title: Small interfering RNAs against the TAR RNA binding protein, TRBP, a Dicer cofactor, inhibit human immunodeficiency virus type 1 long terminal repeat expression and viral production.
abstract: RNA interference (RNAi) is now widely used for gene silencing in mammalian cells. The mechanism uses the RNA-induced silencing complex, in which Dicer, Ago2, and the human immunodeficiency virus type 1 (HIV-1) TAR RNA binding protein (TRBP) are the main components. TRBP is a protein that increases HIV-1 expression and replication by inhibition of the interferon-induced protein kinase PKR and by increasing translation of viral mRNA. After HIV infection, TRBP could restrict the viral RNA through its activity in RNAi or could contribute more to the enhancement of viral replication. To determine which function will be predominant in the virological context, we analyzed whether the inhibition of its expression could enhance or decrease HIV replication. We have generated small interfering RNAs (siRNAs) against TRBP and found that they decrease HIV-1 long terminal repeat (LTR) basal expression 2-fold, and the LTR Tat transactivated level up to 10-fold. In the context of HIV replication, siRNAs against TRBP decrease the expression of viral genes and inhibit viral production up to fivefold. The moderate increase in PKR expression and activation indicates that it contributes partially to viral gene inhibition. The moderate decrease in micro-RNA (miRNA) biogenesis by TRBP siRNAs suggests that in the context of HIV replication, TRBP functions other than RNAi are predominant. In addition, siRNAs against Dicer decrease viral production twofold and impede miRNA biogenesis. These results suggest that, in the context of HIV replication, TRBP contributes mainly to the enhancement of virus production and that Dicer does not mediate HIV restriction by RNAi.
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Parkville, Australia.
authors.forename: Helen S
authors.initials: HS
authors.lastname: Christensen
authors.forename: Aïcha
authors.initials: A
authors.lastname: Daher
authors.forename: Kaitlin J
authors.initials: KJ
authors.lastname: Soye
authors.forename: Lisa B
authors.initials: LB
authors.lastname: Frankel
authors.forename: Marina R
authors.initials: MR
authors.lastname: Alexander
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lainé
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bannwarth
authors.forename: Chi L
authors.initials: CL
authors.lastname: Ong
authors.forename: Sean W L
authors.initials: SW
authors.lastname: Chung
authors.forename: Shahan M
authors.initials: SM
authors.lastname: Campbell
authors.forename: Damian F J
authors.initials: DF
authors.lastname: Purcell
authors.forename: Anne
authors.initials: A
authors.lastname: Gatignol
mesh_terms: D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D016325:HIV Long Terminal Repeat / Q000502:physiology*; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors; D015497:HIV-1 / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases; D035683:MicroRNAs / Q000096:biosynthesis; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D043244:Ribonuclease III / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D014779:Virus Replication; D000099253:Trans-Activation Responsive RNA-Binding Protein
chemical_list: D049452:Green Fluorescent Proteins; D054303:HIV Reverse Transcriptase; D008156:Luciferases; D035683:MicroRNAs; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D043244:Ribonuclease III; D000099253:Trans-Activation Responsive RNA-Binding Protein; C485184:enhanced green fluorescent protein