Functional interaction between a RARE and an AP-2 binding site in the regulation of the human HOX A4 gene promoter.
HOX A genes are induced in a temporal fashion after retinoic acid (RA) treatment in non-N-ras-transformed PA-1 human teratcarcinoma cells. However, In N-ras-transformed PA-1 cells, RA-Induced expression of HOX A genes is delayed. The mRNA for the transcriptional activator AP-2 is overexpressed in these ras-transformed cells, but AP-2 transcriptional activity is inhibited relative to non ras-transformed PA-1 cells. Constitutive expression of AP-2 mimics the effect of ras by transforming cells and inhibiting differentiation in culture. We analyzed 4 kb of the human HOX A4 gene promoter and identified seven putative AP-2-binding sites in the DNA sequence. Transcription assays with variably sized HOX A4 promoter reporter constructs revealed that a 365 bp region of the promoter, -2950 to -3315 relative to the mRNA start, controls RA responsiveness and ras-mediated inhibition of HOX A4 activity. This region contains an AP-2 binding site and a RARE. Elimination of the AP-2 site by site-directed mutagenesis demonstrated that the AP-2 site is involved in RA-mediated transcriptional activation of the human HOX A4 promoter in combination with the RA receptor response element (RARE). In N-ras-transformed cells, low HOX A4 promoter activity results from ras inhibition of AP-2 transactivation.
Doerksen
L F
LF
Department of Tumor Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Bhattacharya
A
A
Kannan
P
P
Pratt
D
D
Tainsky
M A
MA
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D018168:Receptors, Retinoic Acid; D050656:Transcription Factor AP-2; D014157:Transcription Factors; C073547:HOXA4 protein, human; D014212:Tretinoin; D018631:ras Proteins