Caveolin-1, Caveolae and Placental Angiogenesis

描述（由申请人提供）：总体假设是cavo -1 （cavo -1）直接和/或间接与血管内皮生长因子受体（VEGFR）相互作用，集中VEGFR启动的信号事件，即Ras-Raf-MEK1-ERK2/1和PI3K/Akt信号模块，在内皮细胞（EC）的小泡中，从而调节VEGF对EC增殖、迁移和分化的调节。此外，cav-1/caveolae可能通过改变EC中一氧化氮（NO）的生物利用度来调节胎盘血管生成。为了验证这一假设，我们将使用羊胎胎盘动脉EC模型和人胎盘毛细血管内皮细胞系。特异性目的1：进一步阐明体外和体内VEGFR（即KDR、Flt-1和NP-1）是否与cav-1存在物理关联，从而定位于小泡中，以及外源性cav-1的过表达或内源性cav-1的靶向下调是否调节配体依赖性VEGFR激活。特异性目的2：确定内源性cav-1靶向下调或外源性cav-1过表达是否会改变VEGF对细胞周期进入、增殖、迁移和分化的刺激。特异性目的3：确定VEGF是否激活小泡中的Ras/Raf/ERK2/1和PI3K/Akt信号模块。特异性目的4：阐明下调cav-1或cav-1过表达是否调节VEGF刺激MAPK和PI3K/Akt信号通路，以及这些通路在VEGF诱导的细胞周期进入、细胞增殖、迁移和分化中的作用。特异性目的5：确定内源性cav-1的靶向下调或外源性cav-1的过表达是否会改变eNOS活性，从而改变NO的生物利用度，从而调节胎盘血管生成。这些研究将对我们对小泡、VEGF/VEGFR、内皮和血管生成生物学的理解产生重大影响，这些都是生物学上重要的领域，我们首次将其纳入胎盘血管生成和血管舒张的临床相关提案中。考虑到子宫胎盘内皮细胞对妊娠的适应，尤其是胎胎盘和子宫胎盘灌注的增加，与胎儿生长和存活能力直接相关，而这些机制在病理性妊娠（如先兆子痫和IUGR）中功能失调，本研究的最终临床重要性是显而易见的。

DESCRIPTION (provided by applicant): The overall hypothesis is that caveolin-1 (cav-1) interacts with vascular endothelial growth factor (VEGF) receptors (VEGFR) directly and/or indirectly to concentrate VEGFR initiated signaling events, i.e., Ras-Raf-MEK1-ERK2/1 and PI3K/Akt signaling modules, in the caveolae of endothelial cells (EC), thereby modulating VEGF regulation of EC proliferation, migration, and differentiation. Moreover, cav-1/caveolae may regulate placental angiogenesis by modifying the bioavailability of nitric oxide (NO) in EC. To address this hypothesis, an ovine fetoplacental artery EC model and a human placental capillary endothelial cell line will be used. Specific Aim 1: To further clarify if VEGFRs (i.e., KDR, Flt-1, and NP-1) are physically associated with cav-1 in vitro and in vivo, thus localized in the caveolae, and if overexpression of exogenous cav-1 or targeted down-regulation of endogenous cav-1 regulates ligand-dependent VEGFR activation. Specific Aim 2: To determine if targeted down-regulation of endogenous cav-1 or overexpression of exogenous cav-1 alters VEGF stimulation of cell cycle entry, proliferation, migration and differentiation. Specific Aim 3: To determine if VEGF activates the Ras/Raf/ERK2/1 and PI3K/Akt signaling modules in the caveolae. Specific Aim 4: To delineate if down-regulation of cav-1 or cav-1 overexpression modulates VEGF stimulation of MAPK and PI3K/Akt signaling pathways and the role of these pathways in VEGF-induced cell cycle entry, cell proliferation, migration, and differentiation. Specific Aim 5: To determine if targeted down-regulation of endogenous cav-1 or overexpresison of exogenous cav-1 alters eNOS activity thereby altering the bioavaibility Iof NO, which in turn regulates placental angiogenesis. These studies will have a great impact on our understanding of caveoli, VEGF/VEGFR, endothelial, and angiogenesis biology, all are biologically important fields we have integrated in the proposal clinically relevant to placental angiogenesis and vasodilatation for the first time. The ultimate clinical importance of this research is evident when one considers that uteroplacental endothelial adaptations to pregnancy, especially the rises in fetoplacental and uteroplacental perfusion, are linked directly to fetal growth and survivability and that these mechanisms are dysfunctional in pathologic pregnancies such as preeclampsia and IUGR.