Molecular characterization of the Xenopus CCAAT-enhancer binding protein beta gene promoter.
Transcription factors belonging to the CCAAT-enhancer binding protein (C/EBP) family play key roles in the regulation of genes implicated in the control of growth, differentiation, metabolism, and inflammation. The recent limited studies on the promoter regions of C/EBP genes, particularly C/EBPalpha, have indicated the potential existence of species-specific regulatory mechanisms. It is therefore essential that the promoter regions of different C/EBP genes from a wide range of species are investigated in detail. As an important step toward this goal, we report here the characterization of the Xenopus laevis C/EBPbeta gene promoter. Sequence analysis showed that the 1.6-kb promoter region contained putative binding sites for several transcription factors that have previously been implicated in the regulation of the C/EBPs, including C/EBP, CREB, Myb, STAT, and USF. The -288/+91 promoter region was capable of directing high levels of expression in the hepatoma Hep3B cell line. In addition, this minimal promoter could be autoregulated by both C/EBPalpha and C/EBPbeta and activated by lipopolysaccharide, interleukin-6 and CREB. These results therefore demonstrate that several aspects of C/EBPbeta regulation in mammals have been highly conserved in amphibians. However, a comparison of C/EBPbeta gene promoters characterized to date does indicate the existence of species-specific differences in autoregulation.
Foka
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Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, Wales, UK.
Kousteni
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Ramji
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DP
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics* / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular; D017124:Conserved Sequence; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008113:Liver Neoplasms; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D016385:TATA Box; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014982:Xenopus laevis / Q000235:genetics*
D022782:CCAAT-Enhancer-Binding Protein-beta; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014157:Transcription Factors