The viral transactivator E1A regulates the mouse mammary tumor virus promoter in an isoform- and chromatin-specific manner.
Proteins encoded by the adenovirus E1A gene regulate both cellular and viral genes to mediate effects on cell cycle, differentiation, and cell growth control. We have identified the mouse mammary tumor virus (MMTV) promoter as a target of E1A action and investigated the role nucleoprotein structure plays in its response to E1A. Both 12 and 13 S forms target the MMTV promoter when it has a disorganized and accessible chromatin configuration. However, whereas the 13 S form is stimulatory, the 12 S form is repressive. When the MMTV promoter adopts an organized and repressed chromatin structure, it is targeted only by the 13 S form, which stimulates it. Although evidence indicates that E1A interacts with the SWI/SNF remodeling complex, E1A had no effect on chromatin remodeling at the MMTV promoter in organized chromatin. Analysis of E1A mutants showed that stimulation of the MMTV promoter is mediated solely through conserved region 3 and does not require interaction with Rb, p300/CBP-associated factor, or CBP/p300. Imaging analysis showed that E1A colocalizes with MMTV sequences in vivo, suggesting that it functions directly at the promoter. These results indicate that E1A stimulates the MMTV promoter in a fashion independent of chromatin conformation and through a direct mechanism involving interaction with the basal transcription machinery.
Soeth
Edlyn
E
Signal Transduction Group, Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA.
Thurber
Denise B
DB
Smith
Catharine L
CL
D017500:Adenovirus E1A Proteins / Q000378:metabolism* / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005822:Genetic Vectors; D008156:Luciferases / Q000378:metabolism; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D051379:Mice; D008856:Microscopy, Fluorescence; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms; D012313:RNA / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D017500:Adenovirus E1A Proteins; D002843:Chromatin; D020033:Protein Isoforms; D012313:RNA; D008156:Luciferases