CLIC function in angiogenesis

描述（由申请人提供）：CLIC家族由与C相关的六种人蛋白质（1-6）组成。elegans Exc 4，这是管腔形成所必需的。我们研究了CLIC作为血管生成调节因子的作用，发现CLIC 1和CLIC 4在内皮细胞中表达，并且是培养的内皮细胞的增殖、迁移和管腔形成所需的。我们开发了具有异常视网膜血管生成的Clic 4敲除小鼠。Clic 1/Clic 4双突变胚胎在子宫内死亡，并在血管发育中有缺陷，这表明Clic 1和Clic 4在内皮中是功能冗余的。我们假设，小鼠Clic 1和Clic 4功能的发展和病理性血管生成。为了验证这一假设，我们将使用内皮特异性驱动程序（Clic 4 ECKO）删除Clic 4，在Clic 1-/-基因型的背景下，并分析胚胎，出生后视网膜和缺氧驱动的视网膜血管生成过程中的血管表型。尽管Clic基因编码假定的氯离子通道，但哺乳动物CLIC蛋白的分子作用尚不清楚。我们最近发现，鞘氨醇-1-磷酸（S1 P）驱动的内皮细胞迁移，粘附连接的形成，和肌动蛋白应力纤维的形成需要CLIC 1或CLIC 4。通过在内皮细胞中选择性地敲除CLIC，我们记录了CLIC 1和CLIC 4的重叠和不同的内皮功能，突出了CLIC的S1 P受体特异性活性。因此，我们提供了第一个证据，CLIC蛋白作为一个已知的血管生成途径，S1 P信号的一部分，我们的功能研究链接CLIC G蛋白偶联受体信号。我们建议使用体外内皮研究来探索CLIC和S1 P通路之间的分子相互作用。我们将确定内皮细胞是否需要CLIC 1或CLIC 4来介导S1 P驱动的增殖、存活、迁移、屏障形成、胶原凝胶侵入和管腔形成。我们假设CLIC 1和CLIC 4通过PI 3 K/RAC 1和PI 3 K/Akt途径促进S1 P1信号传导。我们假设CLIC 1是S1 P激活S1 P2-RhoA/ROCK通路所必需的，而CLIC 4是S1 P激活S1 P1- RAS/ERK通路所必需的。我们将评估CLIC与S1 P受体或其下游细胞内信号传导组分的结合。S1 P1在视网膜的萌芽血管生成过程中起作用。内皮细胞特异性S1 P1缺失导致视网膜出芽增加，而S1 P1功能获得性降低出芽。通过激活或失活小鼠S1 P1信号，使用药理学和遗传学方法，沿着Clic 4或Clic 1-/-小鼠的内皮损失，我们将解决S1 P信号需要内皮CLIC来调节血管生成发芽的假设。

DESCRIPTION (provided by applicant): The CLIC family consists of six human proteins (1-6) related to C. elegans Exc4, which is essential for lumen formation. We investigated the roles of CLICs as angiogenic regulators and found that CLIC1 and CLIC4 are expressed in endothelial cells and are required for proliferation, migration and lumen formation of cultured endothelial cells. We developed Clic4 knockout mice that had aberrant retinal angiogenesis. Clic1/Clic4 double mutant embryos die in utero and have defects in vascular development, suggesting Clic1 and Clic4 are functionally redundant in the endothelium. We hypothesize that murine Clic1 and Clic4 function in developmental and pathological angiogenesis. To test this hypothesis, we will delete Clic4 using endothelial specific drivers (Clic4ECKO), in the background of the Clic1-/- genotype and analyze vascular phenotypes in the embryo, postnatal retina and during hypoxia-driven retinal angiogenesis. Although Clic genes encode putative chloride channels, the molecular action of mammalian CLIC proteins is poorly defined. We recently discovered that sphingosine-1-phosphate (S1P)-driven endothelial cell migration, adhesion junction formation, and actin stress fiber formation requires CLIC1 or CLIC4. By selective CLIC knockdowns in endothelial cells, we document both overlapping and distinct endothelial functions for CLIC1 and CLIC4, highlighting S1P receptor specific activities for CLICs. Thus, we provide the first evidence that CLIC proteins function as part of a known angiogenic pathway, S1P signaling, and our functional studies link CLICs to G protein coupled receptor signaling. We propose to use in vitro endothelial studies to explore the molecular interactions between CLICs and the S1P pathway. We will determine whether endothelial cells require CLIC1 or CLIC4 to mediate S1P-driven proliferation, survival, migration, barrier formation, collagen gel invasion, and lumen formation. We hypothesize that CLIC1 and CLIC4 promote S1P1 signaling via the PI3K/RAC1 and PI3K/Akt pathways. We hypothesize that CLIC1 is uniquely required for S1P activation of the S1P2-RhoA/ROCK pathway, while CLIC4 is required for S1P activation of the S1P1- RAS/ERK pathway. We will assess binding of CLICs to S1P receptors or their downstream intracellular signaling components. S1P1 functions during sprouting angiogenesis of the retina. Endothelial specific S1P1 loss caused increased retinal sprouting and S1P1 gain-of-function decreased sprouting. By activating or inactivating S1P1 signaling in mice, using both pharmacologic and genetic methods, along with endothelial loss of Clic4 or Clic1-/- mice, we will address the hypothesis that S1P signaling requires endothelial CLICs to regulate angiogenic sprouting.