A naturally occurring mutation near the amino terminus of alphaIIb defines a new region involved in ligand binding to alphaIIbbeta3.
A naturally occurring mutation near the amino terminus of alphaIIb defines a new region involved in ligand binding to alphaIIbbeta3.
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DOI：
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发表时间：
2000
期刊：
影响因子：
20.3
通讯作者：
R. B. Basani;D. French;G. Vilaire;D. Brown;F. Chen;B. Coller;J. Derrick;T. Gartner;J. Bennett;M. Poncz
中科院分区：
文献类型：
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作者：
R. B. Basani;D. French;G. Vilaire;D. Brown;F. Chen;B. Coller;J. Derrick;T. Gartner;J. Bennett;M. Poncz
血小板表面功能性AlphaIIbbeta3复合体表达减少会导致Glanzmann血栓减少症。我们已经在3个不同种族的Glanzmann血小板减少症家系中发现了AlphaIIb(P145)突变。受影响的门诺族患者和荷兰患者分别是P(145)A替换的纯合子和双重杂合子，而中国患者的P(145)L替换是双重杂合子。在COS-1细胞中，这些突变影响了其血小板表面αIIbbeta3受体的表达水平，这一点已通过共转染AlphaIIb(P145A)和Beta3cDNAs得到证实。每个突变还会削弱受影响血小板上的AlphaIIbbeta3与配体相互作用的能力。此外，当αIIb(P145A)和β3在中国仓鼠卵巢细胞中稳定共表达时，细胞表面很容易检测到αIIbbeta3，但激活的单抗PT25-2激活αIIbbeta3后，细胞不能附着于固定化的纤维蛋白原，也不能结合可溶性异硫氰酸荧光素-纤维蛋白原。然而，与AlphaIIb结合的LSARLAF肽与受影响的血小板孵育后，诱导了PF4的分泌，表明突变的AlphaIIbbeta3保留了介导由外向内信号的能力。这些研究表明，涉及alphaIIb(P145)的突变损害了alphaIIbbeta3的表面表达，并且alphaIIb(P145A)突变取消了与激活的整合素的配体结合。对其他表型相似的alphaIIb突变的比较分析表明，这些突变可能聚集在alphaIIb表面的单个区域，并可能定义一个影响配体结合的区域。(血。2000年；95：180188)
Decreased expression of functional alphaIIbbeta3 complexes on the platelet surface produces Glanzmann thrombasthenia. We have identified mutations of alphaIIb(P145) in 3 ethnically distinct families affected by Glanzmann thrombasthenia. Affected Mennonite and Dutch patients were homozygous and doubly heterozygous, respectively, for a P(145)A substitution, whereas a Chinese patient was doubly heterozygous for a P(145)L substitution. The mutations affect expression levels of surface alphaIIbbeta3 receptors on their platelets, which was confirmed by co-transfection of alphaIIb(P145A) and beta3 cDNA constructs in COS-1 cells. Each mutation also impaired the ability of alphaIIbbeta3 on affected platelets to interact with ligands. Moreover, when alphaIIb(P145A) and beta3 were stably coexpressed in Chinese hamster ovary cells, alphaIIbbeta3 was readily detected on the cell surface, but the cells were unable to adhere to immobilized fibrinogen or to bind soluble fluorescein isothiocyanate-fibrinogen after alphaIIbbeta3 activation by the activating monoclonal antibody PT25-2. Nonetheless, incubating affected platelets with the peptide LSARLAF, which binds to alphaIIb, induced PF4 secretion, indicating that the mutant alphaIIbbeta3 retained the ability to mediate outside-in signaling. These studies indicate that mutations involving alphaIIb(P145 )impair surface expression of alphaIIbbeta3 and that the alphaIIb(P145A) mutation abrogates ligand binding to the activated integrin. A comparative analysis of other alphaIIb mutations with a similar phenotype suggests that these mutations may cluster into a single region on the surface of the alphaIIb and may define a domain influencing ligand binding. (Blood. 2000;95:180188)