title: Critical role of TNF receptor type-2 (p75) as a costimulator for IL-2 induction and T cell survival: a functional link to CD28.
abstract: CD28 provides important signals that lower the threshold of T cell activation, augment the production of IL-2, and promote T cell survival. The recent identification of a second family of costimulatory molecules within the TNFR family has reshaped the "two-signal" model of T cell activation. In this study the role of p75 as a T cell costimulatory molecule in controlling cell fate during TCR/CD28-mediated stimulation was examined. We found that p75-deficient T cells possess a profound defect in IL-2 production in response to TCR/CD28-mediated stimulation. Examination of key signaling intermediates revealed that TCR proximal events such as global tyrosine phosphorylation and ZAP70 phosphorylation, as well as downstream MAPK cascades are unperturbed in p75-deficient T cells. In contrast, p75 is nonredundantly coupled to sustained AKT activity and NF-kappaB activation in response to TCR/CD28-mediated stimulation. Moreover, p75-deficient T cells possess a defect in survival during the early phase of T cell activation that is correlated with a striking defect in Bcl-x(L) expression. These data indicate discrete effects of p75 on the intracellular signaling milieu during T cell activation, and reveal the synergistic requirement of TCR, CD28, and p75 toward optimal IL-2 induction and T cell survival. We propose that p75 acts as one of the earliest of the identified costimulatory members of the TNFR family, and is functionally linked to CD28 for initiating and determining T cell fate during activation.
authors.affiliation: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Edward Y
authors.initials: EY
authors.lastname: Kim
authors.forename: Hung-Sia
authors.initials: HS
authors.lastname: Teh
mesh_terms: D000276:Adjuvants, Immunologic / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D018106:CD28 Antigens / Q000502:physiology*; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000172:deficiency; D008213:Lymphocyte Activation / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000172:deficiency; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D047889:Receptors, Tumor Necrosis Factor, Type II; D015290:Second Messenger Systems / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D051020:bcl-X Protein
chemical_list: D000276:Adjuvants, Immunologic; D015703:Antigens, CD; C494812:Bcl2l1 protein, mouse; D018106:CD28 Antigens; D007376:Interleukin-2; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011948:Receptors, Antigen, T-Cell; D018124:Receptors, Tumor Necrosis Factor; D047889:Receptors, Tumor Necrosis Factor, Type II; D051020:bcl-X Protein; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt