达的分子机制。研究将包括确定同源结构域蛋白MHOX在SMα-肌动蛋白启动子顺式元件中的作用，该顺式元件以前被证明是培养的SMC A-II反应所必需的。目标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)确定调节器官培养中完整血管标本中UBF磷酸化增加的激酶(与A.Somlyo一起)。A-II和其他收缩激动剂在体内调节血管发育过程中SMC的生长、分化和成熟的机制，以及在血管对高血压的生理和病理反应中的作用。

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.