1. Direct demonstration of involvement of the adaptor protein ShcA in the regulation of Ca2+-induced platelet aggregation.
- Author
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Higashi T, Yoshioka A, Shirakawa R, Tabuchi A, Nishioka H, Kita T, and Horiuchi H
- Subjects
- Adaptor Proteins, Vesicular Transport genetics, Adaptor Proteins, Vesicular Transport immunology, Animals, Antibodies immunology, Cytosol metabolism, Integrin beta3 metabolism, Mice, Protein Isoforms genetics, Shc Signaling Adaptor Proteins, Src Homology 2 Domain-Containing, Transforming Protein 1, Adaptor Proteins, Signal Transducing, Adaptor Proteins, Vesicular Transport metabolism, Blood Platelets physiology, Calcium metabolism, Platelet Aggregation physiology
- Abstract
Platelet aggregation is mediated by conformational change of integrin alpha(IIb)beta(3). Tyrosine-phosphorylation of cytoplasmic domain of beta(3) upon platelet activation has been demonstrated to play a critical role in this process. Recently, the adaptor protein ShcA has been shown to bind to the tyrosine-phosphorylated beta(3), while it remains open whether ShcA plays any role in platelet aggregation. Here, we show that ShcA bound to tyrosine-phosphorylated beta(3)-tail peptide through its phosphotyrosine-binding domain in vitro. Then, we examined the involvement of ShcA in platelet aggregation by a previously established in vitro assay using platelets permeabilized with streptolysin-O, where exogenous addition of platelet cytosol is required for reconstitution of the Ca(2+)-induced aggregation. When ShcA was specifically depleted with anti-ShcA antibody from the cytosol, this ShcA-depleted cytosol lost the aggregation-supporting activity, which was rescued by addition of purified recombinant ShcA. Thus, ShcA is essential for the Ca(2+)-induced platelet aggregation.
- Published
- 2004
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