| Autor: |
Obergfell, Achim, Judd, Barbi A., del Pozo, Miguel A., Schwartz, Martin A., Koretzky, Gary A., Shattil, Sanford J. |
| Zdroj: |
Journal of Biological Chemistry; February 2001, Vol. 276 Issue: 8 p5916-5923, 8p |
| Abstrakt: |
Platelet adhesion to fibrinogen through integrin αIIbβ3triggers actin rearrangements and cell spreading. Mice deficient in the SLP-76 adapter molecule bleed excessively, and their platelets spread poorly on fibrinogen. Here we used human platelets and a Chinese hamster ovary (CHO) cell expression system to better define the role of SLP-76 in αIIbβ3signaling. CHO cell adhesion to fibrinogen required αIIbβ3and stimulated tyrosine phosphorylation of SLP-76. SLP-76 phosphorylation required coexpression of Syk tyrosine kinase and stimulated association of SLP-76 with the adapter, Nck, and with the Rac exchange factor, Vav1. SLP-76 expression increased lamellipodia formation induced by Syk and Vav1 in adherent CHO cells (p< 0.001). Although lamellipodia formation requires Rac, SLP-76 functioned downstream of Rac by potentiating adhesion-dependent activation of PAK kinase (p< 0.001), a Rac effector that associates with Nck. In platelets, adhesion to fibrinogen stimulated the association of SLP-76 with the SLAP-130 adapter and with VASP, a SLAP-130 binding partner implicated in actin reorganization. Furthermore, SLAP-130 colocalized with VASP at the periphery of spread platelets. Thus, SLP-76 functions to relay signals from αIIbβ3to effectors of cytoskeletal reorganization. Therefore, deficient recruitment of specific adapters and effectors to sites of adhesion may explain the integrin phenotype of SLP-76−/−platelets. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
