title: Two distinct phases of virus-induced nuclear factor kappa B regulation enhance tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in virus-infected cells.
abstract: Cellular transcription factors are often utilized by infecting viruses to promote viral growth and influence cell fate. We have previously shown that nuclear factor kappaB (NF-kappaB) is activated after reovirus infection and that this activation is required for virus-induced apoptosis. In this report we identify a second phase of reovirus-induced NF-kappaB regulation. We show that at later times post-infection NF-kappaB activation is blocked in reovirus-infected cells. This results in the termination of virus-induced NF-kappaB activity and the inhibition of tumor necrosis factor alpha and etoposide-induced NF-kappaB activation in infected cells. Reovirus-induced inhibition of NF-kappaB activation occurs by a mechanism that prevents IkappaBalpha degradation and that is blocked in the presence of the viral RNA synthesis inhibitor, ribavirin. Reovirus-induced apoptosis is mediated by tumor necrosis factor-related apoptosis inducing ligand (TRAIL) in a variety of epithelial cell lines. Herein we show that ribavirin inhibits reovirus-induced apoptosis in TRAIL-resistant HEK293 cells and prevents the ability of reovirus infection to sensitize TRAIL-resistant cells to TRAIL-induced apoptosis. Furthermore, TRAIL-induced apoptosis is enhanced in HEK293 cells expressing IkappaBDeltaN2, which blocks NF-kappaB activation. These results indicate that the ability of reovirus to inhibit NF-kappaB activation sensitizes HEK293 cells to TRAIL and facilitates virus-induced apoptosis in TRAIL-resistant cells. Our findings demonstrate that two distinct phases of virus-induced NF-kappaB regulation are required to efficiently activate host cell apoptotic responses to reovirus infection.
authors.affiliation: Department of Neurology, Medicine, Microbiology, and Immunology, University of Colorado Health Science Center, Denver, Colorado 80262, USA.
authors.forename: Penny
authors.initials: P
authors.lastname: Clarke
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: Meintzer
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Moffitt
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Tyler
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005047:Etoposide / Q000494:pharmacology; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008156:Luciferases / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism; D012087:Reoviridae / Q000378:metabolism; D012254:Ribavirin / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D012367:RNA, Viral; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D012254:Ribavirin; D005047:Etoposide; D008156:Luciferases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases