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Blood, 15 March 2008, Vol. 111, No. 6, pp. 3024-3033. Prepublished online as a Blood First Edition Paper on January 8, 2008; DOI 10.1182/blood-2007-06-098657. This Article Full Text Full Text (PDF) Supplemental Figure All Versions of this Article: blood-2007-06-098657v1 111/6/3024    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Garnacho, C. Articles by Muro, S. Search for Related Content PubMed PubMed Citation Articles by Garnacho, C. Articles by Muro, S. Related Collections Hemostasis, Thrombosis, and Vascular Biology Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY RhoA activation and actin reorganization involved in endothelial CAM-mediated endocytosis of anti-PECAM carriers: critical role for tyrosine 686 in the cytoplasmic tail of PECAM-1 Carmen Garnacho1,2, Vladimir Shuvaev2, Anu Thomas2, Lindsay McKenna1, Jing Sun3, Michael Koval4, Steven Albelda2,3, Vladimir Muzykantov1,2,5, and Silvia Muro1,2,5 1 Department of Pharmacology; 2 Institute for Environmental Medicine; and 3 Pulmonary Critical Care Division of the Department of Medicine, School of Medicine, University of Pennsylvania, Philadelphia; 4 Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, GA; and 5 Targeted Therapeutics Program of the Institute for Translational Medicine, School of Medicine, University of Pennsylvania, Philadelphia Platelet-endothelial cell adhesion molecule-1 (PECAM-1), a transmembrane glycoprotein involved in leukocyte transmigration, represents a good target for endothelial drug delivery (eg, using antibody-directed nanocarriers, anti-PECAM/NCs). Although endothelial cells do not internalize PECAM antibodies, PECAM-1 engagement by multivalent anti-PECAM conjugates and nanocarriers causes endocytosis via a nonclassic CAM-mediated pathway. We found that endothelial uptake of multivalent anti-PECAM complexes is associated with PECAM-1 phosphorylation. Using model REN cells expressing a series of PECAM-1 deletion and point mutants, we found that the PECAM-1 cytoplasmic domain and, more precisely, PECAM-1 tyrosine 686, is critical in mediating RhoA activation and recruitment of EGFP-RhoA to anti-PECAM/NC binding sites at the plasmalemma, actin polymerization into phalloidin-positive stress fibers, and finally CAM endocytosis of anti-PECAM/NCs. Endothelial targeting and endocytosis of anti-PECAM/NCs were markedly efficient and did not compromise endothelial barrier function in vitro (determined by immunostaining of VE-cadherin and 125I-albumin transport across endothelial monolayers) or in vivo (determined by electron microscopy imaging of pulmonary capillaries and 125I-albumin transport from the blood into the lung tissue after intravenous injection of anti-PECAM/NCs in mice). These results reveal PECAM-1 signaling and interactions with the cytoskeleton, which are required for CAM-endocytosis, and may provide safe intra-endothelial drug delivery by anti-PECAM/NCs. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: K. A. Massey and J. E. Schnitzer Targeting and Imaging Signature Caveolar Molecules in Lungs Proceedings of the ATS, August 15, 2009; 6(5): 419 - 430. [Abstract] [Full Text] [PDF]

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