CCAAT/enhancer binding protein gene promoter: binding of nuclear factors during differentiation of 3T3-L1 preadipocytes.
Differentiation of 3T3-L1 preadipocytes into adipocytes is accompanied by increased expression of the nuclear protein C/EBP (CCAAT/enhancer binding protein) and by transcriptional activation of a group of adipose-specific genes. We report here the isolation of the murine C/EBP gene and the characterization of its promoter. Consistent with its proposed role in coordinating transcription during preadipocyte differentiation, an increase in the rate of transcription of the C/EBP gene precedes that of several adipose-specific genes whose promoters are transactivated by C/EBP. DNase I cleavage-inhibition patterns (footprinting) of the C/EBP gene promoter by nuclear factors from differentiated and undifferentiated 3T3-L1 cells identified two sites of differential factor binding. One site in the C/EBP gene promoter between nucleotides -252 and -239 binds a nuclear factor(s) present in preadipocytes that is lost or modified upon differentiation. Another site, between nucleotides -203 and -176, exhibits different but overlapping footprints by nuclear factors present in differentiated and undifferentiated cells. Gel retardation analysis with oligonucleotides corresponding to these sites revealed protein-oligonucleotide complexes containing these differentially expressed nuclear factors. The factor present in differentiated cells that binds at this site was identified as C/EBP (possibly in heterodimeric form with a homologous leucine-zipper protein), suggesting that C/EBP may regulate expression of its own gene.
Christy
R J
RJ
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Kaestner
K H
KH
Geiman
D E
DE
Lane
M D
MD
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D003850:Deoxyribonuclease I; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009710:Nucleotide Mapping; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015183:Restriction Mapping; D016385:TATA Box; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D003850:Deoxyribonuclease I