Tyrosine Phosphatases in Endothelial Growth Control

描述（由申请人提供）：毛细血管和动脉生长失调对我们的健康有重大影响，并导致许多恶性、缺血性和炎症性疾病。确定调节血管生成血管生长的内在分子控制，有望为包括心脏病、糖尿病和癌症在内的各种疾病提供新的治疗方法。虽然以前的工作已经确定了诱导血管形成的内皮受体，很少有人知道的功能性内皮受体的“血管抑制”的信号。我们已经提出了这样的假设，即受体酪氨酸磷酸酶（RPTPs）信号内皮细胞生长停滞后，细胞-细胞接触，通过阿曲他克林接触反受体。我们已经分离出一个RPTP，CD 148（DEP-1/PTPq），并显示：1）CD 148在各种器官的发育和成熟的血管内皮中大量表达，2）CD 148在内皮间位点积聚并且其活性随着细胞密度而增加，3）CD 148纯合突变小鼠在妊娠中期因血管化失败伴内皮血管生长和内皮细胞增殖紊乱而死亡，4）抗胞外域序列的CD 148单克隆抗体具有显著的抗血管生成活性，在体内抑制培养内皮细胞增殖，阻断血管生成，5）CD 148通过胞外域相互作用（分子间缔合）和强迫的CD 148二聚化抑制细胞增殖，6）CD 148与FGF受体组成性缔合，和7）CD 148胞质结构域与PI 3激酶p85亚基和p120连环蛋白分子相互作用并使其去磷酸化。这些发现表明，CD 148在调节细胞-细胞接触后的内皮细胞生长方面具有关键作用。为了进一步确定CD 148在血管形成中的作用，本提案描述了实验方法：1）绘制负责介导分子间缔合的胞外亚结构域的图谱，并阐明其在调节CD 148活性和密度介导的内皮生长停滞中的重要性，2）定义CD t48和FGF受体p85之间的分子相互作用的生物学重要性，和p120连环蛋白在内皮生长控制中的作用; 3）确定CD 148在内皮血管形成中的作用。这些互补的努力将确定一个新的途径，通过CD 148调节内皮细胞的生长，并承诺新的策略，抗血管生成治疗。

DESCRIPTION (provided by applicant): Dysregulated capillary and arterial growth has a major impact on our health and contributes to numerous malignant, ischemic and inflammatory disorders. Definition of the intrinsic molecular controls that regulate angiogenic blood vessel growth promises novel therapeutic approaches for a variety of diseases including heart disease, diabetes and cancer. Although previous works have identified the endothelial receptors that induce vessel formation, little is known about the functional endothelial receptors that transduce "angiostatic" signals. We have advanced the hypothesis that receptor tyrosine phosphatases (RPTPs) signal endothelial growth arrest upon cell-cell contacts, through juxtacrine contact with counter-receptors. We have isolated a RPTP, CD148 (DEP-1/PTPq), from human renal microvascular endothelial cells and shown that: 1) CD148 is abundantly expressed in developing and mature vascular endothelium of various organs, 2) CD148 is accumulated at interendothelial sites and its activity increases with cell density, 3) the CD148 homozygous mutant mice die at mid-gestation due to vascularization failure accompanied by disordered endothelial vessel growth and endothelial cell proliferation, 4) a CD148 monoclonal antibody against the ectodomain sequence has a prominent anti-angiogenic activity to inhibit proliferation of culture endothelial cells and block angiogenesis in vivo, 5) CD148 interacts through the ectodomain (inter-molecular association) and forced CD148 dimerization inhibits cell proliferation, 6) CD148 constitutively associates with FGF receptor, and 7) CD148 cytoplasmic domain interacts with- and dephosphorylates the PI3 kinase p85 subunit and p120 catenin molecules. These findings suggest a pivotal role of CD148 to regulate endothelial cell growth upon cell-ceU contacts. To further define role of CD148 in blood vessel formation, the present proposal describes experimental approaches to: 1) map the extracellular subdomain responsible for mediating inter-molecular associations and elucidate its importance in regulation of CD148 activity and density-mediated endothelial growth arrest, 2) define biological importance of the molecular interaction between CDt48 and FGF receptor, p85, and p120 catenin in endothelial growth control, and 3) determine role of CD148 in endothelial vessel formation. These complementary efforts will identify a novel pathway that regulates endothelial cell growth through CD148 and promise new strategies for anti-angiogenesis therapy.