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Catherine L. Jopling - One of the best experts on this subject based on the ideXlab platform.
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eukaryotic translation initiation factor 4aii contributes to microRNA 122 regulation of hepatitis c virus replication
Nucleic Acids Research, 2018Co-Authors: Choudhary Shoaib Ahmed, Poppy Winlow, Aimee L Parsons, Catherine L. JoplingAbstract:Hepatitis C virus (HCV) is a positive sense RNA virus that persistently infects human liver, leading to cirrhosis and hepatocellular carcinoma. HCV replication requires the liver-specific microRNA-122 (miR-122). In contrast to canonical miRNA-mediated repression via 3’UTR sites, miR-122 positively regulates HCV replication by a direct interaction with the 5’ untranslated region (UTR) of the viral RNA. The protein factor requirements for this unusual miRNA regulation remain poorly understood. Here, we identify eIF4AII, previously implicated in miRNA-mediated repression via 3’UTR sites, as a host factor that is important for HCV replication. We demonstrate that eIF4AII interacts with HCV RNA and that this interaction is miR-122-dependent. We show that effective miR-122 binding to, and regulation of, HCV RNA are reduced following eIF4AII depletion. We find that the previously identified HCV co-factor CNOT1, which has also been implicated in miRNA-mediated repression via 3’UTR sites, contributes to regulation of HCV by eIF4AII. Finally, we show that eIF4AI knockdown alleviates the inhibition of HCV replication mediated by depletion of either eIF4AII or CNOT1. Our results suggest a competition effect between the eIF4A proteins to influence HCV replication by modulation of miR-122 function.
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The P body protein LSm1 contributes to stimulation of hepatitis C virus translation, but not replication, by microRNA-122
Nucleic acids research, 2013Co-Authors: Ashley P. E. Roberts, Rachel Doidge, Alexander W. Tarr, Catherine L. JoplingAbstract:The P body protein LSm1 stimulates translation and replication of hepatitis C virus (HCV). As the liver-specific microRNA-122 (miR-122) is required for HCV replication and is associated with P bodies, we investigated whether regulation of HCV by LSm1 involves miR-122. Here, we demonstrate that LSm1 contributes to activation of HCV internal ribosome entry site (IRES)-driven translation by miR-122. This role for LSm1 is specialized for miR-122 translation activation, as LSm1 depletion does not affect the repressive function of miR-122 at 3′ untranslated region (UTR) sites, or miR-122–mediated cleavage at a perfectly complementary site. We find that LSm1 does not influence recruitment of the microRNA (miRNA)-induced silencing complex to the HCV 5′UTR, implying that it regulates miR-122 function subsequent to target binding. In contrast to the interplay between miR-122 and LSm1 in translation, we find that LSm1 is not required for miR-122 to stimulate HCV replication, suggesting that miR-122 regulation of HCV translation and replication have different requirements. For the first time, we have identified a protein factor that specifically contributes to activation of HCV IRES-driven translation by miR-122, but not to other activities of the miRNA. Our results enhance understanding of the mechanisms by which miR-122 and LSm1 regulate HCV.
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Liver-specific microRNA-122: Biogenesis and function
RNA biology, 2012Co-Authors: Catherine L. JoplingAbstract:microRNA-122 (miR-122) was one of the first examples of a tissue-specific miRNA. It is highly expressed in liver, where it constitutes 70% of the total miRNA pool. miR-122 expression is specific to the vertebrate lineage, where the sequence of the mature miRNA is completely conserved. miR-122 is a target for extensive study due to its association with cholesterol metabolism and hepatocellular carcinoma, and its important role in promoting hepatitis C virus (HCV) replication. This review will discuss the biogenesis and function of miR-122.
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Targeting microRNA-122 to Treat Hepatitis C Virus Infection.
Viruses, 2010Co-Authors: Catherine L. JoplingAbstract:An important host factor for hepatitis C virus (HCV) is microRNA-122 (miR-122). miR-122 is a liver-specific member of a family of small, non-coding RNA molecules known as microRNAs that play major roles in the regulation of gene expression by direct interaction with RNA targets. miR-122 binds directly to two sites in the 5' untranslated region (UTR) of HCV RNA and positively regulates the viral life cycle. The mechanism by which this regulation occurs is still not fully understood. There has been a great deal of interest in potential therapeutics based on small RNAs, and targeting miR-122 to combat HCV is one of the furthest advanced. Chemical inhibitors of miR-122 can be introduced into mammals intravenously and result in potent and specific knockdown of the microRNA, with no detectable adverse effects on liver physiology. This strategy was recently applied to chimpanzees chronically infected with HCV and resulted in a sustained reduction in viral load in the animals. Inhibition of miR-122 therefore presents a very attractive novel approach to treating HCV, a virus for which improved therapeutics are urgently needed.
Michael Niepmann - One of the best experts on this subject based on the ideXlab platform.
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Functional sequestration of microRNA-122 from Hepatitis C Virus by circular RNA sponges.
RNA biology, 2018Co-Authors: Isabelle Jost, Michael Niepmann, Lyudmila A. Shalamova, Gesche K. Gerresheim, Albrecht Bindereif, Oliver RossbachAbstract:Circular RNAs (circRNAs) were recently described as a novel class of cellular RNAs. Two circRNAs were reported to function as molecular sponges, sequestering specific microRNAs, thereby de-repressing target mRNAs. Due to their elevated stability in comparison to linear RNA, circRNAs may be an interesting tool in molecular medicine and biology. In this study, we provide a proof-of-principle that circRNAs can be engineered as microRNA sponges. As a model system, we used the Hepatitis C Virus (HCV), which requires cellular microRNA-122 for its life cycle. We produced artificial circRNA sponges in vitro that efficiently sequester microRNA-122, thereby inhibiting viral protein production in an HCV cell culture system. These circRNAs are more stable than their linear counterparts, and localize both to the cytoplasm and to the nucleus, opening up a wide range of potential applications.
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microRNA-122 dependent binding of Ago2 protein to hepatitis C virus RNA is associated with enhanced RNA stability and translation stimulation.
PLoS ONE, 2013Co-Authors: K. Dominik Conrad, Florian Giering, Corinna Erfurth, Angelina Neumann, Carmen Fehr, Gunter Meister, Michael NiepmannAbstract:Translation of Hepatitis C Virus (HCV) RNA is directed by an internal ribosome entry site (IRES) in the 5′-untranslated region (5′-UTR). HCV translation is stimulated by the liver-specific microRNA-122 (miR-122) that binds to two binding sites between the stem-loops I and II near the 5′-end of the 5′-UTR. Here, we show that Argonaute (Ago) 2 protein binds to the HCV 5′-UTR in a miR-122-dependent manner, whereas the HCV 3′-UTR does not bind Ago2. miR-122 also recruits Ago1 to the HCV 5’-UTR. Only miRNA duplex precursors of the correct length stimulate HCV translation, indicating that the duplex miR-122 precursors are unwound by a complex that measures their length. Insertions in the 5′-UTR between the miR-122 binding sites and the IRES only slightly decrease translation stimulation by miR-122. In contrast, partially masking the miR-122 binding sites in a stem-loop structure impairs Ago2 binding and translation stimulation by miR-122. In an RNA decay assay, also miR-122-mediated RNA stability contributes to HCV translation stimulation. These results suggest that Ago2 protein is directly involved in loading miR-122 to the HCV RNA and mediating RNA stability and translation stimulation.
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Differential stimulation of hepatitis C virus RNA translation by microRNA-122 in different cell cycle phases
Cell cycle (Georgetown Tex.), 2012Co-Authors: Carmen Fehr, K. Dominik Conrad, Michael NiepmannAbstract:Hepatitis C virus (HCV) replicates preferentially in the liver, and in most cases the HCV infection becomes chronic and often results in hepatocellular carcinoma. When the HCV plus-strand RNA genome has been delivered to the cytosol of the infected cell, its translation is directed by the Internal Ribosome Entry Site (IRES) in the 5´-untranslated region (5´-UTR) of the viral RNA. Thereby, IRES activity is modulated by several host factors. In particular, the liver-specific microRNA-122 (miR-122) interacts with two target sites in the HCV 5´-UTR and stimulates HCV translation, thereby most likely contributing to HCV liver tropism. Here we show that HCV IRES-dependent translation efficiency in the hepatoma cell line Huh7 is highest during the G0 and G1 phases of the cell cycle but significantly drops during the S phase and even more in the G2/M phase. The superimposed stimulation of HCV translation by ectopic miR-122 works best during the G0, G1 and G2/M phases but is lower during the S phase. However, the ...
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microRNA-122 stimulates translation of hepatitis C virus RNA
The EMBO journal, 2008Co-Authors: Jura Inga Henke, Carmen Fehr, Dagmar Goergen, Junfeng Zheng, Yutong Song, Christian G. Schüttler, Christiane Jünemann, Michael NiepmannAbstract:Hepatitis C virus (HCV) is a positive strand RNA virus that propagates primarily in the liver. We show here that the liver-specific microRNA-122 (miR-122), a member of a class of small cellular RNAs that mediate post-transcriptional gene regulation usually by repressing the translation of mRNAs through interaction with their 3′-untranslated regions (UTRs), stimulates the translation of HCV. Sequestration of miR-122 in liver cell lines strongly reduces HCV translation, whereas addition of miR-122 stimulates HCV translation in liver cell lines as well as in the non-liver HeLa cells and in rabbit reticulocyte lysate. The stimulation is conferred by direct interaction of miR-122 with two target sites in the 5′-UTR of the HCV genome. With a replication-defective NS5B polymerase mutant genome, we show that the translation stimulation is independent of viral RNA synthesis. miR-122 stimulates HCV translation by enhancing the association of ribosomes with the viral RNA at an early initiation stage. In conclusion, the liver-specific miR-122 may contribute to HCV liver tropism at the level of translation.
Peter Willeit - One of the best experts on this subject based on the ideXlab platform.
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circulating microRNA 122 is associated with the risk of new onset metabolic syndrome and type 2 diabetes
Diabetes, 2017Co-Authors: Peter Willeit, Xiaoke Yin, Dorothee Kaudewitz, Philipp Skroblin, Anna Zampetaki, Alexander R. Moschen, Temo Barwari, Meredith WhiteheadAbstract:microRNA-122 (miR-122) is abundant in the liver and involved in lipid homeostasis, but its relevance to the long-term risk of developing metabolic disorders is unknown. We therefore measured circulating miR-122 in the prospective population-based Bruneck Study (n = 810; survey year 1995). Circulating miR-122 was associated with prevalent insulin resistance, obesity, metabolic syndrome, type 2 diabetes, and an adverse lipid profile. Among 92 plasma proteins and 135 lipid subspecies quantified with mass spectrometry, it correlated inversely with zinc-α-2-glycoprotein and positively with afamin, complement factor H, VLDL-associated apolipoproteins, and lipid subspecies containing monounsaturated and saturated fatty acids. Proteomics analysis of livers from antagomiR-122-treated mice revealed novel regulators of hepatic lipid metabolism that are responsive to miR-122 inhibition. In the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT, n = 155), 12-month atorvastatin reduced circulating miR-122. A similar response to atorvastatin was observed in mice and cultured murine hepatocytes. Over up to 15 years of follow-up in the Bruneck Study, multivariable adjusted risk ratios per one-SD higher log miR-122 were 1.60 (95% CI 1.30-1.96; P < 0.001) for metabolic syndrome and 1.37 (1.03-1.82; P = 0.021) for type 2 diabetes. In conclusion, circulating miR-122 is strongly associated with the risk of developing metabolic syndrome and type 2 diabetes in the general population.
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Circulating microRNA-122 is associated with the risk of new-onset metabolic syndrome and type 2 diabetes
Diabetes, 2016Co-Authors: Peter Willeit, Xiaoke Yin, Dorothee Kaudewitz, Philipp Skroblin, Anna Zampetaki, Alexander R. Moschen, Cristina M. Ramírez, Temo Barwari, Meredith Whitehead, Leigh GoedekeAbstract:microRNA-122 (miR-122) is abundant in the liver and involved in lipid homeostasis, but its relevance to the long-term risk of developing metabolic disorders is unknown. We therefore measured circulating miR-122 in the prospective population-based Bruneck Study (n = 810; survey year 1995). Circulating miR-122 was associated with prevalent insulin resistance, obesity, metabolic syndrome, type 2 diabetes, and an adverse lipid profile. Among 92 plasma proteins and 135 lipid subspecies quantified with mass spectrometry, it correlated inversely with zinc-α-2-glycoprotein and positively with afamin, complement factor H, VLDL-associated apolipoproteins, and lipid subspecies containing monounsaturated and saturated fatty acids. Proteomics analysis of livers from antagomiR-122–treated mice revealed novel regulators of hepatic lipid metabolism that are responsive to miR-122 inhibition. In the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT, n = 155), 12-month atorvastatin reduced circulating miR-122. A similar response to atorvastatin was observed in mice and cultured murine hepatocytes. Over up to 15 years of follow-up in the Bruneck Study, multivariable adjusted risk ratios per one-SD higher log miR-122 were 1.60 (95% CI 1.30–1.96; P
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Abstract 17961: Circulating microRNA-122 is Associated With Incident Metabolic Syndrome and Type-2-diabetes
Circulation, 2015Co-Authors: Peter Willeit, Xiaoke Yin, Dorothee Kaudewitz, Philipp Skroblin, Anna Zampetaki, Alexander R. Moschen, Cristina M. Ramírez, Leigh Goedeke, Noemi Rotllan, Enzo BonoraAbstract:Background: microRNA-122 (miR-122) is highly abundant in the liver and has been implicated in lipid and glucose homeostasis. Methods: Circulating miR-122 levels were measured in the prospective population-based Bruneck Study (n=810) and the ASCOT trial (n=155 pre/post atorvastatin initiation). Using mass spectrometry, we measured 135 lipid subspecies and 93 plasma proteins in Bruneck participants. We also conducted mechanistic studies in pre-clinical models and cultured hepatocytes. We calculated risk ratios over up to 15 years follow-up for cardiometabolic diseases using pooled logistic and Cox regression, incorporating repeated miR-122 measurements. Results: In the Bruneck Study, miR-122 was associated with an adverse metabolic profile, including insulin resistance, obesity, and prevalent metabolic syndrome and diabetes. MiR-122 positively correlated with lipid subspecies containing fatty acids that can be derived from hepatic de novo lipogenesis. In mice, miR-122 inhibition with antagomiR treatment dow...
Joyce A. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Modulation of GB Virus B RNA Abundance by microRNA-122: Dependence on and Escape from microRNA-122 Restriction
Journal of virology, 2013Co-Authors: Selena M. Sagan, Peter Sarnow, Joyce A. WilsonAbstract:Hepatitis C virus (HCV) RNA forms an unusual interaction with human microRNA-122 (miR-122) that promotes viral RNA accumulation in cultured human liver cells and in the livers of infected chimpanzees. GB virus B (GBV-B) is a hepatotropic virus and close relative of HCV. Thus, GBV-B has been used as a surrogate system to study HCV amplification in cultured cells and in infected tamarins. It was discovered that the 5′-terminal sequences of GBV-B RNA, like HCV RNA, forms an Argonaute 2-mediated complex with two miR-122 molecules that are essential for accumulation of GBV-B subgenomic replicon RNA. However, sequences in miR-122 that anneal to each viral RNA genome were different, suggesting distinct overall structural features in HCV:miR-122 and GBV-B:miR-122 complexes. Surprisingly, a deletion that removed both miR-122 binding sites from the subgenomic GBV-B RNAs rendered viral RNA amplification independent from miR-122 and Argonaute 2. This finding suggests that structural features at the end of the viral genome dictate whether miR-122 is required to aid in maintaining viral RNA abundance.
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Requirements for human Dicer and TRBP in microRNA-122 regulation of HCV translation and RNA abundance.
Virology, 2012Co-Authors: Chao Zhang, Adam Huys, Patricia A. Thibault, Joyce A. WilsonAbstract:Abstract microRNA-122 (miR-122) promotes Hepatitis C Virus (HCV) RNA stability, accumulation, and translation through hybridization with the 5′ untranslated region (5′ UTR) of the HCV genome. Depletion of Dicer and TRBP, proteins involved in miRNA biogenesis, reduced HCV RNA accumulation, mature duplex miR-122 abundance, and miR-122 directed mRNA translation suppression, suggesting roles in miR-122 processing. HCV RNA accumulation independent of endogenous mature duplex miR-122 was not affected by Dicer knockdown, suggesting that Dicer is required solely for miR-122 biogenesis, but TRBP knockdown reduced HCV RNA accumulation in this system, suggesting an additional role in supporting HCV RNA accumulation. Mature duplex miR-122 and pre-miR-122 hairpin, but not single-stranded miR-122 (guide or ⁎ strand), augmented HCV RNA accumulation and translation, and Dicer and TRBP were essential for the activity of pre-miR-122 in mouse fibroblasts. Thus, canonical miRNA processing and strand selection is essential for the activity of miR-122 on HCV translation and RNA accumulation.
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Human Ago2 Is Required for Efficient microRNA 122 Regulation of Hepatitis C Virus RNA Accumulation and Translation
Journal of virology, 2010Co-Authors: Joyce A. Wilson, Chao Zhang, Adam Huys, Christopher D. RichardsonAbstract:microRNA 122 (miR-122) increases the accumulation and translation of hepatitis C virus (HCV) RNA in infected cells through direct interactions with homologous sequences in the 5′ untranslated region (UTR) of the HCV genome. Argonaute 2 (Ago2) is a component of the RNA-induced silencing complex (RISC) and mediates small interfering RNA (siRNA)-directed mRNA cleavage and microRNA translational suppression. We investigated the function of Ago2 in HCV replication to determine whether it plays a role in enhancing the synthesis and translation of HCV RNA that is associated with miR-122. siRNA-mediated depletion of Ago2 in human hepatoma cells reduced HCV RNA accumulation in transient HCV replication assays. The treatment did not adversely affect cell viability, as assessed by cell proliferation, capped translation, and interferon assays. These data are consistent with complementary roles for Ago2 and miR-122 in enhancing HCV RNA amplification. By using a transient HCV replication assay that is dependent on an exogenously provided mutant miR-122, we determined that Ago2 depletion still reduced luciferase expression and HCV RNA accumulation, independently of miR-122 biogenesis. miR-122 has previously been found to stimulate HCV translation. Similarly, Ago2 knockdown also reduced HCV translation, and its depletion reduced the ability of miR-122 to stimulate viral translation. These data suggest a direct role for Ago2 in miR-122-mediated translation. Finally, Ago2 was also necessary for efficient miR-122 enhancement of HCV RNA accumulation. These data support a model in which miR-122 functions within an Ago2-containing protein complex to augment both HCV RNA accumulation and translation.
Carmen Fehr - One of the best experts on this subject based on the ideXlab platform.
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microRNA-122 dependent binding of Ago2 protein to hepatitis C virus RNA is associated with enhanced RNA stability and translation stimulation.
PLoS ONE, 2013Co-Authors: K. Dominik Conrad, Florian Giering, Corinna Erfurth, Angelina Neumann, Carmen Fehr, Gunter Meister, Michael NiepmannAbstract:Translation of Hepatitis C Virus (HCV) RNA is directed by an internal ribosome entry site (IRES) in the 5′-untranslated region (5′-UTR). HCV translation is stimulated by the liver-specific microRNA-122 (miR-122) that binds to two binding sites between the stem-loops I and II near the 5′-end of the 5′-UTR. Here, we show that Argonaute (Ago) 2 protein binds to the HCV 5′-UTR in a miR-122-dependent manner, whereas the HCV 3′-UTR does not bind Ago2. miR-122 also recruits Ago1 to the HCV 5’-UTR. Only miRNA duplex precursors of the correct length stimulate HCV translation, indicating that the duplex miR-122 precursors are unwound by a complex that measures their length. Insertions in the 5′-UTR between the miR-122 binding sites and the IRES only slightly decrease translation stimulation by miR-122. In contrast, partially masking the miR-122 binding sites in a stem-loop structure impairs Ago2 binding and translation stimulation by miR-122. In an RNA decay assay, also miR-122-mediated RNA stability contributes to HCV translation stimulation. These results suggest that Ago2 protein is directly involved in loading miR-122 to the HCV RNA and mediating RNA stability and translation stimulation.
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Differential stimulation of hepatitis C virus RNA translation by microRNA-122 in different cell cycle phases
Cell cycle (Georgetown Tex.), 2012Co-Authors: Carmen Fehr, K. Dominik Conrad, Michael NiepmannAbstract:Hepatitis C virus (HCV) replicates preferentially in the liver, and in most cases the HCV infection becomes chronic and often results in hepatocellular carcinoma. When the HCV plus-strand RNA genome has been delivered to the cytosol of the infected cell, its translation is directed by the Internal Ribosome Entry Site (IRES) in the 5´-untranslated region (5´-UTR) of the viral RNA. Thereby, IRES activity is modulated by several host factors. In particular, the liver-specific microRNA-122 (miR-122) interacts with two target sites in the HCV 5´-UTR and stimulates HCV translation, thereby most likely contributing to HCV liver tropism. Here we show that HCV IRES-dependent translation efficiency in the hepatoma cell line Huh7 is highest during the G0 and G1 phases of the cell cycle but significantly drops during the S phase and even more in the G2/M phase. The superimposed stimulation of HCV translation by ectopic miR-122 works best during the G0, G1 and G2/M phases but is lower during the S phase. However, the ...
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microRNA-122 stimulates translation of hepatitis C virus RNA
The EMBO journal, 2008Co-Authors: Jura Inga Henke, Carmen Fehr, Dagmar Goergen, Junfeng Zheng, Yutong Song, Christian G. Schüttler, Christiane Jünemann, Michael NiepmannAbstract:Hepatitis C virus (HCV) is a positive strand RNA virus that propagates primarily in the liver. We show here that the liver-specific microRNA-122 (miR-122), a member of a class of small cellular RNAs that mediate post-transcriptional gene regulation usually by repressing the translation of mRNAs through interaction with their 3′-untranslated regions (UTRs), stimulates the translation of HCV. Sequestration of miR-122 in liver cell lines strongly reduces HCV translation, whereas addition of miR-122 stimulates HCV translation in liver cell lines as well as in the non-liver HeLa cells and in rabbit reticulocyte lysate. The stimulation is conferred by direct interaction of miR-122 with two target sites in the 5′-UTR of the HCV genome. With a replication-defective NS5B polymerase mutant genome, we show that the translation stimulation is independent of viral RNA synthesis. miR-122 stimulates HCV translation by enhancing the association of ribosomes with the viral RNA at an early initiation stage. In conclusion, the liver-specific miR-122 may contribute to HCV liver tropism at the level of translation.