Duration of calcineurin and Erk signals regulates CD4/CD8 lineage commitment of thymocytes.
CD4/CD8 lineage commitment of thymocytes is controlled by the T cell receptor-mediated signals and is mimicked in vitro by a long-pulse stimulation of isolated CD4(+)CD8(+) thymocytes with proper combinations of phorbol myristate acetate and the calcium ionophore ionomycin. CD4 lineage commitment required higher intracellular Ca(2+) levels than CD8 lineage commitment in this culture system. The calcineurin inhibitor FK506 at 1nM inhibited the development of thymocytes to either lineage, but 0.3nM FK506 significantly switched the development from the CD4 cell fate to the CD8 cell fate. The switch in lineage commitment was also observed when 1nM FK506 was added 8h after the start of the culture. Delayed addition of 20microM U0126, an Mek (Erk kinase) inhibitor, also induced the switch. These results suggest that the intensity of calcineurin activity and the duration of both calcineurin and Erk pathway activation are crucial for thymocyte lineage commitment.
Mitsubishi Kagaku Institute of Life Sciences, 11 Minamiooya, Machida-shi, Tokyo 194-8511, Japan.
Satoko
S
Adachi
Makoto
M
Iwata
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019703:Calcineurin / Q000378:metabolism / Q000502:physiology*; D065095:Calcineurin Inhibitors; D020013:Calcium Signaling; D019070:Cell Lineage / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D007700:Kinetics; D020935:MAP Kinase Signaling System; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D016559:Tacrolimus / Q000494:pharmacology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
D065095:Calcineurin Inhibitors; D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D019703:Calcineurin; D016559:Tacrolimus