title: p300 stimulates transcription instigated by ligand-bound thyroid hormone receptor at a step subsequent to chromatin disruption.
abstract: We investigate the role of the transcriptional coactivator p300 in gene activation by thyroid hormone receptor (TR) on addition of ligand. The ligand-bound TR targets chromatin disruption independently of gene activation. Exogenous p300 facilitates transcription from a disrupted chromatin template, but does not itself disrupt chromatin in the presence or absence of ligand-bound receptor. Nevertheless, the acetyltransferase activity of p300 is required to facilitate transcription from a disrupted chromatin template. Expression of E1A prevents aspects of chromatin remodeling and transcriptional activation dependent on TR and p300. E1A selectively inhibits the acetylation of non-histone substrates. E1A does not prevent the assembly of a DNase I-hypersensitive site induced by TR, but does inhibit topological alterations and the loss of canonical nucleosome arrays dependent on the addition of ligand. Mutants of E1A incompetent for interaction with p300 partially inhibit chromatin disruption but still allow nuclear receptors to activate transcription. We conclude that p300 has no essential role in chromatin disruption, but makes use of acetyltransferase activity to stimulate transcription at a subsequent step.
authors.affiliation: Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-5431, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: A
authors.initials: A
authors.lastname: Imhof
authors.forename: T N
authors.initials: TN
authors.lastname: Collingwood
authors.forename: F D
authors.initials: FD
authors.lastname: Urnov
authors.forename: A P
authors.initials: AP
authors.lastname: Wolffe
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000378:metabolism; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D005260:Female; D051548:Histone Acetyltransferases; D066298:In Vitro Techniques; D008024:Ligands; D009687:Nuclear Proteins / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism*; D047488:Retinoid X Receptors; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014981:Xenopus; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
chemical_list: D000123:Acetyltransferases; D018797:Cell Cycle Proteins; D002843:Chromatin; D017931:DNA Primers; D051548:Histone Acetyltransferases; D008024:Ligands; D009687:Nuclear Proteins; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D047488:Retinoid X Receptors; D015534:Trans-Activators; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor