Involvement of a specificity proteins-binding element in regulation of basal and estrogen-induced transcription activity of the BRCA1 gene

Persistent Link:
http://hdl.handle.net/10150/610112
Title:
Involvement of a specificity proteins-binding element in regulation of basal and estrogen-induced transcription activity of the BRCA1 gene
Author:
Hockings, Jennifer; Degner, Stephanie; Morgan, Sherif; Kemp, Michael; Romagnolo, Donato
Affiliation:
Cancer Biology Interdisciplinary Graduate Program, Department of Nutritional Sciences, The University of Arizona, E 4th Street, Tucson, Arizona 85721-0038, USA; Laboratory of Mammary Gland Biology, Department of Nutritional Sciences, The University of Arizona, E 4th Street, Tucson, Arizona 85721-0038, USA
Issue Date:
2008
Publisher:
BioMed Central
Citation:
Breast Cancer Research 2008, 10:R29 (doi:10.1186/bcr1987)
Journal:
Breast Cancer Research
Rights:
© 2008 Hockings et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0)
Collection Information:
This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at repository@u.library.arizona.edu.
Abstract:
INTRODUCTION:Increased estrogen level has been regarded to be a risk factor for breast cancer. However, estrogen has also been shown to induce the expression of the tumor suppressor gene, BRCA1. Upregulation of BRCA1 is thought to be a feedback mechanism for controlling DNA repair in proliferating cells. Estrogens enhance transcription of target genes by stimulating the association of the estrogen receptor (ER) and related coactivators to estrogen response elements or to transcription complexes formed at activator protein (AP)-1 or specificity protein (Sp)-binding sites. Interestingly, the BRCA1 gene lacks a consensus estrogen response element. We previously reported that estrogen stimulated BRCA1 transcription through the recruitment of a p300/ER-alpha complex to an AP-1 site harbored in the proximal BRCA1 promoter. The purpose of the study was to analyze the contribution of cis-acting sites flanking the AP-1 element to basal and estrogen-dependent regulation of BRCA1 transcription.METHODS:Using transfection studies with wild-type and mutated BRCA1 promoter constructs, electromobility binding and shift assays, and DNA-protein interaction and chromatin immunoprecipitation assays, we investigated the role of Sp-binding sites and cAMP response element (CRE)-binding sites harbored in the proximal BRCA1 promoter.RESULTS:We report that in the BRCA1 promoter the AP-1 site is flanked upstream by an element (5'-GGGGCGGAA-3') that recruits Sp1, Sp3, and Sp4 factors, and downstream by a half CRE-binding motif (5'-CGTAA-3') that binds CRE-binding protein. In ER-alpha-positive MCF-7 cells and ER-alpha-negative Hela cells expressing exogenous ER-alpha, mutation of the Sp-binding site interfered with basal and estrogen-induced BRCA1 transcription. Conversely, mutation of the CRE-binding element reduced basal BRCA1 promoter activity but did not prevent estrogen activation. In combination with the AP-1/CRE sites, the Sp-binding domain enhanced the recruitment of nuclear proteins to the BRCA1 promoter. Finally, we report that the MEK1 (mitogen-activated protein kinase kinase-1) inhibitor PD98059 attenuated the recruitment of Sp1 and phosphorylated ER-alpha, respectively, to the Sp and AP-1 binding element.CONCLUSION:These cumulative findings suggest that the proximal BRCA1 promoter segment comprises cis-acting elements that are targeted by Sp-binding and CRE-binding proteins that contribute to regulation of BRCA1 transcription.
EISSN:
1465-542X
DOI:
10.1186/bcr1987
Version:
Final published version
Additional Links:
http://breast-cancer-research.com/content/10/2/R29

Full metadata record

DC FieldValue Language
dc.contributor.authorHockings, Jenniferen
dc.contributor.authorDegner, Stephanieen
dc.contributor.authorMorgan, Sherifen
dc.contributor.authorKemp, Michaelen
dc.contributor.authorRomagnolo, Donatoen
dc.date.accessioned2016-05-20T08:58:51Z-
dc.date.available2016-05-20T08:58:51Z-
dc.date.issued2008en
dc.identifier.citationBreast Cancer Research 2008, 10:R29 (doi:10.1186/bcr1987)en
dc.identifier.doi10.1186/bcr1987en
dc.identifier.urihttp://hdl.handle.net/10150/610112-
dc.description.abstractINTRODUCTION:Increased estrogen level has been regarded to be a risk factor for breast cancer. However, estrogen has also been shown to induce the expression of the tumor suppressor gene, BRCA1. Upregulation of BRCA1 is thought to be a feedback mechanism for controlling DNA repair in proliferating cells. Estrogens enhance transcription of target genes by stimulating the association of the estrogen receptor (ER) and related coactivators to estrogen response elements or to transcription complexes formed at activator protein (AP)-1 or specificity protein (Sp)-binding sites. Interestingly, the BRCA1 gene lacks a consensus estrogen response element. We previously reported that estrogen stimulated BRCA1 transcription through the recruitment of a p300/ER-alpha complex to an AP-1 site harbored in the proximal BRCA1 promoter. The purpose of the study was to analyze the contribution of cis-acting sites flanking the AP-1 element to basal and estrogen-dependent regulation of BRCA1 transcription.METHODS:Using transfection studies with wild-type and mutated BRCA1 promoter constructs, electromobility binding and shift assays, and DNA-protein interaction and chromatin immunoprecipitation assays, we investigated the role of Sp-binding sites and cAMP response element (CRE)-binding sites harbored in the proximal BRCA1 promoter.RESULTS:We report that in the BRCA1 promoter the AP-1 site is flanked upstream by an element (5'-GGGGCGGAA-3') that recruits Sp1, Sp3, and Sp4 factors, and downstream by a half CRE-binding motif (5'-CGTAA-3') that binds CRE-binding protein. In ER-alpha-positive MCF-7 cells and ER-alpha-negative Hela cells expressing exogenous ER-alpha, mutation of the Sp-binding site interfered with basal and estrogen-induced BRCA1 transcription. Conversely, mutation of the CRE-binding element reduced basal BRCA1 promoter activity but did not prevent estrogen activation. In combination with the AP-1/CRE sites, the Sp-binding domain enhanced the recruitment of nuclear proteins to the BRCA1 promoter. Finally, we report that the MEK1 (mitogen-activated protein kinase kinase-1) inhibitor PD98059 attenuated the recruitment of Sp1 and phosphorylated ER-alpha, respectively, to the Sp and AP-1 binding element.CONCLUSION:These cumulative findings suggest that the proximal BRCA1 promoter segment comprises cis-acting elements that are targeted by Sp-binding and CRE-binding proteins that contribute to regulation of BRCA1 transcription.en
dc.language.isoenen
dc.publisherBioMed Centralen
dc.relation.urlhttp://breast-cancer-research.com/content/10/2/R29en
dc.rights© 2008 Hockings et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0)en
dc.titleInvolvement of a specificity proteins-binding element in regulation of basal and estrogen-induced transcription activity of the BRCA1 geneen
dc.typeArticleen
dc.identifier.eissn1465-542Xen
dc.contributor.departmentCancer Biology Interdisciplinary Graduate Program, Department of Nutritional Sciences, The University of Arizona, E 4th Street, Tucson, Arizona 85721-0038, USAen
dc.contributor.departmentLaboratory of Mammary Gland Biology, Department of Nutritional Sciences, The University of Arizona, E 4th Street, Tucson, Arizona 85721-0038, USAen
dc.identifier.journalBreast Cancer Researchen
dc.description.collectioninformationThis item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
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