Regulation of Wnt Signaling by PAP2b During Angiogenesis

血管生成过程中 PAP2b 对 Wnt 信号传导的调节

• 批准号: 7100448
• 负责人: KISHORE K WARY
• 金额: $ 31万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7100448
• 关键词: Wnt gene /protein; angiogenesis; biological signal transduction; cadherins; cell adhesion; cell cell interaction; cell growth regulation; developmental genetics; enhancer binding protein; fibronectins; genetically modified animals; glioblastoma multiforme; integrins; interleukin 8; laboratory mouse; phosphatidate phosphatase; protein protein interaction; small interfering RNA; tissue /cell culture; transcription factor; vascular endothelium

DESCRIPTION (provided by applicant): Angiogenesis, or the remodeling of preexisting quiescent blood vessel, is critical for embryonic development, wound healing, and various pathological conditions including tumor progression and atherosclerosis. We propose to study in molecular terms, the function of phosphatidic acid phosphatase 2b (PAP2b), a plasma- membrane protein that we discovered in a functional assay of angiogenesis. The PAP2b protein is expressed by endothelial cells, exhibits a cell adhesion sequence, and dephosphorylates phosphatidic acid phosphate (PAP) into diacylglycerol and phosphate, that has been implicated in signal transduction and lipid metabolism. The Pap2b gene inactivation is early embryonic lethal (die around E7.5 day) due to lack of functional vasculature. PAP2b is the first lipid phosphate phosphatase protein that is linked to the Wnt signaling pathway. We found that PAP2b is expressed by a subset of primary tumors, and over-expression of PAP2b supports tumor growth and angiogenesis. We observe that PAP2b interacts with p120catenin and promotes cell-cell-interactions, in turn, induces protein complex formation between beta-catenin and lymphoid enhancer-binding factor-1 (LEF-1), this event leads to fibronectin and IL-8 synthesis and secretion. Based upon our preliminary data, we hypothesize that during angiogenesis PAP2b plays a key role in the formation and organization of adhesion structures connecting endothelial cells. The mechanisms include the ability of PAP2b to form and organize large molecular complex, interact with a subset of integrins, and mediate synthesis of fibronectin through LEF-1 transcriptional machinery. The overall aim of this proposal is to determine the mechanism by which the PAP2b interacts with p120catenin, and mediates synthesis of fibronectin. We propose to test our hypothesis through two major specific aims: (1) Characterize the mechanism by which PAP2b interacts with p120catenin, alter LEF-transcription, and induce expression of fibronectin and IL-8, and (2) Examine the functional consequences of conditional deletion of Pap2b gene in the mice using Tie-2/Cre system. Examine the consequences of SiRNA mediated down-regulation of PAP2b using endothelial cells. We anticipate that our studies will further our understanding of the role of endothelial PAP2b in physiological and pathological angiogenesis. Together, these studies are expected to reveal a new target for anti-angiogenic molecular therapy.

描述（由申请人提供）：血管生成，或先前存在的静止血管的重塑，对胚胎发育，伤口愈合和各种病理状况（包括肿瘤进展和动脉粥样硬化）至关重要。我们建议从分子角度研究磷脂酸磷酸酶2b （PAP2b）的功能，这是我们在血管生成功能测定中发现的一种质膜蛋白。PAP2b蛋白由内皮细胞表达，表现出细胞粘附序列，并将磷酸磷脂酸（PAP）去磷酸化为二酰基甘油和磷酸盐，这与信号转导和脂质代谢有关。由于缺乏功能性脉管系统，Pap2b基因失活在胚胎早期是致命的（约在E7.5天死亡）。PAP2b是第一个与Wnt信号通路相关的脂质磷酸磷酸酶蛋白。我们发现PAP2b在原发肿瘤的一个亚群中表达，并且PAP2b的过表达支持肿瘤生长和血管生成。我们观察到PAP2b与p120catenin相互作用并促进细胞-细胞相互作用，进而诱导β -catenin与淋巴细胞增强因子结合因子-1 （LEF-1）之间形成蛋白复合物，该事件导致纤维连接蛋白和IL-8的合成和分泌。根据我们的初步数据，我们假设在血管生成过程中，PAP2b在连接内皮细胞的粘附结构的形成和组织中起关键作用。其机制包括PAP2b形成和组织大分子复合物的能力，与整合素的一个子集相互作用，以及通过LEF-1转录机制介导纤维连接蛋白的合成。本提案的总体目的是确定PAP2b与p120catenin相互作用的机制，并介导纤维连接蛋白的合成。我们提出通过两个主要的具体目标来验证我们的假设：(1)表征PAP2b与p120catenin相互作用的机制，改变lef转录，诱导纤维连接蛋白和IL-8的表达；(2)使用Tie-2/Cre系统检查小鼠条件缺失PAP2b基因的功能后果。研究SiRNA介导的内皮细胞PAP2b下调的后果。我们期望我们的研究将进一步加深我们对内皮细胞PAP2b在生理和病理血管生成中的作用的理解。总之，这些研究有望揭示抗血管生成分子治疗的新靶点。