Cyclic Strain Activates Redox-sensitive Proline-rich Tyrosine Kinase 2 (PYK2) in Endothelial Cells

Jing-Jy Cheng,Yuen-Jen Chao,Danny Ling Wang

doi:10.1074/jbc.m110937200

Abstract

Proline-rich tyrosine kinase 2 (PYK2), structurally related to focal adhesion kinase, has been shown to play a role in signaling cascades. Endothelial cells (ECs) under hemodynamic forces increase reactive oxygen species (ROS) that modulate signaling pathways and gene expression. In the present study, we found that bovine ECs subjected to cyclic strain rapidly induced phosphorylation of PYK2 and Src kinase. This strain-induced PYK2 and Src phosphorylation was inhibited by pretreating ECs with an antioxidant N-acetylcysteine. Similarly, ECs exposed to H(2)O(2) increased both PYK2 and Src phosphorylation. An increased association of Src to PYK2 was observed in ECs after cyclic strain or H(2)O(2) exposure. ECs treated with an inhibitor to Src (PPI) greatly reduced Src and PYK2 phosphorylation, indicating that Src mediated PYK2 activation. Whereas the protein kinase C (PKC) inhibitor (calphostin C) pretreatment was shown to inhibit strain-induced NADPH oxidase activity, ECs treated with either calphostin C or the inhibitor to NADPH oxidase (DPI) reduced strain-induced ROS levels and then greatly inhibited the Src and PYK2 activation. In contrast to the activation of PYK2 and Src with calcium ionophore (ionomycin), ECs treated with a Ca(2+) chelator inhibited both phosphorylation, indicating that PYK2 and Src activation requires Ca(2+). ECs transfected with antisense to PKCalpha, but not antisense to PKCepsilon(,) reduced cyclic strain-induced PYK2 activation. These data suggest that cyclic strain-induced PYK2 activity is mediated via Ca(2+)-dependent PKCalpha that increases NADPH oxidase activity to produce ROS crucial for Src and PYK2 activation. ECs under cyclic strain thus activate redox-sensitive PYK2 via Src and PKC, and this PYK2 activation may play a key role in the signaling responses in ECs under hemodynamic influence.

Highlights

PYK21, a protein-tyrosine kinase related to focal adhesion kinase (FAK), is a recently identified non-receptor tyrosine kinase [1]
Endothelial cells (ECs) subjected to cyclic strain increase intracellular reactive oxygen species (ROS) that are involved in the regulation of cellular responses and gene expression
We found that nonreceptor tyrosine kinase Proline-rich tyrosine kinase 2 (PYK2) is sensitive to redox changes in cyclic strain-treated ECs

Summary

Introduction

PYK21 ( known as RAFTK, CAK␤), a protein-tyrosine kinase related to focal adhesion kinase (FAK), is a recently identified non-receptor tyrosine kinase [1]. This PYK2 activation is redox-sensitive and is mediated via the tyrosine kinase Src. Our findings indicate that cyclic strain to ECs activates PKC-dependent NAD(P)H oxidase activity that is crucial for PYK2 activation via Src. This cyclic strain-induced PYK2 activation may play an important role in signaling cascade during endothelial responses to hemodynamic forces. When ECs were pretreated with a PKC inhibitor (calphostin C), it showed an inhibition of cyclic strain-induced NADPH oxidase activity (Fig. 4A).

Results

Conclusion