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.

TitleOverexpression 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.
Publication TypeJournal Article
Year of Publication2003
AuthorsZhang, HM, Yuan, J, Cheung, P, Luo, H, Yanagawa, B, Chau, D, Stephan-Tozy, N, Wong, BW, Zhang, J, Wilson, JE, McManus, BM, Yang, D
JournalJ Biol Chem
Volume278
Issue35
Pagination33011-9
Date Published2003 Aug 29
ISSN0021-9258
KeywordsAnimals, Apoptosis, Caspase 3, Caspase 9, Caspases, Cell Death, Cell Survival, Chromones, Coloring Agents, Enterovirus B, Human, Enzyme Activation, Enzyme Inhibitors, Genes, Dominant, Glycogen Synthase Kinase 3, GTP Phosphohydrolases, HeLa Cells, Humans, Mice, Morpholines, Myocardium, Phosphatidylinositol 3-Kinases, Phosphorylation, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt, Tetrazolium Salts, Thiazoles, Time Factors, Transfection
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.

DOI10.1074/jbc.M305352200
Alternate JournalJ. Biol. Chem.
PubMed ID12819192