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This Article Full Text Full Text (PDF) All Versions of this Article: 297/1/H304    most recent 00077.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Negash, S. Articles by Raj, J. U. PubMed PubMed Citation Articles by Negash, S. Articles by Raj, J. U.

Role of cGMP-dependent protein kinase in regulation of pulmonary vascular smooth muscle cell adhesion and migration: effect of hypoxia

¹Division of Neonatology, Harbor-UCLA Medical Center, Los Angeles Biomedical Research Institute, Torrance, California; and ²Department of Pediatrics, University of Illinois at Chicago, Chicago, Illinois

Submitted 23 January 2008 ; accepted in final form 26 April 2009

Exposure to prolonged hypoxia can result in pulmonary vascular remodeling and pulmonary hypertension. Hypoxia induces pulmonary vascular smooth muscle cell (PVSMC) proliferation and vascular remodeling by affecting cell adhesion and migration and secretion of extracellular matrix proteins. We previously showed that acute hypoxia decreases cGMP-dependent protein kinase (PKG) activity in PVSMC and that PKG plays a role in maintaining the differentiated contractile phenotype in normoxia. In this study, we investigated the effect of hypoxia on PVSMC adhesion and migration and the role of PKG in these functions. Ovine fetal pulmonary artery SMC were incubated in normoxia (PO₂ 100 Torr) or hypoxia (PO₂ 30–40 Torr) or treated with the PKG inhibitor DT-3 for 24 h in normoxia. To further study the role of PKG in the modulation of adhesion and migration, PVSMC were transiently transfected with a full-length PKG1 [PKG-green fluorescent protein (GFP)] or a dominant-negative construct (G1R-GFP). Cell adhesion to extracellular matrix proteins was determined, and integrin-mediated adhesion was assessed by /β-integrin-mediated cell adhesion array. Exposure to hypoxia (24 h) and pharmacological inhibition of PKG1 by DT-3 significantly promoted adhesion mediated by ₄-, β₁-, and ₅β₁-integrins to fibronectin, laminin, and tenacin and also resulted in increased cell migration. Likewise, inhibition of PKG by expression of a dominant-negative PKG1 construct increased cell adhesion and migration, comparable to that induced by hypoxia. Dynamic actin reorganization associated with integrin-mediated cell adhesion is partly regulated by the actin-binding protein cofilin, the (Ser3) phosphorylation of which inhibits its actin-severing activity. We found that increased PKG expression and activity is associated with decreased cofilin (Ser3) phosphorylation, implying a role for PKG in the modulation of cofilin activity and actin dynamics. Together, these findings identify cGMP/PKG1 signaling as central to the functional differences between PVSMC exposed to normoxia versus hypoxia.

pulmonary artery; vascular remodeling