The role of the CCAAT/enhancer-binding protein in the transcriptional regulation of the gene for phosphoenolpyruvate carboxykinase (GTP).
Previous studies have identified a region in the promoter of the gene for phosphoenolpyruvate carboxykinase (GTP) (PEPCK) (positions -460 to +73) containing the regulatory elements which respond to cyclic AMP, glucocorticoids, and insulin and confer the tissue- and developmental stage-specific properties to the gene. We report that CCAAT/enhancer-binding protein (C/EBP) binds to the cyclic AMP-responsive element CRE-1 as well as to two regions which have been previously shown to bind proteins enriched in liver nuclei. The DNase I footprint pattern provided by the recombinant C/EBP was identical to that produced by a 43-kDa protein purified from rat liver nuclear extracts, using a CRE oligonucleotide affinity column, which was originally thought to be the CRE-binding protein CREB. Transient contransfection experiments using a C/EBP expression vector demonstrated that C/EBP could trans activate the PEPCK promoter. The trans activation occurred through both the upstream, liver-specific protein-binding domains and the CRE. The CRE-binding protein bound only to CRE-1 and not to the upstream C/EBP-binding sites. The results of this study, along with physiological properties of C/EBP, indicate an important role for this transcription factor in providing the PEPCK gene with several of its regulatory characteristics.
Park
E A
EA
Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
Roesler
W J
WJ
Liu
J
J
Klemm
D J
DJ
Gurney
A L
AL
Thatcher
J D
JD
Shuman
J
J
Friedman
A
A
Hanson
R W
RW
D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism*; D015345:Oligonucleotide Probes; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D022762:CCAAT-Enhancer-Binding Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D011994:Recombinant Proteins; D014157:Transcription Factors; D010729:Phosphoenolpyruvate Carboxykinase (GTP)