title: Regulation of the Nur77 orphan steroid receptor in activation-induced apoptosis.
abstract: T-cell receptor (TCR)-mediated apoptosis in immature thymocytes and T-cell hybridomas is calcium dependent and can be inhibited by cyclosporin A (CsA). Induction of the orphan steroid receptor Nur77 (NGFI-B) is required for activation-induced apoptosis. Here, we examined the regulation of Nur77 expression, in response to apoptotic TCR signals, which consists of kinase C and calcium pathways. We show that the major control of Nur77 induction is mediated by the calcium signaling pathway. In contrast, protein kinase C signals induce only a low level of Nur77 activity. Nur77 promoter activity parallels its protein levels. CsA decreases both Nur77 protein levels and promoter activity, and the kinetics of CsA inhibition of apoptosis correlates with a decrease in Nur77 protein levels. TCR signals and kinase C signals result in a similar level of Nur77 protein phosphorylation but mediate differential transactivation activity of Nur77. In addition, Nur77 promoter deletion analysis revealed two RSRF (related to serum-responsive factor) binding sites, which can confer calcium and CsA sensitivity on a heterologous promoter. Taken together, our data suggest that the levels of transcriptional induction of Nur77 play an important role during activation-induced apoptosis and that calcium signals regulate a novel CsA-sensitive nuclear factor required for Nur77 transcription in T cells.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Woronicz
authors.forename: A
authors.initials: A
authors.lastname: Lina
authors.forename: B J
authors.initials: BJ
authors.lastname: Calnan
authors.forename: S
authors.initials: S
authors.lastname: Szychowski
authors.forename: L
authors.initials: L
authors.lastname: Cheng
authors.forename: A
authors.initials: A
authors.lastname: Winoto
mesh_terms: D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D016572:Cyclosporine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D006825:Hybridomas; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007376:Interleukin-2 / Q000096:biosynthesis; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008213:Lymphocyte Activation; D064326:MEF2 Transcription Factors; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D018006:Myogenic Regulatory Factors; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D007476:Ionophores; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; C539818:Nr4a1 protein, mouse; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D009838:Oligodeoxyribonucleotides; D011948:Receptors, Antigen, T-Cell; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D014157:Transcription Factors; D015759:Ionomycin; D016572:Cyclosporine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate