Role of the intracellular domains of GPIb in controlling the adhesive properties of the platelet GPIbN/IX complex
Role of the intracellular domains of GPIb in controlling the adhesive properties of the platelet GPIbN/IX complex
复制标题
DOI：
10.1182/blood-2002-06-1847
复制
发表时间：
2003-05-01
期刊：
影响因子：
20.3
通讯作者：
Lanza, F
中科院分区：
文献类型：
--
作者：
Perrault, C;Mangin, P;Lanza, F
糖蛋白（GP） Ib/V/IX复合物依赖血小板对血管性血友病因子（VWF）的粘附是由GPIbalpha亚基的45-kd n端胞外结构域支持的。最近针对gpib β的粘附阻断抗体（RAMA）的研究结果表明，该亚基在调节vwf介导的血小板粘附方面具有新功能，可能涉及其细胞内表面。通过检测转染GPIb/(V)/IX突变的K562和中国仓鼠卵巢（CHO）细胞对固定化VWF的粘附作用，研究了GPIba和gpibβ细胞质结构域之间的协同作用。携带甘氨酸取代GPIbbeta Ser166磷酸化位点的细胞的粘附比正常细胞低50%，并且对ram的抑制不敏感1。相比之下，forskolin或PGE(1)处理增加了对照细胞的GPIbbeta磷酸化和粘附，这两种作用被RAMA逆转，但对表达Ser166Gly突变的细胞没有影响。GPIbalpha胞内结构域的作用也很明显，因为含有GPIbalpha全部（Delta518-610）或部分（Delta535-568, Delta569-610）缺失的细胞的vwf依赖性粘附，细胞质尾部对RAMA抑制不敏感。跨越gpipha的细胞携带渐进式11个氨基酸缺失。除了含有GPIbalpha Delta569-579的区域表现出与对照细胞相似的行为外，535-590区域对ram - 1同样无反应。这些发现支持GPIbbeta胞内结构域通过磷酸化GPIbbeta Ser166来控制GPIb/V/IX复合物的粘附特性，并指出GPIbbeta和GPIbalpha胞内结构域之间存在串扰。(C) 2003年由美国血液病学会出版。
Glycoprotein (GP) Ib/V/IX complex-dependent platelet adhesion to von Willebrand factor (VWF) is supported by the 45-kd N-terminal extracellular domain of the GPIbalpha subunit. Recent results with an adhesion blocking antibody (RAMA) against GPIbbeta, which is disulfide linked to GPIbalpha, have suggested a novel function of this subunit in regulating VWF-mediated platelet adhesion, possibly involving its intracellular face. A putative cooperation between the GPIba, and GPIbbeta cytoplasmic domains was investigated by measuring the adhesion under flow to immobilized VWF of K562 and Chinese hamster ovary (CHO) cells transfected with GPIb/(V)/IX containing mutations in this region. Adhesion of cells carrying a glycine substitution of the GPIbbeta Ser166 phosphorylation site was 50% lower than normal and became insensitive to inhibition by RAM.1. In contrast, forskolin or PGE(1) treatment increased both the phosphorylation of GPIbbeta and adhesion of control cells, both effects being reversed by RAMA, but had no influence on cells expressing the Ser166Gly mutation. A role of the GPIbalpha intracellular domain was also apparent as the VWF-dependent adhesion of cells containing deletions of the entire (Delta518-610) or portions (Delta535-568, Delta569-610) of the GPIbalpha, cytoplasmic tail was insensitive to RAMA inhibition. Cells carrying progressive 11 amino acid deletions spanning the GPIbalpha. 535-590 region were equally unresponsive to RAM.1, with the exception of those containing GPIbalpha Delta569-579, which behaved like control cells. These findings support a role of the GPIbbeta intracellular domain in controlling the adhesive properties of the GPIb/V/IX complex through phosphorylation of GPIbbeta Ser166 and point to the existence of cross-talk between the GPIbbeta and GPIbalpha intracellular domains. (C) 2003 by The American Society of Hematology.