Litjens P E M H, Van Willigen G, Weeterings C, Ijsseldijk M J W, Van Lier M, Koivunen E, Gahmberg C G, Akkerman J W N
Laboratory for Thrombosis and Haemostasis, Department of Haematology, UMCU, and Institute for Biomembranes, Utrecht University, Utrecht, The Netherlands.
J Thromb Haemost. 2005 Jun;3(6):1274-83. doi: 10.1111/j.1538-7836.2005.01408.x.
RGD is a major recognition sequence for ligands of platelet alpha(IIb)beta3.
To identify potential binding sites for alpha(IIb)beta3 apart from RGD, we screened phage display libraries by blocking the enrichment of RGD-containing phages with a GRGDS peptide and identified a novel integrin recognition tripeptide sequence, VPW.
Platelets adhered to an immobilized cyclic VPW containing peptide in a alpha(IIb)beta3-dependent manner; platelets and alpha(IIb)beta3-expressing CHO cells adhered faster to immobilized alpha(IIb)beta3-ligands in the presence of soluble VPW. In platelets adhering to fibrinogen, VPW accelerated the activation of the tyrosine kinase Syk which controls cytoskeletal rearrangements. In alpha(IIb)beta3-expressing CHO cells, VPW induced a faster formation of stress fibers. Sequence alignment positioned VPW to V980-P981-W982 in the von Willebrand factor (vWf) A-3 domain. In blood from a vWf-deficient individual, VPW increased platelet adhesion to fibrinogen but not to collagen under flow and rescued the impaired adhesion to vWf deficient in A-3.
These data reveal a VPW sequence that contributes to alpha(IIb)beta3 activation in in vitro experiments. Whether the V980-P981-W982 sequence in vWf shows similar properties under in vivo conditions remains to be established.
RGD是血小板α（IIb）β3配体的主要识别序列。
为了识别除RGD之外的α（IIb）β3潜在结合位点，我们用GRGDS肽阻断含RGD噬菌体的富集，从而筛选噬菌体展示文库，并鉴定出一种新的整合素识别三肽序列VPW。
血小板以α（IIb）β3依赖的方式黏附于固定化的含环VPW肽；在可溶性VPW存在的情况下，血小板和表达α（IIb）β3的CHO细胞能更快地黏附于固定化的α（IIb）β3配体。在黏附于纤维蛋白原的血小板中，VPW加速了控制细胞骨架重排的酪氨酸激酶Syk的激活。在表达α（IIb）β3的CHO细胞中，VPW诱导应力纤维更快形成。序列比对将VPW定位到血管性血友病因子（vWf）A-3结构域中的V980 - P981 - W982处。在一名vWf缺陷个体的血液中，VPW增加了血小板在流动状态下对纤维蛋白原的黏附，但未增加对胶原蛋白的黏附，并挽救了对A-3缺陷的vWf的黏附受损情况。
这些数据揭示了一个在体外实验中有助于α（IIb）β3激活的VPW序列。vWf中的V980 - P981 - W982序列在体内条件下是否具有相似特性仍有待确定。
