GCN2 has inhibitory effect on human immunodeficiency virus-1 protein synthesis and is cleaved upon viral infection

PLoS One. 2012;7(10):e47272. doi: 10.1371/journal.pone.0047272. Epub 2012 Oct 23.

Abstract

The reversible phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eIF2alpha) is a well-characterized mechanism of translational control in response to a wide variety of cellular stresses, including viral infection. Beside PKR, the eIF2alpha kinase GCN2 participates in the cellular response against viral infection by RNA viruses with central nervous system tropism. PKR has also been involved in the antiviral response against HIV-1, although this antiviral effect is very limited due to the distinct mechanisms evolved by the virus to counteract PKR action. Here we report that infection of human cells with HIV-1 conveys the proteolytic cleavage of GCN2 and that purified HIV-1 and HIV-2 proteases produce direct proteolysis of GCN2 in vitro, abrogating the activation of GCN2 by HIV-1 RNA. Transfection of distinct cell lines with a plasmid encoding an HIV-1 cDNA clone competent for a single round of replication resulted in the activation of GCN2 and the subsequent eIF2alpha phosphorylation. Moreover, transfection of GCN2 knockout cells or cells with low levels of phosphorylated eIF2alpha with the same HIV-1 cDNA clone resulted in a marked increase of HIV-1 protein synthesis. Also, the over-expression of GCN2 in cells led to a diminished viral protein synthesis. These findings suggest that viral RNA produced during HIV-1 infection activates GCN2 leading to inhibition of viral RNA translation, and that HIV-1 protease cleaves GCN2 to overcome its antiviral effect.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • COS Cells
  • Cell Line
  • Chlorocebus aethiops
  • Eukaryotic Initiation Factor-2 / metabolism
  • HIV-1 / genetics
  • HIV-1 / metabolism*
  • HIV-1 / pathogenicity*
  • HeLa Cells
  • Humans
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA, Viral / metabolism
  • Real-Time Polymerase Chain Reaction
  • Viral Proteins / biosynthesis*
  • Viral Proteins / genetics

Substances

  • Eukaryotic Initiation Factor-2
  • RNA, Viral
  • Viral Proteins
  • EIF2AK4 protein, human
  • Protein Serine-Threonine Kinases

Grants and funding

This work was supported in part by grants BFU2007-62987 (to CDH) BFU2006-12822 and BFU2009-09469 (to JJB) from the Dirección General de Investigación Científica y Técnica (DGICYT), a grant from the Fundación Ramón Areces (to CDH), a grant from Universidad Autónoma de Madrid and the Government of Madrid (to JJB), grants PS09-02029 and RD06-0006-0035 (to MAM-F) and PI081495 (to JLJ) from Fondo de Investigaciones Sanitarias, and an institutional grant from the Fundación Ramón Areces to the Centro de Biología Molecular Severo Ochoa. JDP was supported by a Ph.D. fellowship from the Ministerio de Ciencia y Tecnología (Government of Spain). JLJ is supported by Programa de Investigación de la Consejería de Sanidad de la Comunidad de Madrid. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.