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

@article{citeulike:2791452, abstract = {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. 10.1128/MCB.23.1.335-348.2003}, author = {Acevedo, Mari L. and Kraus, Lee W.}, citeulike-article-id = {2791452}, citeulike-linkout-0 = {http://dx.doi.org/10.1128/MCB.23.1.335-348.2003}, citeulike-linkout-1 = {http://mcb.asm.org/cgi/content/abstract/23/1/335}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/12482985}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=12482985}, day = {1}, doi = {10.1128/MCB.23.1.335-348.2003}, journal = {Mol. Cell. Biol.}, keywords = {cbp, estrogen-receptor, mediator, p300, srcs}, month = {January}, number = {1}, pages = {335--348}, posted-at = {2008-08-14 21:02:22}, priority = {2}, title = {Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor {alpha}-Dependent Transcription with Chromatin Templates}, url = {http://dx.doi.org/10.1128/MCB.23.1.335-348.2003}, volume = {23}, year = {2003} }

TY - JOUR ID - citeulike:2791452 L3 - citeulike-article-id:2791452 N2 - 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. 10.1128/MCB.23.1.335-348.2003 IS - 1 JF - Mol. Cell. Biol. EP - 348 TI - Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor {alpha}-Dependent Transcription with Chromatin Templates VL - 23 SP - 335 KW - cbp KW - estrogen-receptor KW - mediator KW - p300 KW - srcs AU - Acevedo, Mari AU - Kraus, Lee PY - 2003/01/01/ UR - http://dx.doi.org/10.1128/MCB.23.1.335-348.2003 ER -