Structural and biophysical characterization of Tie receptor/integrin interactions

病理性血管生成是肿瘤生长、发展和转移的重要组成部分，目前很少有治疗选择。尽管在过去的几十年里，人们对血管生成已经有了大量的了解，但人们仍然不清楚完整的膜受体如何相互合作，以响应细胞外信号来影响细胞信号。血管生成中的两个重要受体家族，Ties和整合素，通过由外向内和由内向外的信号传导对细胞外环境作出反应。最近，有报道称内皮特异性酪氨酸激酶受体Tie2与两种内皮整合素异源二聚体- 5 - 1和- v - 3形成复合物，为细胞外刺激的整合提供了方便的解释。然而，我们的初步研究表明，整合素与细胞膜上的Tie1和Tie2结合，并且这种结合严格地通过细胞外结构域发生。为了阐明这些相互作用的生物学作用，将使用包括共免疫沉淀、共聚焦显微镜和FRET在内的生化和生物物理方法来跟踪受体/整合素结合对Tie2配体血管生成素-1和-2以及整合素配体纤维连接蛋白和玻璃体连接蛋白的反应。此外，通过x射线晶体学或冷冻电子显微镜对整合素/Tie复合物进行结构测定，将确定生长因子受体-整合素信号转导的基础。

DESCRIPTION: Pathological angiogenesis is an essential component of tumor growth, development, and metastasis for which few therapeutic options exist. Although a great deal about angiogenesis has been learned over the past several decades, it remains unclear how integral membrane receptors cooperate with one another to influence cellular signaling in response to extracellular cues. Two important families of receptors in angiogenesis, the Ties and Integrins, respond to the extracellular environment via outside-in and, in the case of Integrins, inside- out signaling. Recently, it was reported that the endothelial specific tyrosine kinase receptor, Tie2, forms complexes with two of the endothelial Integrins heterodimers, �5�1 and �v�3, providing a convenient clarification for the integration of extracellular stimuli. However, our preliminary studies suggest that Integrins bind to both Tie1 and Tie2 on the cellular membrane, and that binding occurs strictly through the extracellular domains. To elucidate the biological role of these interactions, biochemical and biophysical methods including co-immunoprecipitation, confocal microscopy, and FRET will be used to follow receptor/Integrin association in response to the Tie2 ligands Angiopoietin-1 and -2 as well as the Integrin ligands fibronectin, and vitronectin. Furthermore, structural determination either through x-ray crystallography or cryo-electron microscopy of an Integrin/Tie complex will identify the basis for growth factor receptor-integrin signal transduction.