Glycogen synthase kinase 3 negatively regulates IFN regulatory factor 3 transactivation through phosphorylation at its linker region
Journal
Innate Immunity
Journal Volume
20
Journal Issue
1
Pages
78-87
Date Issued
2014
Author(s)
Abstract
Upon virus infection, the host innate immune response is initiated through the activation of IFN regulatory factor 3 (IRF3) and NF-κB signaling pathways to induce IFN production. Previously, we demonstrated EBV BGLF4 kinase suppresses IRF3 function in a kinase activity-dependent manner. The replacement of Ser123, Ser173 and Thr180 into alanines at the proline-rich linker region of IRF3 abolishes BGLF4-mediated suppression. In this study, we show that BGLF4 phosphorylates glutathione-S-transferase (GST)-IRF3(110-202), but not GST-IRF3(110-202)3A mutant (S123/S173/T180A) in vitro. Compared with activation mimicking mutant IRF3(5D), the phosphorylation-defective IRF3(5D)3A shows a higher transactivation activity in reporter assays, whereas the phosphorylation-mimicking IRF3(5D)2D1E, with Ser123 and Ser173 mutated to aspartate and Thr180 to glutamate, has a much lower activity. To explore whether similar cellular regulation also exists in the absence of virus infection, candidate cellular kinases were predicted and the transactivation activity of IRF3 was examined with various kinase inhibitors. Glycogen synthase kinase 3 (GSK3) inhibitor LiCl specifically enhanced both IRF3(5D) and wild type IRF3 activity, even without stimulation. Expression of constitutive active GSK3β(S9A) represses LiCl-mediated enhancement of IRF3 transactivation activity. In vitro, both GSK3α and GSK3β phosphorylate IRF3 at the linker region. Collectively, data here suggest GSK3 phosphorylates IRF3 linker region in a way similar to viral kinase BGLF4. ? The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Subjects
EBV BGLF4 kinase; GSK3; IRF3; proline-rich linker region
SDGs
Other Subjects
aspartic acid; bglf 4 protein kinase; glutamic acid; glutathione transferase; glycogen synthase kinase 3; glycogen synthase kinase 3alpha; glycogen synthase kinase 3beta; interferon regulatory factor 3; protein kinase; serine; threonine; unclassified drug; article; comparative study; controlled study; enzyme regulation; Epstein Barr virus; in vitro study; protein expression; protein phosphorylation; transactivation; virus infection; wild type; EBV BGLF4 kinase; GSK3; IRF3; proline-rich linker region; Glutathione Transferase; Glycogen Synthase Kinase 3; HEK293 Cells; Herpesvirus 4, Human; Humans; Interferon Regulatory Factor-3; Interferon-gamma; Mutagenesis, Insertional; Mutation; Phosphorylation; Transcriptional Activation; Viral Fusion Proteins; Virus Diseases
Type
journal article