Autocrine Mechanisms of Angiogenesis

描述（由申请人提供）：我们广泛的初步工作产生了意想不到的假设，即转化生长因子-β 1（TGF-β 1）对内皮细胞的成熟凋亡作用是由内源性血管内皮生长因子（VEGF）介导的。这一结论是基于我们的发现，TGF-β 1刺激血管内皮细胞表达VEGF和VEGF的单克隆抗体阻断TGF-β 1诱导的细胞凋亡。由于细胞凋亡是血管形成的一个重要组成部分，这种新的内皮细胞凋亡机制可能在血管生成和血管发生中发挥重要作用。因此，我们建议：1.表征内源性VEGF介导TGF-β 1对内皮细胞的凋亡活性的VEGF受体和下游信号通路。我们将研究内源性VEGF激活的信号转导通路，以响应TGF-β 1治疗，以及VEGF和TGF-β 1特异性通路之间的潜在串扰。合成抑制剂和显性失活突变体的使用将提供介导TGF-β 1凋亡信号的信号传导途径的鉴定。2.研究VEGF介导的细胞凋亡在体内外血管生成中的作用。TGF-β 1诱导细胞凋亡和血管形成。基于我们的初步工作，我们假设TGF-β 1的血管生成和血管生成活性是由VEGF介导的自分泌机制。我们建议使用血管生成和血管生成的体外和体内模型来测试我们的假设。结果将阐明血管形成是由VEGF和TGF-β 1，两个有效的血管生成诱导剂的相互作用控制的机制。详细了解VEGF和TGF-β 1相互作用的机制，对于开发旨在控制血管生成的药物治疗具有重要意义。

DESCRIPTION (provided by applicant): Our extensive preliminary work has generated the unexpected hypothesis that the well-established apoptotic effect of transforming growth factor-beta 1 (TGF-b1) on endothelial cells is mediated by endogenous vascular endothelial growth factor (VEGF). This conclusion is based on our findings that TGF-b1 stimulates endothelial cell expression of VEGF and that monoclonal antibodies to VEGF block TGF-b1-induced apoptosis. Because apoptosis is an essential component of vessel formation, this novel mechanism of endothelial cell apoptosis may have an important role in angiogenesis and vasculogenesis. We therefore propose: 1. To characterize the VEGF receptor(s) and downstream signaling pathways through which endogenous VEGF mediates the apoptotic activity of TGF-b1 on endothelial cells. We will investigate signal transduction pathways activated by endogenous VEGF in response to TGF-b1 treatment, and potential cross-talk between VEGF- and TGF-b1-specific pathways. The use of synthetic inhibitors and dominant negative mutants will afford the identification of the signaling pathway(s) that mediate TGF-b1 apoptotic signal(s). 2. To study the role of VEGF-mediated apoptosis in angiogenesis and vasculogenesis in vitro and in vivo. TGF-b1 induces both apoptosis and vessel formation. Based on our preliminary work, we hypothesize that the angiogenic and vasculogenic activities of TGF-b1 are mediated by VEGF with an autocrine mechanism. We propose to test our hypothesis using in vitro and in vivo models of angiogenesis and vasculogenesis. The results will elucidate the mechanisms through which vessel formation is controlled by the interplay of VEGF and TGF-b1, two potent angiogenesis inducers. A detailed understanding of the mechanisms through which VEGF and TGF-b1 interact can have important implications for the development of pharmacological treatments aimed at the control of angiogenesis.