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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.

Abstract：

: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.

journal_name

Endocrinology

journal_title

Endocrinology

authors

Hoare S,Copland JA,Wood TG,Jeng YJ,Izban MG,Soloff MS

doi

10.1210/endo.140.5.6710

subject

Has Abstract

pub_date

1999-05-01 00:00:00

pages

2268-79

issue

eissn

0013-7227

issn

1945-7170

journal_volume

140

pub_type

杂志文章

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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.