miR-370 suppresses HBV gene expression and replication by targeting nuclear factor IA

Advances in the understanding of circRNAs that influence viral replication in host cells

Circular RNAs (circRNAs) are non-coding RNAs discovered in recent years, which are produced by back-splicing involving the 3' and 5' ends of RNA molecules. There is increasing evidence that circRNAs have important roles in cancer, neurological diseases, cardiovascular and cerebrovascular diseases, and other diseases. In addition, host circRNAs and virus-encoded circRNAs participate in the body's immune response, with antiviral roles. This review summarizes the mechanisms by which host and viral circRNAs interact during the host immune response. Comprehensive investigations have revealed that host circRNAs function as miRNA sponges in a particular manner, primarily by inhibiting viral replication. Viral circRNAs have more diverse functions, which generally involve promoting viral replication. In addition, in contrast to circRNAs from RNA viruses, circRNAs from DNA viruses can influence host cell migration, proliferation, and apoptosis, along with their effects on viral replication. In summary, circRNAs have potential as diagnostic and therapeutic targets, offering a foundation for the diagnosis and treatment of viral diseases.

miR-HCC2 suppresses hepatitis B virus replication by inhibiting the activity of the enhancer I/X promoter

miR-HCC2 has been reported to markedly promote the growth, metastasis, and stemness of hepatocellular carcinoma (HCC) cells in vitro and in vivo. Deep sequencing showed that miR-HCC2 was significantly upregulated in hepatitis B virus (HBV)-positive (HBV+) HCC tissue samples compared with HBV-negative (HBV-) HCC tissue samples. miR-HCC2 expression was further evaluated in HCC tissues and cells, and the expression of miR-HCC2 was found to be significantly higher in HBV+ HCC tissues and cells than in HBV- HCC tissues and cells, suggesting that high miR-HCC2 expression could be induced by HBV infection. To explore the relationship between miR-HCC2 and HBV, we investigated the effect of miR-HCC2 on HBV antigen expression, transcription, and replication. We found that miR-HCC2 was involved in the negative feedback regulation of HBV replication. Further mechanistic studies revealed that miR-HCC2 suppressed HBV replication by inhibiting the activity of the enhancer I/X promoter. Our study demonstrates the effect of the inhibition of miR-HCC2 on HBV gene expression and replication, which can help to illustrate the complex regulatory network involving host miRNAs and HBV.

MicroRNAs: Small molecules with big impacts in liver injury

A type of small noncoding RNAs known as microRNAs (miRNAs) fine-tune gene expression posttranscriptionally by binding to certain messenger RNA targets. Numerous physiological processes in the liver, such as differentiation, proliferation, and apoptosis, are regulated by miRNAs. Additionally, there is growing evidence that miRNAs contribute to liver pathology. Extracellular vesicles like exosomes, which contain secreted miRNAs, may facilitate paracrine and endocrine communication between various tissues by changing the gene expression and function of distal cells. The use of stable miRNAs as noninvasive biomarkers was made possible by the discovery of these molecules in body fluids. Circulating miRNAs reflect the conditions of the liver that are abnormal and may serve as new biomarkers for the early detection, prognosis, and evaluation of liver pathological states. miRNAs are appealing therapeutic targets for a range of liver disease states because altered miRNA expression is associated with deregulation of the liver's metabolism, liver damage, liver fibrosis, and tumor formation. This review provides a comprehensive review and update on miRNAs biogenesis pathways and mechanisms of miRNA-mediated gene silencing. It also outlines how miRNAs affect hepatic cell proliferation, death, and regeneration as well as hepatic detoxification. Additionally, it highlights the diverse functions that miRNAs play in the onset and progression of various liver diseases, including nonalcoholic fatty liver disease, alcoholic liver disease, fibrosis, hepatitis C virus infection, and hepatocellular carcinoma. Further, it summarizes the diverse liver-specific miRNAs, illustrating the potential merits and possible caveats of their utilization as noninvasive biomarkers and appealing therapeutic targets for liver illnesses.

Role of circRNAs in viral infection and their significance for diagnosis and treatment (Review)

Circular RNAs (circRNAs) are a class of non-coding RNAs with a circular, covalent structure that lack both 5' ends and 3' poly(A) tails, which are stable and specific molecules that exist in eukaryotic cells and are highly conserved. The role of circRNAs in viral infections is being increasingly acknowledged, since circRNAs have been discovered to be involved in several viral infections (such as hepatitis B virus infection and human papilloma virus infection) through a range of circRNA/microRNA/mRNA regulatory axes. These findings have prompted investigations into the potential of circRNAs as targets for the diagnosis and treatment of viral infection-related diseases. The aim of the present review was to systematically examine and discuss the role of circRNAs in several common viral infections, as well as their potential as diagnostic markers and therapeutic targets.

Can a metabolism-targeted therapeutic intervention successfully subjugate SARS-COV-2? A scientific rational

As a process entailing a high turnover of the host cell molecules, viral replication is required for a successful viral infection and requests virus capacity to acquire the macromolecules required for its propagation. To this end, viruses have adopted several strategies to harness cellular metabolism in accordance with their specific demands. Most viruses upregulate specific cellular anabolic pathways and are largely dependent on such alterations. RNA viruses, for example, upregulate both glycolysisand glycogenolysis providing TCA cycle intermediates essential for anabolic lipogenesis. Also, these infections usually induce the PPP, leading to increased nucleotide levels supporting viral replication. SARS-CoV-2 (the cause of COVID-19)that has so far spread from China throughout the world is also an RNA virus. Owing to the more metabolic plasticity of uninfected cells, a promising approach for specific antiviral therapy, which has drawn a lot of attention in the recent years, would be the targeting of metabolic changes induced by viruses. In the current review, we first summarize some of virus-induced metabolic adaptations and then based on these information as well as SARS-CoV-2 pathogenesis, propose a potential therapeutic modality for this calamitous world-spreading virus with the hope of employing this strategy for near-future clinical application.

Gene signatures of SARS-CoV/SARS-CoV-2-infected ferret lungs in short- and long-term models

Coronaviruses (CoVs) consist of six strains, and the severe acute respiratory syndrome coronavirus (SARS-CoV), newly found coronavirus (SARS-CoV-2) has rapidly spread leading to a global outbreak. The ferret (Mustela putorius furo) serves as a useful animal model for studying SARS-CoV/SARS-CoV-2 infection and developing therapeutic strategies. A holistic approach for distinguishing differences in gene signatures during disease progression is lacking. The present study discovered gene expression profiles of short-term (3 days) and long-term (14 days) ferret models after SARS-CoV/SARS-CoV-2 infection using a bioinformatics approach. Through Gene Ontology (GO) and MetaCore analyses, we found that the development of stemness signaling was related to short-term SARS-CoV/SARS-CoV-2 infection. In contrast, pathways involving extracellular matrix and immune responses were associated with long-term SARS-CoV/SARS-CoV-2 infection. Some highly expressed genes in both short- and long-term models played a crucial role in the progression of SARS-CoV/SARS-CoV-2 infection, including DPP4, BMP2, NFIA, AXIN2, DAAM1, ZNF608, ME1, MGLL, LGR4, ABHD6, and ACADM. Meanwhile, we revealed that metabolic, glucocorticoid, and reactive oxygen species-associated networks were enriched in both short- and long-term infection models. The present study showed alterations in gene expressions from short-term to long-term SARS-CoV/SARS-CoV-2 infection. The current result provides an explanation of the pathophysiology for post-infectious sequelae and potential targets for treatment.

MiR-214 inhibits snakehead vesiculovirus (SHVV) replication by targeting host GS

MicroRNAs (miRNAs) are small noncoding RNAs that have been reported to play important roles in virus replication. Snakehead vesiculovirus (SHVV) is a new rhabdovirus isolated from diseased hybrid snakehead and has caused heavy economical losses in cultured snakehead fish in China. Our previous study has revealed that miR-214 inhibited SHVV replication, but the underline mechanism was not completely understood. In this study, glycogen synthase (GS) gene was identified as a target gene of miR-214. Overexpression of miR-214 reduced cellular GS gene expression. Knockdown of GS by siRNA, similar to the overexpression of miR-214, inhibited SHVV replication. Moreover, we found that siGS-mediated inhibition of SHVV replication could be restored by reducing cellular miR-214 level via using miR-214 inhibitor, indicating that miR-214 inhibited SHVV replication at least partially via targeting GS. This study provided information for understanding the molecular mechanism of SHVV pathogenicity and a potential antiviral strategy against SHVV infection.

Differential expression profile of hepatic circular RNAs in chronic hepatitis B

CircRNAs exert gene regulatory effects by sequestering target microRNAs (miRNAs) and play a vital role in the onset and development of disease. Until recently, little has been known about the expression, regulation and biological function of circRNAs in both health and chronic hepatitis B (CHB).To identify hepatic circRNAs associated with CHB, we performed RNA sequencing using liver biopsies from untreated CHB patients and controls. We then established a bioinformatics pipeline for identification of CHB-associated circRNAs and in silico analysis of the circRNA-miRNA-mRNA pathways. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR) to confirm these results. The profiles of hepatic circRNA expression were significantly different in CHB compared with controls, with a total of 99 dysregulated circRNAs identified to be correlated with CHB. Computational analysis of the circRNA-miRNA-mRNA pathways revealed a large number of miRNAs (665), which were putatively targeted by the differentially expressed hepatic circRNAs. Interestingly, four of the predicted CHB-related circRNA-miRNA-mRNA pathways were found to be involved in the pathogenesis of HBV infection and progression of HBV-associated liver disease. Among these pathways, regression analysis of gene expression revealed a strong positive correlation between hsa_circ_0000650 and TGFβ2 and a negative correlation between hsa_circ_0000650 and miR-6873-3p, which hinted that hsa_circ_0000650 interacted with TGFβ2 mediated by miR-6873-3p. This study firstly demonstrates that patients with CHB present different profiles of hepatic circRNAs and circRNA/miRNA interactions. Thus, circRNAs have promise as novel mechanisms underlying the pathogenesis and progression of CHB.

miR-370 regulates ISG15 expression and influences IFN-α sensitivity in hepatocellular carcinoma cells

BACKGROUND:

Interferon-α (IFN-α) is an adjuvant to chemotherapy and radiotherapy for hepatocellular carcinoma (HCC), but some HCC patients do not respond to treatment with IFN-α.

METHODS:

We performed loss-of-function and gain-of-function experiments to examine the role of ISG15 in the IFN-α sensitivity of LH86, HLCZ01, SMMC7721, and Huh7 cell lines and tumor samples.

RESULTS:

The overexpression of ISG15 reduced apoptosis in Huh7 and LH86 cells in the presence of IFN-α, whereas the shRNA-mediated knock down of ISG15 expression increased apoptosis in both Huh7 and LH86 cells. We identified a putative miR-370 target site in the 3’-UTR in the ISG15 mRNA, and the level of miR-370 expression in HCC cell lines reflected the level of IFN-α-induced apoptosis exhibited by each. Both HCC cell lines and tumor samples had significantly lower levels of miR-370 than the control cells and tissues (P< 0.05). The overexpression of miR-370 in IFN-α-treated LH86 and Huh7 cells increased apoptosis and reduced the volume of LH86- and Huh7-derived xenograft tumors in mice treated with IFN-α compared with the control tumors.

CONCLUSIONS:

Our findings suggest that miR-370 functions as an HCC tumor suppressor and regulator of IFN-α sensitivity and that miR-370 might be a useful prognostic marker for HCC patients.

MiR-185-5p suppresses HBV gene expression by targeting ELK1 in hepatoma carcinoma cells

AIMS

To investigate the role and underlying mechanism of miR-185-5p in hepatitis B virus (HBV) expression and replication.

MAIN METHODS

The relative levels of hepatitis B surface antigen and hepatitis B e antigen were detected by enzyme-linked immunosorbent assay (ELISA). The HBV DNA copies in the cultures medium were measured by RT-qPCR. The HBV large surface antigen promoter (S1p) activity was analyzed by luciferase reporter assay. The target relationship between miR-185-5p and ELK1 was identified by bioinformatics analysis and EGFP fluorescent reporter assay. The ELK1 expression was determined by RT-qPCR and Western blot.

KEY FINDINGS

miR-185-5p significantly decreased HBV large surface antigen promoter activity and subsequently the production of HBV proteins and HBV DNA copies in vitro. Further, we identified the ETS transcription factor ELK1 is a target of miR-185-5p. Overexpression and knockdown experiments showed overexpression of ELK1 stimulated HBV large surface antigen promoter activity and promoted the production of HBV proteins and HBV DNA copies, whereas knockdown of ELK1 has the opposite effects. Moreover, the rescue of ELK1 expression reversed the suppression of miR-185-5p on HBV replication and gene expression. Further mechanistic study showed that the ETS binding sites within the HBV large surface antigen promoter are required for the repression effect of miR-185-5p on HBV.

SIGNIFICANCE

There are few reports about the interaction between miRNAs and the transcription from HBV S1p, we found that miR-185-5p decreases HBV S1p activity by targeting ELK1, which may provide a promising therapeutic strategy for HBV infection.

Micro-RNAs in hepatitis B virus-related chronic liver diseases and hepatocellular carcinoma

MicroRNAs (miRNAs) are small non-coding RNAs that modulate gene expression at the post-transcriptional level by affecting both the stability and translation of complementary mRNAs. Several studies have shown that miRNAs are important regulators in the conflicting efforts between the virus (to manipulate the host for its successful propagation) and the host (to inhibit the virus), culminating in either the elimination of the virus or its persistence. An increasing number of studies report a role of miRNAs in hepatitis B virus (HBV) replication and pathogenesis. In fact, HBV is able to modulate different host miRNAs, particularly through the transcriptional transactivator HBx protein and, conversely, different cellular miRNAs can regulate HBV gene expression and replication by a direct binding to HBV transcripts or indirectly targeting host factors. The present review will discuss the role of miRNAs in the pathogenesis of HBV-related diseases and their role as a biomarker in the management of patients with HBV-related disease and as therapeutic targets.

miR-200c targets nuclear factor IA to suppress HBV replication and gene expression via repressing HBV Enhancer I activity

BACKGROUND

Hepatitis B virus (HBV) chronic infection is a health problem in the worldwide, with a underlying higher risk of liver cirrhosis and hepaticocellular carcinoma. A number of studies indicate that microRNAs (miRNAs) play vital roles in HBV replication. This study was designed to explore the potential molecular mechanism of miR-200c in HBV replication.

METHODS

The expression of miR-200c, nuclear factor IA (NFIA) mRNA, HBV DNA, and HBV RNA (pregenomic RNA (pgRNA), and total RNA) were measured by qRCR. The levels of HBsAg and HBeAg were detected by ELISA. NFIA expression at protein level was measured by western blot. The direct interaction between miR-200c and NFIA were identified by Targetscan software and Dual-Luciferase reporter analysis. Enhance I activity were detected by Dual-Luciferase reporter assay.

RESULTS

miR-200c expression was prominently reduced in pHBV1.3-tranfected Huh7 and in stable HBV-producing cell line (HepG2.2.15). The enforced expression of miR-200c significantly suppressed HBV replication, as demonstrated by the reduced levels of HBV protein (HBsAg and HBeAg) and, DNA and RNA (pgRNA and total RNA) levels. NFIA was proved to be a target of miR-200c and NFIA overexpression notably stimulated HBV replication. In addition, the inhibitory effect of miR-200c on HBV Enhance I activity was abolished following restoration of NFIA.

CONCLUSIONS

miR-200c repressed HBV replication by directly targeting NFIA, which might provide a novel therapeutic target for HBV infection.

miR-146 promotes HBV replication and expression by targeting ZEB2

Hepatitis B virus (HBV) is associated with the development of a wide spectrum of liver diseases. The involvement of miRNAs in HBV replication is being gradually identified. Among these miRNAs, miR-146a expression was found to be positively correlated with HBV replication levels. However, the regulatory relationship between miR-146a and HBV replication is still unclear. In the present study, miR-146a was upregulated in HBV-expressing HepG2.2.15 cells compared with HepG2 cells. Overexpression of miR-146a or knockdown of Zinc finger E-box-binding homeobox 2 (ZEB2) promoted HBV replication and expression, while downregulation of miR-146a or overexpression of ZEB2 suppressed HBV replication and expression. In addition, miR-146a was demonstrated to directly target ZEB2. Furthermore, ZEB2 silencing abated anti-miR-146a-induced inhibition on HBV replication and expression. These findings suggested that miR-146a promoted HBV replication by targeting ZEB2, providing a new antiviral strategy for HBV infection.

The role of microRNAs in hepatocyte metabolism and hepatitis B virus replication

Though efficient vaccines against hepatitis B virus (HBV) and antiviral therapies are available, chronic HBV infection is still a global health problem. The process of HBV infection and HBV life cycle are extensively studied in last decades, however, the mechanisms of HBV-induced alterations of host cell metabolisms and host factors involved in modulating of viral replication are not fully understood. Thus, it is an important issue to examine these specific HBV-host interactions for development of novel strategies for antiviral therapies. Recently, microRNAs (miRNAs), a class of post-transcriptional regulatory small RNA, seem to be the relevant fine tuning factors of various cellular activities and pathways, including cell growth, metabolism, and viral replication. In this review, we summarize the up to date knowledge concerning the virus-host interactions and emphasizing on the role of miRNAs in regulation of HBV replication and host cell metabolism.