Cell-type specific activity of two glucocorticoid responsive units of rat tyrosine aminotransferase gene is associated with multiple binding sites for C/EBP and a novel liver-specific nuclear factor.
The structures of two remote glucocorticoid responsive units (GRUs) that cooperatively interact to promote cell-type specific glucocorticoid induction of rat tyrosine aminotransferase gene expression have been analyzed. DNAase I footprinting and gel mobility shift analyses reveal a complex array of contiguous and overlapping sites for cell type-specific DNA binding proteins. Apart from the glucocorticoid receptor, two liver-specific nuclear factors possess multiple binding sites in each of these GRUs: C/EBP and a newly identified liver-specific factor: HNF5. C/EBP possesses four binding sites in each GRU; a DNA-binding protein with similar binding specificity has been identified in fibroblasts; this protein could be related to AP-3. HNF5 possesses two binding sites in one GRU and four in the other. There are also HNF5 binding sites in numerous regulatory regions of other liver-specific genes. The interaction of HNF5 with DNA gives a characteristic DNAase I footprint with hypersensitive sites in the middle of the recognition sequence. Some of the C/EBP and HNF5 binding sites overlap in a conserved arrangement.
Grange
T
T
Institut Jacques Monod du CNRS, Université Paris, France.
Roux
J
J
Rigaud
G
G
Pictet
R
R
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D022762:CCAAT-Enhancer-Binding Proteins; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*; D014444:Tyrosine Transaminase / Q000235:genetics* / Q000378:metabolism
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA; D014444:Tyrosine Transaminase; D003850:Deoxyribonuclease I