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Address correspondence to Christopher D. O'Brien, Dept. of Pulmonary/Critical Care, University of Pennsylvania, 838 BRB II/III, 421 Curie Blvd., Philadelphia, PA 19104. Tel.: (215) 746-6709. Fax: (215) 573-4469. E-mail: christoo{at}mail.med.UPENN.edu
Hydrogen peroxide (H2O2) released by neutrophils is an important mediator of endothelial cell (EC) injury and vascular inflammation via its effect on EC-free Ca2+, [Ca2+]i. Although the underlying mechanisms are not well understood, platelet endothelial cell adhesion molecule (PECAM)-1/CD-31 is a critical modulator of neutrophilEC transmigration. PECAM-1 is also known to regulate EC calcium signals and to undergo selective tyrosine phosphorylation. Here, we report that PECAM-1 molecules transduce EC responses to hydrogen peroxide. In human umbilical vein EC and REN cells (a PECAM-1negative EC-like cell line) stably transfected with PECAM-1 (RHP), noncytolytic H2O2 exposure (100200 µM H2O2) activated a calcium-permeant, nonselective cation current, and a transient rise in [Ca2+]i of similar time course. Neither response was observed in untransfected REN cells, and H2O2-evoked cation current was ablated in REN cells transfected with PECAM-1 constructs mutated in the cytoplasmic tyrosinecontaining domain. The PECAM-dependent H2O2 current was inhibited by dialysis of antiPECAM-1 cytoplasmic domain antibodies, required Src family tyrosine kinase activity, was independent of inositol trisphosphate receptor activation, and required only an intact PECAM-1 cytoplasmic domain. PECAM-1dependent H2O2 currents and associated [Ca2+]i transients may play a significant role in regulating neutrophilendothelial interaction, as well as in oxidant-mediated endothelial response and injury.
Key Words: hydrogen peroxide; capacitative current; calcium; tyrosine kinase; ion channels
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J. Cell Biol. 2002 157: 10.
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