TYROSINE PHOSPHATASES IN ENDOTHELIAL GROWTH CONTROL

定义调节血管生成和血管生成血管生长的内在分子控制有望为实体瘤、糖尿病视网膜病变、关节炎、皮肤和其他疾病的治疗提供靶点。发育组装、重塑和维持微血管完整性是由内皮细胞对局部环境信号的反应调节的动态过程，通过表面受体传导。成熟血管内皮的基本特性之一是细胞环境对增殖的依赖性约束。我们提出了内皮受体酪氨酸磷酸酶ECRTP/CD148在与反受体近距离接触时转导细胞生长停滞信号的假设。一种单克隆抗体ECRTP。ab1特异性结合ECRTP/CD148外结构域序列，将其表达定位于肾脏和其他组织的动脉和毛细血管内皮。内皮祖细胞在与发育中的肾小球毛细血管结合之前表达ECRTP/CD148，并且ECRTP/CD148在内皮间接触点积累。ECRTP的二价形式。在小鼠角膜实验中，Ab1阻断培养内皮细胞的增殖和迁移，抑制血管生成，促进细胞内酪氨酸磷酸化。缺陷细胞系中ECRTP/CD148的表达赋予抗体诱导的生长抑制，这种抑制依赖于内在的酪氨酸磷酸酶活性。目前的提案描述了以下计划：1)定义CD148的功能性拮抗受体，2)鉴定ECRTP/CD148的细胞内底物及其在内皮生长阻滞中的作用，以及3)定义ECRTP/CD148在血管发育中的功能。同源重组ES系和小鼠将确定ECRTP/CD148在发育性血管组装中的功能。这些研究将扩展血管生成分子调控的定义，并将为抗血管生成治疗确定新的分子靶点。

Definition of the intrinsic molecular controls that regulate angiogenic and vasculogenic blood vessel growth promises to provide targets for therapy of solid tumors, diabetic retinopathy, arthritis, skin and other diseases. Developmental assembly, remodeling and maintenance of microvascular integrity are dynamic processes regulated by endothelial responses to local environmental cues, transduced through surface receptors. One of the properties fundamental to endothelium in mature vessels is cell context dependent constraints over proliferation. We have advanced the hypothesis that an endothelial receptor tyrosine phosphatase, ECRTP/CD148, transduces cell growth arrest signals on juxtacrine contact with a counter-receptor. A monoclonal antibody, ECRTP.ab1, that specifically binds ECRTP/CD148 ectodomain sequences localizes its expression to endothelium of arteries and capillaries in kidney, and other tissues. Endothelial progenitor cells express ECRTP/CD148 prior to their incorporation into developing glomerular capillaries of kidney, and ECRTP/CD148 accumulates at inter-endothelial points of contact. Bivalent forms of ECRTP.ab1 block cultured endothelial cell proliferation and migration, inhibit angiogenesis in a mouse corneal assay, and promote dephosphorylation of intracellular tyrosine phosphoproteins. Expression of ECRTP/CD148 in deficient cell lines confers antibody-induced growth inhibition that is dependent upon intrinsic tyrosine phosphatase activity. The current proposal describes plans to: 1) define a functional counter-receptor to CD148, 2) to identify intracellular substrates of ECRTP/CD148 and their role in endothelial growth arrest, and 3) to define ECRTP/CD148 function during vascular development. Homologous recombinant ES lines and mice will define function of ECRTP/CD148 in developmental vascular assembly. These studies will extend definition of molecular controls regulating angiogenesis, and will define new molecular targets for anti-angiogenic therapies.