Emetine blocks RNA processing bodies and impacts
on HIV replication
A.L.C. Valadão1, B.M. Peterlin2, A. Tanuri1, R.S. Aguiar1
1Universidade 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-1NL4-3. 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.
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