GPIbα-selective activation of platelets induces platelet signaling events comparable to GPVI activation events
GPIbα-selective activation of platelets induces platelet signaling events comparable to GPVI activation events
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DOI：
10.3109/09537101003695339
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发表时间：
2010-01-01
期刊：
影响因子：
3.3
通讯作者：
Berndt, Michael C.
中科院分区：
文献类型：
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作者：
Gardiner, Elizabeth E.;Arthur, Jane F.;Berndt, Michael C.
血小板糖蛋白（GP）Ib-IX-V（其结合血管性血友病因子（VWF））和GPVI（其结合胶原蛋白）在血小板上形成粘附-信号传导复合物并介导流动血液中的血小板粘附。GPIb-IX-V/GPVI与VWF/胶原蛋白结合后的血小板活化对于在受损或暴露的内皮部位引发和发展保护性血栓至关重要。我们研究了血小板GPIb α（GPIb-IX-V的主要配体结合亚基）通过COS-7细胞上的多价表面表达的GPIb α结合VWF-A1结构域选择性接合后的血小板聚集和信号传导。表达含有R543 W突变的VWF-A1结构域的COS-7细胞（在2B型血管性血友病中发现的功能获得性突变）用作GPIb-IX-V的选择性激动剂。1200，VWF-A1/R543 W细胞引起洗涤血小板的快速自发聚集，该聚集是GPIb α和α（IIb）β（3）依赖性的（被抑制性抗VWF-A1、抗GPIb α和抗α（IIb）β（3）抗体阻断）。血小板聚集对Src、磷酸肌醇3-激酶（PI 3-激酶）或Syk的抑制剂也敏感，证实了这些蛋白质在GPIb α介导的信号转导中的作用。VWF-A1/R543 W与GPIb α结合后的血小板酪氨酸磷酸化模式和Syk的特异性酪氨酸磷酸化与胶原或胶原相关肽（CRP）与GPVI结合诱导的模式相当。这些数据表明由GPIb α的特异性连接触发的信号传导事件可以导致稳健的血小板活化，并有助于将GPIb-IX-V定义为血小板上的粘附和信号传导受体。
Platelet glycoprotein (GP) Ib-IX-V, which binds von Willebrand factor (VWF), and GPVI, which binds collagen, form an adhesion-signaling complex on platelets and mediate platelet adhesion in flowing blood. Platelet activation following engagement of GPIb-IX-V/GPVI by VWF/collagen is critical for initiation and development of a protective thrombus across a site of damaged or exposed endothelium. We examined platelet aggregation and signaling following selective engagement of platelet GPIb alpha (the major ligand-binding subunit of GPIb-IX-V) by a multivalent surface-expressed GPIb alpha-binding VWF-A1 domain on COS-7 cells. COS-7 cells expressing the VWF-A1 domain containing an R543W mutation (a gain-of-function mutation found in Type 2B von Willebrand's Disease) were used as a selective agonist for GPIb-IX-V. When incubated in a cell-to-platelet ratio of up to 1 : 1200, VWF-A1/R543W cells caused rapid, spontaneous aggregation of washed platelets that was GPIb alpha -and alpha(IIb)beta(3)-dependent (blocked by inhibitory anti-VWF-A1, anti-GPIb alpha and anti-alpha(IIb)beta(3) antibodies). Platelet aggregation was also sensitive to inhibitors of Src, phosphoinositide 3-kinase (PI3-kinase) or Syk, confirming a role for these proteins in GPIb alpha-mediated signal transduction. Platelet tyrosine phosphorylation patterns and specific tyrosine phosphorylation of Syk after GPIb alpha engagement by VWF-A1/R543W was comparable to that induced by engagement of GPVI by collagen or collagen-related peptide (CRP). These data indicate signaling events triggered by specific ligation of GPIb alpha can lead to robust platelet activation and help define GPIb-IX-V as both an adhesion and signaling receptor on platelets.