Regulation of NADPH Oxidase by Angiotensin II-Role in Myometrial Hypertrophy

描述（由申请人提供）：子宫肥大是妊娠期为适应胎儿生长和分娩时需要收缩而发生的生理过程。已知生长因子、性激素和细胞因子在正常妊娠或纤维化期间刺激子宫平滑肌生长。血管紧张素II是一种有据可查的血管平滑肌生长因子。然而，血管紧张素II在子宫生长中的作用尚不明确，尽管其浓度增加，并且妊娠妇女子宫肌层受体亚型向1型血管紧张素II受体显著转换。NADPH氧化酶异构体通过产生活性氧，已被证明对血管平滑肌和心肌细胞中由1型受体介导的血管紧张素II的生长促进作用负责。我们已经在人子宫肌层和人子宫平滑肌细胞系中鉴定了几种NADPH氧化酶同工型。我们还发现NADPH氧化酶抑制剂阻断了血管紧张素诱导的活性氧的产生以及子宫平滑肌蛋白的合成。因此，我们假设血管紧张素II通过激活NADPH氧化酶在妊娠期子宫肌瘤生长中起重要作用，而NADPH氧化酶依赖于1型血管紧张素II受体和下游信号通路。我们进一步假设NADPH氧化酶被定位并激活在小泡中，小泡是一种质膜结构，在那里发现了几种被提出的信号转导途径的元素。这些包括血管紧张素II型1受体，NADPH氧化酶异构体1 （Nox1）的催化单元，G蛋白和表皮生长因子受体。我们将采用分子生物学、细胞生物学和生物化学相结合的方法，在子宫平滑肌细胞系中研究以下具体目标：1)血管紧张素II在调节子宫平滑肌细胞中NADPH氧化酶的表达和激活中的作用；2) NADPH氧化酶在血管紧张素II受体介导的肌层生长（肥大）和信号传导中的作用。目前有很大的兴趣在活性氧的作用在产科病理。众所周知，许多早产病例与细胞因子诱导活性氧产生的感染有关。活性氧的过量产生会导致收缩衰竭、僵硬和钙超载。因此，我们预测血管紧张素II-NADPH氧化酶-活性氧途径在分娩过程中也起作用。

DESCRIPTION (provided by applicant): Uterine hypertrophy is a physiological process occurring in pregnancy to accommodate fetal growth and the need for contraction at delivery. Growth factors, sex hormones and cytokines are known to stimulate uterine smooth muscle growth during normal pregnancy or fibrosis. Angiotensin II is a well documented vascular smooth muscle growth factor. However, the role of angiotensin II in uterine growth is not well defined, despite the fact that its concentration is increased and there is a significant switch in myometrial receptor subtype towards the type 1 angiotensin II receptor in pregnant women. NADPH oxidase isoforms, via generation of reactive oxygen species, have been shown to be responsible for the growth promoting effect of angiotensin II which is mediated by type 1 receptor in vascular smooth muscle and cardiac myocytes. We have identified several NADPH oxidase isoforms in human myometrium and in a human uterine smooth muscle cell line. We also found that a NADPH oxidase inhibitor blocked angiotensin ll-induced production of reactive oxygen species as well as uterine smooth muscle protein synthesis. Therefore, we hypothesize that angiotensin II plays an important role in myometrial growth during pregnancy via activation of NADPH oxidase, which is dependent on the type 1 angiotensin II receptor and downstream signaling pathways. We further hypothesize that NADPH oxidase is localized and activated in caveolae, the plasma membrane structures where several elements of a proposed signal transduction pathway were found. These include angiotensin II type 1 receptor, the catalytic unit of NADPH oxidase isoform 1 (Nox1), G proteins, and epidermal growth factor receptor. We will employ a combination of molecular biology, cell biology, and biochemical methods to study, in the uterine smooth muscle cell line, the following specific aims: 1) The role of angiotensin II in regulation of NADPH oxidase expression and activation in myometrial smooth muscle cells; and 2) The role of NADPH oxidase in angiotensin II receptor-mediated myometrial growth (hypertrophy) and signaling. Currently there is a great deal of interest in the role of reactive oxygen species in obstetric pathologies. It is known that many cases of preterm delivery are associated with infection where cytokines induce reactive oxygen species production. Excessive generation of reactive oxygen species contributes to contractile failure, rigor and calcium overload. Thus we predict that the angiotensin II-NADPH oxidase-reactive oxygen species pathway plays a role in labor process as well.