Enhancement of hepatitis C viral RNA abundance by precursor miR-122 molecules

Cox, Erica M.; Sagan, Selena M.; Mortimer, Stefanie; Doudna, Jennifer A.; Sarnow, Peter

doi:10.1261/rna.040865.113

Cited by 16 publications

(8 citation statements)

References 38 publications

(48 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…S8A and S8B Fig shows that the abundance of pri-miR-122 is not affected by the depletion of Rab27a in uninfected and infected cells, suggesting that Rab27a modulates miR-122 abundance at a post-transcriptional step. Because precursor-miR-122 (pre-miR-122) can not be detected in cultured Huh7 cells, we determined the effect of Rab27a on the stability of a pre-miR-122 species that is resistant to the cleavage by Dicer [ 32 ]. Thus, the intracellular decay of a dicer-resistant pre-p3 (dNx12) that is functional in regulating mRNAs with miR-122 target sites [ 32 ] was examined ( S9A Fig ).…”

Section: Resultsmentioning

confidence: 99%

Supporting Role for GTPase Rab27a in Hepatitis C Virus RNA Replication through a Novel miR-122-Mediated Effect

2015

Self Cite

View full text Add to dashboard Cite

The small GTPase Rab27a has been shown to control membrane trafficking and microvesicle transport pathways, in particular the secretion of exosomes. In the liver, high expression of Rab27a correlates with the development of hepatocellular carcinoma. We discovered that low abundance of Rab27a resulted in decreased hepatitis C virus (HCV) RNA and protein abundances in virus-infected cells. Curiously, both cell-associated and extracellular virus yield decreased in Rab27a depleted cells, suggesting that reduced exosome secretion did not cause the observed effect. Instead, Rab27a enhanced viral RNA replication by a mechanism that involves the liver-specific microRNA miR-122. Rab27a surrounded lipid droplets and was enriched in membrane fractions that harbor viral replication proteins, suggesting a supporting role for Rab27a in viral gene expression. Curiously, Rab27a depletion decreased the abundance of miR-122, whereas overexpression of miR-122 in Rab27a-depleted cells rescued HCV RNA abundance. Because intracellular HCV RNA abundance is enhanced by the binding of two miR-122 molecules to the extreme 5’ end of the HCV RNA genome, the diminished amounts of miR-122 in Rab27a-depleted cells could have caused destabilization of HCV RNA. However, the abundance of HCV RNA carrying mutations on both miR-122-binding sites and whose stability was supported by ectopically expressed miR-122 mimetics with compensatory mutations also decreased in Rab27a-depleted cells. This result indicates that the effect of Rab27a depletion on HCV RNA abundance does not depend on the formation of 5’ terminal HCV/miR-122 RNA complexes, but that miR-122 has a Rab27a-dependent function in the HCV lifecycle, likely the downregulation of a cellular inhibitor of HCV gene expression. These findings suggest that the absence of miR-122 results in a vulnerability not only to exoribonucleases that attack the viral genome, but also to upregulation of one more cellular factor that inhibit viral gene expression.

show abstract

Section: Resultsmentioning

confidence: 99%

Supporting Role for GTPase Rab27a in Hepatitis C Virus RNA Replication through a Novel miR-122-Mediated Effect

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…These data may reflect the enhanced binding strength of miR-122 to S2 proposed by Mortimer and Doudna (32). This also has implications for explorations of the functions of miR-122, where Huh7.5 cells were supplemented with additional miR-122; and it is possible that supplementation may disproportionately measure effects of miR-122 binding to S1 (5,10,11,15,27,28).…”

Section: Discussionmentioning

confidence: 99%

Regulation of Hepatitis C Virus Genome Replication by Xrn1 and MicroRNA-122 Binding to Individual Sites in the 5′ Untranslated Region

Thibault

Huys

Amador-Cañizares

et al. 2015

J Virol

View full text Add to dashboard Cite

miR-122 is a liver-specific microRNA (miRNA) that binds to two sites (S1 and S2) on the 5= untranslated region (UTR) of the hepatitis C virus (HCV) genome and promotes the viral life cycle. It positively affects viral RNA stability, translation, and replication, but the mechanism is not well understood. To unravel the roles of miR-122 binding at each site alone or in combination, we employed miR-122 binding site mutant viral RNAs, Hep3B cells (which lack detectable miR-122), and complementation with wild-type miR-122, an miR-122 with the matching mutation, or both. We found that miR-122 binding at either site alone increased replication equally, while binding at both sites had a cooperative effect. Xrn1 depletion rescued miR-122-unbound fulllength RNA replication to detectable levels but not to miR-122-bound levels, confirming that miR-122 protects HCV RNA from Xrn1, a cytoplasmic 5=-to-3= exoribonuclease, but also has additional functions. In cells depleted of Xrn1, replication levels of S1-bound HCV RNA were slightly higher than S2-bound RNA levels, suggesting that both sites contribute, but their contributions may be unequal when the need for protection from Xrn1 is reduced. miR-122 binding at S1 or S2 also increased translation equally, but the effect was abolished by Xrn1 knockdown, suggesting that the influence of miR-122 on HCV translation reflects protection from Xrn1 degradation. Our results show that occupation of each miR-122 binding site contributes equally and cooperatively to HCV replication but suggest somewhat unequal contributions of each site to Xrn1 protection and additional functions of miR-122. Hepatitis C virus (HCV) is a hepatotropic virus that infects an estimated 150 million humans worldwide, a significant portion of whom do not know their status due to the largely asymptomatic nature of the infection (1). The virus is transmitted by blood-to-blood contact, and humans are the only known reservoir. Chronic infection occurs in approximately 70% of cases and can lead to sequelae such as metabolic disease, steatosis, hepatocellular carcinoma, and decompensated liver disease late in infection (2).One of the major determinants of the virus' hepatotropism is its requirement for the liver-specific, liver-abundant miR-122 microRNA (miRNA) (3, 4). miR-122 binds to two sites at the 5= end of the virus' positive-sense RNA genome and has been shown to directly enhance viral RNA accumulation, since mutation of the miR-122 binding sites abolishes RNA accumulation, and the provision of exogenous miR-122 sequences that have compensatory mutations to restore binding also reinstates RNA accumulation (4-10). Argonaute-2, one of the key effector proteins in the microRNA pathway and a component of the RNA-induced silencing complex (RISC), binds in association with miR-122 and is required to increase HCV replication, while several other proteins in the microRNA pathway and RISC have been implicated in either the biogenesis or activity of miR-122 (5, 11-14). Although miR-122 uses canonical microRNA se...

show abstract

“…Jopling et al (2005) showed that cellular HCV RNA decreased when miR-122 was inactivated. Since then, several published studies have revealed a requirement of miR-122 and/or its precursor molecule for HCV replication and stability (Jangra et al, 2010;Cox et al, 2013;Mortimer and Doudna, 2013) and successfully validated an anti-miR-122 therapy for suppression of viremia in chronically HCV infected primates (Lanford et al, 2010). Moreover, a study in which the serum from 102 HCV patients were compared to healthy controls identified a 23-fold increase of miR-122, indicating that it may be a useful biomarker to detect chronic HCV infections (van der Meer et al, 2013).…”

Section: Viral Hepatitismentioning

confidence: 99%

Regulation of microRNAs and their role in liver development, regeneration and disease

Finch

Marquardt

Yeoh

et al. 2014

The International Journal of Biochemistry & Cell Biology

View full text Add to dashboard Cite

Since their discovery more than a decade ago microRNAs have been demonstrated to have profound effects on almost every aspect of biology. Numerous studies in recent years have shown that microRNAs have important roles in development and in the etiology and progression of disease. This review is focused on microRNAs and the roles they play in liver development, regeneration and liver disease; particularly chronic liver diseases such as alcoholic liver disease, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, viral hepatitis and primary liver cancer. The key microRNAs identified in liver development and chronic liver disease will be discussed together with, where possible, the target messenger RNAs that these microRNAs regulate to profoundly alter these processes. This article is part of a Directed Issue entitled: The Non-coding RNA Revolution.

show abstract

Enhancement of hepatitis C viral RNA abundance by precursor miR-122 molecules

Cited by 16 publications

References 38 publications

Supporting Role for GTPase Rab27a in Hepatitis C Virus RNA Replication through a Novel miR-122-Mediated Effect

Supporting Role for GTPase Rab27a in Hepatitis C Virus RNA Replication through a Novel miR-122-Mediated Effect

Regulation of Hepatitis C Virus Genome Replication by Xrn1 and MicroRNA-122 Binding to Individual Sites in the 5′ Untranslated Region

Regulation of microRNAs and their role in liver development, regeneration and disease

Contact Info

Product

Resources

About