Impaired AP-1 dimers and NFAT complex formation in immature thymocytes during in vivo glucocorticoid-induced apoptosis.
Ca2+-regulated nuclear factor of activated T cell (NFAT) family members are transcription factors crucial for the expression of various cytokine and other immunoregulatory genes. Moreover, NFAT transcription factors are involved in the regulation of development, maturation and selection of thymocytes. Typically, the NFAT complex is made up of NFATc (NFATc1-4) protein and activator protein-1 (AP-1) transcription factor. AP-1 is a dimer consisting of two Jun proteins (homodimers) or Jun and Fos proteins (heterodimers). We have previously reported that NFAT DNA-binding activity significantly decreases in the thymus during glucocorticoid-induced apoptosis. In this study, we demonstrate that the expression and phosphorylation status of the NFAT proteins do not change during glucocorticoid-induced apoptosis. This suggests that glucocorticoids do not disturb a signal transduction pathway leading to the activation of NFATc proteins in thymocytes. Although the levels of particular Jun and Fos proteins do not decrease after glucocorticoid administration, the formation or DNA-binding activity of some AP-1 dimers is specifically abolished. Thus, the observed inhibition of NFAT transcription factor activity during glucocorticoid-induced apoptosis is likely to be a consequence of this perturbation or the lack of a proper AP-1 component.
Wisniewska
Marta
M
Laboratory of Transcription Regulation, Department of Cell Biology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Pyrzynska
Beata
B
Kaminska
Bozena
B
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D051379:Mice; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D009687:Nuclear Proteins; D010750:Phosphoproteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D003907:Dexamethasone; D004247:DNA