Cooperative coactivation of estrogen receptor alpha in ZR-75 human breast cancer cells by SNURF and TATA-binding protein.
SNURF is a small RING finger protein that binds the zinc finger region of steroid hormone receptors and enhances Sp1- and androgen receptor-mediated transcription in COS and CV-1 cells. In this study, we show that SNURF coactivates both wild-type estrogen receptor alpha (ERalpha) (4-fold)- and HE19 (ERalpha deletion of activation function 1 (AF1)) (210-fold)-mediated activation of an estrogen-responsive element promoter in ZR-75 cells. In mammalian two-hybrid assays in ZR-75 cells SNURF interactions were estrogen (E2)-dependent and were not observed with the antiestrogen ICI 182,780. ERalpha interacted with multiple regions of SNURF; SNURF interactions with ERalpha were dependent on AF2, and D538N, E542Q, and D545N mutations in helix 12 abrogated both SNURF-ERalpha binding and coactivation. Moreover, peptide fusion proteins that inhibit interactions between helix 12 of ERalpha with LXXLL box-containing proteins also blocked ERalpha coactivation by SNURF. However, cotransfection of SNURF with prototypical steroid receptor coactivators 1, 2, and 3 that contain LXXLL box motifs did not enhance E2 responsiveness, whereas TATA-binding protein (TBP) and SNURF cooperatively coactivated ERalpha-mediated transactivation. The results are consistent with a unique model for cooperative coactivation of ERalpha that requires ligand binding, repositioning of helix 12, recruitment of TBP, and interaction with SNURF, which binds both ERalpha and TBP.
Saville
Bradley
B
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
Poukka
Hetti
H
Wormke
Mark
M
Janne
Olli A
OA
Palvimo
Jorma J
JJ
Stoner
Matthew
M
Samudio
Ismael
I
Safe
Stephen
S
D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D047628:Estrogen Receptor alpha; D004967:Estrogens / Q000378:metabolism; D000077267:Fulvestrant; D017353:Gene Deletion; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism*; D051958:Nuclear Receptor Coactivator 2; D009841:Oligonucleotides / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011960:Receptors, Estrogen / Q000737:chemistry / Q000378:metabolism*; D020218:Response Elements; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D016335:Zinc Fingers
D002843:Chromatin; D004268:DNA-Binding Proteins; D004965:Estrogen Antagonists; D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D004967:Estrogens; D008024:Ligands; D009687:Nuclear Proteins; D051958:Nuclear Receptor Coactivator 2; D009841:Oligonucleotides; D010455:Peptides; C114070:RNF4 protein, human; D011960:Receptors, Estrogen; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D000077267:Fulvestrant; D004958:Estradiol; D008156:Luciferases