Structural and biophysical characterization of Tie receptor/integrin interactions

描述：病理性血管生成是肿瘤生长、发展和转移的重要组成部分，目前治疗方案很少。尽管在过去的几十年里，人们已经了解了很多关于血管生成的知识，但仍然不清楚完整的膜受体是如何相互协作来影响细胞信号对细胞外信号的响应。在血管生成中有两个重要的受体家族，连接和整合素，它们通过由外向内和整合素对细胞外环境做出反应，对于整合素来说，是由内向外的信号。最近有报道，内皮细胞特异性酪氨酸激酶受体Tie2与两种内皮整合素异二聚体5和3形成复合体，为细胞外刺激的整合提供了方便的澄清。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，并且结合严格地通过细胞外域发生。为了阐明这些相互作用的生物学作用，将使用包括免疫共沉淀、共聚焦显微镜和FRET在内的生化和生物物理方法来跟踪Tie2配体Angiopoietin-1和-2以及整合素配体FN和Vitronectin对受体/整合素的影响。此外，通过X射线结晶学或低温电子显微镜对整合素/TiE复合体进行结构测定，将为生长因子受体-整合素信号转导奠定基础。

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.