title: Bclx regulates the survival of double-positive thymocytes.
abstract: The bclx gene has been shown to regulate programmed cell death in vitro. We now show that Bclx expression increases dramatically when T cells differentiate from CD4- CD8- (double negative) thymocytes to CD4+ CD8+ [double positive (DP)] thymocytes. In contrast single-positive (SP) thymocytes express negligible amounts of Bclx protein. This expression pattern contrasts with that of Bcl2, which is present in double-negative thymocytes, down-regulated in DP thymocytes, and reinduced upon maturation to SP thymocytes. Elimination of Bclx by gene targeting dramatically shortens the survival of DP thymocytes but not the survival of SP thymocytes or peripheral SP T cells. These data suggest that the induction of Bclx during thymic maturation plays a critical role in regulating the length of time DP thymocytes survive in the absence of selection.
authors.affiliation: Howard Hughes Medical Institute, Children's Hospital, Boston, MA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ma
authors.forename: J C
authors.initials: JC
authors.lastname: Pena
authors.forename: B
authors.initials: B
authors.lastname: Chang
authors.forename: E
authors.initials: E
authors.lastname: Margosian
authors.forename: L
authors.initials: L
authors.lastname: Davidson
authors.forename: F W
authors.initials: FW
authors.lastname: Alt
authors.forename: C B
authors.initials: CB
authors.lastname: Thompson
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D016923:Cell Death; D002470:Cell Survival / Q000276:immunology; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D015870:Gene Expression; D051379:Mice / Q000276:immunology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology; D013234:Stem Cells / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D051020:bcl-X Protein
chemical_list: D000911:Antibodies, Monoclonal; C494812:Bcl2l1 protein, mouse; D015704:CD4 Antigens; D016827:CD8 Antigens; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051020:bcl-X Protein