West Nile virus genome amplification requires the functional activities of the proteasome

Gilfoy, Felicia D.; Fayzulin, Rafik; Mason, Peter W.

doi:10.1016/j.virol.2008.11.034

Cited by 33 publications

(34 citation statements)

References 68 publications

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“…Interestingly, while the proteasome impacts the replication of many viruses including positive strand RNA viruses such as flaviviruses (Gao and Luo, 2006; Gilfoy et al, 2009), to our knowledge, a role for the proteasome in alphavirus entry has not been previously described. We found that depletion of dSEC61A, dVCP and dPMSD11 reduce the levels of the entry receptor dNRAMP post-transcriptionally.…”

Section: Discussionmentioning

confidence: 94%

Genome-wide RNAi Screen Identifies SEC61A and VCP as Conserved Regulators of Sindbis Virus Entry

et al. 2013

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SUMMARY Alphaviruses are a large class of insect-borne human pathogens and little is known about the host factor requirements for infection. To identify such factors we performed a genome-wide RNAi screen using model Drosophila cells and validated 94 genes that impacted infection of Sindbis virus (SINV), the prototypical alphavirus. We identified a conserved role for SEC61A and VCP in facilitating SINV entry in insects and mammals. SEC61A and VCP selectively regulate trafficking of the entry receptor NRAMP2, and loss of these proteins, or pharmacological inhibition, leads to altered NRAMP2 trafficking to lysosomal compartments, and proteolytic digestion within lysosomes. NRAMP2 is the major iron transporter in cells, and loss of NRAMP2 attenuates intracellular iron transport. Thus, this study reveals new genes and pathways involved in both infection and iron homeostasis that may serve as targets for antiviral therapeutics or for iron imbalance disorders.

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Section: Discussionmentioning

confidence: 94%

Genome-wide RNAi Screen Identifies SEC61A and VCP as Conserved Regulators of Sindbis Virus Entry

et al. 2013

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“…RepliVAX WN was generated in BHK (VEErep/Pac-Ubi-C*) cells as previously described (19). Firefly luciferaseexpressing SCFV particles (FLUC-SCFV) containing a WNV replicon genome expressing a humanized FLUC gene were generated in BHK (VEErep/C*-prM-E-Pac) cells as previously described (20). RepliVAX WN and FLUC-SCFV were titrated using Vero cells as previously described (21).…”

Section: Methodsmentioning

confidence: 99%

TLR3- and MyD88-Dependent Signaling Differentially Influences the Development of West Nile Virus-Specific B Cell Responses in Mice following Immunization with RepliVAX WN, a Single-Cycle Flavivirus Vaccine Candidate

Xia

Winkelmann

Gorder

et al. 2013

J Virol

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“…5A). Proteasome subunits were identified in a small-scale siRNA-based study (encompassing ϳ5,500 genes) using WNV replicons containing a luciferase reporter, and proteasome was proposed to be required for a postinternalization step in WNV infection (10). This observation prompted us to decipher which step of the WNV life cycle would require a functional proteasome and whether exploitation of the ubiquitin/proteasome system is a hallmark of flavivirus infection.…”

Section: Effect Of Proteasome Inhibitors On Flavivirus Infectionmentioning

confidence: 99%

Appraising the Roles of CBLL1 and the Ubiquitin/Proteasome System for Flavivirus Entry and Replication

Fernandez-Garcia

Meertens

Bonazzi

et al. 2011

J Virol

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The ubiquitin ligase CBLL1 (also known as HAKAI) has been proposed to be a critical cellular factor exploited by West Nile virus (WNV) for productive infection. CBLL1 has emerged as a major hit in a recent RNA interference screen designed to identify cellular factors required for the early stages of the WNV life cycle. Follow-up experiments showed that HeLa cells knocked down for CBLL1 by a small interfering RNA (siRNA) failed to internalize WNV particles and resisted infection. Furthermore, depletion of a free-ubiquitin pool by the proteasome inhibitor MG132 abolished WNV endocytosis, suggesting that CBLL1 acts in concert with the ubiquitin proteasome system to mediate virus internalization. Here, we examined the effect of CBLL1 knockdown and proteasome inhibitors on infection by WNV and other flaviviruses. We identified new siRNAs that repress the CBLL1 protein and strongly inhibit the endocytosis of Listeria monocytogenes, a bacterial pathogen known to require CBLL1 to invade host cells. Strikingly, however, we detected efficient WNV, dengue virus, and yellow fever virus infection of human cells, despite potent downregulation of CBLL1 by RNA interference. In addition, we found that the proteasome inhibitors MG132 and lactacystin did not affect WNV internalization but strongly repressed flavivirus RNA translation and replication. Together, these data do not support a requirement for CBLL1 during flavivirus entry and rather suggest an essential role of the ubiquitin/proteasome pathway for flavivirus genome amplification.West Nile virus (WNV), dengue virus (DV), and yellow fever virus (YFV) are mosquito-borne flaviviruses that cause neurological disease and hemorrhagic fever in humans and constitute major public health threats (11,19). They are lipidenveloped viruses that contain a single-stranded, positive-sense RNA genome (12, 16). To initiate their infectious life cycle, flaviviruses interact via their envelope glycoprotein (E protein) with still-uncharacterized cellular receptors (2), enter the host cell by clathrin-mediated endocytosis, and traffic through the endosomal pathway (5,15,27). Endosome acidification triggers major conformational changes in their E proteins that induce fusion of the viral and host cell membranes (4,13,20), resulting in the release of the viral capsid and genomic RNA into the cytosol. The viral genome is translated in the cytoplasm as a single polyprotein, which is co-and posttranslationally processed by both host cell signalases and the virus-encoded protease NS2B/NS3 into three structural and seven nonstructural (NS) proteins (12, 16). Because flaviviruses encode only 10 proteins, they need to subvert and/or counteract host cell functions for viral propagation (8). Understanding the interplay between flaviviruses and the host cell machinery could provide important insights into the molecular mechanisms of viral pathogenesis and could facilitate the development of a novel generation of antiviral drugs targeting host cell factors. A recent genome-wide RNA interference (RNAi) scree...

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West Nile virus genome amplification requires the functional activities of the proteasome

Cited by 33 publications

References 68 publications

Genome-wide RNAi Screen Identifies SEC61A and VCP as Conserved Regulators of Sindbis Virus Entry

Genome-wide RNAi Screen Identifies SEC61A and VCP as Conserved Regulators of Sindbis Virus Entry

TLR3- and MyD88-Dependent Signaling Differentially Influences the Development of West Nile Virus-Specific B Cell Responses in Mice following Immunization with RepliVAX WN, a Single-Cycle Flavivirus Vaccine Candidate

Appraising the Roles of CBLL1 and the Ubiquitin/Proteasome System for Flavivirus Entry and Replication

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