title: HIV-1 Tat RNA silencing suppressor activity is conserved across kingdoms and counteracts translational repression of HIV-1.
abstract: The RNA silencing pathway is an intracellular innate response to virus infections and retro-transposons. Many plant viruses counter this host restriction by RNA silencing suppressor (RSS) activity of a double-stranded RNA-binding protein, e.g., tomato bushy stunt virus P19. Here, we demonstrate P19 and HIV-1 Tat function across the plant and animal kingdoms and suppress a common step in RNA silencing that is downstream of small RNA maturation. Our experiments reveal that RNA silencing in HIV-1 infected human cells severely attenuates the translational output of the unspliced HIV-1 gag mRNA, and possibly all HIV-1 transcripts. The attenuation in gag mRNA translation is exacerbated by K51A substitution in the Tat double-stranded RNA-binding domain. Tat, plant virus RSS, or Dicer downregulation rescues robust gag translation and bolsters HIV-1 virion production. The reversal of HIV-1 translation repression by plant RSS supports the recent finding in Arabidopsis that plant miRNAs operate by translational inhibition. Our results identify common features between RNA silencing suppression of plant and animal viruses. We suggest that RNA silencing-mediated translation repression plays a strategic role in determining the viral set-point in a newly HIV-1-infected patient.
authors.affiliation: Center for Retrovirus Research and Department of Veterinary Biosciences, Molecular, Cellular and Developmental Biology Graduate Program, Comprehensive Cancer Center, Ohio State University, Columbus, OH 43210, USA.
authors.forename: Shuiming
authors.initials: S
authors.lastname: Qian
authors.forename: Xuehua
authors.initials: X
authors.lastname: Zhong
authors.forename: Lianbo
authors.initials: L
authors.lastname: Yu
authors.forename: Biao
authors.initials: B
authors.lastname: Ding
authors.forename: Peter
authors.initials: P
authors.lastname: de Haan
authors.forename: Kathleen
authors.initials: K
authors.lastname: Boris-Lawrie
mesh_terms: D002460:Cell Line; D015683:Gene Products, gag / Q000096:biosynthesis; D015658:HIV Infections; D015497:HIV-1 / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D007113:Immunity, Innate; D010942:Plant Viruses / Q000235:genetics / Q000472:pathogenicity; D014176:Protein Biosynthesis; D034622:RNA Interference / Q000276:immunology*; D012367:RNA, Viral; D014764:Viral Proteins / Q000502:physiology; D014779:Virus Replication; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000502:physiology*
chemical_list: D015683:Gene Products, gag; C493885:P19 protein, tomato bushy stunt virus; D012367:RNA, Viral; D014764:Viral Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus