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Open Access Research

A deficiency of uPAR alters endothelial angiogenic function and cell morphology

Rashna D Balsara12, Reid Merryman1, Farhaad Virjee1, Claire Northway1, Francis J Castellino12 and Victoria A Ploplis12*

Author Affiliations

1 W. M. Keck Center for Transgene Research, University of Notre Dame, 230 Raclin-Carmichael Hall, Notre Dame, Indiana 46556, USA

2 Department of Chemistry and Biochemistry, University of Notre Dame, 230 Raclin-Carmichael Hall, Notre Dame, Indiana 46556, USA

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Vascular Cell 2011, 3:10  doi:10.1186/2045-824X-3-10

Published: 2 May 2011

Abstract

The angiogenic potential of a cell requires dynamic reorganization of the cytoskeletal architecture that involves the interaction of urokinase-type plasminogen activator receptor (uPAR) with the extracellular matrix. This study focuses on the effect of uPAR deficiency (uPAR-/-) on angiogenic function and associated cytoskeletal organization. Utilizing murine endothelial cells, it was observed that adhesion, migration, proliferation, and capillary tube formation were altered in uPAR-/- cells compared to wild-type (WT) cells. On a vitronectin (Vn) matrix, uPAR-/- cells acquired a "fried egg" morphology characterized by circular actin organization and lack of lamellipodia formation. The up-regulation of β1 integrin, FAK(P-Tyr925), and paxillin (P-Tyr118), and decreased Rac1 activation, suggested increased focal adhesions, but delayed focal adhesion turnover in uPAR-/- cells. This accounted for the enhanced adhesion, but attenuated migration, on Vn. VEGF-enriched Matrigel implants from uPAR-/- mice demonstrated a lack of mature vessel formation compared to WT mice. Collectively, these results indicate that a uPAR deficiency leads to decreased angiogenic functions of endothelial cells.