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Blood, 15 June 2007, Vol. 109, No. 12, pp. 5260-5269. Prepublished online as a Blood First Edition Paper on March 1, 2007; DOI 10.1182/blood-2006-10-054015. This Article Full Text Full Text (PDF) Supplemental Figures and Videos All Versions of this Article: blood-2006-10-054015v1 109/12/5260    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 Jirousková, M. Articles by Coller, B. S. Search for Related Content PubMed PubMed Citation Articles by Jirousková, M. Articles by Coller, B. S. Related Collections Hemostasis, Thrombosis, and Vascular Biology Cell Adhesion and Motility Cytoskeleton Signal Transduction Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  HEMOSTASIS, THROMBOSIS, AND VASCULAR BIOLOGY Ligand density dramatically affects integrin IIbß3-mediated platelet signaling and spreading Markéta Jirouková1, Jyoti K. Jaiswal2, and Barry S. Coller1 Laboratory of 1 Blood and Vascular Biology and 2 Cellular Biophysics, Rockefeller University, New York, NY The impact of ligand density on integrin-mediated cell adhesion and outside-in signaling is not well understood. Using total internal reflection fluorescent microscopy, conformation-specific antibodies, and Ca2+ flux measurements, we found that the surface density of fibrinogen affects IIbß3-mediated platelet signaling, adhesion, and spreading. Adhesion to fibrinogen immobilized at low density leads to rapid increases in cytosolic Ca2+ and sequential formation of filopodia and lamellipodia. In contrast, adhesion to high-density fibrinogen results in transient or no increases in Ca2+ and simultaneous formation of filopodia and lamellipodia. IIbß3 receptors at the basal surface of platelets engage fibrinogen in a ringlike pattern at the cell edges under both conditions. This engagement is, however, more dynamic and easily reversed on high-density fibrinogen. Src and Rac activity and actin polymerization are important for adhesion to low-density fibrinogen, whereas PKC/PI3 kinases contribute to platelet spreading on high-density fibrinogen. We conclude that 2 fundamentally different signaling mechanisms can be initiated by a single integrin receptor interacting with the same ligand when it is immobilized at different densities. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: S. M. Schoenwaelder, A. Ono, W. S. Nesbitt, J. Lim, K. Jarman, and S. P. Jackson Phosphoinositide 3-Kinase p110{beta} Regulates Integrin {alpha}IIb{beta}3 Avidity and the Cellular Transmission of Contractile Forces J. Biol. Chem., January 22, 2010; 285(4): 2886 - 2896. [Abstract] [Full Text] [PDF]

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