Portal de Periódicos da CAPES

Distinct Role of Pyk2 in Mediating Thromboxane Generation Downstream of Both G12/13 and Integrin αIIbβ3 in Platelets

2013; Elsevier BV; Volume: 288; Issue: 25 Linguagem: Inglês

10.1074/jbc.m113.461087

1083-351X

Soochong Kim, Lina Cipolla, Gianni Francesco Guidetti, Mitsuhiko Okigaki, Jianguo Jin, Mauro Torti, Satya P. Kunapuli,

HER2/EGFR in Cancer Research

Proline-rich tyrosine kinase 2 (Pyk2) is activated by various agonists in platelets. We evaluated the signaling mechanism and the functional role of Pyk2 in platelets by using pharmacological inhibitors and Pyk2-deficient platelets. We found that platelet aggregation and secretion in response to 2-methylthio-ADP (2-MeSADP) and AYPGKF were diminished in the presence of Pyk2 inhibitors or in Pyk2-deficient platelets, suggesting that Pyk2 plays a positive regulatory role in platelet functional responses. It has been shown that ADP-, but not thrombin-induced thromboxane (TxA2) generation depends on integrin signaling. Unlike ADP, thrombin activates G12/13 pathways, and G12/13 pathways can substitute for integrin signaling for TxA2 generation. We found that Pyk2 was activated downstream of both G12/13 and integrin-mediated pathways, and both 2-MeSADP- and AYPGKF-induced TxA2 generation was significantly diminished in Pyk2-deficient platelets. In addition, TxA2 generation induced by co-stimulation of Gi and Gz pathways, which is dependent on integrin signaling, was inhibited by blocking Pyk2. Furthermore, inhibition of 2-MeSADP-induced TxA2 generation by fibrinogen receptor antagonist was not rescued by co-stimulation of G12/13 pathways in the presence of Pyk2 inhibitor. We conclude that Pyk2 is a common signaling effector downstream of both G12/13 and integrin αIIbβ3 signaling, which contributes to thromboxane generation.Background:Pyk2 is abundantly expressed in platelets.Results:Pyk2 regulates thromboxane A2 generation induced by both 2-methylthio-ADP and AYPGKF.Conclusion:Pyk2 is an important functional tyrosine kinase that is activated by both G12/13 and integrin αIIbβ3 in platelets.Significance:Understanding the mechanism of activation of Pyk2 enhances our understanding of the platelet inside-out and outside-in signaling events. Proline-rich tyrosine kinase 2 (Pyk2) is activated by various agonists in platelets. We evaluated the signaling mechanism and the functional role of Pyk2 in platelets by using pharmacological inhibitors and Pyk2-deficient platelets. We found that platelet aggregation and secretion in response to 2-methylthio-ADP (2-MeSADP) and AYPGKF were diminished in the presence of Pyk2 inhibitors or in Pyk2-deficient platelets, suggesting that Pyk2 plays a positive regulatory role in platelet functional responses. It has been shown that ADP-, but not thrombin-induced thromboxane (TxA2) generation depends on integrin signaling. Unlike ADP, thrombin activates G12/13 pathways, and G12/13 pathways can substitute for integrin signaling for TxA2 generation. We found that Pyk2 was activated downstream of both G12/13 and integrin-mediated pathways, and both 2-MeSADP- and AYPGKF-induced TxA2 generation was significantly diminished in Pyk2-deficient platelets. In addition, TxA2 generation induced by co-stimulation of Gi and Gz pathways, which is dependent on integrin signaling, was inhibited by blocking Pyk2. Furthermore, inhibition of 2-MeSADP-induced TxA2 generation by fibrinogen receptor antagonist was not rescued by co-stimulation of G12/13 pathways in the presence of Pyk2 inhibitor. We conclude that Pyk2 is a common signaling effector downstream of both G12/13 and integrin αIIbβ3 signaling, which contributes to thromboxane generation. Pyk2 is abundantly expressed in platelets. Pyk2 regulates thromboxane A2 generation induced by both 2-methylthio-ADP and AYPGKF. Pyk2 is an important functional tyrosine kinase that is activated by both G12/13 and integrin αIIbβ3 in platelets.