MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Acevedo, M. L.
Right arrow Articles by Kraus, W. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Acevedo, M. L.
Right arrow Articles by Kraus, W. L.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, January 2003, p. 335-348, Vol. 23, No. 1
0270-7306/03/$08.00+0     DOI: 10.1128/MCB.23.1.335-348.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor {alpha}-Dependent Transcription with Chromatin Templates

Mari Luz Acevedo1,2 and W. Lee Kraus1,2,3*

Department of Molecular Biology and Genetics,1 Graduate Field of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853,2 Department of Pharmacology, Weill Medical College of Cornell University, New York, New York 100213

Received 22 August 2002/ Returned for modification 3 October 2002/ Accepted 15 October 2002

Ligand-dependent transcriptional activation by nuclear receptors involves the recruitment of various coactivators to the promoters of hormone-regulated genes assembled into chromatin. Nuclear receptor coactivators include histone acetyltransferase complexes, such as p300/CBP-steroid receptor coactivator (SRC), as well as the multisubunit mediator complexes ("Mediator"), which may help recruit RNA polymerase II to the promoter. We have used a biochemical approach, including an in vitro chromatin assembly and transcription system, to examine the functional role for Mediator in the transcriptional activity of estrogen receptor {alpha} (ER{alpha}) with chromatin templates, as well as functional interplay between Mediator and p300/CBP during ER{alpha}-dependent transcription. Using three different approaches to functionally inactivate Mediator (immunoneutralization, immunodepletion, and inhibitory polypeptides), we find that Mediator is required for maximal transcriptional activation by ligand-activated ER{alpha}. In addition, we demonstrate synergism between Mediator and p300/CBP-SRC during ER{alpha}-dependent transcription with chromatin templates, but not with naked DNA. This synergism is important for promoting the formation of a stable transcription preinitiation complex leading to the initiation of transcription. Interestingly, we find that Mediator has an additional distinct role during ER{alpha}-dependent transcription not shared by p300/CBP-SRC: namely, to promote preinitiation complex formation for subsequent rounds of transcription reinitiation. These results suggest that one functional consequence of Mediator-ER{alpha} interactions is the stimulation of multiple cycles of transcription reinitiation. Collectively, our results indicate an important role for Mediator, as well as its functional interplay with p300/CBP-SRC, in the enhancement of ER{alpha}-dependent transcription with chromatin templates.

* Corresponding author. Mailing address: Department of Molecular Biology and Genetics, Cornell University, 465 Biotechnology Building, Ithaca, NY 14853. Phone: (607) 255-6087. Fax: (607) 255-6249. E-mail: wlk5{at}cornell.edu.

Molecular and Cellular Biology, January 2003, p. 335-348, Vol. 23, No. 1
0022-538X/03/$08.00+0     DOI: 10.1128/MCB.23.1.335-348.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2003 by the American Society for Microbiology. All rights reserved.