Overexpression of interferon-gamma-inducible GTPase inhibits coxsackievirus B3-induced apoptosis through the activation of the phosphatidylinositol 3-kinase/Akt pathway and inhibition of viral replication

J Biol Chem. 2003 Aug 29;278(35):33011-9. doi: 10.1074/jbc.M305352200. Epub 2003 Jun 20.

Abstract

Our previous studies using differential mRNA display have shown that interferon-gamma-inducible GTPase (IGTP), was up-regulated in coxsackievirus B3 (CVB3)-infected mouse hearts. In order to explore the effect of IGTP expression on CVB3-induced pathogenesis, we have established a doxycycline-inducible Tet-On HeLa cell line overexpressing IGTP and have analyzed activation of several signaling molecules that are involved in cell survival and death pathways. We found that following IGTP overexpression, protein kinase B/Akt was strongly activated through phosphorylation, which leads to phosphorylation of glycogen synthase kinase-3 (GSK-3). Furthermore, in the presence of CVB3 infection, the intensity of the phosphorylation of Akt was further enhanced and associated with a delayed activation of caspase-9 and caspase-3. These data indicate that IGTP expression appears to confer cell survival in CVB3-infected cells, which was confirmed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt cell viability assay. However, the ability of IGTP to induce phosphorylation of Akt and to promote cell survival was attenuated by the phosphotidylinositol-3 kinase (PI3-K) inhibitor LY294002. Transient transfection of the cells with a dominant negative Akt construct followed by doxycycline induction and CVB3 infection reversed Akt phosphorylation to basal levels and returned caspase-3 activity to levels similar to those when the PI3-K inhibitor LY294002 was added. Moreover, IGTP expression inhibited viral replication and delayed CVB3-induced cleavage of eukaryotic translation initiation factor 4G, indicating that IGTP-mediated cell survival relies on not only the activation of PI3-K/Akt, inactivation of GSK-3 and suppression of caspase-9 and caspase-3 but also the inhibition of viral replication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Caspase 3
  • Caspase 9
  • Caspases / metabolism
  • Cell Death
  • Cell Survival
  • Chromones / pharmacology
  • Coloring Agents / pharmacology
  • Enterovirus B, Human / genetics*
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • GTP Phosphohydrolases / metabolism*
  • GTP Phosphohydrolases / physiology*
  • Genes, Dominant
  • Glycogen Synthase Kinase 3 / metabolism
  • HeLa Cells
  • Humans
  • Mice
  • Morpholines / pharmacology
  • Myocardium / enzymology
  • Myocardium / pathology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphorylation
  • Protein Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Tetrazolium Salts / pharmacology
  • Thiazoles / pharmacology
  • Time Factors
  • Transfection

Substances

  • Chromones
  • Coloring Agents
  • Enzyme Inhibitors
  • Morpholines
  • Phosphoinositide-3 Kinase Inhibitors
  • Proto-Oncogene Proteins
  • Tetrazolium Salts
  • Thiazoles
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • AKT1 protein, human
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Glycogen Synthase Kinase 3
  • CASP3 protein, human
  • CASP9 protein, human
  • Casp3 protein, mouse
  • Casp9 protein, mouse
  • Caspase 3
  • Caspase 9
  • Caspases
  • GTP Phosphohydrolases
  • Igtp protein, mouse
  • thiazolyl blue