Akt inhibits the orphan nuclear receptor Nur77 and T-cell apoptosis.
Akt is a common mediator of cell survival in a variety of circumstances. Although some candidate Akt targets have been described, the function of Akt is not fully understood, particularly because of the cell type- and context-dependent apoptosis regulation. In this study, we demonstrate that one of the mechanisms by which Akt antagonizes apoptosis involves the inhibition of Nur77, a transcription factor implicated in T-cell receptor-mediated apoptosis. It has been suggested that Akt phosphorylates Nur77 directly, but whether Akt suppresses biological functions of Nur77 remains unknown. We found that Akt inhibited the DNA binding activity of Nur77 and stimulated its association with 14-3-3 in a phosphorylation site-dependent manner. Moreover, we found that expression of Akt suppressed Nur77-induced apoptosis in fibroblasts and activation-induced cell death of T-cell hybridomas. The inhibition of Nur77 by Akt suggests a mechanism that explains how T-cell receptor activation can promote survival in some instances even when Nur77 is induced. Collectively, these results may suggest that Akt is a negative regulator of Nur77 in T-cell apoptosis.
Masuyama
N
N
Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Oishi
K
K
Mori
Y
Y
Ueno
T
T
Takahama
Y
Y
Gotoh
Y
Y
D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005802:Genes, MHC Class II; D006801:Humans; D006825:Hybridomas / Q000166:cytology; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D009924:Organ Culture Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000502:physiology; D011987:Receptors, Steroid; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016415:Sequence Alignment; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D048948:14-3-3 Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase; C539821:NR4A1 protein, human; C539818:Nr4a1 protein, mouse; C494918:AKT1 protein, human