title: Maintenance of human T cell anergy: blocking of IL-2 gene transcription by activated Rap1.
abstract: In the absence of costimulation, T cells activated through their antigen receptor become unresponsive (anergic) and do not transcribe the gene encoding interleukin-2 (IL-2) when restimulated with antigen. Anergic alloantigen-specific human T cells contained phosphorylated Cbl that coimmunoprecipitated with Fyn. The adapter protein CrkL was associated with both phosphorylated Cbl and the guanidine nucleotide-releasing factor C3G, which catalyzes guanosine triphosphate (GTP) exchange on Rap1. Active Rap1 (GTP-bound form) was present in anergic cells. Forced expression of low amounts of Rap1-GTP in Jurkat T cells recapitulated the anergic defect and blocked T cell antigen receptor (TCR)- and CD28-mediated IL-2 gene transcription. Therefore, Rap1 functions as a negative regulator of TCR-mediated IL-2 gene transcription and may be responsible for the specific defect in IL-2 production in T cell anergy.
authors.affiliation: Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA. vassiliki_boussiotis@macmailgw.dfci.harvard.edu
authors.forename: V A
authors.initials: VA
authors.lastname: Boussiotis
authors.forename: G J
authors.initials: GJ
authors.lastname: Freeman
authors.forename: A
authors.initials: A
authors.lastname: Berezovskaya
authors.forename: D L
authors.initials: DL
authors.lastname: Barber
authors.forename: L M
authors.initials: LM
authors.lastname: Nadler
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D018106:CD28 Antigens / Q000276:immunology; D017635:Clonal Anergy; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D020662:Guanine Nucleotide Exchange Factors; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050721:Proto-Oncogene Proteins c-cbl; D051076:Proto-Oncogene Proteins c-fyn; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D044767:Ubiquitin-Protein Ligases; D020668:rap GTP-Binding Proteins; D020663:ras Guanine Nucleotide Exchange Factors; D018631:ras Proteins / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018106:CD28 Antigens; C082869:CRKL protein; D020662:Guanine Nucleotide Exchange Factors; D007376:Interleukin-2; D009687:Nuclear Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; D020663:ras Guanine Nucleotide Exchange Factors; D006160:Guanosine Triphosphate; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins; D018631:ras Proteins; C067419:CBL protein, human