HuR, a Protein Implicated in Oncogene and Growth Factor mRNA Decay, Binds to the 3′ Ends of Hepatitis C Virus RNA of Both Polarities

Spångberg, Karin; Wiklund, Lisa; Schwartz, Stefan

doi:10.1006/viro.2000.0461

Cited by 75 publications

(73 citation statements)

References 46 publications

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“…RPL22 and GAPDH interact specifically with the 3Ј NTR (38). PTBP1, ELAVL1, and HNRNPC bind to the 3Ј termini of both (ϩ) and (Ϫ) strands, suggesting they may be components of the RNA synthesis initiation complexes (39,40).…”

Section: Discussionmentioning

confidence: 99%

Cellular cofactors affecting hepatitis C virus infection and replication

Randall

Panis²,

Cooper

et al. 2007

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

496

454

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Recently identified hepatitis C virus (HCV) isolates that are infectious in cell culture provide a genetic system to evaluate the significance of virus-host interactions for HCV replication. We have completed a systematic RNAi screen wherein siRNAs were designed that target 62 host genes encoding proteins that physically interact with HCV RNA or proteins or belong to cellular pathways thought to modulate HCV infection. This includes 10 host proteins that we identify in this study to bind HCV NS5A. siRNAs that target 26 of these host genes alter infectious HCV production >3-fold. Included in this set of 26 were siRNAs that target Dicer, a principal component of the RNAi silencing pathway. Contrary to the hypothesis that RNAi is an antiviral pathway in mammals, as has been reported for subgenomic HCV replicons, siRNAs that target Dicer inhibited HCV replication. Furthermore, siRNAs that target several other components of the RNAi pathway also inhibit HCV replication. MicroRNA profiling of human liver, human hepatoma Huh-7.5 cells, and Huh-7.5 cells that harbor replicating HCV demonstrated that miR-122 is the predominant microRNA in each environment. miR-122 has been previously implicated in positively regulating the replication of HCV genotype 1 replicons. We find that 2-O-methyl antisense oligonucleotide depletion of miR-122 also inhibits HCV genotype 2a replication and infectious virus production. Our data define 26 host genes that modulate HCV infection and indicate that the requirement for functional RNAi for HCV replication is dominant over any antiviral activity this pathway may exert against HCV.antivirals ͉ miR-122 ͉ RNAi ͉ HCVcc-siRNA H epatitis C virus (HCV) has a notable ability to establish persistent infections in Ϸ70% of cases, resulting in 130 million chronically infected people throughout the world (1). This prevalence has spurred considerable interest in the study of HCV-host interactions, on both cellular and molecular levels. The inability to grow HCV in cell culture led some groups to focus on the identification of cellular proteins that interact with individual HCV proteins or RNA elements, resulting in the accumulation of a large number of putative HCV-host interactions. Unfortunately, the significance of most of these with respect to the HCV life cycle is currently unknown (reviewed in ref.2). Over the past 6 years, cell culture systems have been developed that enable the characterization of HCV replication and entry (3-6). This effort recently culminated in the development of cell culture systems that reproduce the entire viral life cycle (7-9). A number of virus-host interactions have been characterized by using these experimental systems. For example, CD81 has been demonstrated to play a role in HCV entry (10-12).Sequence-specific gene silencing of RNAi is ideal for assessing the genetic phenotypes associated with virus-host interactions. We have previously shown that siRNAs are highly effective at silencing either host or viral RNAs in cells that contain replicating HCV, demonstrating th...

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Section: Discussionmentioning

confidence: 99%

Cellular cofactors affecting hepatitis C virus infection and replication

Randall

Panis²,

Cooper

et al. 2007

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

496

454

View full text Add to dashboard Cite

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“…The RNA structure itself may also render the negative strand resistant to cellular RNases in the absence of viral protein binding (49) and carry out other functions by direct interaction with host factors (48,52). Characterization of the HCV 3Ј-terminal RNA fold may therefore be of value for the identification of structural features essential FIG.…”

Section: Discussionmentioning

confidence: 99%

Secondary structure and hybridization accessibility of the hepatitis C virus negative strand RNA 5′‐terminus

Smith

2004

Journal of Viral Hepatitis

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The 3 -terminal sequences of hepatitis C virus (HCV) positive-and negative-strand RNAs contribute cis-acting functions essential for viral replication. The secondary structure and protein-binding properties of these highly conserved regions are of interest not only for the further elucidation of HCV molecular biology, but also for the design of antisense therapeutic constructs. The RNA structure of the positive-strand 3 untranslated region has been shown previously to influence binding by various host and viral proteins and is thus thought to promote HCV RNA synthesis and genome stability. Recent studies have attributed analogous functions to the negative-strand 3 terminus. We evaluated the HCV negative-strand secondary structure by enzymatic probing with single-strand-specific RNases and thermodynamic modeling of RNA folding. The accessibility of both 3 -terminal sequences to hybridization by antisense constructs was evaluated by RNase H cleavage mapping in the presence of combinatorial oligodeoxynucleotide libraries. The mapping results facilitated identification of antisense oligodeoxynucleotides and a 10-23 deoxyribozyme active against the positivestrand 3 -X region RNA in vitro.The untranslated regions (UTRs) of the hepatitis C virus (HCV) positive-strand genome and negative-strand intermediate contain cis-acting sequences essential for viral translation and RNA replication. The 341-nucleotide (nt) 5Ј-UTR of the positive strand acts as an internal ribosome entry site (IRES) to direct cap-independent translation of the single ϳ3,000-codon-long HCV open reading frame (38, 40). The tripartite 3Ј-UTR consists of a short upstream variable region, a central poly(U)-polypyrimidine stretch of variable length, and a terminal highly conserved 98-nt sequence (38). With the exception of the variable region, all sequence elements in the 3Ј-UTR are necessary for intracellular replication of HCV RNA (16,29,56).A number of in vitro studies (26,35,36,39,58) have established that the terminal 98-nt X region sequence can serve as a minimal template for de novo initiation of negative-strand synthesis by the viral RNA-dependent RNA polymerase, NS5B. The 3Ј terminus of the HCV negative strand reportedly plays an analogous role in positive-strand RNA synthesis (25,36,39). The binding of HCV 3Ј termini to various host proteins may exert subtle effects on IRES-mediated translation (16,23,34,55) or protect viral transcripts from degradation by cytoplasmic RNases (15,48,49).The replicative and protein-binding functions of heteropolymeric regions in the HCV 3Ј termini are, in many instances, dependent on the ability of the primary sequence to fold into higher-order RNA structure. In vitro, the X region sequence is capable of adopting a three-stem-loop structure, with the 3Ј-terminal 46 nt forming a thermodynamically stable stem-loop, SL I (6). Mutational analysis indicates that the duplex structure forming the base of SL I influences both the site and efficiency of de novo initiation by NS5B (26,35). Preservation of the interior stem-...

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“…The mechanisms by which viruses protect their mRNAs from general RNA decay have been previously reviewed. [18][19][20] For viruses to escape ZAP-specific viral mRNA degradation, one intriguing possibility is that viruses might encode factors that either inactivate ZAP or block ZAP-mediated RNA degradation. An analogous example is that many viruses encode suppressors of RNA silencing (SRS) 21 to protect the virus from inhibition by host RNA silencing.…”

Section: Specificity Of the Antiviral Activity Of Zapmentioning

confidence: 99%