Chromatin-dependent E1A activity modulates NF-kappaB RelA-mediated repression of glucocorticoid receptor-dependent transcription.
The role of chromatin-dependent regulatory mechanisms in the repression of glucocorticoid-dependent transcription from the murine mammary tumor virus (MMTV) promoter by p65 and E1A was investigated by using chromatin and transiently transfected reporters. The p65 RelA subunit of NF-kappaB represses MMTV expression on either transient or integrated reporters. In contrast, the viral oncoprotein E1A represses a transient but not an integrated MMTV. E1A repression is attenuated by chromatin, suggesting p65 but not E1A manipulates chromatin appropriately to inhibit the GR. Coexpression of p65 and E1A additively represses the transient MMTV but restores the transcriptional activation of the chromatin MMTV in response to glucocorticoids. This indicates that E1A has a dominant chromatin-dependent activity that attenuates repression by p65. E1A, p65, and GR bind the MMTV promoter, and chromatin remodeling enhances binding on both repressed and activated promoters. In addition, p65 requires Brg for repression of the integrated MMTV. This suggests that neither p65 repression nor E1A attenuation of repression results from an inhibition of remodeling that prevents transcription factor binding. Furthermore, p300/CBP is also required for both repression and attenuation by p65 and E1A. E1A and p65 mutants that do not bind p300/CBP are inactive, indicative of a requirement for p300/CBP-dependent complex formation for both repression and attenuation with chromatin. These data suggest that both the p65-dependent repression and the E1A-mediated attenuation of repression require the Brg1-dependent chromatin remodeling function and p300/CBP-dependent complex formation at a promoter assembled within chromatin.
Burkhart
Barbara A
BA
Laboratory of Molecular Carcinogenesis, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Hebbar
Pratibha B
PB
Trotter
Kevin W
KW
Archer
Trevor K
TK
D002460:Cell Line; D002843:Chromatin / Q000502:physiology*; D042002:Chromatin Assembly and Disassembly; D004265:DNA Helicases; D051518:Fibroblast Growth Factor 3; D005346:Fibroblast Growth Factors / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D016328:NF-kappa B / Q000502:physiology*; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011965:Receptors, Glucocorticoid / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology*; D051996:Transcription Factor RelA; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic
D002843:Chromatin; C496444:FGF3 protein, human; D051518:Fibroblast Growth Factor 3; D016328:NF-kappa B; D009687:Nuclear Proteins; D011965:Receptors, Glucocorticoid; D012097:Repressor Proteins; D015534:Trans-Activators; D051996:Transcription Factor RelA; D014157:Transcription Factors; D005346:Fibroblast Growth Factors; C084108:SMARCA4 protein, human; D004265:DNA Helicases