Regulation of prothymosin α gene expression by estrogen in estrogen receptor-containing breast cancer cells via upstream half-palindromic estrogen response element motifs

Paolo G.V. Martini, Benita S. Katzenellenbogen

Research output: Contribution to journalArticle

Abstract

Prothymosin α (PTα), a protein associated with cell proliferation and chromatin remodeling, and found to selectively enhance ER transcriptional activity by interacting with a repressor of ER activity, is shown to be a primary response gene to estrogen. Prothymosin α mRNA was rapidly increased by estrogen, followed by a 6-fold increase in prothymosin α protein content in ER-containing breast cancer cells. Analysis of the prothymosin α promoter and 5′-flanking region, and electrophoretic gel mobility shift studies showed the strong inducibility by the estradiol-ER complex to be mediated by two consensus half-palindromic estrogen response elements at -750 and -1051, which directly bind the ER. Estrogenic stimulation of prothymosin α required a DNA binding form of ER with a functional activation function-2 domain. The prothymosin α 5′-regulatory region also contains multiple Sp1 sites. Although addition of Sp1 did not further enhance estradiol-ER stimulated prothymosin α transcriptional activity in breast cancer cells, transfection and response element mutagenesis studies using Drosophila cells, which are deficient in Sp1, revealed that Sp1 and the estradiol occupied-ER can each activate the prothymosin α gene independently of the other and act in an additive manner. These observations, documenting robust prothymosin α up-regulation by the estradiol-ER complex via widely spaced half-palindromic estrogen response element motifs, are reminiscent of those shown previously for the ovalbumin gene and suggest that the use of multiple half response elements may be a more common mode for regulation of gene expression by the ER than previously appreciated. In addition, these observations suggest interrelationships between cell proliferation and gene transcriptional activities and indicate a positive mechanism by which PTα, which increases ER transcriptional effectiveness, is itself up-regulated by the estrogen-ER complex.

Original languageEnglish (US)
Pages (from-to)3493-3501
Number of pages9
JournalEndocrinology
Volume142
Issue number8
DOIs
StatePublished - Jan 1 2001

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Gene Expression Regulation
Response Elements
Estrogen Receptors
Estrogens
Breast Neoplasms
Estradiol
Genes
Cell Proliferation
Chromatin Assembly and Disassembly
5' Flanking Region
Nucleic Acid Regulatory Sequences
Ovalbumin
Mutagenesis
Drosophila
Transfection
Proteins
Up-Regulation
Gels
Messenger RNA
DNA

ASJC Scopus subject areas

  • Endocrinology

Cite this

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title = "Regulation of prothymosin α gene expression by estrogen in estrogen receptor-containing breast cancer cells via upstream half-palindromic estrogen response element motifs",
abstract = "Prothymosin α (PTα), a protein associated with cell proliferation and chromatin remodeling, and found to selectively enhance ER transcriptional activity by interacting with a repressor of ER activity, is shown to be a primary response gene to estrogen. Prothymosin α mRNA was rapidly increased by estrogen, followed by a 6-fold increase in prothymosin α protein content in ER-containing breast cancer cells. Analysis of the prothymosin α promoter and 5′-flanking region, and electrophoretic gel mobility shift studies showed the strong inducibility by the estradiol-ER complex to be mediated by two consensus half-palindromic estrogen response elements at -750 and -1051, which directly bind the ER. Estrogenic stimulation of prothymosin α required a DNA binding form of ER with a functional activation function-2 domain. The prothymosin α 5′-regulatory region also contains multiple Sp1 sites. Although addition of Sp1 did not further enhance estradiol-ER stimulated prothymosin α transcriptional activity in breast cancer cells, transfection and response element mutagenesis studies using Drosophila cells, which are deficient in Sp1, revealed that Sp1 and the estradiol occupied-ER can each activate the prothymosin α gene independently of the other and act in an additive manner. These observations, documenting robust prothymosin α up-regulation by the estradiol-ER complex via widely spaced half-palindromic estrogen response element motifs, are reminiscent of those shown previously for the ovalbumin gene and suggest that the use of multiple half response elements may be a more common mode for regulation of gene expression by the ER than previously appreciated. In addition, these observations suggest interrelationships between cell proliferation and gene transcriptional activities and indicate a positive mechanism by which PTα, which increases ER transcriptional effectiveness, is itself up-regulated by the estrogen-ER complex.",
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N2 - Prothymosin α (PTα), a protein associated with cell proliferation and chromatin remodeling, and found to selectively enhance ER transcriptional activity by interacting with a repressor of ER activity, is shown to be a primary response gene to estrogen. Prothymosin α mRNA was rapidly increased by estrogen, followed by a 6-fold increase in prothymosin α protein content in ER-containing breast cancer cells. Analysis of the prothymosin α promoter and 5′-flanking region, and electrophoretic gel mobility shift studies showed the strong inducibility by the estradiol-ER complex to be mediated by two consensus half-palindromic estrogen response elements at -750 and -1051, which directly bind the ER. Estrogenic stimulation of prothymosin α required a DNA binding form of ER with a functional activation function-2 domain. The prothymosin α 5′-regulatory region also contains multiple Sp1 sites. Although addition of Sp1 did not further enhance estradiol-ER stimulated prothymosin α transcriptional activity in breast cancer cells, transfection and response element mutagenesis studies using Drosophila cells, which are deficient in Sp1, revealed that Sp1 and the estradiol occupied-ER can each activate the prothymosin α gene independently of the other and act in an additive manner. These observations, documenting robust prothymosin α up-regulation by the estradiol-ER complex via widely spaced half-palindromic estrogen response element motifs, are reminiscent of those shown previously for the ovalbumin gene and suggest that the use of multiple half response elements may be a more common mode for regulation of gene expression by the ER than previously appreciated. In addition, these observations suggest interrelationships between cell proliferation and gene transcriptional activities and indicate a positive mechanism by which PTα, which increases ER transcriptional effectiveness, is itself up-regulated by the estrogen-ER complex.

AB - Prothymosin α (PTα), a protein associated with cell proliferation and chromatin remodeling, and found to selectively enhance ER transcriptional activity by interacting with a repressor of ER activity, is shown to be a primary response gene to estrogen. Prothymosin α mRNA was rapidly increased by estrogen, followed by a 6-fold increase in prothymosin α protein content in ER-containing breast cancer cells. Analysis of the prothymosin α promoter and 5′-flanking region, and electrophoretic gel mobility shift studies showed the strong inducibility by the estradiol-ER complex to be mediated by two consensus half-palindromic estrogen response elements at -750 and -1051, which directly bind the ER. Estrogenic stimulation of prothymosin α required a DNA binding form of ER with a functional activation function-2 domain. The prothymosin α 5′-regulatory region also contains multiple Sp1 sites. Although addition of Sp1 did not further enhance estradiol-ER stimulated prothymosin α transcriptional activity in breast cancer cells, transfection and response element mutagenesis studies using Drosophila cells, which are deficient in Sp1, revealed that Sp1 and the estradiol occupied-ER can each activate the prothymosin α gene independently of the other and act in an additive manner. These observations, documenting robust prothymosin α up-regulation by the estradiol-ER complex via widely spaced half-palindromic estrogen response element motifs, are reminiscent of those shown previously for the ovalbumin gene and suggest that the use of multiple half response elements may be a more common mode for regulation of gene expression by the ER than previously appreciated. In addition, these observations suggest interrelationships between cell proliferation and gene transcriptional activities and indicate a positive mechanism by which PTα, which increases ER transcriptional effectiveness, is itself up-regulated by the estrogen-ER complex.

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