title: Binding of equine infectious anemia virus rev to an exon splicing enhancer mediates alternative splicing and nuclear export of viral mRNAs.
abstract: In addition to facilitating the nuclear export of incompletely spliced viral mRNAs, equine infectious anemia virus (EIAV) Rev regulates alternative splicing of the third exon of the tat/rev mRNA. In the presence of Rev, this exon of the bicistronic RNA is skipped in a fraction of the spliced mRNAs. In this report, the cis-acting requirements for exon 3 usage were correlated with sequences necessary for Rev binding and transport of incompletely spliced RNA. The presence of a purine-rich exon splicing enhancer (ESE) was required for exon 3 recognition, and the addition of Rev inhibited exon 3 splicing. Glutathione-S-transferase (GST)-Rev bound to probes containing the ESE, and mutation of GAA repeats to GCA within the ESE inhibited both exon 3 recognition in RNA splicing experiments and GST-Rev binding in vitro. These results suggest that Rev regulates alternative splicing by binding at or near the ESE to block SR protein-ESE interactions. A 57-nucleotide sequence containing the ESE was sufficient to mediate Rev-dependent nuclear export of incompletely spliced RNAs. Rev export activity was significantly inhibited by mutation of the ESE or by trans-complementation with SF2/ASF. These results indicate that the ESE functions as a Rev-responsive element and demonstrate that EIAV Rev mediates exon 3 exclusion through protein-RNA interactions required for efficient export of incompletely spliced viral RNAs.
authors.affiliation: Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: M
authors.initials: M
authors.lastname: Belshan
authors.forename: G S
authors.initials: GS
authors.lastname: Park
authors.forename: P
authors.initials: P
authors.lastname: Bilodeau
authors.forename: C M
authors.initials: CM
authors.lastname: Stoltzfus
authors.forename: S
authors.initials: S
authors.lastname: Carpenter
mesh_terms: D017398:Alternative Splicing; D001665:Binding Sites; D001692:Biological Transport; D002467:Cell Nucleus; D005091:Exons / Q000235:genetics*; D015694:Gene Products, rev / Q000235:genetics* / Q000378:metabolism; D004860:Infectious Anemia Virus, Equine / Q000235:genetics*; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors
chemical_list: D015694:Gene Products, rev; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors