Abstract

Emetine blocks RNA processing bodies and impacts on HIV replication

A.L.C. Valadão¹, B.M. Peterlin², A. Tanuri¹, R.S. Aguiar<sup>1

1</sup>Universidade Federal do Rio de Janeiro, Genética, Rio de Janeiro, Brazil, ²University of California San Francisco, San Francisco, United States

Background: RNA processing bodies (P bodies) are essential for HIV replication. P bodies are dynamic cytoplasmic foci, where mRNA species are stored or degraded. We observed robust synthesis and release of virus like particles (VLPs), but they lacked HIV genomic RNA and were not infectious in cells treated with siRNAs against P bodies components. In addition to RNAi approaches, we wanted to determine if pharmacological disruption of P bodies also inhibits HIV replication. It is well known that emetine disrupts P bodies. Emetine is a drug clinically used in the treatment of protozoan infection, besides its anti-cancer properties.
Methods: TZM-BL cells were infected with HIV-1_NL4-3. 20h post-infection cells were extensively washed and incubated with different concentrations of emetine. Viral particles were harvested for an additional 24 h and evaluated for p24 levels, viral infectivity and genomic RNA incorporation. Levels of constitutive gene expression and cells viability were also evaluated. Immunofluorescence assays were performed in the same cells and examined for the presence of P bodies.
Results: Emetine did not diminish the production of VLPs, but diminished greatly their infectivity. In addition, cells remained viable during the course of these experiments and the emetine treatment did not affect global RNA expression levels. In TZM-BL cells treated with emetine, decreased viral infectivity correlates with the disappearance of P bodies. They disappear completely with 800 ng/ml of emetine, which corresponds to the total loss of viral infectivity. Moreover, the genomic RNA incorporation was reduced in VLPs from emetine treated cells.
Conclusions: We found that not only the disruption of P bodies by specific siRNAs, but also by emetine, leads to the release of virus like particles (VLPs) that contain no HIV gRNA and are not infectious. This rises the possibility to use emetine or dehydroemetine in anti-viral therapy.