Activation function 2 mediates dioxin-induced recruitment of estrogen receptor alpha to CYP1A1 and CYP1B1.
We investigated the role of the activation function 1 (AF1) and AF2 domains of estrogen receptor alpha (ERalpha) in mediating dioxin-dependent recruitment of ERalpha to cytochrome P4501A1 (CYP1A1) and CYP1B1 in HuH-7 human hepatoma cells. Dioxin-induced recruitment of ERalpha wildtype (ERalpha-WT) and an ERalpha AF1 deletion mutant (ERalpha-DeltaAF1), but not a transcriptional inactive AF2 mutant (ERalpha-AF2mut) to CYP1A1 and CYP1B1. Direct interactions between AHR and the AF1 and AF2 domains of ERalpha were observed, and were independent of mutations in the AF2. Expression of ERalpha-WT increased dioxin-induced CYP1A1 and CYP1B1-regulated reporter activity, and CYP1A1 and CYP1B1 mRNA levels. However, no increases in gene expression above vector controls were observed in cells transfected with ERalpha-DeltaAF1 or ERalpha-AF2mut. Our data show that the AF2 domain contributes to dioxin-induced recruitment of ERalpha to AHR target genes, but that both the AF1 and AF2 domains are required for ERalpha-dependent increases in AHR activity.
MacPherson
Laura
L
Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ont, Canada.
Lo
Raymond
R
Ahmed
Shaimaa
S
Pansoy
Andrea
A
Matthews
Jason
J
D001189:Aryl Hydrocarbon Hydroxylases; D045744:Cell Line, Tumor; D019363:Cytochrome P-450 CYP1A1 / Q000235:genetics*; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists / Q000378:metabolism*; D017384:Sequence Deletion
C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1