VRAC and Rho in pulmonary EC proliferation

描述（由申请人提供）： 肺内皮细胞（EC）的增殖是肺正常发育所必需的，并且参与了使晚期肺动脉高压复杂化的血管闭塞性丛状病变的发病机制。离子通道在调节肺EC细胞周期中的作用尚未完全阐明。最近，体积调节阴离子通道（VRAC）已涉及调节血管生成。这些通道通常与细胞肿胀（Icswell）激活的电流相关。我们提供的证据表明，EC丝裂原VEGF激活VRAC，肿胀和VEGF激活不同的信号通路，阻断VRAC完全抑制人肺微血管EC（HPMVEC）的增殖。基于这些信息，我们假设：VRAC的激活是肺内皮细胞促有丝分裂刺激的关键步骤，内皮细胞肿胀或促有丝分裂剂激活的不同信号通路导致基因激活的模式，急性和慢性缺氧分别利用与细胞肿胀和促有丝分裂剂相似的信号通路激活VRAC和基因表达。 我们提出了三个具体的目标：1）在人PMVEC中测试假设，即虽然有丝分裂原和细胞肿胀都激活VRAC，但不同的上游信号通路将刺激与通道激活联系起来。 2)检验有丝分裂原和细胞肿胀激活依赖于VRAC激活和与VRAC激活相关的不同信号通路的独特基因表达模式的假设。 3)检验急性和慢性缺氧分别通过类似于细胞肿胀和有丝分裂原的机制起作用的假设。 在我们的研究完成后，我们预期有更充分的定义VRAC和相关的信号通路在调节肺内皮细胞增殖的作用，我们预期的工作将提供重要的线索，肺血管疾病的发病机制。

DESCRIPTION (provided by applicant): Proliferation of pulmonary endothelial cells (EC) is required for normal lung development and is involved in the pathogenesis of the vaso-occlusive plexiform lesions that complicate advanced pulmonary hypertension. The role of ion channels in regulating pulmonary EC cell cycle has not been fully elucidated. Recently, volume-regulated anion channels (VRAC) have been implicated in modulating angiogenesis. These channels are classically associated with the current activated by cell swelling (Icswell). We provide evidence that the EC mitogen VEGF activates VRAC, swelling and VEGF activate distinct signaling pathways, and blockade of VRAC completely inhibits proliferation of human pulmonary microvascular EC (HPMVEC). Based on this information we hypothesize: Activation of VRAC is a critical step in mitogenic stimulation of pulmonary endothelial cells, Divergent signaling pathways activated by endothelial cell swelling or mitogens result in tmique patterns of gene activation and Acute and chronic hypoxia activate VRAC and gene expression utilizing similar signaling pathways to cell swelling and mitogens, respectively. We propose three specific aims: 1) Test the hypothesis in human PMVEC that while mitogens and cell swelling both activate VRAC, distinct upstream signaling pathways link the stimuli to channel activation. 2) Test the hypothesis that mitogens and cell swelling activate unique patterns of gene expression dependent both on activation of VRAC and the distinct signaling pathways associated with VRAC activation. 3) Test the hypothesis that acute and chronic hypoxia act via mechanisms similar to cell swelling and mitogens, respectively. Upon completion of our studies we anticipate having more fully defined the role of VRAC and associated signaling pathways in regulation of pulmonary endothelial cell proliferation; work we anticipate will provide important clues to the pathogenesis of pulmonary vascular disease.