miRNA-548ah promotes the replication and expression of hepatitis B virus by targeting histone deacetylase 4

Potential role of microRNAs in personalized medicine against hepatitis: a futuristic approach

MicroRNAs (miRNAs) have been the subject of extensive research for many years, primarily in the context of diseases such as cancer. However, our appreciation of their significance in viral infections, particularly in hepatitis, has increased due to the discovery of their association with both the host and the virus. Hepatitis is a major global health concern and can be caused by various viruses, including hepatitis A to E. This review highlights the key factors associated with miRNAs and their involvement in infections with various viruses that cause hepatitis. The review not only emphasizes the expression profiles of miRNAs in hepatitis but also puts a spotlight on their potential for diagnostics and therapeutic interventions. Ongoing extensive studies are propelling the therapeutic application of miRNAs, addressing both current limitations and potential strategies for the future of miRNAs in personalized medicine. Here, we discuss the potential of miRNAs to influence future medical research and an attempt to provide a thorough understanding of their diverse roles in hepatitis and beyond.

MicroRNAs in infectious diseases: potential diagnostic biomarkers and therapeutic targets

MicroRNAs (miRNAs) are conserved, short, non-coding RNAs that play a crucial role in the post-transcriptional regulation of gene expression. They have been implicated in the pathogenesis of cancer and neurological, cardiovascular, and autoimmune diseases. Several recent studies have suggested that miRNAs are key players in regulating the differentiation, maturation, and activation of immune cells, thereby influencing the host immune response to infection. The resultant upregulation or downregulation of miRNAs from infection influences the protein expression of genes responsible for the immune response and can determine the risk of disease progression. Recently, miRNAs have been explored as diagnostic biomarkers and therapeutic targets in various infectious diseases. This review summarizes our current understanding of the role of miRNAs during viral, fungal, bacterial, and parasitic infections from a clinical perspective, including critical functional mechanisms and implications for their potential use as biomarkers and therapeutic targets.

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 but Key Players in Viral Infections and Immune Responses to Viral Pathogens

Since the discovery of microRNAs (miRNAs) in C. elegans in 1993, the field of miRNA research has grown steeply. These single-stranded non-coding RNA molecules canonically work at the post-transcriptional phase to regulate protein expression. miRNAs are known to regulate viral infection and the ensuing host immune response. Evolving research suggests miRNAs are assets in the discovery and investigation of therapeutics and diagnostics. In this review, we succinctly summarize the latest findings in (i) mechanisms underpinning miRNA regulation of viral infection, (ii) miRNA regulation of host immune response to viral pathogens, (iii) miRNA-based diagnostics and therapeutics targeting viral pathogens and challenges, and (iv) miRNA patents and the market landscape. Our findings show the differential expression of miRNA may serve as a prognostic biomarker for viral infections in regard to predicting the severity or adverse health effects associated with viral diseases. While there is huge market potential for miRNA technology, the novel approach of using miRNA mimics to enhance antiviral activity or antagonists to inhibit pro-viral miRNAs has been an ongoing research endeavor. Significant hurdles remain in terms of miRNA delivery, stability, efficacy, safety/tolerability, and specificity. Addressing these challenges may pave a path for harnessing the full potential of miRNAs in modern medicine.

Study on the role of histone epigenetic modification in replication of hepatitis B virus

Hepatitis B virus (HBV) infection is a global health problem and lacks effective therapies in clinic. This study attempted to investigate the role of histone deacetylase 3 (HDAC3) in HBV replication. Cells were treated with 1.3 folds of HBV genome. The expression patterns of HDAC3, miR-29a-3p, and nuclear factor of activated T-cells 5 (NFAT5) in cells were determined by real-time quantitative polymerase chain reaction and Western blot analysis. HBV replication was assessed by measurements of HBV DNA, HBV RNA, hepatitis B surface antigen, and hepatitis B E antigen. After chromatin immunoprecipitation and RNA pull-down assays to testify gene interactions, rescue experiments and animal experiments were performed to assess the role of miR-29a-3p/NFAT5 in HBV replication and the role of HDAC3 in vivo. HDAC3 level was decreased by pHBV1.3 plasmid in a concentration-dependent manner. HDAC3 overexpression can inhibit HBV replication, which was neutralized by miR-29a-3p overexpression or NFAT5 downregulation. Mechanically, HDAC3 overexpression reduced the enrichment of histone 3 lysine 9 acetylation on the miR-29a-3p promoter to inhibit miR-29a-3p expression and then promote NFAT5 transcription. In vivo, HDAC3 restrained HBV replication through the miR-29a-3p/NFAT5 axis. Overall, HDAC3 downregulation was associated with HBV replication and HDAC3 overexpression inhibited HBV replication through H3K9ac/miR-29a-3p/NFAT5.

RNA-binding motif protein 24 inhibits HBV replication in vivo

Despite the extensive use of effective vaccines and antiviral drugs, chronic hepatitis B virus (HBV) infection continues to pose a serious threat to global public health. Therapies with novel mechanisms of action against HBV are being explored for achieving a functional cure. In this study, five murine models of HBV replication were used to investigate the inhibitory effect of RNA binding motif protein 24 (RBM24) on HBV replication. The findings revealed that RBM24 serves as a host restriction factor and suppresses HBV replication in vivo. The transient overexpression of RBM24 in hydrodynamics-based mouse models of HBV replication driven by the CMV or HBV promoters suppressed HBV replication. Additionally, the ectopic expression of RBM24 decreased viral accumulation and the levels of HBV covalently closed circular DNA (cccDNA) in an rcccDNA mouse model. The liver-directed transduction of adeno-associated viruses (AAV)-RBM24 mediated the stable hepatic expression of RBM24 in pAAV-HBV1.2 and HBV/tg mouse models, and markedly reduced the levels of HBV cccDNA and other viral indicators. Altogether, these findings revealed that RBM24 inhibits the replication of HBV in vivo, and RBM24 may be a potential therapeutic target for combating HBV infections.

miR-548c-3p targets TRIM22 to attenuate the Peg–IFN–α therapeutic efficacy in HBeAg-positive patients with chronic hepatitis B

Chronic hepatitis B (CHB) patients treated with interferon shows encouraging results. However, its clinical efficacy is limited by significant individual differences in treatment responses. We identified an interferon-inducible effector, TRIM22, as the likely causal target of such differential responses. We found that TRIM22 was highly expressed in interferon-responsive patients and negatively correlated with HBV DNA and HBeAg serum levels. Stable cells overexpressing TRIM22 carried significantly less HBsAg, HBeAg, and HBV DNA, and cells with knocked-down TRIM22 by shRNA displayed higher levels of these markers than controls. Integrated bioinformatics analysis and subsequent experiments revealed that TRIM22 overexpression significantly increased the supernatant levels of IL-1β and IL-8, two important cytokines of NOD2/NF-κB pathway involved in interferon-induced antiviral activities. We identified three candidate microRNAs binding to 3'UTR of TRIM22 at various locations through typical imperfect paring using the TargetScan program. MiR-548c-3p appeared to be highly expressed, while the TRIM22 level was low in the suboptimal response group of CHB patients. The Luciferase reporter assay revealed an interaction between miR-548c-3p and the 3'UTR of TRIM22, leading to a controlled suppression of TRIM22 endogenous expression. This resulted in interferon's substantially weakened therapeutic efficacy, as indicated by the elevation of the serum levels of HBsAg, HBeAg and HBV DNA in miR-548c-3p-transfected HepAD38 cells. Our study demonstrated that a particular miR-548c-3p is the key negative regulator of TRIM22 in CHB patients with a weak response to interferon treatment, providing a novel marker and target in interferon-α therapy evaluation.

The role of non-coding RNAs in the diagnosis of different stages (HCC, CHB, OBI) of hepatitis B infection

Despite the availability of an effective hepatitis B virus (HBV) vaccine and universal immunization schedules, HBV has remained a health problem in various stages such as occult hepatitis B infection (OBI), chronic hepatitis B (CHB), and hepatocellular carcinoma (HCC), which is considered one of the possible phases during chronic HBV infection. OBI is defined as the persistence of HBV genomes in hepatocytes of patients with a negative HBV surface antigen (HBsAg) test and detectable or undetectable HBV DNA in the blood. OBI is occasionally associated with infection caused by mutant viruses that produce a modified HBsAg that is undetected by diagnostic procedures or with replication-defective variations. Many aspects of HBV (OBI more than any other stage) including prevalence, pathobiology, and clinical implications has remained controversial. According to a growing body of research, non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been linked to the development and progression of a number of illnesses, including viral infectious disorders. Despite a shortage of knowledge regarding the expression and biological activities of lncRNAs and miRNAs in HBV infection, Hepatitis B remains a major global public health concern. This review summarizes the role of lncRNAs in the diagnosis and treatment of different stages of hepatitis B infection.

HDAC4 in cancer: A multitasking platform to drive not only epigenetic modifications

Controlling access to genomic information and maintaining its stability are key aspects of cell life. Histone acetylation is a reversible epigenetic modification that allows access to DNA and the assembly of protein complexes that regulate mainly transcription but also other activities. Enzymes known as histone deacetylases (HDACs) are involved in the removal of the acetyl-group or in some cases of small hydrophobic moieties from histones but also from the non-histone substrate. The main achievement of HDACs on histones is to repress transcription and promote the formation of more compact chromatin. There are 18 different HDACs encoded in the human genome. Here we will discuss HDAC4, a member of the class IIa family, and its possible contribution to cancer development.

Positive programming of the GC-IGF1 axis mediates adult osteoporosis susceptibility in male offspring rats induced by prenatal dexamethasone exposure

Prenatal dexamethasone exposure (PDE) can lead to offspring long bone dysplasia and continue to postnatal, and this is an important cause of fetal-derived osteoporosis. Studies have confirmed that intrauterine endogenous GC overexposure mediates multiple organ dysplasia and adult-related disease susceptibility in offspring through the glucocorticoid-insulin-like growth factor1 (GC-IGF1) axis. However, it remains unknown if exogenous dexamethasone can regulate bone development in offspring through the GC-IGF1 axis. We determined that the PDE fetal rats exhibited poor osteogenic differentiation, decreased bone mass that continued to adolescence, and increased susceptibility to osteoporosis in adulthood. Concurrently, PDE decreased the serum corticosterone concentration and IGF1 expression in offspring before and after birth, while the increased serum corticosterone concentration induced by chronic stress reversed the inhibition of IGF1 expression induced by PDE. Furthermore, PDE decreased the expression of GRα and miR-130a-5p, increased HDAC4, and decreased H3K27 acetylation in the IGF1 promoter region in bone tissue, and the above changes were negatively compensated after chronic stress. In vitro, a low concentration of corticosterone inhibited the expression of GRα and miR130a-5p, upregulated the expression of HDAC4, inhibited the promoter region H3K27 acetylation, and expression of IGF1 in bone marrow mesenchymal stem cell (BMSCs) osteoblast differentiated cells and inhibited osteogenic differentiation of BMSCs. GRα overexpression, miR-130a-5p mimic treatment, or HDAC4 siRNA exposure reversed the downstream molecular alterations caused by low corticosterone concentrations. In conclusion, PDE-induced intrauterine hypoglucocorticoid exposure could positively program IGF1 expression in bone tissue through the GRα/miR-130a-5p/HDAC4 pathways, thus mediating osteogenic dysdifferentiation and adult osteoporosis susceptibility in male offspring rats.

The Computational Analysis of Single Nucleotide Associated with MicroRNA Affecting Hepatitis B Infection

BACKGROUND

MicroRNAs (miRNAs) have a pivotal role in Hepatitis B Virus (HBV) infection and its complications by targeting the cellular transcription factors required for gene expression or directly binding to HBV transcripts. Single Nucleotide Polymorphisms (SNPs) in miRNA genes affect their expression and the regulation of target genes, clinical course, diagnosis, and therapeutic interventions of HBV infection.

METHODS

Computational assessment and cataloging of miRNA gene polymorphisms targeting mRNA transcripts straightly or indirectly through the regulation of hepatitis B infection by annotating the functional impact of SNPs on mRNA-miRNA and miRNA-RBS (miRNA binding sites) interaction were screened by applying various universally available datasets such as the miRNA SNP3.0 software.

RESULTS

2987 SNPs were detected in 139 miRNAs affecting hepatitis B infection. Among them, 313 SNPs were predicted to have a significant role in the progression of hepatitis B infection. The computational analysis also revealed that 45 out of the 313 SNPs were located in the seed region and were more important than others. Has-miR-139-3p had the largest number of SNPs in the seed region (n=6). On the other hand, proteoglycans in cancer, adherens junction, lysine degradation, NFkappa B signaling cascade, ECM-receptor binding, viral carcinogenesis, fatty acid metabolism, TGF-beta signaling pathway, p53 signaling pathway, immune evasion related pathways, and fatty acid biosynthesis were the most important pathways affected by these 139 miRNAs.

CONCLUSION

The results revealed 45 SNPs in the seed region of 25 miRNAs as the catalog in miRNA genes that regulated the hepatitis B infection. The results also showed the most important pathways regulated by these miRNAs that can be targeted for therapeutic purposes.

Prenatal dexamethasone exposure programs the decreased testosterone synthesis in offspring rats by low level of endogenous glucocorticoids

Prenatal dexamethasone exposure (PDE) can decrease maternal endogenous glucocorticoid level and induce testicular dysplasia in male offspring rats. In this study we investigated low level endogenous glucocorticoid-mediated testicular dysplasia in PDE offspring and elucidated the intrauterine epigenetic programming mechanisms. Pregnant rats were injected with dexamethasone (0.2 mg·kg^-1·d^-1, sc) on gestational day (GD) 9-20. The offspring rat blood and testis were collected after euthanasia on GD20, postnatal week (PW) 12 or PW28. We showed that PDE induced abnormal morphology of testis and significantly decreased the expression of testosterone synthesis-related genes as well as testosterone production before and after birth. Meanwhile, serum corticosterone, the expression and histone 3 lysine 14 acetylation (H3K14ac) of testicular insulin-like growth factor 1 (IGF1) were significantly decreased. After the pregnant rats were subjected to chronic stress for 2 weeks (PW10-12), serum corticosterone level was increased in the adult PDE offspring, and the above-mentioned other indicators were also improved. Cultured Leydig cells (TM3) were treated with corticosterone (62.5-500 nM) in vitro. We showed that corticosterone concentration-dependently inhibited glucocorticoid receptor α (GRα) and miR-124-3p expression, increased histone deacetylase 5 (HDAC5) expression, and decreased IGF1 H3K14ac level and the expression of IGF1/steroidogenic acute regulatory protein (StAR), suggesting that corticosterone at lower than physiological level (<500 nM) inhibited testosterone synthesis by reducing H3K14ac and the expression level of IGF1 through GRα/miR-124-3p/HDAC5 pathway. In conclusion, PDE can cause persistent inhibition of testosterone synthesis before and after birth in the offspring rats by low level of endogenous glucocorticoids.

Integrated Analysis of miRNA-mRNA Expression in Mink Lung Epithelial Cells Infected With Canine Distemper Virus

Canine distemper (CD) caused by canine distemper virus (CDV) is one of the major infectious diseases in minks, bringing serious economic losses to the mink breeding industry. By an integrated analysis of microRNA (miRNA)-messenger RNA (mRNA), the present study analyzed the changes in the mink transcriptome upon CDV infection in mink lung epithelial cells (Mv. l. Lu cells) for the first time. A total of 4,734 differentially expressed mRNAs (2,691 upregulated and 2,043 downregulated) with |log2(FoldChange) |&gt;1 and P-adj&lt;0.05 and 181 differentially expressed miRNAs (152 upregulated and 29 downregulated) with |log2(FoldChange) |&gt;2 and P-adj&lt;0.05 were identified. Gene Ontology (GO) enrichment indicated that differentially expressed genes (DEGs) were associated with various biological processes and molecular function, such as response to stimulus, cell communication, signaling, cytokine activity, transmembrane signaling receptor activity and signaling receptor activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the combination of miRNA and mRNA was done for immune and inflammatory responses, such as Janus kinase (JAK)-signal transducer and activator (STAT) signaling pathway and nuclear factor (NF)-kappa B signaling pathway. The enrichment analysis of target mRNA of differentially expressed miRNA revealed that mir-140-5p and mir-378-12 targeted corresponding genes to regulate NF-kappa B signaling pathway. JAK-STAT signaling pathway could be modulated by mir-425-2, mir-139-4, mir-140-6, mir-145-3, mir-140-5p and mir-204-2. This study compared the influence of miRNA-mRNA expression in Mv. l. Lu cells before and after CDV infection by integrated analysis of miRNA-mRNA and analyzed the complex network interaction between virus and host cells. The results can help understand the molecular mechanism of the natural immune response induced by CDV infection in host cells.

The gut microbial metabolite, 3,4-dihydroxyphenylpropionic acid, alleviates hepatic ischemia/reperfusion injury via mitigation of macrophage pro-inflammatory activity in mice

Hepatic ischemia/reperfusion injury (HIRI) is a serious complication that occurs following shock and/or liver surgery. Gut microbiota and their metabolites are key upstream modulators of development of liver injury. Herein, we investigated the potential contribution of gut microbes to HIRI. Ischemia/reperfusion surgery was performed to establish a murine model of HIRI. 16S rRNA gene sequencing and metabolomics were used for microbial analysis. Transcriptomics and proteomics analysis were employed to study the host cell responses. Our results establish HIRI was significantly increased when surgery occurred in the evening (ZT12, 20:00) when compared with the morning (ZT0, 08:00); however, antibiotic pretreatment reduced this diurnal variation. The abundance of a microbial metabolite 3,4-dihydroxyphenylpropionic acid was significantly higher in ZT0 when compared with ZT12 in the gut and this compound significantly protected mice against HIRI. Furthermore, 3,4-dihydroxyphenylpropionic acid suppressed the macrophage pro-inflammatory response in vivo and in vitro. This metabolite inhibits histone deacetylase activity by reducing its phosphorylation. Histone deacetylase inhibition suppressed macrophage pro-inflammatory activation and diminished the diurnal variation of HIRI. Our findings revealed a novel protective microbial metabolite against HIRI in mice. The potential underlying mechanism was at least in part, via 3,4-dihydroxyphenylpropionic acid-dependent immune regulation and histone deacetylase (HDAC) inhibition in macrophages.

Maternally derived low glucocorticoid mediates adrenal developmental programming alteration in offspring induced by dexamethasone

Adverse environments during pregnancy can increase susceptibility to chronic diseases in adult offspring. The occurrence and development of fetal-originated diseases were associated with adrenal developmental programming and homeostasis alteration in offspring. Dexamethasone is widely used for preterm delivery-related pregnancy diseases, but the intrauterine programming alteration and its occurrence mechanism of prenatal dexamethasone exposure (PDE) on adrenal development in offspring have not been clarified. In this study, prenatal dexamethasone therapy could inhibit neonatal development and cause a low exposure of maternally derived glucocorticoid in clinic. Then, we established a rat model of PDE and observed a similar phenomenon. Further, the adrenal steroidogenic function was continuously inhibited in the PDE male offspring rats, accompanied by the decreased H3K27ac level of adrenal insulin-like growth factor 1 (IGF1) and its expression. Moreover, chronic stress in PDE adult offspring rats could reverse the changes of the above indicators through the high level of glucocorticoid. In combination with in vivo, in vitro and a series of interference experiments, we confirmed that the low level of endogenous glucocorticoids inhibited the adrenal IGF1 expression and steroidogenic function through the GRα/miR-370-3p/Sirt3 pathway. In summary, PDE could continuously inhibit the adrenal steroidogenic function in the male offspring, which is associated with the maternally derived low glucocorticoid-mediated the adrenal developmental programming alteration in offspring. This study provides a theoretical and experimental basis for explaining the adrenal development origin of PDE-induced adult chronic diseases.

Silencing hepatitis B virus covalently closed circular DNA: The potential of an epigenetic therapy approach

Global prophylactic vaccination programmes have helped to curb new hepatitis B virus (HBV) infections. However, it is estimated that nearly 300 million people are chronically infected and have a high risk of developing hepatocellular carcinoma. As such, HBV remains a serious health priority and the development of novel curative therapeutics is urgently needed. Chronic HBV infection has been attributed to the persistence of the covalently closed circular DNA (cccDNA) which establishes itself as a minichromosome in the nucleus of hepatocytes. As the viral transcription intermediate, the cccDNA is responsible for producing new virions and perpetuating infection. HBV is dependent on various host factors for cccDNA formation and the minichromosome is amenable to epigenetic modifications. Two HBV proteins, X (HBx) and core (HBc) promote viral replication by modulating the cccDNA epigenome and regulating host cell responses. This includes viral and host gene expression, chromatin remodeling, DNA methylation, the antiviral immune response, apoptosis, and ubiquitination. Elimination of the cccDNA minichromosome would result in a sterilizing cure; however, this may be difficult to achieve. Epigenetic therapies could permanently silence the cccDNA minichromosome and promote a functional cure. This review explores the cccDNA epigenome, how host and viral factors influence transcription, and the recent epigenetic therapies and epigenome engineering approaches that have been described.

The Epigenetic Modulation of Cancer and Immune Pathways in Hepatitis B Virus-Associated Hepatocellular Carcinoma: The Influence of HBx and miRNA Dysregulation

Hepatitis B virus (HBV)-associated hepatocellular carcinoma (HBV-HCC) pathogenesis is fueled by persistent HBV infection that stealthily maintains a delicate balance between viral replication and evasion of the host immune system. HBV is remarkably adept at using a combination of both its own, as well as host machinery to ensure its own replication and survival. A key tool in its arsenal, is the HBx protein which can manipulate the epigenetic landscape to decrease its own viral load and enhance persistence, as well as manage host genome epigenetic responses to the presence of viral infection. The HBx protein can initiate epigenetic modifications to dysregulate miRNA expression which, in turn, can regulate downstream epigenetic changes in HBV-HCC pathogenesis. We attempt to link the HBx and miRNA induced epigenetic modulations that influence both the HBV and host genome expression in HBV-HCC pathogenesis. In particular, the review investigates the interplay between CHB infection, the silencing role of miRNA, epigenetic change, immune system expression and HBV-HCC pathogenesis. The review demonstrates exactly how HBx-dysregulated miRNA in HBV-HCC pathogenesis influence and are influenced by epigenetic changes to modulate both viral and host genome expression. In particular, the review identifies a specific subset of HBx induced epigenetic miRNA pathways in HBV-HCC pathogenesis demonstrating the complex interplay between HBV infection, epigenetic change, disease and immune response. The wide-ranging influence of epigenetic change and miRNA modulation offers considerable potential as a therapeutic option in HBV-HCC.

Histone Deacetylase Inhibitors Romidepsin and Vorinostat Promote Hepatitis B Virus Replication by Inducing Cell Cycle Arrest

BACKGROUND AND AIMS

Chronic hepatitis B virus (HBV) infection is a global public health challenge. HBV reactivation usually occurs in cancer patients after receiving cytotoxic chemotherapy or immunosuppressive therapies. Romidepsin (FK228) and vorinostat (SAHA) are histone deacetylase inhibitors (HDACi) approved by the Food and Drug Administration as novel antitumor agents. The aim of this study was to explore the effects and mechanisms of HDACi treatment on HBV replication.

METHODS

To assess these effects, human hepatoma cell lines were cultured and cell viability after FK228 or SAHA treatment was measured by the CCK-8 cell counting kit-8 assay. Then, HBV DNA and RNA were quantified by real-time PCR and Southern blotting. Furthermore, analysis by western blotting, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and flow cytometry was performed.

RESULTS

FK228/SAHA treatment significantly promoted HBV replication and biosynthesis in both HBV-replicating cells and HBV-transgenic mouse model. Flow cytometry assay indicated that FK228/SAHA enhanced HBV replication by inducing cell cycle arrest through modulating the expression of cell cycle regulatory proteins. In addition, simultaneous inhibition of HDAC1/2 by FK228 promoted HBV replication more effectively than the broad spectrum HDAC inhibitor SAHA.

CONCLUSIONS

Overall, our results demonstrate that cell cycle blockage plays an important role in FK228/SAHA-enhanced HBV replication, thus providing a potential avenue for rational use of HDACi in patients with chronic hepatitis B.

Suppression of complement component 2 expression by hepatitis B virus contributes to the viral persistence in chronic hepatitis B patients

Previously, we identified rare missense mutations of complement component 2 (C2) to be associated with chronic hepatitis B (CHB) by exome sequencing. However, up to now, little is known about the role of C2 in CHB. In the present study, we aimed to perform preliminary exploration about the underlying role of C2 in CHB. Serum samples from 113 CHB patients and 30 healthy controls, and liver biopsy samples from 5 CHB patients and 3 healthy controls were obtained from the Third Affiliated Hospital of Sun Yat-sen University between January 2018 and January 2020. HepG2.2.15 and HepG2-NTCP cells infected with HBV were used to examine the influence of HBV infection on C2 expression. IFN-treated HepG2.2.15 cells were used to assess the effect of IFN on C2 expression. C2-overexpressing or C2-silencing HepG2.2.15 cells were constructed to evaluate the effect of C2 on HBV infection. Western blot and RT-qPCR were used to measure C2 expression in biopsy samples. HBeAg and HBsAg in culture medium and C2 of serum samples were measured by ELISA. HBV-DNA was measured by RT-qPCR. GSE84044, GSE54747 and GSE27555 were downloaded from GEO. C2 expression in liver tissue and serum was significantly lower in CHB patients compared to healthy controls, and significantly higher C2 expression was found in CHB patients with lower ALT, AST, Scheuer grade and stages compared to CHB patients with higher ALT, AST, Scheuer grades and Scheuer stage. Besides, HBV infection could decrease C2 expression by increasing expression of Sp1 and reducing expression of HDAC4. Moreover, C2 could enhance the anti-virus effect of IFN on HepG2.2.15 cells and also inhibit HBV replication in HepG2.2.15 cells by inhibition of p38-MAPK signalling pathway. In conclusion, HBV may promote viral persistence in CHB patients by inhibiting C2 expression.

Hepatitis B virus biology and life cycle

Hepatitis B virus (HBV) specifically infects hepatocytes and causes severe liver diseases. The HBV life cycle is unique in that the genomic DNA (relaxed-circular partially double-stranded DNA: rcDNA) is converted to a molecular template DNA (covalently closed circular DNA: cccDNA) to amplify a viral RNA intermediate, which is then reverse-transcribed back to viral DNA. The highly stable characteristics of cccDNA result in chronic infection and a poor rate of cure. This complex life cycle of HBV offers a variety of targets to develop antiviral agents. We provide here an update on the current knowledge of HBV biology and its life cycle, which may help to identify new antiviral targets.

The cooperative complex of Argonaute-2 and microRNA-146a regulates hepatitis B virus replication through flap endonuclease 1

AIM

Hepatitis B virus (HBV) is a major cause of a variety of liver diseases. Existing antiviral drugs cannot eradicate HBV from our body, and the main reason is unclear on the molecular mechanism of HBV replication. Flap endonuclease 1 (FEN1) can repair relaxed circular DNA (HBV rcDNA) to covalently closed circular DNA (HBV cccDNA) that promotes HBV DNA replication, while its specific regulatory detail remains unclear. In addition, miR-146a is close related to regulation in HBV replication. This study aims to explore whether miR-146a regulates HBV cccDNA formation through FEN1.

MAIN METHODS

We investigated the expression of miR-146a, FEN1 and HBV copies in HBV stable replication cell line HepG2.2.15 and its parent cell line HepG2 transfected miR-146a and FEN1 plasmid by qRT-PCR and western blot, to identify the cooperation of Argonaute-2 (Ago2) and miR-146a by Ago2 siRNA and Ago2 RNA Binding Protein Immunoprecipitation (RIP).

KEY FINDINGS

Compared with the control group, we found that the expression of miR-146a was significantly up-regulated in HepG2.2.15, and the expression of FEN1 and HBV copies were also significantly up-regulated. On contrary, the expression of target gene of miR-146a, interleukin-1 receptor-associated kinase 1 (IRAK1) and tumor necrosis factor receptor-associated factor-6 (TRAF6), was significantly decreased in HepG2.2.15. With the use of Ago2 siRNA and then Ago2 RIP, we found that Ago2 performed as a carrier for miR-146a to promote HBV replication.

SIGNIFICANCE

The results suggest a novel miR-146a → FEN1 → HBV DNA regulatory axis in HBV replication life. Ago2 cooperates with miR-146a to regulate the transcription and expression level of FEN1 protein through the downstream target gene IRAK1/TRAF6, and to promote HBV replication.

The role of histone deacetylase 4 during chondrocyte hypertrophy and endochondral bone development

Chondrocyte hypertrophy represents a crucial turning point during endochondral bone development. This process is tightly regulated by various factors, constituting a regulatory network that maintains normal bone development. Histone deacetylase 4 (HDAC4) is the most well-characterized member of the HDAC class IIa family and participates in different signalling networks during development in various tissues by promoting chromatin condensation and transcriptional repression. Studies have reported that HDAC4-null mice display premature ossification of developing bones due to ectopic and early-onset chondrocyte hypertrophy. Overexpression of HDAC4 in proliferating chondrocytes inhibits hypertrophy and ossification of developing bones, which suggests that HDAC4, as a negative regulator, is involved in the network regulating chondrocyte hypertrophy. Overall, HDAC4 plays a key role during bone development and disease. Thus, understanding the role of HDAC4 during chondrocyte hypertrophy and endochondral bone formation and its features regarding the structure, function, and regulation of this process will not only provide new insight into the mechanisms by which HDAC4 is involved in chondrocyte hypertrophy and endochondral bone development, but will also create a platform for developing a therapeutic strategy for related diseases.

Cite this article:Bone Joint Res. 2020;9(2):82–89.

MicroRNAs regulate innate immunity against uropathogenic and commensal-like Escherichia coli infections in the surrogate insect model Galleria mellonella

Uropathogenic Escherichia coli (UPEC) strains cause symptomatic urinary tract infections in humans whereas commensal-like E. coli strains in the urinary bladder cause long-term asymptomatic bacteriuria (ABU). We previously reported that UPEC and ABU strains differentially regulate key DNA methylation and histone acetylation components in the surrogate insect host Galleria mellonella to epigenetically modulate innate immunity-related gene expression, which in turn controls bacterial growth. In this follow-up study, we infected G. mellonella larvae with UPEC strain CFT073 or ABU strain 83972 to identify differences in the expression of microRNAs (miRNAs), a class of non-coding RNAs that regulate gene expression at the post-transcriptional level. Our small RNA sequencing analysis showed that UPEC and ABU infections caused significant changes in the abundance of miRNAs in the larvae, and highlighted the differential expression of 147 conserved miRNAs and 95 novel miRNA candidates. We annotated the G. mellonella genome sequence to investigate the miRNA-regulated expression of genes encoding antimicrobial peptides, signaling proteins, and enzymatic regulators of DNA methylation and histone acetylation in infected larvae. Our results indicate that miRNAs play a role in the epigenetic reprograming of innate immunity in G. mellonella larvae to distinguish between pathogenic and commensal strains of E. coli.

HDAC11 restricts HBV replication through epigenetic repression of cccDNA transcription

Hepatitis B virus (HBV) infection remains an important public health problem worldwide. Covalently closed circular DNA (cccDNA) exhibits as an individual minichromosome and is the molecular basis of HBV infection persistence and antiviral treatment failure. In the current study, we demonstrated that histone deacetylase 11 (HDAC11) inhibits HBV transcription and replication in HBV-transfected Huh7 cells. By using an HBV in vitro infection system, HDAC11 was found to affect the transcriptional activity of cccDNA but did not affect cccDNA production. Chromatin immunoprecipitation (ChIP) assays were utilized to analyze the epigenetic modifications of cccDNA. The results show that HDAC11 specifically reduced the acetylation level of cccDNA-bound histone H3 but did not affect that of histone H4. Furthermore, HDAC11 overexpression decreased the levels of cccDNA-bound acetylated H3K9 (H3K9ac) and H3K27 (H3K27ac). In conclusion, HDAC11 restricts HBV replication through epigenetic repression of cccDNA transcription. These findings reveal the novel role of HDAC11 in HBV infection, further broadening our knowledge regarding the functions of HDAC11 and the roles of HDACs in the epigenetic regulation of HBV cccDNA.

Vitamin D Alleviates Rotavirus Infection through a Microrna-155-5p Mediated Regulation of the TBK1/IRF3 Signaling Pathway In Vivo and In Vitro

(1) Background: Vitamin D (VD) plays a vital role in anti-viral innate immunity. However, the role of VD in anti-rotavirus and its mechanism is still unclear. The present study was performed to investigate whether VD alleviates rotavirus (RV) infection through a microRNA-155-5p (miR-155-5p)-mediated regulation of TANK-binding kinase 1 (TBK1)/interferon regulatory factors 3 (IRF3) signaling pathway in vivo and in vitro. (2) Methods: The efficacy of VD treatment was evaluated in DLY pig and IPEC-J2. Dual-luciferase reporter activity assay was performed to verify the role of miR-155-5p in 1α,25-dihydroxy-VD₃ (1,25D3) mediating the regulation of the TBK1/IRF3 signaling pathway. (3) Results: A 5000 IU·kg^–1 dietary VD₃ supplementation attenuated RV-induced the decrease of the villus height and crypt depth (p < 0.05), and up-regulated TBK1, IRF3, and IFN-β mRNA expressions in the jejunum (p < 0.05). Incubation with 1,25D3 significantly decreased the RV mRNA expression and the RV antigen concentration, and increased the TBK1 mRNA and protein levels, and the phosphoprotein IRF3 (p-IRF3) level (p < 0.05). The expression of miR-155-5p was up-regulated in response to an RV infection in vivo and in vitro (p < 0.05). 1,25D3 significantly repressed the up-regulation of miR-155-5p in vivo and in vitro (p < 0.05). Overexpression of miR-155-5p remarkably suppressed the mRNA and protein levels of TBK1 and p-IRF3 (p < 0.01), while the inhibition of miR-155-5p had an opposite effect. Luciferase activity assays confirmed that miR-155-5p regulated RV replication by directly targeting TBK1, and miR-155-5p suppressed the TBK1 protein level (p < 0.01). (4) Conclusions: These results indicate that miR-155-5p is involved in 1,25D3 mediating the regulation of the TBK1/IRF3 signaling pathway by directly targeting TBK1.