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PKR-dependent and -independent mechanisms are involved in translational shutoff during Sindbis virus infection

Rodion Gorchakov1, Elena Frolova, Bryan R G Williams

  • 1Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1019, USA.

Journal of Virology
|July 29, 2004
PubMed

Insights

Sindbis virus (SIN) infection inhibits cellular mRNA translation via PKR-dependent and independent pathways. Manipulating these mechanisms enhances heterologous gene expression from SIN replicons.

Area of Science:

  • Virology
  • Molecular Biology
  • Cellular Metabolism

Background:

  • Sindbis virus (SIN) replication significantly alters host cell metabolism.
  • A key event during SIN infection is the potent inhibition of cellular messenger RNA (mRNA) translation.
  • Protein kinase R (PKR) is known to play a role in translational control during viral infections.

Purpose of the Study:

  • To investigate the mechanisms underlying translational shutoff during SIN infection.
  • To determine the relative contributions of PKR-dependent and independent pathways.
  • To explore strategies for enhancing heterologous gene expression from SIN-based replicons.

Main Methods:

  • Studied SIN replication in PKR-deficient mouse embryo fibroblasts.
  • Utilized cells expressing catalytically inactive PKR.
  • Analyzed translation of cellular mRNAs and SIN subgenomic RNA.

Main Results:

  • PKR-dependent inhibition is not the sole or major pathway for translational shutoff during SIN infection.
  • A significant PKR-independent mechanism also inhibits cellular translation.
  • SIN subgenomic RNA translation is resistant to inhibition, benefiting viral replication.

Conclusions:

  • Both PKR-dependent and non-PKR-dependent pathways contribute to SIN-induced translational shutoff.
  • These mechanisms can be modulated by expressing mutated SIN nsP2 or kinase-defective PKR.
  • Downregulating both pathways enhances heterologous gene expression from SIN and other alphavirus replicons.

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