Impaired AP-1 dimers and NFAT complex formation in immature thymocytes during in vivo glucocorticoid-induced apoptosis

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• 作者：Wisniewska ; Marta ; Pyrzynska ; Beata ; Kaminska ; Bozena
• 关键词：Thymocytes ; Apoptosis ; NFAT ; AP-1 ; Glucocorticoid receptor ; Fos proteins ; Jun proteins ; GR ; glucocorticoid receptor ; Dex ; dexamethasone ; NFAT ; nuclear factor of activated T cells ; AP-1 ; activator protein-1
• 刊名：Cell Biology International
• 出版年：2004
• 出版时间：November, 2004
• 年：2004
• 卷：28
• 期：11
• 页码：773-780
• 全文大小：335 K

文摘

Ca(2+)-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.