[en] Eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2), known as PKR, is a key antiviral kinase activated by double-stranded RNA (dsRNA) typically produced during viral replication. Upon activation, PKR phosphorylates eIF2α, leading to the inhibition of translation and viral replication. However, many viruses have evolved mechanisms to counteract PKR activity. In Cardioviruses, the leader protein (L), a short peptide cleaved from the N-terminus of the viral polyprotein, not only inhibits PKR but also blocks interferon production and disrupts nucleocytoplasmic trafficking (NCT). L disrupts NCT by recruiting host RSK kinases to the nuclear pore complex (NPC), where RSK phosphorylates FG-nucleoporins, thereby impairing NCT. L mutations that affect NCT disruption also impact PKR inhibition, suggesting a mechanistic link between NCT and PKR activity. Recombinant TMEV and EMCV viruses designed to disrupt NCT through different mechanisms exhibited some extent of PKR inhibition, supporting the link between NCT disruption and PKR inhibition. Immunostaining and live-cell imaging revealed that, during mitosis and after L-induced NCT disruption, a fraction of PKR maps to the nucleoli, where PKR remains inactive despite its recruitment by dsRNA-like structures. This suggests that nucleolar sequestration contributes to PKR inhibition. Additionally, L-mediated NCT disruption leads to the release of nuclear RNA-binding proteins (nRBPs) into the cytosol, which may bind or modify viral dsRNA, further preventing PKR activation. Collectively, these results highlight nucleocytoplasmic trafficking as a critical regulatory mechanism governing PKR activation. Thus, beyond the specific action of cardiovirus L protein, our study reveals that interference with host nucleocytoplasmic transport can significantly impact the subcellular localization and functional regulation of immune effectors such as PKR.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Milcamps, Romane; Université catholique de Louvain, de Duve Institute, Brussels, Belgium
Lizcano-Perret, Belén; Université catholique de Louvain, de Duve Institute, Brussels, Belgium
Wavreil, Fanny; Université catholique de Louvain, de Duve Institute, Brussels, Belgium
Lebrun, Marielle ; Université de Liège - ULiège > Département des sciences de la vie > Virologie - Immunologie
Aloise, Chiara; Utrecht University, Section of Virology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht, the Netherlands
Vertommen, Didier; MASSPROT platform, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
Herinckx, Gaëtan; MASSPROT platform, de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
van Kuppeveld, Frank J M; Utrecht University, Section of Virology, Division of Infectious Diseases and Immunology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht, the Netherlands
Sadzot, Catherine ; Université de Liège - ULiège > GIGA > GIGA Immunobiology - Virology and Immunology
Michiels, Thomas ; Université catholique de Louvain, de Duve Institute, Brussels, Belgium
Language :
English
Title :
Cardiovirus-Mediated PKR inhibition results from nucleocytoplasmic trafficking disruption.
F.R.S.-FNRS - Fonds de la Recherche Scientifique FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture Loterie Nationale
Funding text :
RM was the recipient of an Aspirant fellowship from the Fonds de la recherche scientifique-FNRS and BLP was the recient of a FRIA fellowship. Work was supported by FNRS (PDR T.0154.23), EOS (EOS ID: 30981113 and 40007527), and Loterie Nationale through support to the de Duve Institute. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We are grateful to Patrick Van Der Smissen for his long-standing help in confocal microscopy and Nicolas Dauguet for his expert assistance with cell sorting.Funding: RM was the recipient of an Aspirant fellowship from the Fonds de la recherche scientifique-FNRS and BLP was the recient of a FRIA fellowship. Work was supported by FNRS (PDR T.0154.23), EOS (EOS ID: 30981113 and 40007527), and Loterie Nationale through support to the de Duve Institute. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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