Activation domains of CCAAT enhancer binding protein delta: regions required for native activity and prostaglandin E2-dependent transactivation of insulin-like growth factor I gene expression in rat osteoblasts.
In osteoblasts, hormones such as prostaglandin E2 that activate protein kinase A increase the translocation of transcription factor CCAAT/enhancer binding protein delta (C/EBPdelta) from the cytoplasm to the nucleus where it rapidly induces IGF-I gene expression. In this study, we identified activation and suppression domains in C/EBPdelta using native and heterologous gene promoter assay systems. We demonstrated functional interactions between C/EBPdelta and trans-gene-expressed cAMP response element binding protein-binding protein, and showed that the ability of C/EBPdelta to promote gene expression was suppressed by viral protein E1A, which blocks the activity of native cAMP response element binding protein-binding protein. Site-directed mutations at serines 62 or 191 within C/EBPdelta reduced its basal transcriptional activity, whereas mutation at serine 191 suppressed the stimulatory effect of prostaglandin E2 on C/EBPdelta function as well as its DNA binding potential. These results are consistent with the location of serine 191 in the DNA binding domain of C/EBPdelta. Our studies provide the first evidence for regions of C/EBPdelta that are important for basal and for hormone-induced transcriptional activity, and for its interactions with other enhancers and suppressers of gene expression.
Ji
Changhua
C
Department of Surgery, Yale University School of Medicine, New Haven, Connecticut 06520-8041, USA. thomas.mccarthy@yale.edu.
Chang
Weizhong
W
Centrella
Michael
M
McCarthy
Thomas L
TL
D000818:Animals; D051743:CCAAT-Enhancer-Binding Protein-delta; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D050882:CREB-Binding Protein; D015232:Dinoprostone / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010006:Osteoblasts / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D022762:CCAAT-Enhancer-Binding Proteins; C497254:Cebpd protein, rat; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051743:CCAAT-Enhancer-Binding Protein-delta; D007334:Insulin-Like Growth Factor I; D050882:CREB-Binding Protein; C494365:Crebbp protein, rat; D015232:Dinoprostone