Novel role of proline-rich nonreceptor tyrosine kinase 2 in vascular wall remodeling after balloon injury.

OBJECTIVE To investigate the role of Pyk2, a proline-rich nonreceptor tyrosine kinase, in G protein-coupled receptor agonist, thrombin-induced human aortic smooth muscle cell growth and migration, and injury-induced vascular wall remodeling. METHODS AND RESULTS Thrombin, a G protein-coupled receptor agonist, activated Pyk2 in a time-dependent manner and inhibition of its stimulation attenuated thrombin-induced human aortic smooth muscle cell migration and proliferation. Thrombin also activated Grb2-associated binder protein 1, p115 Rho guanine nucleotide exchange factor, Rac1, RhoA, and p21-activated kinase 1 (Pak1) and interference with stimulation of these molecules attenuated thrombin-induced human aortic smooth muscle cell migration and proliferation. In addition, adenovirus-mediated expression of dominant negative Pyk2 inhibited thrombin-induced Grb2-associated binder protein 1, p115 rho guanine nucleotide exchange factor, Rac1, RhoA and Pak1 stimulation. Balloon injury also caused activation of Pyk2, Grb2-associated binder protein 1, p115 rho guanine nucleotide exchange factor, Rac1, RhoA, and Pak1 in the carotid artery of rat, and these responses were sensitive to inhibition by the dominant negative Pyk2. Furthermore, inhibition of Pyk2 activation resulted in reduced recruitment of smooth muscle cells onto the luminal surface and their proliferation in the intimal region leading to suppression of neointima formation. CONCLUSIONS Together, these results demonstrate for the first time that Pyk2 plays a crucial role in G protein-coupled receptor agonist thrombin-induced human aortic smooth muscle cell growth and migration, as well as balloon injury-induced neointima formation.