title: A role for mammalian target of rapamycin in regulating T cell activation versus anergy.
abstract: Whether TCR engagement leads to activation or tolerance is determined by the concomitant delivery of multiple accessory signals, cytokines, and environmental cues. In this study, we demonstrate that the mammalian target of rapamycin (mTOR) integrates these signals and determines the outcome of TCR engagement with regard to activation or anergy. In vitro, Ag recognition in the setting of mTOR activation leads to full immune responses, whereas recognition in the setting of mTOR inhibition results in anergy. Full T cell activation is associated with an increase in the phosphorylation of the downstream mTOR target S6 kinase 1 at Thr(421)/Ser(424) and an increase in the mTOR-dependent cell surface expression of transferrin receptor (CD71). Alternatively, the induction of anergy results in markedly less S6 kinase 1 Thr(421)/Ser(424) phosphorylation and CD71 surface expression. Likewise, the reversal of anergy is associated not with proliferation, but rather the specific activation of mTOR. Importantly, T cells engineered to express a rapamycin-resistant mTOR construct are resistant to anergy induction caused by rapamycin. In vivo, mTOR inhibition promotes T cell anergy under conditions that would normally induce priming. Furthermore, by examining CD71 surface expression, we are able to distinguish and differentially isolate anergic and activated T cells in vivo. Overall, our data suggest that by integrating environmental cues, mTOR plays a central role in determining the outcome of Ag recognition.
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University Medical Institutions, Baltimore, MD 21231, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Collins
authors.forename: Michael A
authors.initials: MA
authors.lastname: Lutz
authors.forename: Amy N
authors.initials: AN
authors.lastname: Allen
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Kole
authors.forename: Paul E
authors.initials: PE
authors.lastname: Zarek
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Powell
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects; D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology; D017635:Clonal Anergy / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D011494:Protein Kinases / Q000276:immunology* / Q000378:metabolism; D011990:Receptors, Transferrin / Q000096:biosynthesis / Q000276:immunology; D019893:Ribosomal Protein S6 Kinases / Q000276:immunology / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D058570:TOR Serine-Threonine Kinases
chemical_list: D015703:Antigens, CD; C068126:CD71 antigen; D007166:Immunosuppressive Agents; D011990:Receptors, Transferrin; D011494:Protein Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus