Functional interactions between the estrogen receptor and the transcription activator Sp1 regulate the estrogen-dependent transcriptional activity of the vitellogenin A1 io promoter.
Two distinct, TATA box-containing promoters regulate the transcriptional activity of the Xenopus vitellogenin A1 gene. These two promoters are of different strength and are separated by 1.8 kilobase pairs of untranslated sequence. Estrogen receptor (ER) and its ligand, 17beta-estradiol, induce the activity of both promoters. The estrogen response elements (EREs) are located proximal to the downstream i promoter while no ERE-like sequences have been identified in the vicinity of the upstream io promoter. We show here, that transcriptional activity of the upstream io promoter is Sp1-dependent. Moreover, we demonstrate that estrogen inducibility of the io promoter results from functional interactions between the io bound Sp1 and the ER bound at the proximity of i. Functional interactions between Sp1 and ER do not require the presence of a TATA box for transcriptional activation, as is demonstrated using the acyl-CoA oxidase promoter. The relative positions that ER and Sp1 occupy with respect to the initiation site determines whether these two transcription activators can synergize for transcription initiation.
Batistuzzo de Medeiros
S R
SR
Institut de Biologie animale, Université de Lausanne, CH-1015 Lausanne, Switzerland.
Krey
G
G
Hihi
A K
AK
Wahli
W
W
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004331:Drosophila melanogaster; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011960:Receptors, Estrogen / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D016385:TATA Box; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation; D014162:Transfection; D014819:Vitellogenins / Q000096:biosynthesis* / Q000235:genetics*; D014982:Xenopus laevis
D004967:Estrogens; D015345:Oligonucleotide Probes; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor; D014819:Vitellogenins