Document Detail

Small GTPases and LFA-1 reciprocally modulate adhesion and signaling.
MedLine Citation:
PMID:  17624948     Owner:  NLM     Status:  MEDLINE    
Leukocyte-function-associated antigen-1 (LFA-1) is an integrin that is critical for T-cell adhesion and immunologic responses. As a transmembrane receptor and adhesion molecule, LFA-1 signals bidirectionally, whereby information about extracellular ligands is passed outside-in while cellular activation is transmitted inside-out to the adhesive ectodomain. Here, we review the role of small guanosine triphosphatases (GTPases) in LFA-1 signaling. Rap1, a Ras-related GTPase, appears to be central to LFA-1 function. Rap1 is regulated by receptor signaling [e.g. T-cell receptor (TCR), CD28, and cytotoxic T-lymphocyte antigen-4 (CTLA-4)] and by adapter proteins [e.g. adhesion and degranulation-promoting adapter protein (ADAP) and Src kinase-associated phosphoprotein of 55 kDa (SKAP-55)]. Inside-out signaling flows through Rap1 to regulator of adhesion and cell polarization enriched in lymphoid tissues (RAPL) and Rap1-GTP interacting adapter molecule (RIAM) that act in conjunction with the cytoskeleton on the cytosolic domain of LFA-1 to increase adhesion of the ectodomain. Outside-in signaling also relies on small GTPases such as Rho proteins. Vav-1, a guanine nucleotide exchange factor for Rho proteins, is activated as a consequence of LFA-1 engagement. Jun-activating binding protein-1 (JAB-1) and cytohesin-1 have been implicated as possible outside-in signaling intermediates. We have recently shown that Ras is also downstream of LFA-1 engagement: LFA-1 signaling through phospholipase D (PLD) to RasGRP1 was required for Ras activation on the plasma membrane following stimulation of TCR.
Adam Mor; Michael L Dustin; Mark R Philips
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Immunological reviews     Volume:  218     ISSN:  0105-2896     ISO Abbreviation:  Immunol. Rev.     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-07-12     Completed Date:  2007-09-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7702118     Medline TA:  Immunol Rev     Country:  Denmark    
Other Details:
Languages:  eng     Pagination:  114-25     Citation Subset:  IM    
Department of Medicine, NYU School of Medicine, New York, NY 10016, USA.
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MeSH Terms
Adaptor Proteins, Signal Transducing / metabolism
Cell Adhesion
Lymphocyte Function-Associated Antigen-1 / immunology*,  metabolism*
Models, Immunological
Monomeric GTP-Binding Proteins / immunology*,  metabolism*
Signal Transduction / immunology*
Reg. No./Substance:
0/Adaptor Proteins, Signal Transducing; 0/Lymphocyte Function-Associated Antigen-1; EC GTP-Binding Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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