Adhesive ligand binding to integrin alpha IIb beta 3 stimulates tyrosine phosphorylation of novel protein substrates before phosphorylation of pp125FAK.
Adhesive ligand binding to integrin alpha IIb beta 3 stimulates tyrosine phosphorylation of novel protein substrates before phosphorylation of pp125FAK.
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DOI：
10.1083/jcb.122.2.473
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发表时间：
1993-07
影响因子：
7.8
通讯作者：
Shattil, S J
中科院分区：
文献类型：
--
作者：
Huang, M M;Lipfert, L;Cunningham, M;Brugge, J S;Ginsberg, M H;Shattil, S J
多种血小板蛋白的酪氨酸磷酸化受到凝血酶和其他引起血小板聚集和分泌的激动剂的刺激。包括蛋白酪氨酸激酶pp125FAK在内的这些蛋白质的亚类的磷酸化依赖于血小板聚集，血小板聚集是在纤维蛋白原与整合素α IIb β 3结合之后发生的。在这份报告中，我们研究了是否纤维蛋白原结合，本身，触发酪氨酸磷酸化的过程中没有外源性激动剂。用抗β 3抗体（抗LIBS6）的Fab片段诱导可溶性纤维蛋白原的结合，该抗体直接暴露α IIb β 3中的纤维蛋白原结合位点。50 - 68 kD和140 kD的蛋白质以纤维蛋白原依赖的方式在酪氨酸残基上磷酸化。这种反应并不需要前列腺素的合成，增加胞浆游离钙，血小板聚集或颗粒分泌，也不与酪氨酸磷酸化的pp125FAK。当（a）用激动剂如肾上腺素、ADP或凝血酶而不是抗LIBS6刺激纤维蛋白原结合;（B）片段X，纤维蛋白原的二聚体纤溶酶衍生片段代替纤维蛋白原;或（c）α II B β 3复合物被抗体交联时，也观察到50 - 68-kD和140-kD蛋白的酪氨酸磷酸化，即使在不存在纤维蛋白原的情况下。相反，当配体由来源于纤维蛋白原的单体细胞识别肽（RGDS或γ 400 - 411）组成时，没有观察到酪氨酸磷酸化。纤维蛋白原依赖的酪氨酸磷酸化被细胞松弛素D抑制。这些研究表明，纤维蛋白原与α IIb β 3的结合启动了一个酪氨酸磷酸化过程，该过程先于血小板聚集和pp125FAK的磷酸化。这种反应可能取决于整合素受体的寡聚化和肌动蛋白聚合的状态，组织过程可能使酪氨酸激酶与其底物并置。
Tyrosine phosphorylation of multiple platelet proteins is stimulated by thrombin and other agonists that cause platelet aggregation and secretion. The phosphorylation of a subset of these proteins, including a protein tyrosine kinase, pp125FAK, is dependent on the platelet aggregation that follows fibrinogen binding to integrin alpha IIb beta 3. In this report, we examined whether fibrinogen binding, per se, triggers a process of tyrosine phosphorylation in the absence of exogenous agonists. Binding of soluble fibrinogen was induced with Fab fragments of an anti-beta 3 antibody (anti-LIBS6) that directly exposes the fibrinogen binding site in alpha IIb beta3. Proteins of 50-68 KD and 140 kD became phosphorylated on tyrosine residues in a fibrinogen- dependent manner. This response did not require prostaglandin synthesis, an increase in cytosolic free calcium, platelet aggregation or granule secretion, nor was it associated with tyrosine phosphorylation of pp125FAK. Tyrosine phosphorylation of the 50-68-kD and 140-kD proteins was also observed when (a) fibrinogen binding was stimulated by agonists such as epinephrine, ADP, or thrombin instead of by anti-LIBS6; (b) fragment X, a dimeric plasmin-derived fragment of fibrinogen was used instead of fibrinogen; or (c) alpha IIb beta 3 complexes were cross-linked by antibodies, even in the absence of fibrinogen. In contrast, no tyrosine phosphorylation was observed when the ligand consisted of monomeric cell recognition peptides derived from fibrinogen (RGDS or gamma 400-411). Fibrinogen-dependent tyrosine phosphorylation was inhibited by cytochalasin D. These studies demonstrate that fibrinogen binding to alpha IIb beta 3 initiates a process of tyrosine phosphorylation that precedes platelet aggregation and the phosphorylation of pp125FAK. This reaction may depend on the oligomerization of integrin receptors and on the state of actin polymerization, organizational processes that may juxtapose tyrosine kinases with their substrates.