The presence of m6A within the 5´-UTR of the HIV-1 genomic RNA defines its use as mRNA or as the packaged genome
Fecha
20182018
Institución
Resumen
The HIV-1 genome is a positive sense RNA (gRNA), which is found as a dimer in the viral particle. During the late
stages, the gRNA acts as an mRNA encoding Gag and Gag-Pol, and is also the genome packaged into the new viral
particles. Although it is known that the 5´UTR is key in the regulation on the transition translation-packaging, the
molecular mechanisms involved are not well understood. It was recently reported that HIV-1 gene expression is posttranscriptionally
regulated by the presence of N6-methyladenosine (m6A) along the gRNA. Here, we show that the
hypermethylation of the gRNA through the overexpression of the METTL3/14 complex induces a strong decrease of
the gRNA packaged into released viral particles. We also observed that this effect was dynamic since overexpression
of the FTO (but not ALKBH5) induced an increase in the packaged gRNA. Interestingly, m6A-seq analyses revealed that
the 5´UTR of the gRNA is methylated within the cell, but not in the viral particle, indicating that the absence of m6A
within the 5´UTR is probably necessary for the packaging of the gRNA. We also identified A198 and the A242 as the
potential methylated residues. We are currently investigating the impact of m6A within the 5´-UTR on the interaction
with Gag as well as the dimerization of the gRNA and their structure in order to understand the molecular mechanism
involved in this regulation.
Fondecyt 1160176; Anillo ACT-1408.