Species-Specific Inhibition of Necroptosis by HCMV UL36

Viral infection activates cellular antiviral defenses including programmed cell death (PCD). Many viruses, particularly those of the <i>Herpesviridae</i> family, encode cell death inhibitors that antagonize different forms of PCD. While some viral inhibitors are broadly active in cells o...

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Auteurs principaux: Elena Muscolino, Claudia Castiglioni, Renke Brixel, Giada Frascaroli, Wolfram Brune
Format: article
Langue:EN
Publié: MDPI AG 2021
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Accès en ligne:https://doaj.org/article/78a69bb246cd4b8da573c3db788e7c44
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Résumé:Viral infection activates cellular antiviral defenses including programmed cell death (PCD). Many viruses, particularly those of the <i>Herpesviridae</i> family, encode cell death inhibitors that antagonize different forms of PCD. While some viral inhibitors are broadly active in cells of different species, others have species-specific functions, probably reflecting the co-evolution of the herpesviruses with their respective hosts. Human cytomegalovirus (HCMV) protein UL36 is a dual cell death pathway inhibitor. It blocks death receptor-dependent apoptosis by inhibiting caspase-8 activation, and necroptosis by binding to the mixed lineage kinase domain-like (MLKL) protein and inducing its degradation. While UL36 has been shown to inhibit apoptosis in human and murine cells, the specificity of its necroptosis-inhibiting function has not been investigated. Here we show that UL36 interacts with both human and murine MLKL, but has a higher affinity for human MLKL. When expressed by a recombinant mouse cytomegalovirus (MCMV), UL36 caused a modest reduction of murine MLKL levels but did not inhibit necroptosis in murine cells. These data suggest that UL36 inhibits necroptosis, but not apoptosis, in a species-specific manner, similar to ICP6 of herpes simplex virus type 1 and MC159 of molluscum contagiosum virus. Species-specific necroptosis inhibition might contribute to the narrow host range of these viruses.