Valosin-Containing Protein (VCP/p97) Is Required for Poliovirus Replication and Is Involved in Cellular Protein Secretion Pathway in Poliovirus Infection

eWe have shown that the circulating vaccine-derived polioviruses responsible for poliomyelitis outbreaks in Madagascar have recombinant genomes composed of sequences encoding capsid proteins derived from poliovaccine Sabin, mostly type 2 (PVS2), and sequences encoding nonstructural proteins derived from other human enteroviruses. Interestingly, almost all of these recombinant genomes encode a nonstructural 3A protein related to that of field coxsackievirus A17 (CV-A17) strains. Here, we investigated the repercussions of this exchange, by assessing the role of the 3A proteins of PVS2 and CV-A17 and their putative cellular partners in viral replication. We found that the Golgi protein acyl-coenzyme A binding domain-containing 3 (ACBD3), recently identified as an interactor for the 3A proteins of several picornaviruses, interacts with the 3A proteins of PVS2 and CV-A17 at viral RNA replication sites, in human neuroblastoma cells infected with either PVS2 or a PVS2 recombinant encoding a 3A protein from CV-A17 [PVS2-3A(CV-A17)]. The small interfering RNA-mediated downregulation of ACBD3 significantly increased the growth of both viruses, suggesting that ACBD3 slowed viral replication. This was confirmed with replicons. Furthermore, PVS2-3A(CV-A17) was more resistant to the replication-inhibiting effect of ACBD3 than the PVS2 strain, and the amino acid in position 12 of 3A was involved in modulating the sensitivity of viral replication to ACBD3. Overall, our results indicate that exchanges of nonstructural proteins can modify the relationships between enterovirus recombinants and cellular interactors and may thus be one of the factors favoring their emergence.

Section: Discussionmentioning

confidence: 98%

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confidence: 99%

The Golgi Protein ACBD3, an Interactor for Poliovirus Protein 3A, Modulates Poliovirus Replication

Téoulé

Brisac

Pelletier

et al. 2013

“…VCP was identified in two RNA interference screening experiments to be involved in poliovirus replication (52) and in the regulation of Sindbis virus entry (53). VCP colocalizes with poliovirus nonstructural proteins in virus-infected cells (52). It is likely that hijacking host AAAϩATPases to modulate RC assembly or the viral life cycle is conserved among positivestrand RNA viruses.…”

Section: Discussionmentioning

confidence: 99%

“…VPS4 is involved in brome mosaic virus and tomato bushy stunt virus RC formation by cooperating with ESCRT complexes (49,50) and in HCV virion production (51). VCP was identified in two RNA interference screening experiments to be involved in poliovirus replication (52) and in the regulation of Sindbis virus entry (53). VCP colocalizes with poliovirus nonstructural proteins in virus-infected cells (52).…”

Section: Discussionmentioning

confidence: 99%

Affinity Purification of the Hepatitis C Virus Replicase Identifies Valosin-Containing Protein, a Member of the ATPases Associated with Diverse Cellular Activities Family, as an Active Virus Replication Modulator

Fang

Zou

et al. 2016

Like almost all of the positive-strand RNA viruses, hepatitis C virus (HCV) induces host intracellular membrane modification to form the membrane-bound viral replication complex (RC), within which viral replicases amplify the viral RNA genome. Despite accumulated information about how HCV co-opts host factors for viral replication, our knowledge of the molecular mechanisms by which viral proteins hijack host factors for replicase assembly has only begun to emerge. Purification of the viral replicase and identification of the replicase-associated host factors to dissect their roles in RC biogenesis will shed light on the molecular mechanisms of RC assembly. To purify the viral replicase in the context of genuine viral replication, we developed an HCV subgenomic replicon system in which two different affinity tags were simultaneously inserted in frame into HCV NS5A and NS5B. After solubilizing the replicon cells, we purified the viral replicase by two-step affinity purification and identified the associated host factors by mass spectrometry. We identified valosin-containing protein (VCP), a member of the ATPases associated with diverse cellular activities (AAA؉ATPase) family, as an active viral replication modulator whose ATPase activity is required for viral replication. A transient replication assay indicated that VCP is involved mainly in viral genome amplification. VCP associated with viral replicase and colocalized with a viral RC marker. Further, in an HCV replicase formation surrogate system, abolishing VCP function resulted in aberrant distribution of HCV NS5A. We propose that HCV may co-opt a host AAA؉ATPase for its replicase assembly. IMPORTANCEAlmost all of the positive-strand RNA viruses share a replication strategy in which viral proteins modify host membranes to form the membrane-associated viral replicase. Viruses hijack host factors to facilitate this energy-unfavorable process. Understanding of this fundamental process is hampered by the challenges of purifying the replicase because of the technical difficulties involved. In this study, we developed an HCV subgenomic replicon system in which two different affinity tags were simultaneously inserted in frame into two replicase components. Using this dual-affinity-tagged replicon system, we purified the viral replicase and identified valosin-containing protein (VCP) AAA؉ATPase as a pivotal viral replicase-associated host factor that is required for viral genome replication. Abolishing VCP function resulted in aberrant viral protein distribution. We propose that HCV hijacks a host AAA؉ATPase for its replicase assembly. Understanding the molecular mechanism of VCP regulates viral replicase assembly may lead to novel antiviral strategies targeting the most conserved viral replication step.T he positive-strand RNA viruses are the largest class of viruses and include many medically and economically important pathogens, including hepatitis C virus (HCV); picornaviruses, which cause hand, foot, and mouth disease; and flaviviruses, such as the West N...

“…Despite the protective role of type I interferon (IFN-I) in EV71 infection, EV71 inoculation is unable to elicit production of these interferons. Most members of the picornavirus family, including poliovirus, rhinovirus, echovirus, and encephalomyocarditis virus, use strategies to inhibit IFN-I induction by interfering with melanoma differentiation-associated gene 5 (MDA-5) and retinoic acid-inducible gene I (RIG-I) (3)(4)(5) or by restricting IFN secretion through repression of the cellular secretory pathway (6). Recent studies revealed that the 3C protease of EV71 associated with RIG-I and cleaved TRIF (TIR-domain-containing adapter-inducing interferon beta) and IRF7 (interferon regulatory factor 7) (7,8); moreover, EV71 inhibited IFN-Iinduced ISGs (interferon stimulating genes) in host cells by reducing IFNAR1 (type I interferon receptor 1) levels in host cells (9).…”

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confidence: 99%

Downregulation of MicroRNA miR-526a by Enterovirus Inhibits RIG-I-Dependent Innate Immune Response

He²,

Zheng

et al. 2014

Retinoic acid-inducible gene I (RIG-I) is an intracellular RNA virus sensor that induces type I interferon-mediated host-protective innate immunity against viral infection. Although cylindromatosis (CYLD) has been shown to negatively regulate innate antiviral response by removing K-63-linked polyubiquitin from RIG-I, the regulation of its expression and the underlying regulatory mechanisms are still incompletely understood. Here we show that RIG-I activity is regulated by inhibition of CYLD expression mediated by the microRNA miR-526a. We found that viral infection specifically upregulates miR-526a expression in macrophages via interferon regulatory factor (IRF)-dependent mechanisms. In turn, miR-526a positively regulates virus-triggered type I interferon (IFN-I) production, thus suppressing viral replication, the underlying mechanism of which is the enhancement of RIG-I K63-linked ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virusinduced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein, while ectopic miR526a expression inhibits the replication of EV71 virus. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and suggest a novel mechanism for the evasion of the innate immune response controlled by EV71. IMPORTANCERNA virus infection upregulates the expression of miR-526a in macrophages through IRF-dependent pathways. In turn, miR526a positively regulates virus-triggered type I IFN production and inhibits viral replication, the underlying mechanism of which is the enhancement of RIG-I K-63 ubiquitination by miR-526a via suppression of the expression of CYLD. Remarkably, virus-induced miR-526a upregulation and CYLD downregulation are blocked by enterovirus 71 (EV71) 3C protein; cells with overexpressed miR-526a were highly resistant to EV71 infection. The collective results of this study suggest a novel mechanism of the regulation of RIG-I activity during RNA virus infection by miR-526a and propose a novel mechanism for the evasion of the innate immune response controlled by EV71.