Document Detail

Identification of a GABP alpha/beta binding site involved in the induction of oxytocin receptor gene expression in human breast cells, potentiation by c-Fos/c-Jun.
MedLine Citation:
PMID:  10218980     Owner:  NLM     Status:  MEDLINE    
Oxytocin (OT) receptors (OTRs) mediate reproductive functions, including the initiation of labor and milk ejection. OTR messenger RNA levels are highly regulated, reaching the greatest concentration in the uterus at the end of gestation, and in the mammary gland during lactation. Factors directly effecting changes in OTR gene expression in the mammary gland are not known, so the present studies were done to elucidate possible regulators by characterizing the human OTR gene promoter and 5'-flanking sequence. By analyzing expression of promoter-luciferase constructs, we localized a region between -85 and -65 that was required for both basal and serum-induced expression in a mammary tumor cell line (Hs578T) that expresses inducible, endogenous OTRs. This DNA region contains an ets family target sequence (5'-GGA-3'), and a CRE/AP-1-like motif. The specific Ets factor binding to the OTR promoter was identified, by electrophoretic mobility immunoshift assays, to be GABP alpha/beta. Co-transfection of a -85 OTR/luciferase construct with vectors expressing GABP alpha and GABP beta1 had only a modest effect on expression, but cotransfection with GABP alpha/beta- with c-Fos/c-Jun-expressing plasmids resulted in an increase of almost 10-fold in luciferase activity. Mutation of either the GABP- or CRE-like binding sites obliterated the induction. These findings are consistent with the involvement of protein kinase C activity in serum induction of the endogenous gene in Hs578T cells. We showed the requirement for GABP alpha/beta and c-Fos/c-Jun in endogenous OTR gene expression, using oligonucleotide GABP and AP-1 binding decoys to inhibit serum-induced increases in 125I-labeled OT antagonist binding to Hs578T cells. Our work is the first characterization of the proximal promoter region of the human OTR gene, and it sets the stage for studying regulation of OTR expression in breast cells.
S Hoare; J A Copland; T G Wood; Y J Jeng; M G Izban; M S Soloff
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Endocrinology     Volume:  140     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  1999 May 
Date Detail:
Created Date:  1999-05-06     Completed Date:  1999-05-06     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2268-79     Citation Subset:  AIM; IM    
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555-1062, USA.
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MeSH Terms
Base Sequence
Binding Sites
Breast / metabolism*
Breast Neoplasms
DNA / chemistry
DNA-Binding Proteins / chemistry,  genetics,  metabolism*
GA-Binding Protein Transcription Factor
Gene Expression*
Genes, fos*
Genes, jun*
Molecular Sequence Data
Promoter Regions, Genetic
Receptors, Oxytocin / genetics*
Recombinant Fusion Proteins
Sp1 Transcription Factor / metabolism
Transcription Factor AP-1 / genetics,  metabolism
Transcription Factors / chemistry,  genetics,  metabolism*
Tumor Cells, Cultured
Grant Support
Reg. No./Substance:
0/DNA-Binding Proteins; 0/GA-Binding Protein Transcription Factor; 0/Receptors, Oxytocin; 0/Recombinant Fusion Proteins; 0/Sp1 Transcription Factor; 0/Transcription Factor AP-1; 0/Transcription Factors; 9007-49-2/DNA

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