Analyzing the mechanism of Rap1 activation in platelets: Rap1 activation is related to the release reaction mediated through the collagen receptor GPVI

Stephanie M. Jung, Masaaki Ohnuma, Naohide Watanabe, Mamiko Sonoda, Makoto Handa, Masaaki Moroi

研究成果: Article査読

7 被引用数 (Scopus)

抄録

The abundant Rap1 in platelets becomes activated when these cells are stimulated by various agonists, but its function has remained unknown. In view of this, we developed an assay to quantitatively measure activated Rap1 and used it to determine relationships between Rap1 activation and several platelet functions: integrin α2β1 activation, tyrosine phosphorylation, and the release reaction. We looked at how these processes are affected by the protein kinase C inhibitor BIMI, tyrosine kinase inhibitor PP2, PI 3-kinase inhibitor wortmannin, and ADP scavenger apyrase. In CRP (collagen related peptide)-activated platelets, all the inhibitors severely inhibited Rap1 activation, but had little effect on integrin α2β1 activation, indicating that the integrin activation mechanism is different from the Rap1 activation mechanism, at least in GPVI-dependent activation. With p85α-null mouse platelets, we demonstrated that Rap1 activation involves PI 3-kinase p85α-dependent tyrosine phosphorylation. All the inhibitors similarly decreased Rap1 activation and the serotonin release reaction, and the inhibition of Rap1 activation was not due to the lack of released ADP. Our results indicate that platelet Rap1 activation is closely related to the release reaction and not to integrin α2β1 activation in GPVI-mediated platelet activation.

本文言語English
ページ(範囲)509-521
ページ数13
ジャーナルThrombosis Research
118
4
DOI
出版ステータスPublished - 2006
外部発表はい

ASJC Scopus subject areas

  • 血液学

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