Involvement of PYK2 in Angiotensin II Signaling of Vascular Smooth Muscle Cells

Abstract

Abstract-PYK2, a recently identified Ca 2ϩ -sensitive tyrosine kinase, has been implicated in extracellular signal-regulated kinase (ERK) activation via several G protein-coupled receptors. We have reported that angiotensin II (Ang II) induces Ca 2ϩ -dependent transactivation of the epidermal growth factor receptor (EGFR) which serves as a scaffold for preactivated c-Src and downstream adaptors (Shc/Grb2), leading to ERK activation in cultured rat vascular smooth muscle cells (VSMC). Herein we demonstrate the involvement of PYK2 in this cascade. Ang II rapidly induced tyrosine phosphorylation of PYK2, whose effect was completely inhibited by an AT 1 receptor antagonist and an intracellular Ca 2ϩ chelator. A Ca 2ϩ ionophore also induced PYK2 tyrosine phosphorylation to a level comparable with that by Ang II, whereas phorbol ester-induced phosphorylation was less than that by Ang II. Moreover, PYK2 formed a complex coprecipitable with catalytically active c-Src after Ang II stimulation. Although a selective EGFR kinase inhibitor completely abolished Ang II-induced recruitment of Grb2 to EGFR and markedly attenuated Ang II-induced ERK activation, it had no effect on Ang II-induced PYK2 tyrosine phosphorylation or its association with c-Src and Grb2. These data suggest that the AT 1 receptor uses Ca 2ϩ -dependent PYK2 to activate c-Src, thereby leading to EGFR transactivation, which preponderantly recruits Grb2 in rat VSMC.

Dependence of Gonadotropin-releasing Hormone-induced Neuronal MAPK Signaling on Epidermal Growth Factor Receptor Transactivation

“…Depending on the cell type, EGF-R transactivation has been reported to be mediated by G i protein ␤␥-subunits (40,41), Ca 2ϩ (26,30), PKC (10,37,42), and heparinbinding EGF (HB-EGF) released by matrix metalloproteinases (43,44). However, the latter does not appear to be a universal mechanism for transactivation of the EGF-R by GPCRs (17,45).…”

“…These data suggest that whereas PKC is an important mediator of GnRH-induced signals, its stimulatory action is upstream of the EGF-R in GT1-7 cells. GPCR-mediated activation of Pyk2 and ERK1/2 is reported to be dependent on both Ca 2ϩ (26,30,41,50) and PKC (19,37,39,51). PKC is also known to cause activation of Src (24) and the EGF-R (10,24,44,45) in several cell types.…”

“…It also stimulates Jun N-terminal kinase in ␣T3-1 cells (24) and p38-MAPK in L␤T2 gonadotrophs (25). Activation of these MAPKs by other GPCRs, such as angiotensin II (26,27), endothelin (28), adrenomedullin (29), and acetylcholine (30), is mediated through the proline-rich protein tyrosine kinase, Pyk2. In general, Pyk2 activation in conjunction with Src kinase appears to be a key element in GPCR-mediated transactivation of the EGF-R (31).…”

The galanin receptor type 2 initiates multiple signaling pathways in small cell lung cancer cells by coupling to Gq, Gi and G12 proteins

“…In these cellular settings Pyk2, a focal adhesion kinase related tyrosine kinase independently activated by Ca 2+ and phorbol esters (Lev et al, 1995), has recently been placed upstream of receptor tyrosine kinases in the signaling pathway from G q/11 -coupled receptors to ERKs (Eguchi et al, 1999;Solto , 1998). To better understand mitogenic signaling by G q/11 -coupled receptors in SCLC cells, a detailed analysis of the role of receptor tyrosine kinases like c-kit and of non-receptor tyrosine kinases such as Pyk2 should be enlightening in the future.…”

ANG II and LPA induce Pyk2 tyrosine phosphorylation in intestinal epithelial cells: role of Ca2+, PKC, and Rho kinase

“…Pyk2 is activated by tyrosine phosphorylation in response to various stimuli, including growth factors, neurotransmitters, bioactive lipids, adhesion to the extracellular matrix, and stress signals (16,17,22,26,30,59). Organization of the actin cytoskeleton plays an important role in Pyk2 regulation (6,19,22).…”