Yamazaki Yasuo, Tokunaga Yuko, Takani Koji, Morita Takashi
Department of Biochemistry, Meiji Pharmaceutical University, Tokyo, Japan.
Pathophysiol Haemost Thromb. 2005;34(4-5):197-9. doi: 10.1159/000092423.
Vascular endothelial growth factor-A165 (VEGF-A165) exhibits diverse biological effects through binding to its receptor KDR (VEGFR-2). Heparin-like molecules are known to modulate their interaction. There have been reports that VEGF-A lacking the C-terminal heparin binding region significantly reduced mitogenic activity. Recently, we found novel heparin-binding VEGFs from snake venoms, designated VEGF-Fs, which specifically recognize kinase domain containing receptor (KDR). The C-terminal heparin-binding region is almost completely absent in VEGF-Fs when compared with other heparin-binding VEGFs, despite their heparin-binding potential. In this congress, we report that the C-terminal heparin-binding region of VEGF-F specifically/preferentially interacts with the VEGF-bondable heparin/heparan sulfate, but not with those associated with bFGF or TFPI. We also present the identification of a VEGF receptor-binding protein from the venom of eastern cottonmouth (Agkistrodon piscivorus piscivorus). Sequence analysis revealed the isolated KDR-binding protein (designated KDR-bp) is identical to Lys49PLA2, an inactive PLA2 homologue with strong myoxicity. KDR-bp binds to the extracellular domain of KDR with subnanomolar affinity. The interaction between KDR-bp and KDR was blocked by VEGF-A165, and KDR-bp specifically inhibited VEGF-A165-stimulated endothelial cell proliferation, indicating KDR-bp is an antagonistic ligand for KDR. This is the first observation demonstrating that an exogenous factor antagonizes the VEGF receptor, furthermore, it is the first identification of the target molecule of the myotoxic PLA2 from viper venom.
血管内皮生长因子-A165（VEGF-A165）通过与其受体KDR（VEGFR-2）结合而表现出多种生物学效应。已知类肝素分子可调节它们之间的相互作用。有报道称，缺乏C末端肝素结合区域的VEGF-A显著降低了促有丝分裂活性。最近，我们从蛇毒中发现了新型的肝素结合VEGF，命名为VEGF-Fs，它们能特异性识别含激酶结构域的受体（KDR）。与其他肝素结合VEGF相比，VEGF-Fs的C末端肝素结合区域几乎完全缺失，尽管它们具有肝素结合潜力。在本次大会上，我们报告VEGF-F的C末端肝素结合区域特异性/优先与可结合VEGF的肝素/硫酸乙酰肝素相互作用，而不与那些与碱性成纤维细胞生长因子（bFGF）或组织因子途径抑制物（TFPI）相关的肝素相互作用。我们还展示了从东部噬鱼蝮（Agkistrodon piscivorus piscivorus）毒液中鉴定出一种VEGF受体结合蛋白。序列分析显示，分离出的KDR结合蛋白（命名为KDR-bp）与Lys49磷脂酶A2相同，Lys49磷脂酶A2是一种具有强肌毒性的无活性磷脂酶A2同源物。KDR-bp以亚纳摩尔亲和力结合KDR的细胞外结构域。VEGF-A165可阻断KDR-bp与KDR之间的相互作用，并且KDR-bp特异性抑制VEGF-A165刺激的内皮细胞增殖，表明KDR-bp是KDR的拮抗配体。这是首次观察到外源性因子拮抗VEGF受体，此外，这也是首次鉴定出蝰蛇毒中具有肌毒性的磷脂酶A2的靶分子。
