title: Human T lymphotropic virus type 1 regulatory and accessory gene transcript expression and export are not rex dependent.
abstract: Human T lymphotropic virus type 1 (HTLV-1) requires regulated gene expression from unspliced and alternatively spliced transcripts for efficient replication and persistence. HTLV-1 Rex is known to facilitate cytoplasmic export of unspliced, gag/pol and incompletely spliced env mRNAs, but its contribution to the expression of other viral transcripts has not been experimentally assessed. In this study, we utilized HTLV-1 proviral clones, cellular fractionation, and real-time reverse transcriptase PCR to determine the role of Rex on the expression and export of all viral mRNAs. Our results indicate that the steady-state levels of the different viral mRNAs are modulated by Rex, which we attribute to a redistribution of completely spliced mRNAs toward incompletely spliced mRNAs. Furthermore, we confirmed the positive effect of Rex on the unspliced gag/pol mRNA and singly spliced env mRNA, resulting in increased cytoplasmic expression. However, the cytoplasmic export of the alternatively spliced HTLV-1 mRNAs encoding the accessory proteins and the antisense Hbz mRNA are independent of direct Rex regulation. This is consistent with the conclusion that viral mRNAs that contain the cis-acting repressive sequence (CRS) and/or a fully functional splice donor site require a Rex/RxRE interaction for efficient cytoplasmic expression.
authors.affiliation: Center for Retrovirus Research, The Ohio State University, Columbus, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Priya
authors.initials: P
authors.lastname: Kannian
authors.forename: Han
authors.initials: H
authors.lastname: Yin
authors.forename: Matthew
authors.initials: M
authors.lastname: Kesic
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Green
mesh_terms: D001483:Base Sequence; D015967:Gene Expression Regulation, Viral; D016355:Genes, pX; D015490:HTLV-I Infections / Q000235:genetics / Q000821:virology*; D015368:Human T-lymphotropic virus 1 / Q000472:pathogenicity*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D012326:RNA Splicing; D012367:RNA, Viral / Q000235:genetics; D013601:T-Lymphocytes / Q000821:virology*
chemical_list: D012367:RNA, Viral