Binding of cellular nucleolin with the viral core RNA G-quadruplex structure suppresses HCV replication

Abstract

Hepatitis C virus (HCV) infection is a major cause of human chronic liver disease and hepatocellular carcinoma. G-quadruplex (G4) is an important four-stranded secondary structure of nucleic acids. Recently, we discovered that the core gene of HCV contains a G4 RNA structure; however, the interaction between the HCV core RNA G4 and host cellular proteins, and the roles of the HCV core RNA G4 in HCV infection and pathogenesis remain elusive. Here, we identified a cellular protein, nucleolin (NCL), which bound and stabilized the HCV core RNA G4 structure. We demonstrated the direct interaction and colocalization between NCL and wild-type core RNA G4 at both in vitro and in cell physiological conditions of the alive virus; however no significant interaction was found between NCL and G4-modified core RNA. NCL is also associated with HCV particles. HCV infection induced NCL mRNA and protein expression, while NCL suppressed wild-type viral replication and expression, but not G4-modified virus. Silencing of NCL greatly enhanced viral RNA replication. Our findings provide new insights that NCL may act as a host factor for anti-viral innate immunity, and binding of cellular NCL with the viral core RNA G4 structure is involved in suppressing HCV replication.

G-Quadruplexes Are Present in Human Coronaviruses Including SARS-CoV-2

“…Viral G4 also associated with host proteins. Cellular nucleolin interacted with viral core G4 to suppress HCV replication (Bian et al, 2019). Nucleolin directly binds to EBV G4 in EBNV1 mRNA sequence to inhibit EBNV1 protein expression (Lista et al, 2017).…”

Viral G-quadruplexes: New frontiers in virus pathogenesis and antiviral therapy

“…Conversely, nucleolin silencing was directly correlated with increased HCV RNA expression. 48 These results strongly suggest the existence of a host anti-viral immunity mechanism involving G4 structures. Additional bioinformatic studies based on a different algorithm showed the presence of a very interesting G4-forming sequence in the stem-loop IIy of the HCV negative strand, precisely in the 3'-UTR, which is the initiation site for the (+)-strand replication.…”

“…The one located in the core gene was characterized as the most stable G4. 48 Its stabilization with the G4 ligands TMPyP4 and a PDS derivative (PDP) promoted viral RNA-dependent RNA polymerase stalling, with consequent reduction in HCV core protein levels. In vivo analysis revealed that PDP led to G4-mediated antiviral activity in the low micromolar range, by inhibiting intracellular replication of different HCV genotypes.…”

Neutralization of IL‐10 produced by B cells promotes protective immunity during persistent HCV infection in humanized mice

“…Huh7.5.1 cells were cultured in complete DMEM (Thermo Fisher Scientific, Waltham, MA, USA) with 10% fetal bovine serum (FBS, HyClone, Logan, USA). Expansion of cell culture-derived HCV (HCVcc, genotype 2a, Japanese fulmi-nant hepatitis 1, JFH1 isolate) was performed using Huh7.5.1 cells as described in our previous publication [38]. In brief, Huh7.5.1 cells were infected with HCVcc (MOI of ß1; 1 × 10 7 RNA copies/mL).…”