JAK-STAT signaling pathways are activated in the brain following reovirus infection.
Reovirus infection provides a classic experimental model system for studying the pathogenesis of viral infections of the central nervous system (CNS), with apoptosis acting as the major mechanism of cell death. The authors have examined the role of signal transducer and activator of transcription (STAT)1, a component of Janus-activated kinase (JAK)-STAT signaling, a pathway implicated in antiviral responses and pathways regulating apoptosis, following reovirus infection. Infection of primary cortical neuron cultures with reovirus serotype 3 strain Abney (T3A) resulted in phosphorylation of STAT1 at sites critical for transcriptional activity. Activated STAT1 was also detected in the brain of neonatal mice following T3A infection, with a nuclear pattern of expression in areas of virus-induced injury. Activation of STAT proteins is typically mediated by JAKs. The authors observed JAK2 phosphorylation (Tyr 1007/1008) in brain lysates from T3A-infected mice. Inhibition of JAK activity with the inhibitor AG-490 blocked reovirus-induced STAT1 activation in neuronal cultures, indicating reovirus-induced STAT activation is JAK dependent. Pretreatment of neuronal cultures with antibody raised against interferon (IFN)-alpha/betaR2 inhibited T3A-induced STAT1 phosphorylation, whereas neither IFN-gamma or IFN-gammaR2 antibody pretreatment had any effect on T3A-induced STAT1 phosphorylation. Mice lacking the STAT1 gene demonstrated increased susceptibility to reovirus infection, with increased mortality and higher viral titers in the brain compared to wild-type animals. The results demonstrate activation of a type I IFN-mediated, JAK-dependent STAT signaling pathway following reovirus infection and suggest that STAT1 is a key component of host defense mechanisms against reovirus infection in the brain.
Goody
Robin J
RJ
Departments of Neurology, University of Colorado at Denver and Health Sciences Center, Denver, Colorado, USA.
Beckham
J David
JD
Rubtsova
Kira
K
Tyler
Kenneth L
KL
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D001921:Brain / Q000378:metabolism / Q000821:virology*; D002460:Cell Line; D018792:Encephalitis, Viral / Q000378:metabolism* / Q000473:pathology; D005347:Fibroblasts / Q000166:cytology; D016898:Interferon-alpha / Q000378:metabolism; D016899:Interferon-beta / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D009474:Neurons / Q000166:cytology; D010766:Phosphorylation; D012088:Reoviridae Infections / Q000378:metabolism* / Q000473:pathology; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050795:STAT2 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation
D016898:Interferon-alpha; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; C494080:Stat1 protein, mouse; C494085:Stat2 protein, mouse; D016899:Interferon-beta; D053612:Janus Kinases