Let-7b is a novel regulator of hepatitis C virus replication

Plasma microRNAs (miRNAs) change in abundance in response to disease and have been associated with liver fibrosis severity in chronic hepatitis C virus (HCV) infection. However, the early dynamics of miRNA release during acute HCV infection are poorly understood. In addition, circulating miRNA signatures have been difficult to reproduce among separate populations. We studied plasma miRNA abundance during acute HCV infection to identify an miRNA signature of early infection. We measured 754 plasma miRNAs by quantitative PCR array in a discovery cohort of 22 individuals before and during acute HCV infection and after spontaneous resolution (n ‫؍‬ 11) or persistence (n ‫؍‬ 11) to identify a plasma miRNA signature. The discovery cohort derived from the Baltimore Before and After Acute Study of Hepatitis. During acute HCV infection, increases in miR-122 (P < 0.01) and miR-885-5p (P corrected < 0.05) and a decrease in miR-494 (P corrected < 0.05) were observed at the earliest time points after virus detection. Changes in miR-122 and miR-885-5p were sustained in persistent (P < 0.001) but not resolved HCV infection. The circulating miRNA signature of acute HCV infection was confirmed in a separate validation cohort that was derived from the San Francisco-based You Find Out (UFO) Study (n ‫؍‬ 28). As further confirmation, cellular changes of signature miRNAs were examined in a tissue culture model of HCV in hepatoma cells: HCV infection induced extracellular release of miR-122 and miR-885-5p despite unperturbed intracellular levels. In contrast, miR-494 accumulated intracellularly (P < 0.05). Collectively, these data are inconsistent with necrolytic release of hepatocyte miRNAs into the plasma during acute HCV infection of humans. IMPORTANCEMicroRNAs are small noncoding RNA molecules that emerging research shows can transmit regulatory signals between cells in health and disease. HCV infects 2% of humans worldwide, and chronic HCV infection is a major cause of severe liver disease. We profiled plasma miRNAs in injection drug users before, during, and (in the people with resolution) after HCV infection. We discovered miRNA signatures of acute and persistent viremia and confirmed these findings two ways: (i) in a separate cohort of people with newly acquired HCV infection and (ii) in an HCV cell culture system. Our results demonstrate that acute HCV infection induces early changes in the abundance of specific plasma miRNAs that may affect the host response to HCV infection. H epatitis C virus (HCV) is a single-stranded positive-sense hepatotropic RNA virus that infects over 170 million people worldwide. Acute HCV infection progresses to chronic infection in ϳ75% of cases (1-3). Little is understood about early hostpathogen interactions due to a lack of representative animal models and the difficulty in studying acute HCV, which is largely asymptomatic.MicroRNAs (miRNAs) are 18-to 25-nucleotide noncoding RNA molecules with widespread gene network regulatory capacity. miRNAs are readily detectable in cell-free compo...

Section: Study and Array Characteristics The Median (Interquartile Rmentioning

confidence: 80%

Acute Hepatitis C Virus Infection Induces Consistent Changes in Circulating MicroRNAs That Are Associated with Nonlytic Hepatocyte Release

El-Diwany

Wasilewski

Witwer

et al. 2015

“…During the course of our study, Cheng et al reported that let-7b inhibited HCV infectivity by interacting with the HCV genome (26). Here, we investigated whether there was another mechanism contributing to let-7b's anti-HCV activity.…”

Section: Ifn-␣ and Il-28b Regulate Distinct Mirna Expression Profilesmentioning

confidence: 91%

High-Throughput Profiling of Alpha Interferon- and Interleukin-28B-Regulated MicroRNAs and Identification of let-7s with Anti-Hepatitis C Virus Activity by Targeting IGF2BP1

Cheng

Niu

et al. 2013

Hepatitis C virus (HCV) infection is a major cause of severe liver disease. Interferon (IFN)/ribavirin treatment remains the standard therapeutic regimen for HCV infection in most countries. IFN-stimulated genes are believed to contribute to antiviral effects. However, emerging evidence suggests that microRNAs (miRNAs), a class of noncoding small RNAs, are involved in the control of viral infection. Here, we systematically profiled the hepatocyte expression of a set of 750 miRNAs in response to alpha interferon (IFN-␣) and interleukin-28B (IL-28B) treatments. The anti-HCV activity of differentially expressed miRNAs was evaluated using cell culture-derived HCV in vitro. The results demonstrate that let-7b had a significant anti-HCV effect by inhibiting HCV replication and viral protein translation in human hepatoma cells. In particular, we show that the inhibition of let-7b attenuated the anti-HCV effects of IFN-␣ and IL-28B. Furthermore, we show that the host factor insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) is a target of let-7b. IGF2BP1 was required for HCV replication, and its expression was downregulated by IFN-␣ and IL-28B. Deletion of the wild-type seed region of let-7b abolished its antiviral activity. Finally, we demonstrate that other let-7 family miRNAs were able to inhibit HCV and to suppress IGF2BP1 expression. In conclusion, we provide an example of a host miRNA regulated by type I and type III IFNs that inhibits HCV replication and infectivity by targeting host targets. These results highlight the important role of miRNAs in the host antiviral immune response and provide a novel candidate for anti-HCV therapy.

“…Infectious HCV particles (HCVcc) were produced as described previously (23,24). Briefly, in vitro-transcribed genomic JC1-Luc2A RNA was delivered into Huh7.5.1 cells by electroporation.…”

Section: Cells and Materialsmentioning

confidence: 99%

Hepatitis C Virus Replication Is Modulated by the Interaction of Nonstructural Protein NS5B and Fatty Acid Synthase

Huang

Tseng

Liao

et al. 2013

Self Cite

Hepatitis C virus (HCV) is a positive-stranded RNA virus classified in the Hepacivirus genus in the family Flaviviridae. The 9.6-kb viral RNA genome encodes a precursor polyprotein that is processed to generate at least 10 viral proteins, including structural proteins (core, E1, E2, and p7) and nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) (1). The NS5B RNA polymerase, together with other nonstructural viral proteins (NS3, NS4A, NS4B, and NS5A) and host factors, constitutes the active replication complexes (RC) for viral RNA replication. These proteins are directly or indirectly associated with the endoplasmic reticulum (ER)-derived structure called the "membranous web," where replication occurs (2, 3). However, the exact host factors and detailed interactions within the RC remain to be determined.HCV infection usually causes chronic hepatitis and frequently leads to cirrhosis and hepatocellular carcinoma (HCC). Besides, HCV-induced end-stage liver disease is an important indication for liver transplantation in most of the Western countries (4, 5). At present, no effective vaccine to prevent HCV infection is available. The current treatment strategies for HCV infection are valid only for individuals with a particular single nucleotide polymorphism (SNP) in the interleukin-28B gene or for infections caused by certain viral genotypes (6). Accordingly, the prevalence of hepatic steatosis in HCV-infected patients is much higher than that in the general population or in hepatitis B virus (HBV)-infected patients (7). Hepatic steatosis has also been reported to be associated with an increased rate of HCC in chronic hepatitis C patients (8).Lipid metabolic pathways are essential for the entry, secretion, and replication of HCV. For example, apolipoprotein E (apoE) is essential for the production of HCVcc (HCV produced in cell culture) and for viral entry (9, 10). Downregulation of apoA-I decreases levels of HCV replication and viral particle production in cell culture (11). HCV coopts the secretory pathway of very low density lipoprotein (VLDL) for its own secretion (12, 13). Moreover, HCV replication is regulated through induction of lipogenic gene expression in HCV replicon cells (14) or geranylgeranylation of host proteins required for HCV RNA replication (15,16). Fatty acid synthesis is also required for HCV RNA replication (14). Inhibition of fatty acid synthase (FASN) by cerulenin (17) or C75 (18) reduces the replication of subgenomic HCV replicons as well as JFH-1-based HCVcc virion production. Although the underlying mechanisms are not yet completely understood, these studies imply that FASN is essential for HCV replication.In this study, HCV NS5B was used as the bait to screen for NS5B-interacting proteins that are present in Huh7 hepatoma cell lysates. After mass spectrophotometric analysis, FASN was found to interact with NS5B, and this interaction was further confirmed in vitro and in vivo. Our data indicate that FASN interacts with NS5B to enhance NS5B RNA-dependent RNA polymerase (RdRp) act...