title: Interactions between Marek's disease virus encoded or induced factors and the Rous sarcoma virus long terminal repeat promoter.
abstract: Marek's disease virus transactivates promoters of avian leukemia and sarcoma viruses. In this study, a series of RSV-LTR promoter deletion mutants were used to map sites within the LTR important for MDV-mediated transactivation. MDV-responsive elements within RSV-LTR promoters were localized to a 28-bp segment (nucleotides -109 to -137) which contains a GGTGG pentanucleotide repeat element (PRE). Nuclear extract proteins from uninfected cells bound to the RSV PRE in a sequence-specific manner. Extracts from cells infected with MDV produced novel, sequence-specific complexes with RSV PRE probes. Transactivation in other herpesvirus-retrovirus systems has been shown to depend, at least in part, on expression of herpesvirus immediate-early genes. In this report, we demonstrate that MDV ICP4 is capable of transactivating RSV-LTR promoters containing an intact PRE region. Transactivation with an isolated MDV ICP4 gene expressed from its cognate promoter was less efficient than with intact MDV, suggesting that other MDV-encoded factors are likely to play a role in MDV-mediated transactivation of RSV-LTR promoters. RSV-LTR promoters lacking a PRE region were not efficiently transactivated by MDV ICP4. We conclude that MDV ICP4 may be at least partially responsible for transactivation of RSV-LTR promoters and that this transactivation is likely to be dependent upon presence of a PRE region within RSV-LTR promoters.
authors.affiliation: Institute of Biomedicine, Latvian University, Riga.
authors.forename: U T
authors.initials: UT
authors.lastname: Banders
authors.forename: P M
authors.initials: PM
authors.lastname: Coussens
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D002642:Chick Embryo; D004279:DNA, Viral; D008381:Herpesvirus 2, Gallid / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014764:Viral Proteins
chemical_list: D004279:DNA, Viral; D009687:Nuclear Proteins; D015534:Trans-Activators; D014764:Viral Proteins; C075882:ICP4 protein, Gallid herpesvirus 2