title: Ternary complex factor SAP-1 is required for Erk-mediated thymocyte positive selection.
abstract: Thymocyte selection and differentiation requires extracellular signal-regulated kinase (Erk) signaling, but transcription factor substrates of Erk in thymocytes are unknown. We have characterized the function of SAP-1 (Elk4), an Erk-regulated transcription factor, in thymocyte development. Early thymocyte development was normal, but single-positive thymocyte and peripheral T cell numbers were reduced, reflecting a T cell-autonomous defect. T cell receptor-induced activation of SAP-1 target genes such as Egr1 was substantially impaired in double-positive thymocytes, although Erk activation was normal. Analysis of T cell receptor transgenes showed that positive selection was reduced by 80-90% in SAP-1-deficient mice; heterozygous mice showed a moderate defect. Negative selection was unimpaired. SAP-1 thus directly links Erk signaling to the transcriptional events required for thymocyte positive selection.
authors.affiliation: Transcription Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Fields, London WC2A 3PX, UK.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Costello
authors.forename: Robert H
authors.initials: RH
authors.lastname: Nicolas
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Ian
authors.initials: I
authors.lastname: Rosewell
authors.forename: Richard
authors.initials: R
authors.lastname: Treisman
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D020935:MAP Kinase Signaling System; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000254:growth & development / Q000276:immunology*; D014158:Transcription, Genetic; D050808:ets-Domain Protein Elk-4
chemical_list: D004268:DNA-Binding Proteins; C494194:Elk4 protein, mouse; D011948:Receptors, Antigen, T-Cell; D050808:ets-Domain Protein Elk-4; D020928:Mitogen-Activated Protein Kinases