title: Expression of the Bcl-2 family member A1 is developmentally regulated in T cells.
abstract: During T cell development, cells that fail to meet stringent selection criteria undergo programmed cell death. Thymocyte and peripheral T cell susceptibility to apoptosis is influenced by expression of Bcl-2 family members, some of which are expressed in a developmentally patterned manner. We previously showed developmentally regulated expression of A1, an anti-apoptotic Bcl-2 family member, among B cell developmental subsets. Here we show that cells of the T lineage also express A1 in a developmentally regulated manner. Both A1 mRNA and A1 protein are readily detectable in the thymus, and while present among DN cells, A1 mRNA is up-regulated to very high levels among double-positive (DP) thymocytes. It is then down-regulated to moderate levels among single-positive (SP) thymocytes, and finally expressed at approximately 25-fold lower levels among mature SP CD4(+) and CD8(+) lymph node T cells than among DP thymocytes. Furthermore, we find that in vitro TCR ligation up-regulates A1 expression among both DP and SP thymocytes. Together, these data show that A1 expression is developmentally regulated in T lymphocytes and is responsive to TCR signaling, suggesting that A1 may play a role in maintaining the viability of DP thymocytes.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6082, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Tomayko
authors.forename: J A
authors.initials: JA
authors.lastname: Punt
authors.forename: J M
authors.initials: JM
authors.lastname: Bolcavage
authors.forename: S L
authors.initials: SL
authors.lastname: Levy
authors.forename: D M
authors.initials: DM
authors.lastname: Allman
authors.forename: M P
authors.initials: MP
authors.lastname: Cancro
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002454:Cell Differentiation; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015778:Minor Histocompatibility Antigens; D016133:Polymerase Chain Reaction; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D051818:Replication Protein C; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000378:metabolism
chemical_list: D000199:Actins; C096816:BCL2-related protein A1; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C096063:MATA1 protein, S cerevisiae; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D051818:Replication Protein C