Rab18 Binds to Hepatitis C Virus NS5A and Promotes Interaction between Sites of Viral Replication and Lipid Droplets

Salloum, Shadi; Wang, Hongliang; Ferguson, Charles; Parton, Robert G.; Tai, Andrew W.

doi:10.1371/journal.ppat.1003513

Cited by 131 publications

(114 citation statements)

References 70 publications

Supporting

Mentioning

108

Contrasting

Order By: Relevance

“…Rab8, which regulates vesicular trafficking from the Golgi apparatus to the plasma membrane, is involved in DENV release (30,31). Rab18 was found to have a role in HCV replication by Rab18 knockdown in Huh7 cells with HCV replicon (32), probably by binding with HCV NS5A and promoting the physical association of NS5A and other replicase components with LDs (33). Furthermore, HCV NS5A and NS5B were found to associate with FASN in HCV replicon cells (34).…”

Section: Discussionmentioning

confidence: 99%

Rab18 Facilitates Dengue Virus Infection by Targeting Fatty Acid Synthase to Sites of Viral Replication

Tang

Lin

Liao

et al. 2014

J Virol

View full text Add to dashboard Cite

Positive-sense RNA viruses, such as dengue virus (DENV), hijack the intracellular membrane machinery for their own replication. The Rab18 protein, a member of the Rab GTPase family, key regulators of membrane trafficking, is located on the organelles involved in DENV infection, such as the endoplasmic reticulum (ER) and lipid droplets (LDs). In this study, we addressed the potential involvement of Rab18 in DENV infection by using cells overexpressing the wild-type, GTP-bound active form, or GDP-bound inactive form of Rab18 and cells with Rab18 knockdown. DENV replication, measured by viral protein, viral RNA, and viral progeny production, as well as LD induction, was reduced in cells with inactive Rab18 and in cells deprived of Rab18 expression, suggesting a positive role of Rab18 in the DENV life cycle. Interestingly, the interaction of fatty acid synthase (FASN), a key lipogenic enzyme in lipid biosynthesis, with DENV NS3 protein relied on the conversion of the GDP-bound to the GTP-bound form of Rab18. Furthermore, the targeting of FASN to sites participating in DENV infection, such as the ER and LDs, depends on functional Rab18. Thus, Rab18-mediated membrane trafficking of FASN and NS3 facilitates DENV replication, probably by ensuring a sufficient and coordinated lipid supply for membrane proliferation and arrangement. IMPORTANCE Infection by dengue virus (DENV), an important mosquito-borne virus threatening ϳ40% of the world's population, can cause mild dengue fever or severe dengue hemorrhagic fever and dengue shock syndrome. The pathogenesis mechanisms of DENVrelated diseases are not clear, but high viral replication is believed to be a risk factor for the severe form of DENV infection. Thus, understanding the detailed mechanism of DENV replication might help address this devastating virus. Here, we found that Rab18, a small GTPase involved in vesicle trafficking and located in the endoplasmic reticulum network and on the surfaces of lipid droplets, positively regulates DENV replication. The functional machinery of Rab18 is required to recruit the enzyme fatty acid synthase to sites of DENV replication and to interact with DENV NS3 protein to promote fatty acid biosynthesis. Thus, DENV usurps Rab18 to facilitate its own replication. Dengue virus (DENV), a member of the genus Flavivirus of the family Flaviviridae, is the causative agent of dengue fever, dengue hemorrhagic fever, and dengue shock syndrome (1). Other members of the family, such as hepatitis C virus (HCV), yellow fever virus, West Nile virus, and Japanese encephalitis virus, are also involved in human diseases. DENV is enveloped and contains a single-stranded positive-sense RNA genome. Like other positive-sense RNA viruses, DENV modifies host cytoplasmic membranes to form platforms for viral replication (2, 3). DENV replication occurs in close association with virus-induced membrane structures derived from the endoplasmic reticulum (ER) network, with spatial coupling between sites of viral replication and virion assembly (4). The memb...

show abstract

Section: Discussionmentioning

confidence: 99%

Rab18 Facilitates Dengue Virus Infection by Targeting Fatty Acid Synthase to Sites of Viral Replication

Tang

Lin

Liao

et al. 2014

J Virol

View full text Add to dashboard Cite

show abstract

“…Chlamydia releases proteins to recruit specific Rabs, redirecting them to the Golgi (7), and Salmonella interacts with the GTPase effector SKIP to assure its localization in the perinuclear region (8). Prior studies have shown the involvement of several Rab proteins in the HCV lifecycle as well (9,10).…”

mentioning

confidence: 99%

Hepatitis C virus promotes virion secretion through cleavage of the Rab7 adaptor protein RILP

Wozniak

Long

Jones-Jamtgaard

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Hepatitis C virus (HCV) is an enveloped RNA virus that modifies intracellular trafficking processes. The mechanisms that HCV and other viruses use to modify these events are poorly understood. In this study, we observed that two different RNA viruses, HCV and Sendai, cause inhibition of ras-related protein Rab-7 (Rab7)-dependent endosome-lysosome fusion. In both cases, viral infection causes cleavage of the Rab7 adaptor protein RILP (Rab interacting lysosomal protein), which is responsible for linking Rab7 vesicles to dynein motor complexes. RILP cleavage results in the generation of a cleaved RILP fragment (cRILP) missing the N terminus of the molecule. Although RILP localizes in a perinuclear fashion, cRILP moves to the cell periphery. Both knockdown of RILP and expression of cRILP reproduced the HCV-induced trafficking defect, and restoring full-length RILP reversed the trafficking effects of virus. For the first 3 d after electroporation of HCV RNA, intracellular virus predominates over secreted virus, but the quantity of intracellular virus then rapidly declines as secreted virus dominates. The transition from the intracellular-predominant to the secretion-predominant phenotype corresponds to the time course of cRILP generation. Expressing cRILP directly prevents intracellular virus accumulation at early times without affecting net virus production. The ability of cRILP to promote virus secretion could be prevented by a kinesin inhibitor. HCV thus modifies cellular trafficking by cleaving RILP, which serves to redirect Rab7-containing vesicles to a kinesindependent trafficking mode promoting virion secretion. Cleavage of a Rab adaptor protein is thus a mechanism by which viruses modify trafficking patterns of infected cells.T he hepatitis C virus (HCV) is a major cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV is a positive-stranded RNA virus. It replicates on modified ER membranes (1), and virions are subsequently assembled on the surface of ER-associated lipid droplets (2). The processes necessary for virion trafficking to the plasma membrane and exocytosis have not been well defined. There is considerable evidence that HCV alters several membrane trafficking steps. It rearranges the ER to form the membranous web replication complex (3, 4), and it suppresses the fusion of autophagosomes and lysosomes, resulting in the accumulation of autophagic vacuoles (5). Although the mechanisms responsible for HCVinduced membrane rearrangements are poorly understood, it is logical to assume that redirection of vesicle trafficking pathways by HCV serve the viral lifecycle by initiating genome replication, preventing virion degradation, and optimizing virion secretion.A key molecule in the regulation of membrane trafficking is rasrelated protein Rab-7 (Rab7), a member of the small GTPase family that acts as a switch triggering the assembly of vesicle microtubule motor protein linkage complexes (6). Rab7 facilitates the maturation of endosomes and autophagosomes and also promotes the microtubule-...

show abstract

“…Recently, the interaction between DGAT1 and NS5A was confirmed and was shown to be the bridge between Core and NS5A, facilitating HCV assembly (21,22). Two additional proteins, Rab18 and TIP47, were shown to interact with NS5A and promote the interaction between viral replication sites and LD (23)(24)(25). In addition, signal peptidase complex subunit 1 (SPCS1) facilitates the interaction between NS2 and E2 and is involved in the early step of the assembly of infectious particles (26).…”

mentioning

confidence: 99%

Phosphatidylserine-Specific Phospholipase A1 Involved in Hepatitis C Virus Assembly through NS2 Complex Formation

Guo

Pei

Yang

et al. 2015

J Virol

View full text Add to dashboard Cite

Several members of the phospholipase family have been reported to be involved in hepatitis C virus (HCV) replication. Here, we identified another phospholipase, phosphatidylserine-specific phospholipase A1 (PLA1A), as a host factor involved in HCV assembly. PLA1A was upregulated by HCV infection, and PLA1A knockdown significantly reduced J399EM (genotype 2a) HCV propagation at the assembly step but not the entry, RNA replication, and protein translation steps of the life cycle. Protein localization and interaction analysis further revealed a role of PLA1A in the interaction of NS2-E2 and NS2-NS5A, as the formation of the NS2-E2 and NS2-NS5A complexes was weakened in the absence of PLA1A. In addition, PLA1A stabilized the NS2/NS5A dotted structure during infection. These data suggest that PLA1A plays an important role in bridging the membrane-associated NS2-E2 complex and the NS5A-associated replication complex via its interaction with E2, NS2, and NS5A, which leads to a coordinating interaction between the structural and nonstructural proteins and facilitates viral assembly. IMPORTANCEHepatitis C virus (HCV) genomic replication is driven by the replication complex and occurs at the membranous web, while the lipid droplet is the organelle in which virion assembly is initiated. In this study, we identified phosphatidylserine-specific phospholipase A1 (PLA1A), a member of phospholipase A 1 family, as a novel host factor involved in the assembly process of HCV. PLA1A, which is induced by HCV infection at a late infection stage, interacts with HCV E2, NS2, and NS5A proteins and enhances and stabilizes the NS2-E2 and NS2-NS5A complex formation, which is essential for viral assembly. Thus, PLA1A is an important host factor which is involved in the initiation of the viral assembly in close proximity to Core-decorated lipid droplets through bringing together the HCV replication complex and envelope complex. Hepatitis C virus (HCV) is a major cause of chronic liver disease, affecting approximately 185 million people worldwide (1). HCV is a positive single-stranded RNA virus belonging to the Flaviviridae family. The HCV 9.6-kb genome contains a large open reading frame encoding a single polyprotein that is processed into its structural proteins (Core, E1, and E2) and nonstructural (NS) proteins (p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B) by host and viral proteinases (2). The structural proteins are components of the virion, while nonstructural proteins NS3 to NS5B compose the minimal viral replicase governing RNA replication (3, 4).The overall HCV life cycle has been well defined since the development of an infectious HCV cell culture system (5-7). HCV genomic replication is driven by the replication complex (RC) and occurs at the membranous web, a rearranged membrane structure induced by virus infection (8-10). Recent progress regarding the study of the assembly process demonstrates that the lipid droplet (LD) is the organelle in which virion assembly is initiated (11) and that, in addition to the structural prote...

show abstract

Rab18 Binds to Hepatitis C Virus NS5A and Promotes Interaction between Sites of Viral Replication and Lipid Droplets

Cited by 131 publications

References 70 publications

Rab18 Facilitates Dengue Virus Infection by Targeting Fatty Acid Synthase to Sites of Viral Replication

Rab18 Facilitates Dengue Virus Infection by Targeting Fatty Acid Synthase to Sites of Viral Replication

Hepatitis C virus promotes virion secretion through cleavage of the Rab7 adaptor protein RILP

Phosphatidylserine-Specific Phospholipase A1 Involved in Hepatitis C Virus Assembly through NS2 Complex Formation

Contact Info

Product

Resources

About