A twenty-two-fold increase in the relative affinity of estrogen receptor to poly (dA-dC).poly (dG-dT) in the presence of polyamines.
We studied the relative efficacy of polyamines to facilitate the binding of estrogen receptor to poly(dA-dC).poly(dG-dT). In the absence of polyamines, 1,400 micrograms/ml of this polynucleotide eluted 50% of bound estrogen receptor from DNA-cellulose. In contrast, 50% estrogen receptor was eluted by 65 micrograms/ml of poly(dA-dC).poly(dG-dT) complexed with 150 microM spermidine. Putrescine and spermine also enhanced the ability of poly(dA-dC).poly(dG-dT) to elute estrogen receptor, but the magnitude of the effect was not as high as that of spermidine. Control experiments with calf thymus DNA and poly(dA-dT).poly(dA-dT) showed 6- and 3-fold increase, respectively in their affinity for estrogen receptor in the presence of spermidine. The dramatic increase in the affinity of poly(dA-dC).poly(dG-dT) for estrogen receptor in the presence of polyamines might be a result of the conversion of the polynucleotide to the left-handed Z-DNA form. These results show that polyamines are capable of participating in estrogenic regulation of gene expression by altering the affinity of the receptor for specific DNA sequences.
Thomas
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Department of Medicine, University of Minnesota Hospital and Clinic, University of Minnesota, Minneapolis 55455.
Kiang
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D000818:Animals; D001667:Binding, Competitive; D002846:Chromatography, Affinity / Q000379:methods; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D011089:Polydeoxyribonucleotides / Q000378:metabolism*; D011700:Putrescine / Q000494:pharmacology*; D011817:Rabbits; D011960:Receptors, Estrogen / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D013095:Spermidine / Q000494:pharmacology*; D013096:Spermine / Q000494:pharmacology*; D014599:Uterus / Q000378:metabolism
D011089:Polydeoxyribonucleotides; D011960:Receptors, Estrogen; D013096:Spermine; C028333:poly(d(A-C).d(G-T)); D004247:DNA; D013095:Spermidine; D011700:Putrescine