Background: 

Pressure-induced vascular remodeling is a major problem in cardiovascular disease. Although clinical consequences are well known, little is known about the molecular and cellular events starting this process. We here define a specifically pressure-activated signaling cascade leading to the phosphorylation of the focal adhesion protein zyxin which then, as a transcription factor, orchestrates endothelial gene expression.

Methods: 

Human primary cultured endothelial cells (EC) were exposed to cyclic strain as a surrogate stimulus for increased pressure. Zyxin phosphorylation was analyzed by 2D-gelelectrophoresis and transfection eGFP-tagged zyxin constructs with wild type or point-mutated sequence. In situ perfusion of freshly isolated femoral arteries from wild type and NPR-A knockout mice was done using a pressure myograph.

Results: 

Cyclic strain (10% at 0.5 Hz) resulted in the dissociation of zyxin from focal adhesions and its translocation to the nucleus in EC. The use of several phosphorylation-incompetent eGFP-zyxin constructs revealed that zyxin is phosphorylated by protein kinase G (PKG) at serine-142 in response to stretch and that this phosphorylation is necessary for its nuclear translocation. The activation of PKG involves a complex chain of signaling events, namely the activation of TRP channels leading to the release of endothelin-1 and, in an ET_B-R-mediated manner, that of atrial natriuretic peptide which then activates NPR-A and, subsequently, PKG.

Conclusion: 

Wall tension-induced phosphorylation of zyxin at serine-142 causes a complex change in endothelial gene expression. We here describe the signaling pathway leading to this first step towards endothelial phenotype changes at the onset of pressure-induced vascular remodeling.