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Cofilin-Mediated F-Actin Severing Is Regulated by the Rap GTPase and Controls the Cytoskeletal Dynamics That Drive Lymphocyte Spreading and BCR Microcluster Formation.
MedLine Citation:
PMID:  22068232     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
When lymphocytes encounter APCs bearing cognate Ag, they spread across the surface of the APC to scan for additional Ags. This is followed by membrane contraction and the formation of Ag receptor microclusters that initiate the signaling reactions that lead to lymphocyte activation. Breakdown of the submembrane cytoskeleton is likely to be required for the cytoskeleton reorganization that drives cell spreading and for removing physical barriers that limit Ag receptor mobility. In this report, we show that Ag receptor signaling via the Rap GTPases promotes the dephosphorylation and activation of the actin-severing protein cofilin and that this results in increased severing of cellular actin filaments. Moreover, we show that this cofilin-mediated actin severing is critical for the changes in actin dynamics that drive B and T cell spreading, for the formation of BCR microclusters, and for the increased mobility of BCR microclusters within the plasma membrane after BCR engagement. Finally, using a model APC, we show that activation of this Rap-cofilin signaling module controls the amount of Ag that is gathered into BCR microclusters and that this is directly related to the magnitude of the resulting BCR signaling that is initiated during B cell-APC interactions. Thus, Rap-dependent activation of cofilin is critical for the early cytoskeletal changes and BCR reorganization that are involved in APC-dependent lymphocyte activation.
Authors:
Spencer A Freeman; Victor Lei; May Dang-Lawson; Kensaku Mizuno; Calvin D Roskelley; Michael R Gold
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-7
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  -     ISSN:  1550-6606     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Microbiology and Immunology, I and Cell and Developmental Biology Research Groups, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
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