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Blood, 15 February 2007, Vol. 109, No. 4, pp. 1515-1523. Prepublished online as a Blood First Edition Paper on October 5, 2006; DOI 10.1182/blood-2006-07-034009.
HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY Caveolin-1 regulates expression of junction-associated proteins in brain microvascular endothelial cells1 Blood-Brain Barrier Laboratory, Department of Pharmacology, University of Connecticut Health Center, Farmington Recent evidence from this laboratory indicated that reduced expression of caveolin-1 accompanied the diminished expression of tight junction (TJ)associated proteins occludin and zonula occludens-1 (ZO-1) following stimulation of brain microvascular endothelial cells (BMECs) with the chemokine CCL2 (formerly called MCP-1). Because attenuated caveolin-1 levels have also been correlated with heightened permeability of other endothelia, the objective of this study was to test the hypothesis that reduced caveolin-1 expression is causally linked to the action of CCL2 on BMEC junctional protein expression and barrier integrity. This was achieved using adenovirus to nondestructively deliver caveolin-1 siRNA (Ad-siCav-1) to BMEC monolayers, which model the blood-brain barrier (BBB). Treatment with siRNA reduced the caveolin-1 protein level as well as occludin and ZO-1. Additionally, occludin exhibited dissociation from the cytoskeletal framework. These changes were attended by comparable alterations in adherens junction (AJ)associated proteins, VE-cadherin and ß-catenin, increased BMEC paracellular permeability, and facilitated the ability of CCL2 to stimulate monocytic transendothelial migration. Furthermore, treating BMECs with cavtratin, a synthetic cell-permeable peptide encoding the caveolin-1 scaffolding domain, antagonized effects of both Ad-siCav-1 and CCL2. These results collectively highlight caveolin-1 loss as a critical step in CCL2-induced modulation of BMEC junctional protein expression and integrity, and possibly serve a crucial role in regulating inflammation at the BBB.
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| Copyright © 2007 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||||