Stimulation of CD28 with B7-2 promotes focal adhesion-like cell contacts where Rho family small G proteins accumulate in T cells.
Unless a costimulatory signal is provided, TCR recognition of Ag bound to the MHC is insufficient to induce optimal T cell proliferation or the production of IL-2. Here we show that the stimulation of CD28, a T cell costimulatory receptor, by a specific Ab increases F-actin contents in T cells. The interaction between T cells and B7-2-transfected Chinese hamster ovary cells expressing the CD28 ligand leads to the rearrangement of the actin cytoskelton in the region of cell-cell contact. Within the Rho family of G proteins, Rac1, but not Rho, translocates to the sites of cell-cell contact where Tailin also accumulates. These results indicate that the interaction between B7-2 and CD28 establishes a focal adhesion-like cell contact between T cell and APCs. The results also suggest that CD28 signaling is primarily transduced by a cytoskeletal rearrangement/signaling pathway mediated by the Rho family G proteins.
Kaga
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The John P. Robarts Research Institute, The Department of Microbiology and Immunology, London, Ontario, Canada.
Ragg
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Rogers
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Ochi
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D008841:Actin Cytoskeleton / Q000502:physiology; D000199:Actins / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D051940:B7-2 Antigen; D018106:CD28 Antigens / Q000502:physiology*; D016466:CHO Cells; D002448:Cell Adhesion; D006224:Cricetinae; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology*; D016608:Talin / Q000378:metabolism; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins
D000199:Actins; D015703:Antigens, CD; D051940:B7-2 Antigen; D018106:CD28 Antigens; C497965:Cd86 protein, mouse; D008562:Membrane Glycoproteins; D016608:Talin; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins