Receptor tyrosine kinases as mediators of injury-induced bradykinin B 1 receptor expression in rabbit aortic smooth muscle

Abstract

Prolonged in vitro incubation of rabbit aortic rings allows recording contractile responses mediated by the inducible bradykinin B 1 receptors; addition of interleukin (IL)-1 or epidermal growth factor (EGF) to the bathing fluid increases the rate of sensitization, a process partially inhibited by the nonspecific Tyr-kinase inhibitor genistein. The recent development of specific inhibitors for receptor associated Tyr-kinase activities (tyrphostin AG 1478 for EGF receptor, sunitinib for VEGF receptor and others) allows assessing the role of such signaling molecules in this process. AG 1478 reduced the potentiating effects of exogenous EGF, and also the spontaneous sensitization to the agonist des-Arg 9-bradykinin. Sunitinib or GM 6001, a wide spectrum inhibitor of metalloproteinases, had no effect on these responses. In rabbit aortic smooth muscle cells, the cytokines IL-1β and EGF increased the density of binding sites for [ 3H]Lys-des-Arg 9-bradykinin in 4 h; AG 1478 reduced only the effect of exogenous EGF. IL-1 receptor antagonist decreased both the effect of IL-1β and of EGF in rabbit smooth muscle cells. EGF was weakly and slowly coupled to nuclear factor-κB nuclear translocation in these cells, as compared to the effect of IL-1β. EGF-induced EGF receptor autophosphorylation and ERK1/2 phosphorylation was selectively inhibited by AG 1478 in smooth muscle cells; Lys-des-Arg 9-bradykinin did not transactivate EGF receptor in these cells. While the Tyr-kinase activity sensitive to AG 1478 is recruited by tissue damage and exogenous EGF to upregulate bradykinin B 1 receptors in freshly isolated aortas, this signaling system interacts with others (e.g., IL-1) for the optimal expression of B 1 receptors.