title: Influenza A virus NS1 protein-induced JNK activation and apoptosis are not functionally linked.
abstract: Expression of the influenza A virus (IAV) nonstructural protein (NS1) results in the activation of c-Jun N-terminal kinase (JNK). Both NS1 and JNK are involved in apoptosis induction. To investigate their interrelationship, we stably expressed a tamoxifen inducible NS1 oestrogen receptor fusion-protein (NS1ERT) in mammalian cells. Upon tamoxifen stimulation, NS1ERT-expressing cells partially rescued the attenuated replication of NS1-deficient IAVs and also inhibited interferon up-regulation, confirming the functional competence of NS1ERT. Tamoxifen-induced NS1ERT created a cytopathic phenotype and led to the activation of JNK and apoptosis. Induction of NS1F103SERT mutant failed to activate JNK, but induced apoptosis, whereas the induction of NS1M106IERT led to JNK phosphorylation, but not apoptosis, indicating that JNK activation and apoptosis induction are not functionally linked. Further mutational analysis highlighted that apoptosis induction is a function of the C-terminal effector domain of NS1. Finally, IAVs encoding mutant NS1 revealed a modulating effect of NS1 on apoptosis induction in a genuine infection. With respect to apoptogenicity, an NS1 mutant virus that results in a super activation of JNK behaves similarly to the JNK nonactivating virus expressing NS1F103S, thus confirming that NS1-mediated JNK activation and apoptosis induction are also functionally independent from each other in vivo.
authors.affiliation: Institute of Virology (IVM), University Hospital Münster, WWU, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nacken
authors.affiliation: Institute of Virology (IVM), University Hospital Münster, WWU, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Wixler
authors.affiliation: Institute of Virology (IVM), University Hospital Münster, WWU, Germany.|Cluster of Excellence "Cells in Motion", University of Muenster, Germany.|Interdisciplinary Center of Clinical Research (IZKF), UKM, WWU, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Ehrhardt
authors.affiliation: Institute of Virology (IVM), University Hospital Münster, WWU, Germany.|Cluster of Excellence "Cells in Motion", University of Muenster, Germany.|Interdisciplinary Center of Clinical Research (IZKF), UKM, WWU, Germany.
authors.forename: Stephan
authors.identifier: 0000-0003-1751-1723
authors.initials: S
authors.lastname: Ludwig
mesh_terms: D000072283:A549 Cells; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002460:Cell Line; D004285:Dogs; D004789:Enzyme Activation; D057809:HEK293 Cells; D006801:Humans; D009980:Influenza A virus / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D061985:Madin Darby Canine Kidney Cells; D011960:Receptors, Estrogen / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000378:metabolism; D013629:Tamoxifen / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C085820:INS1 protein, influenza virus; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D017361:Viral Nonstructural Proteins; D013629:Tamoxifen; D048031:JNK Mitogen-Activated Protein Kinases
keywords: JNK; NS1; apoptosis; influenza; viruses