TEF-1 transrepression in BeWo cells is mediated through interactions with the TATA-binding protein, TBP.
Transcription enhancer factor-1 (TEF-1) has been implicated in transactivating a placental enhancer (CSEn) that regulates human chorionic somatomammotropin (hCS) gene activity. We demonstrated that TEF-1 represses hCS promoter activity in choriocarcinoma (BeWo) cells (Jiang, S.W., and Eberhardt, N.L. (1995) J. Biol. Chem. 270, 13609-13915), suggesting that TEF-1 interacts with basal transcription factors. Here we demonstrate that hTEF-1 overexpression inhibits minimal hCS promoters containing TATA and/or initiator elements, Rous sarcoma virus and thymidine kinase promoters in BeWo cells. Cotransfection of TEF-1 antisense oligonucleotides alleviated exogenous TEF-1-mediated repression and increased basal hCS promoter activity, indicating that endogenous TEF-1 exerts repressor activity. GST-TEF-1 fusion peptides fixed to glutathione-Sepharose beads retained in vitro-generated human TATA-binding protein, hTBP. The TEF-1 proline-rich domain was essential for TBP binding, but polypeptides also containing the zinc finger domain bound TBP with higher apparent affinity. TBP supershifted hTEF-GT-IIC DNA complexes, but TEF-1 inhibited in vitro binding of TBP to the TATA motif. Coexpression of TBP and TEF-1 in BeWo cells alleviated TEF-1-mediated transrepression, indicating that the TBP-TEF-1 interaction is functional in vivo. The data indicate that TEF-1 transrepression is mediated by direct interactions with TBP, possibly by inhibiting preinitiation complex formation.
Jiang
S W
SW
Endocrine Research Unit, Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Eberhardt
N L
NL
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002822:Choriocarcinoma; D003001:Cloning, Molecular; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011247:Pregnancy; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012097:Repressor Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D016385:TATA Box; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms
D015342:DNA Probes; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors; D011388:Prolactin; D008156:Luciferases