The scaffolding protein CG-NAP/AKAP450 is a critical integrating component of the LFA-1-induced signaling complex in migratory T cells.
T cell migration represents a complex highly coordinated process involving participation of surface receptor/ligand interactions, cytoskeletal rearrangements, and phosphorylation-dependent signaling cascades. Members of the A-kinase anchoring protein (AKAP) family of giant scaffolding proteins can assemble and compartmentalize multiple signaling and structural molecules thereby providing a platform for their targeted positioning and efficient interactions. We characterize here the expression, intracellular distribution, and functional role of the scaffolding protein CG-NAP (centrosome and Golgi localized protein kinase N-associated protein)/AKAP450 in the process of active T cell motility induced via LFA-1 integrins. This protein is predominantly localized at the centrosome and Golgi complex. T cell locomotion triggered by LFA-1 ligation induces redistribution of CG-NAP/AKAP450 along microtubules in trailing cell extensions. Using an original in situ immunoprecipitation approach, we show that CG-NAP/AKAP450 is physically associated with LFA-1 in the multimolecular signaling complex also including tubulin and the protein kinase C beta and delta isoenzymes. CG-NAP/AKAP450 recruitment to this complex was specific for the T cells migrating on LFA-1 ligands, but not on the beta(1) integrin ligand fibronectin. Using the GFP-tagged C-terminal CG-NAP/AKAP450 construct, we demonstrate that expression of the intact CG-NAP/AKAP450 and its recruitment to the LFA-1-associated multimolecular complex is critically important for polarization and migration of T cells induced by this integrin.
El Din El Homasany
Basma Salah
BS
Department of Clinical Medicine, Trinity College, Dublin Molecular Medicine Center, Dublin, Ireland.
Volkov
Yuri
Y
Takahashi
Mikiko
M
Ono
Yoshitaka
Y
Keryer
Guy
G
Delouvée
Annie
A
Looby
Eileen
E
Long
Aideen
A
Kelleher
Dermot
D
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018385:Centrosome / Q000378:metabolism; D002634:Chemotaxis, Leukocyte; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism; D046912:Multiprotein Complexes / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000502:physiology
D054758:A Kinase Anchor Proteins; C119719:AKAP9 protein, human; D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D016169:Lymphocyte Function-Associated Antigen-1; D046912:Multiprotein Complexes