Orthopoxviruses Require a Functional Ubiquitin-Proteasome System for Productive Replication▿
| Autor: | Nicholas van Buuren, Brianne Couturier, Robyn Shipclark, Wendy C. Magee, Kelly Watmough, Stephanie Campbell, Michele Barry, Alastair Teale |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
DNA Replication
Proteasome Endopeptidase Complex viruses Immunology macromolecular substances Orthopoxvirus Ubiquitin-Activating Enzymes Virus Replication Microbiology Virus chemistry.chemical_compound Mice Viral Proteins Virology Cricetinae Chlorocebus aethiops Animals Humans Poxviridae Protease Inhibitors biology Ubiquitin Ectromelia virus virus diseases biology.organism_classification Ubiquitin ligase Virus-Cell Interactions chemistry Viral replication Insect Science DNA Viral biology.protein Monkeypox virus Vaccinia Proteasome Inhibitors HeLa Cells |
| Popis: | Cellular homeostasis depends on an intricate balance of protein expression and degradation. The ubiquitinproteasome pathway plays a crucial role in specifically targeting proteins tagged with ubiquitin for destruction. This degradation can be effectively blocked by both chemically synthesized and natural proteasome inhibitors. Poxviruses encode a number of proteins that exploit the ubiquitin-proteasome system, including virally encoded ubiquitin molecules and ubiquitin ligases, as well as BTB/kelch proteins and F-box proteins, which interact with cellular ubiquitin ligases. Here we show that poxvirus infection was dramatically affected by a range of proteasome inhibitors, including MG132, MG115, lactacystin, and bortezomib (Velcade). Confocal microscopy demonstrated that infected cells treated with MG132 or bortezomib lacked viral replication factories within the cytoplasm. This was accompanied by the absence of late gene expression and DNA replication; however, early gene expression occurred unabated. Proteasomal inhibition with MG132 or bortezomib also had dramatic effects on viral titers, severely blocking viral replication and propagation. The effects of MG132 on poxvirus infection were reversible upon washout, resulting in the production of late genes and viral replication factories. Significantly, the addition of an ubiquitin-activating enzyme (E1) inhibitor had a similar affect on late and early protein expression. Together, our data suggests that a functional ubiquitinproteasome system is required during poxvirus infection. The Poxviridae family is a large family of DNA viruses that replicate entirely within the cytoplasm of the cell. The bestcharacterized member of the poxvirus family is vaccinia virus, a member of the Orthopoxvirus genus, which also includes ectromelia virus (the causative agent of mousepox), cowpox virus, monkeypox virus, and variola virus, which caused the devastating illness smallpox (35, 57). Vaccinia virus was successfully employed in a vaccination program resulting in the eventual eradiation of smallpox (57). Despite the successful eradication of variola virus, poxvirus infections continue to elicit clinically relevant diseases in humans and other animals (20, 27, 30, 33, 41, 42). Aspects of the poxvirus life cycle and virus-host interaction are active areas of research, since efforts to improve and expand poxvirus-based therapies are often hampered by our incomplete understanding of poxvirus biology. The poxvirus replication cycle is complicated due to the existence of two infectious forms of the virus, intracellular mature virus (IMV) and extracellular enveloped virus (EEV), which differ in the numbers of phospholipid bilayers surrounding their cores (56, 58). Upon infection, both IMV and EEV release virion cores into the cytosol. Early viral mRNA is synthesized within viral cores, and these typically encode products required for immune evasion, core uncoating, release of genomic DNA, and DNA replication (35). Late gene synthesis follows DNA replication, producing both structural and non |
| Databáze: | OpenAIRE |
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