Protein tyrosine phosphatase-dependent proteolysis of focal adhesion complexes in endothelial cell apoptosis. Harrington, Elizabeth O., Anthony Smeglin, Julie Newton, Gajarah Ballard, and Sharon Rounds. Pulmonary/Critical Care Medicine Section, Providence Veterans Affairs Medical Center, and Department of Medicine, Brown University School of Medicine, Providence, Rhode Island 02908
APStracts 7:0264L, 2000.
Adenosine and/or homocysteine cause endothelial cell apoptosis, a mechanism requiring protein tyrosine phosphatase (PTPase) activity. We investigated the role of focal adhesion contact disruption in adenosine-homocysteine endothelial cell apoptosis. Analysis of focal adhesion kinase (FAK), paxillin, and vinculin demonstrated disruption of focal adhesion complexes after 4 h of treatment with adenosine-homocysteine followed by caspase-induced proteolysis of FAK, paxillin, and p130CAS. No significant changes were noted in tyrosine phosphorylation of FAK or paxillin. Pretreatment with the caspase inhibitor Z-Val-Ala-Asp-fluoromethylketone prevented adenosine-homocysteine-induced DNA fragmentation and FAK, paxillin, and p130CAS proteolysis. Asp-Glu-Val-Asp-ase activity was detectable in endothelial cells after 4 h of treatment with adenosine- homocysteine. The PTPase inhibitor sodium orthovanadate did not prevent endothelial cell retraction or FAK, paxillin, or vinculin redistribution. Sodium orthovanadate did block adenosine-homocysteine-induced FAK, paxillin, and p130CAS proteolysis and Asp-Glu-Val-Asp-ase activity. Thus disruption of focal adhesion contacts and caspase- induced degradation of focal adhesion contact proteins occurs in adenosine-homocysteine endothelial cell apoptosis. Focal adhesion contact disruption induced by adenosine- homocysteine is independent of PTPase or caspase activation. These studies demonstrate that disruption of focal adhesion contacts is an early, but not an irrevocable, event in endothelial cell apoptosis. 

Received 11 July 2000; accepted in final form 7 September 2000
APS Manuscript Number L234-0.
Article publication pending Am J Physiol Lung Cell Mol Physiol
ISSN 1080-4757 Copyright 2000 The American Physiological Society.
Published in APStracts on 30 November 2000