Association of CBFA2 mutation with decreased platelet PKC-θ and impaired receptor-mediated activation of GPIIb-IIIa and pleckstrin phosphorylation:: proteins regulated by CBFA2 play a role in GPIIb-IIIa activation

被引:60
作者
Sun, LS [1 ]
Mao, GF [1 ]
Rao, AK [1 ]
机构
[1] Temple Univ, Sch Med, Div Hematol & Thromboembol Dis, Philadelphia, PA 19140 USA
关键词
D O I
10.1182/blood-2003-07-2299
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The mechanisms by which agonists activate glycoprotein (GP) IIb-IIIa function remain unclear. We have reported data on a patient with thrombocytopenia and impaired receptor-mediated aggregation, phosphorylation of pleckstrin (a protein kinase C [PKC] substrate), and activation of the GPIIb-IIIa complex. Abnormalities in hematopoietic transcription factors have been associated with thrombocytopenia and platelet dysfunction. To define the molecular mechanisms, we amplified from patient platelet RNA exons 3 to 6 of core-binding factor A2 (CBFA2) cDNA, which encompasses the DNA-binding Runt domain; a 13-nucleotide (nt) deletion was found (796-808 nt). The gDNA revealed a heterozygous mutation (G >T) in intron 3 at the splice acceptor site for exon 4, leading to a frameshift with premature termination in the Runt domain. On immunoblotting, platelet CBFA2, PKC-theta, albumin, and IgG were decreased, but pleckstrin, PKC-alpha, -beta1, -betaII, -eta, -epsilon, -delta, and -zeta, and fibrinogen were normal. Our conclusions are that (1) CBFA2 mutation is associated with not only thrombocytopenia, but also impaired platelet protein phosphorylation and GPIIb-IIIa activation; (2) proteins regulated by CBFA2 are required for inside-out signal transduction-dependent activation of GPIIb-IIIa; and (3) we have documented the first deficiency of a human PKC isozyme (PKC-theta), suggesting a major role of this isozyme in platelet production and function. (C) 2004 by The American Society of Hematology.
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页码:948 / 954
页数:7
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