Protein kinase A activation of estrogen receptor α transcription does not require proteasome activity and protects the receptor from ligand-mediated degradation

Houng Wei Tsai, John A. Katzenellenbogen, Benita S. Katzenellenbogen, Margaret A. Shupnik

Research output: Contribution to journalArticle

Abstract

17β-Estradiol (E2)-stimulated estrogem receptor (ERα) transcription is accompanied by protein degradation via the 26S-proteasome pathway. Inhibition of proteasome activity stabilizes ERα protein and abolishes E2-activated transcription, suggesting functional linkages between transcription and degradation. It is not known whether ligand-independent ERalpha; activation is coupled to proteolysis. In pituitary cells, forskolin (FSK) stimulates ERα transcription through the protein kinase A (PKA) pathway. This study examined interactions between E2-dependent and PKA-stimulated pathways in GH3 cells by measuring transcription of a transfected reporter gene and endogenous ERα levels. E2 stimulated estrogen response element-mediated transcription 2- to 3-fold and decreased ERα protein levels to 40%. In contrast, FSK stimulated ERα transcription without decreasing ERα protein. Treatment with FSK plus E2 resulted in synergistic ERα transactivation, and FSK specifically prevented E2-induced ERα degradation. PKA is required for protection and was prevented by H89 (a PKA inhibitor), but not PD98059 (a MAPK kinase inhibitor). Propyl-pyrazole-triol and R,R-diethyl-tetrahydrochrysene, selective ERα agonists, reduced ERα protein by 50% while stimulating ERα transcriptional activity 4-to 8-fold. The antagonist ICI 182,780 similarly decreased ERα levels, but prevented ER activation. FSK prevented all ligand-induced ERα degradation. Lactacystin, a proteasome inhibitor, abolished E2-stimulated, but not FSK-stimulated, ERα transcription. Thus, stimulation of ERα transcription by the PKA-dependent pathway is dissociated from receptor degradation and proteasome activity. These data suggest a mechanism of ERα transcriptional activation by PKA that is distinct from E2 activation and that may contribute to the synergistic transcriptional activation of ERα by ligand-dependent and PKA-dependent pathways.

Original languageEnglish (US)
Pages (from-to)2730-2738
Number of pages9
JournalEndocrinology
Volume145
Issue number6
DOIs
StatePublished - Jun 1 2004

Fingerprint

Proteasome Endopeptidase Complex
Cyclic AMP-Dependent Protein Kinases
Estrogen Receptors
Colforsin
Ligands
Transcriptional Activation
Proteolysis
Proteins
Proteasome Inhibitors
Estrogen Receptor alpha
Mitogen-Activated Protein Kinase Kinases
Response Elements
Protein Kinase Inhibitors
Reporter Genes
Estradiol
Estrogens

ASJC Scopus subject areas

  • Endocrinology

Cite this

Protein kinase A activation of estrogen receptor α transcription does not require proteasome activity and protects the receptor from ligand-mediated degradation. / Tsai, Houng Wei; Katzenellenbogen, John A.; Katzenellenbogen, Benita S.; Shupnik, Margaret A.

In: Endocrinology, Vol. 145, No. 6, 01.06.2004, p. 2730-2738.

Research output: Contribution to journalArticle

@article{29215d1e2a824649a408e2175ed2c5c0,
title = "Protein kinase A activation of estrogen receptor α transcription does not require proteasome activity and protects the receptor from ligand-mediated degradation",
abstract = "17β-Estradiol (E2)-stimulated estrogem receptor (ERα) transcription is accompanied by protein degradation via the 26S-proteasome pathway. Inhibition of proteasome activity stabilizes ERα protein and abolishes E2-activated transcription, suggesting functional linkages between transcription and degradation. It is not known whether ligand-independent ERalpha; activation is coupled to proteolysis. In pituitary cells, forskolin (FSK) stimulates ERα transcription through the protein kinase A (PKA) pathway. This study examined interactions between E2-dependent and PKA-stimulated pathways in GH3 cells by measuring transcription of a transfected reporter gene and endogenous ERα levels. E2 stimulated estrogen response element-mediated transcription 2- to 3-fold and decreased ERα protein levels to 40{\%}. In contrast, FSK stimulated ERα transcription without decreasing ERα protein. Treatment with FSK plus E2 resulted in synergistic ERα transactivation, and FSK specifically prevented E2-induced ERα degradation. PKA is required for protection and was prevented by H89 (a PKA inhibitor), but not PD98059 (a MAPK kinase inhibitor). Propyl-pyrazole-triol and R,R-diethyl-tetrahydrochrysene, selective ERα agonists, reduced ERα protein by 50{\%} while stimulating ERα transcriptional activity 4-to 8-fold. The antagonist ICI 182,780 similarly decreased ERα levels, but prevented ER activation. FSK prevented all ligand-induced ERα degradation. Lactacystin, a proteasome inhibitor, abolished E2-stimulated, but not FSK-stimulated, ERα transcription. Thus, stimulation of ERα transcription by the PKA-dependent pathway is dissociated from receptor degradation and proteasome activity. These data suggest a mechanism of ERα transcriptional activation by PKA that is distinct from E2 activation and that may contribute to the synergistic transcriptional activation of ERα by ligand-dependent and PKA-dependent pathways.",
author = "Tsai, {Houng Wei} and Katzenellenbogen, {John A.} and Katzenellenbogen, {Benita S.} and Shupnik, {Margaret A.}",
year = "2004",
month = "6",
day = "1",
doi = "10.1210/en.2003-1470",
language = "English (US)",
volume = "145",
pages = "2730--2738",
journal = "Endocrinology",
issn = "0013-7227",
publisher = "The Endocrine Society",
number = "6",

}

TY - JOUR

T1 - Protein kinase A activation of estrogen receptor α transcription does not require proteasome activity and protects the receptor from ligand-mediated degradation

AU - Tsai, Houng Wei

AU - Katzenellenbogen, John A.

AU - Katzenellenbogen, Benita S.

AU - Shupnik, Margaret A.

PY - 2004/6/1

Y1 - 2004/6/1

N2 - 17β-Estradiol (E2)-stimulated estrogem receptor (ERα) transcription is accompanied by protein degradation via the 26S-proteasome pathway. Inhibition of proteasome activity stabilizes ERα protein and abolishes E2-activated transcription, suggesting functional linkages between transcription and degradation. It is not known whether ligand-independent ERalpha; activation is coupled to proteolysis. In pituitary cells, forskolin (FSK) stimulates ERα transcription through the protein kinase A (PKA) pathway. This study examined interactions between E2-dependent and PKA-stimulated pathways in GH3 cells by measuring transcription of a transfected reporter gene and endogenous ERα levels. E2 stimulated estrogen response element-mediated transcription 2- to 3-fold and decreased ERα protein levels to 40%. In contrast, FSK stimulated ERα transcription without decreasing ERα protein. Treatment with FSK plus E2 resulted in synergistic ERα transactivation, and FSK specifically prevented E2-induced ERα degradation. PKA is required for protection and was prevented by H89 (a PKA inhibitor), but not PD98059 (a MAPK kinase inhibitor). Propyl-pyrazole-triol and R,R-diethyl-tetrahydrochrysene, selective ERα agonists, reduced ERα protein by 50% while stimulating ERα transcriptional activity 4-to 8-fold. The antagonist ICI 182,780 similarly decreased ERα levels, but prevented ER activation. FSK prevented all ligand-induced ERα degradation. Lactacystin, a proteasome inhibitor, abolished E2-stimulated, but not FSK-stimulated, ERα transcription. Thus, stimulation of ERα transcription by the PKA-dependent pathway is dissociated from receptor degradation and proteasome activity. These data suggest a mechanism of ERα transcriptional activation by PKA that is distinct from E2 activation and that may contribute to the synergistic transcriptional activation of ERα by ligand-dependent and PKA-dependent pathways.

AB - 17β-Estradiol (E2)-stimulated estrogem receptor (ERα) transcription is accompanied by protein degradation via the 26S-proteasome pathway. Inhibition of proteasome activity stabilizes ERα protein and abolishes E2-activated transcription, suggesting functional linkages between transcription and degradation. It is not known whether ligand-independent ERalpha; activation is coupled to proteolysis. In pituitary cells, forskolin (FSK) stimulates ERα transcription through the protein kinase A (PKA) pathway. This study examined interactions between E2-dependent and PKA-stimulated pathways in GH3 cells by measuring transcription of a transfected reporter gene and endogenous ERα levels. E2 stimulated estrogen response element-mediated transcription 2- to 3-fold and decreased ERα protein levels to 40%. In contrast, FSK stimulated ERα transcription without decreasing ERα protein. Treatment with FSK plus E2 resulted in synergistic ERα transactivation, and FSK specifically prevented E2-induced ERα degradation. PKA is required for protection and was prevented by H89 (a PKA inhibitor), but not PD98059 (a MAPK kinase inhibitor). Propyl-pyrazole-triol and R,R-diethyl-tetrahydrochrysene, selective ERα agonists, reduced ERα protein by 50% while stimulating ERα transcriptional activity 4-to 8-fold. The antagonist ICI 182,780 similarly decreased ERα levels, but prevented ER activation. FSK prevented all ligand-induced ERα degradation. Lactacystin, a proteasome inhibitor, abolished E2-stimulated, but not FSK-stimulated, ERα transcription. Thus, stimulation of ERα transcription by the PKA-dependent pathway is dissociated from receptor degradation and proteasome activity. These data suggest a mechanism of ERα transcriptional activation by PKA that is distinct from E2 activation and that may contribute to the synergistic transcriptional activation of ERα by ligand-dependent and PKA-dependent pathways.

UR - http://www.scopus.com/inward/record.url?scp=2542501575&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=2542501575&partnerID=8YFLogxK

U2 - 10.1210/en.2003-1470

DO - 10.1210/en.2003-1470

M3 - Article

C2 - 15033909

AN - SCOPUS:2542501575

VL - 145

SP - 2730

EP - 2738

JO - Endocrinology

JF - Endocrinology

SN - 0013-7227

IS - 6

ER -