Journal of Leukocyte Biology Myeloid cells, immune suppression, tumor immunology
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A more recent version of this article appeared on February 1, 2008

Published online before print November 5, 2007
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© by The Society for Leukocyte Biology
Journal of Leukocyte Biology, doi:10.1189/jlb.0107056

Received for publication January 23, 2007.
Revised September 27, 2007.
Accepted for publication October 8, 2007.

Article

Angiopoietin-mediated endothelial P-selectin translocation: cell signaling mechanisms

Ricardo Maliba , Alexandre Brkovic , Paul-Éduard Neagoe , Louis R. Villeneuve , and Martin G. Sirois @

Montreal Heart Institute and Department of Pharmacology, Université de Montréal, Montreal (Quebec), Canada

@ To whom correspondence should be addressed. E-mail: martin.sirois{at}icm-mhi.org.


  Abstract

Recently identified, angiopoietin-1 (Ang1) and -2 (Ang2) bind to the tyrosine kinase receptor Tie2 and contribute to orchestrate blood vessel formation during angiogenesis. Ang1 mediates vessel maturation and integrity by favoring the recruitment of pericytes and smooth muscle cells. Ang2, initially identified as a Tie2 antagonist, may under certain circumstances, induce Tie2 phosphorylation and biological activities. As inflammation exists in a mutually dependent association with angiogenesis, we sought to determine if Ang1 and/or Ang2 could modulate proinflammatory activities, namely P-selectin translocation, in bovine aortic endothelial cells (EC) and dissect the mechanisms implicated. P-selectin, an adhesion molecule found in the Weibel-Palade bodies of EC, is translocated rapidly to the cell surface upon EC activation during inflammatory processes. Herein, we report that Ang1 and Ang2 (1 nM) are capable of mediating a rapid Tie2 phosphorylation as well as a rapid and transient endothelial P-selectin translocation maximal within 7.5 min (125% and 100% increase, respectively, over control values). In addition, we demonstrate for the first time that angiopoietin-mediated endothelial P-selectin translocation is calcium-dependent and regulated through phospholipase C-{gamma} activation.

Key Words: Tie2 receptor • adhesion molecules • angiogenic factors






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Copyright © 2007 by the Society for Leukocyte Biology.