title: Regulation of LFA-1-dependent inflammatory cell recruitment by Cbl-b and 14-3-3 proteins.
abstract: Inside-out signaling regulation of the beta2-integrin leukocyte function-associated antigen-1 (LFA-1) by different cytoplasmic proteins, including 14-3-3 proteins, is essential for adhesion and migration of immune cells. Here, we identify a new pathway for the regulation of LFA-1 activity by Cbl-b, an adapter molecule and ubiquitin ligase that modulates several signaling pathways. Cbl-b-/- mice displayed increased macrophage recruitment in thioglycollate-induced peritonitis, which was attributed to Cbl-b deficiency in macrophages, as assessed by bone marrow chimera experiments. In vitro, Cbl-b-/- bone marrow-derived mononuclear phagocytes (BMDMs) displayed increased adhesion to endothelial cells. Activation of LFA-1 in Cbl-b-deficient cells was responsible for their increased endothelial adhesion in vitro and peritoneal recruitment in vivo, as the phenotype of Cbl-b deficiency was reversed in Cbl-b-/-LFA-1-/- mice. Consistently, LFA-1-mediated adhesion of BMDM to ICAM-1 but not VLA-4-mediated adhesion to VCAM-1 was enhanced by Cbl-b deficiency. Cbl-b deficiency resulted in increased phosphorylation of T758 in the beta2-chain of LFA-1 and thereby in enhanced association of 14-3-3beta protein with the beta2-chain, leading to activation of LFA-1. Consistently, disruption of the 14-3-3/beta2-integrin interaction abrogated the enhanced ICAM-1 adhesion of Cbl-b-/- BMDMs. In conclusion, Cbl-b deficiency activates LFA-1 and LFA-1-mediated inflammatory cell recruitment by stimulating the interaction between the LFA-1 beta-chain and 14-3-3 proteins.
authors.affiliation: Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Choi
authors.forename: Valeria V
authors.initials: VV
authors.lastname: Orlova
authors.forename: Susanna C
authors.initials: SC
authors.lastname: Fagerholm
authors.forename: Susanna M
authors.initials: SM
authors.lastname: Nurmi
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Christie M
authors.initials: CM
authors.lastname: Ballantyne
authors.forename: Carl G
authors.initials: CG
authors.lastname: Gahmberg
authors.forename: Triantafyllos
authors.initials: T
authors.lastname: Chavakis
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000276:immunology*; D000818:Animals; D018821:CD18 Antigens / Q000235:genetics / Q000276:immunology; D002448:Cell Adhesion / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology; D039041:Integrin alpha4beta1 / Q000235:genetics / Q000276:immunology; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000276:immunology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000235:genetics / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D050722:Oncogene Protein v-cbl / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000276:immunology
chemical_list: D048948:14-3-3 Proteins; D018821:CD18 Antigens; C090509:Icam1 protein, mouse; D039041:Integrin alpha4beta1; D016169:Lymphocyte Function-Associated Antigen-1; D050722:Oncogene Protein v-cbl; D018799:Intercellular Adhesion Molecule-1; D044767:Ubiquitin-Protein Ligases