Heparin modulates integrin function in human platelets.
Heparin modulates integrin function in human platelets.
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肝素调节人血小板中的整合素功能。
DOI：
10.1067/mva.2001.112696
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发表时间：
2001
影响因子：
4.3
通讯作者：
Suda,Y
中科院分区：
文献类型：
--
作者：
Sobel,M;Fish,WR;Toma,N;Luo,S;Bird,K;Mori,K;Kusumoto,S;Blystone,SD;Suda,Y
目的肝素可与人血小板结合，并可引起活化和聚集，但其机制尚不清楚。为了解肝素对血小板功能的影响，我们确定了肝素与血小板的结合部位，并测定了肝素对血小板整合素膜糖蛋白αIIbβ3(糖蛋白IIb/IIIa)功能的影响。用放射配基结合分析法检测肝素对纤维蛋白原与血小板结合的影响。结果交联层析和亲和层析实验证实整合素αIIbβ3为肝素结合位点。肝素的聚集是钙依赖的。低浓度的普通猪粘膜肝素(2-5U/m L)显著增加纤维蛋白原I-125与活化的血小板的结合，而高剂量则不能。肝素介导的血小板聚集可被纤维蛋白原结合的竞争性抑制剂GRGDS多肽(5 mmoL/L)完全阻断，并可被解离整合蛋白复合体的乙二胺四乙酸乙二酯(2 mmoL/L)所阻断。结论肝素在体外和体外均能与αIIbβ3整合素结合，肝素可增加纤维蛋白原与整合素的结合。肝素介导的聚集需要完整的整合素和配体，并导致Rap2易位到细胞骨架--配体结合的一个由外向内的信号。肝素可直接调节血小板整合素功能，很可能是通过直接结合和调节整合素功能。(《血管外科杂志》2001；33：587-94。)
PurposeHeparin binds to human platelets and can cause activation and aggregation, although the mechanisms are unknown. To determine how heparin alters platelet function, we identified platelet-binding sites for heparin and measured heparin's influence on the function of platelet integrin αIIbβ3(glycoprotein IIb/IIIa).MethodsPhotoaffinity cross-linking and affinity chromatography experiments were performed to identify platelet membrane proteins that bind heparin. Heparin's effect on fibrinogen binding to platelets was measured with a radioligand-binding assay. The translocation to the cytoskeleton of Rap2, a guanosine triphosphate–binding protein, was measured from platelets aggregating in response to heparin and other agonists.ResultsCross-linking and affinity chromatographic experiments positively identified the integrin αIIbβ3as a heparin-binding site. Heparin aggregation was calcium dependent. Low concentrations of unfractionated porcine mucosal heparin (2-5 U/mL) significantly increased fibrinogen I 125 binding to activated platelets, whereas higher doses did not. Heparin-mediated platelet aggregation was completely blocked by GRGDS peptide (5 mmol/L), a competitive inhibitor of fibrinogen binding, and was blocked by EDTA (2 mmol/L), which dissociates the functional integrin complex. Aggregation was associated with Rap2 translocation to the cytoskeleton, a sign of outside-in signaling.ConclusionsHeparin binds to the αIIbβ3integrin in vitro and ex vivo, and heparin increases fibrinogen binding to the integrin. Heparin-mediated aggregation requires an intact integrin and ligand and leads to Rap2 translocation to the cytoskeleton—an outside-in signal of ligand engagement. Heparin may directly modulate platelet integrin function, most likely through direct binding and modulation of integrin function. (J Vasc Surg 2001;33:587-94.)