Regulation of hepatitis B virus core promoter by transcription factors HNF1 and HNF4 and the viral X protein.
Ontology highlight
ABSTRACT:
SUBMITTER: Zheng Y
PROVIDER: S-EPMC421633 | biostudies-other | 2004 Jul
REPOSITORIES: biostudies-other
Similar Datasets
Project description:We aimed to identify microRNAs (miRNAs) under transcriptional control of the HNF1? transcription factor, and investigate whether its effect manifests in serum.The Polish cohort (N?=?60) consisted of 11 patients with HNF1B-MODY, 17 with HNF1A-MODY, 13 with?GCK-MODY, an HbA1c-matched type 1 diabetic group (n?=?9) and ten healthy controls. Replication was performed in 61 clinically-matched British patients mirroring the groups in the Polish cohort. The Polish cohort underwent miRNA serum level profiling with quantitative real-time PCR (qPCR) arrays to identify differentially expressed miRNAs. Validation was performed using qPCR. To determine whether serum content reflects alterations at a cellular level, we quantified miRNA levels in a human hepatocyte cell line (HepG2) with small interfering RNA knockdowns of HNF1? or HNF1?.Significant differences (adjusted p?<?0.05) were noted for 11 miRNAs. Five of them differed between HNF1A-MODY and HNF1B-MODY, and, amongst those, four (miR-24, miR-27b, miR-223 and miR-199a) showed HNF1B-MODY-specific expression levels in the replication group. In all four cases the miRNA expression level was lower in HNF1B-MODY than in all other tested groups. Areas under the receiver operating characteristic curves ranged from 0.79 to 0.86, with sensitivity and specificity reaching 91.7% (miR-24) and 82.1% (miR-199a), respectively. The cellular expression pattern of miRNA was consistent with serum levels, as all were significantly higher in HNF1?- than in HNF1?-deficient HepG2 cells.We have shown that expression of specific miRNAs depends on HNF1? function. The impact of HNF1? deficiency was evidenced at serum level, making HNF1?-dependent miRNAs potentially applicable in the diagnosis of HNF1B-MODY.
| S-EPMC4901123 | biostudies-literature
Project description:Background and Aims: Chronic HBV infection is a major cause of liver disease and cancer. Virus-host interactions and the pathogenesis of virus-induced liver disease are only partially understood. Hypoxia has been shown to play a major role in disease biology and carcinogenesis and HBV replicates a naturally hypoxic organ. In this study we aimed to investigate the role of liver hypoxia for HBV infection. Methods: Using cell culture, animal models and human tissues we investigated the impact of hyproxia on the HBV life cycle. Results: Establishing liver cell-based model systems that mimic hepatic oxygen, we uncover a major role of hypoxia in regulating HBV transcription. Hypoxia-inducible factors (HIFs) perturb HBV replication and expression in cell-based and animal models. Conservation of hypoxia responsive elements in the viral basal core promoter uncover an essential role for HIFs in regulating the hepadnaviridae family of hepatotropic viruses. Conclusions: Identifying a role for this conserved oxygen sensors in regulating HBV replication provides a new understanding of virus-host interactions and liver disease biology, improve state-of-the-art HBV model systems and unravels new opportunities for therapeutic targeting of chronic hepatitis B.
2023-07-20 | PXD020086 | Pride
Project description:Hepatocyte nuclear factor 4alpha (HNF4alpha) is a member of the nuclear receptor superfamily that plays a central role in organ development and metabolic functions. Mutations on HNF4alpha cause maturity-onset diabetes of the young (MODY), a dominant monogenic cause of diabetes. In order to understand the molecular mechanism of promoter recognition and the molecular basis of disease-causing mutations, the recombinant HNF4alpha DNA-binding domain was prepared and used in a study of its binding properties and in crystallization with a 21-mer DNA fragment that contains the promoter element of another MODY gene, HNF1alpha. The HNF4alpha protein displays a cooperative and specific DNA-binding activity towards its target gene-recognition elements. Crystals of the complex diffract to 2.0 A using a synchrotron-radiation source under cryogenic (100 K) conditions and belong to space group C2, with unit-cell parameters a = 121.63, b = 35.43, c = 70.99 A, beta = 119.36 degrees . A molecular-replacement solution has been obtained and structure refinement is in progress. This structure and the binding studies will provide the groundwork for detailed functional and biochemical studies of the MODY mutants.
| S-EPMC2374247 | biostudies-literature
Project description:Background & aimsHypoxia inducible factors (HIFs) are a hallmark of inflammation and are key regulators of hepatic immunity and metabolism, yet their role in HBV replication is poorly defined. HBV replicates in hepatocytes within the liver, a naturally hypoxic organ, however most studies of viral replication are performed under conditions of atmospheric oxygen, where HIFs are inactive. We therefore investigated the role of HIFs in regulating HBV replication.MethodsUsing cell culture, animal models, human tissue and pharmacological agents inhibiting the HIF-prolyl hydroxylases, we investigated the impact of hypoxia on the HBV life cycle.ResultsCulturing liver cell-based model systems under low oxygen uncovered a new role for HIFs in binding HBV DNA and activating the basal core promoter, leading to increased pre-genomic RNA and de novo HBV particle secretion. The presence of hypoxia responsive elements among all primate members of the hepadnaviridae highlights an evolutionary conserved role for HIFs in regulating this virus family.ConclusionsIdentifying a role for this conserved oxygen sensor in regulating HBV transcription suggests that this virus has evolved to exploit the HIF signaling pathway to persist in the low oxygen environment of the liver. Our studies show the importance of considering oxygen availability when studying HBV-host interactions and provide innovative routes to better understand and target chronic HBV infection.Lay summaryViral replication in host cells is defined by the cellular microenvironment and one key factor is local oxygen tension. Hepatitis B virus (HBV) replicates in the liver, a naturally hypoxic organ. Hypoxia inducible factors (HIFs) are the major sensors of low oxygen; herein, we identify a new role for these factors in regulating HBV replication, revealing new therapeutic targets.
| S-EPMC8214165 | biostudies-literature
Project description:Hepatitis B virus (HBV) is a stealth virus that exhibits only minimal induction of the interferon system, which is required for both innate and adaptive immune responses. However, 90% of acutely infected adults can clear the virus, suggesting the presence of additional mechanisms that facilitate viral clearance. Here, we report that Maf bZIP transcription factor F (MafF) promotes host defense against infection with HBV. Using a small interfering RNA (siRNA) library and an HBV/NanoLuc (NL) reporter virus, we screened to identify anti-HBV host factors. Our data showed that silencing of MafF led to a 6-fold increase in luciferase activity after HBV/NL infection. Overexpression of MafF reduced HBV core promoter transcriptional activity, which was relieved upon mutation of the putative MafF binding region. Loss of MafF expression through CRISPR/Cas9 editing (in HepG2-hNTCP-C4 cells) or siRNA silencing (in primary hepatocytes [PXB cells]) induced HBV core RNA and HBV pregenomic RNA (pgRNA) levels, respectively, after HBV infection. MafF physically binds to the HBV core promoter and competitively inhibits HNF-4α binding to an overlapping sequence in the HBV enhancer II sequence (EnhII), as seen by chromatin immunoprecipitation (ChIP) analysis. MafF expression was induced by interleukin-1β (IL-1β) or tumor necrosis factor alpha (TNF-α) treatment in both HepG2 and PXB cells, in an NF-κB-dependent manner. Consistently, MafF expression levels were significantly enhanced and positively correlated with the levels of these cytokines in patients with chronic HBV infection, especially in the immune clearance phase. IMPORTANCE HBV is a leading cause of chronic liver diseases, infecting about 250 million people worldwide. HBV has developed strategies to escape interferon-dependent innate immune responses. Therefore, the identification of other anti-HBV mechanisms is important for understanding HBV pathogenesis and developing anti-HBV strategies. MafF was shown to suppress transcription from the HBV core promoter, leading to significant suppression of the HBV life cycle. Furthermore, MafF expression was induced in chronic HBV patients and in primary human hepatocytes (PXB cells). This induction correlated with the levels of inflammatory cytokines (IL-1β and TNF-α). These data suggest that the induction of MafF contributes to the host's antiviral defense by suppressing transcription from selected viral promoters. Our data shed light on a novel role for MafF as an anti-HBV host restriction factor.
| S-EPMC8274605 | biostudies-literature
Project description:Hepatitis B virus (HBV) has a 3.2 kb circular DNA genome. It employs four promoters in conjunction with a single polyadenylation signal to generate 3.5, 2.4, 2.1 and 0.7 kb co-terminal RNAs. The 3.5 kb RNA is subdivided into the precore RNA for e-antigen expression and pregenomic RNA for genome replication. When introduced to a genotype A clone, several core promoter mutations markedly enhanced HBV genome replication, but suppressed e-antigen expression through up-regulation of pregenomic RNA at the expense of precore RNA. In this study, we found such mutations also diminished envelope proteins and hepatitis B surface antigen, products of the 2.1 and 2.4 kb subgenomic RNAs. Indeed, Northern blot analysis revealed overall increase in 3.5 kb RNA, but reduction in all subgenomic RNAs. To validate transcriptional interference, we subcloned 1.1×, 0.7× and 0.6× HBV genome, respectively, to a vector with or without a cytomegalovirus (CMV) promoter at the 5' end, so as to produce the pregenomic RNA, 2.4 kb RNA, and 2.1 kb RNA in large excess or not at all. Parallel transfection of the three pairs of constructs into a human hepatoma cell line confirmed the ability of pregenomic RNA to suppress all subgenomic transcripts and established the ability of the 2.4 and 2.1 kb RNAs to suppress the 0.7 kb RNA. Consistent with our findings, pregenomic RNA of the related duck HBV has been reported to interfere with transcription of the subgenomic RNAs. Transcriptional interference might explain why HBV produces so little 0.7 kb RNA and HBx protein despite a strong X promoter.
| S-EPMC6542254 | biostudies-literature
Project description:AIM:To identify the distribution of hepatitis B virus (HBV) subgenotype and basal core promoter (BCP) mutations among patients with HBV-associated liver disease in Indonesia. METHODS:Patients with chronic hepatitis (CH, n = 61), liver cirrhosis (LC, n = 62), and hepatocellular carcinoma (HCC, n = 48) were included in this study. HBV subgenotype was identified based on S or preS gene sequence, and mutations in the HBx gene including the overlapping BCP region were examined by direct sequencing. RESULTS:HBV genotype B (subgenotypes B2, B3, B4, B5 and B7) the major genotype in the samples, accounted for 75.4%, 71.0% and 75.0% of CH, LC and HCC patients, respectively, while the genotype C (subgenotypes C1, C2 and C3) was detected in 24.6%, 29.0%, and 25.0% of CH, LC, and HCC patients, respectively. Subgenotypes B3 (84.9%) and C1 (82.2%) were the main subgenotype in HBV genotype B and C, respectively. Serotype adw2 (84.9%) and adrq+ (89.4%) were the most prevalent in HBV genotype B and C, respectively. Double mutation (A1762T/G1764A) in the BCP was significantly higher in LC (59.7%) and HCC (54.2%) than in CH (19.7%), suggesting that this mutation was associated with severity of liver disease. The T1753V was also higher in LC (46.8%), but lower in HCC (22.9%) and CH (18.0%), suggesting that this mutation may be an indicator of cirrhosis. CONCLUSION:HBV genotype B/B3 and C/C1 are the major genotypes in Indonesia. Mutations in BCP, such as A1762T/G1764A and T1753V, might have an association with manifestations of liver disease.
| S-EPMC2731954 | biostudies-literature
Project description:BackgroundMuch evidence has demonstrated the influence of Hepatitis B virus (HBV) mutations on the clinical course of HBV infection. As large (L) protein plays a crucial role for viral entry, we hypothesized that mutations in the pre-S1 promoter region might affect the expression of L protein and subsequently change the biological characters of virus.MethodsPatients infected with genotype C HBV were enrolled for analysis. HBV DNA sequences were inserted into a TA cloning vector and analyzed. To evaluate the effects of mutations in the pre-S1 promoter region, promoter activity and the expression of mRNA and L protein were analyzed using HepG2 cells.ResultsIn total, 35 patients were enrolled and 13 patients (37.1%) had a single base substitution in the pre-S1 promoter region; the most frequent substitution was a G-to-A substitution at the 2765th base (G2765A) in the Sp1 region. The HBV viral load showed a negative correlation with the substitution ratio of the Sp1 region or G2765A (r = - 0.493 and - 0.473, respectively). Among those with a viral load ≤5.0 log IU/ml, patients with the G2765A substitution showed a significantly lower HBV viral load than those with the wild-type sequence. HepG2 cells transfected with the G2765A substitution vector showed reduced luciferase activity of the pre-S1 promoter, as well as reduced expression of pre-S1 mRNA and L protein. Furthermore, the G2765A substitution greatly reduced the L protein expression level of vector-produced virus particles.ConclusionG2765A substitution in the pre-S1 promoter reduced the expression of L protein and resulted in a low viral load and less severe disease in chronic HBV infections.
| S-EPMC6498540 | biostudies-literature
Project description:BackgroundThe core protein (HBc) of hepatitis B virus (HBV) has been implicated in the malignant transformation of chronically-infected hepatocytes and displays pleiotropic functions, including RNA- and DNA-binding activities. However, the mechanism by which HBc interacts with the human genome to exert effects on hepatocyte function remains unknown. This study investigated the distribution of HBc binding to promoters in the human genome and evaluated its effects on the related genes' expression.ResultsWhole-genome chromatin immunoprecipitation microarray (ChIP-on-chip) analysis was used to identify HBc-bound human gene promoters. Gene Ontology and pathway analyses were performed on related genes. The quantitative polymerase chain reaction assay was used to verify ChIP-on-chip results. Five novel genes were selected for luciferase reporter assay evaluation to assess the influence of HBc promoter binding. The HBc antibody immunoprecipitated approximately 3100 human gene promoters. Among these, 1993 are associated with known biological processes, and 2208 regulate genes with defined molecular functions. In total, 1286 of the related genes mediate primary metabolic processes, and 1398 encode proteins with binding activity. Sixty-four of the promoters regulate genes related to the mitogen-activated protein kinase (MAPK) pathways, and 41 regulate Wnt/beta-catenin pathway genes. The reporter gene assay indicated that HBc binding up-regulates proto-oncogene tyrosine-protein kinase (SRC), type 1 insulin-like growth factor receptor (IGF1R), and neurotrophic tyrosine kinase receptor 2 (NTRK2), and down-regulates v-Ha-ras Harvey rat sarcoma viral oncogene (HRAS).ConclusionHBc has the ability to bind a large number of human gene promoters, and can disrupt normal host gene expression. Manipulation of the transcriptional profile in HBV-infected hepatocytes may represent a key pathogenic mechanism of HBV infection.
| S-EPMC3484065 | biostudies-literature
Project description:Hepatitis B virus (HBV) core promoter activity is positively and negatively regulated by nuclear receptors, a superfamily of ligand-activated transcription factors, via cis-acting sequences located in the viral genome. In this study, we investigated the role of farnesoid X receptor alpha (FXRalpha) in modulating transcription from the HBV core promoter. FXRalpha is a liver-enriched nuclear receptor activated by bile acids recognizing hormone response elements by forming heterodimers with retinoid X receptor alpha (RXRalpha). Electrophoretic mobility shift assays demonstrated that FXRalpha-RXRalpha heterodimers can bind two motifs on the HBV enhancer II and core promoter regions, presenting high homology to the consensus (AGGTCA) inverted repeat FXRalpha response elements. In transient transfection of the human hepatoma cell line Huh-7, bile acids enhanced the activity of a luciferase reporter containing the HBV enhancer II and core promoter sequences through FXRalpha. Moreover, using a greater-than-genome-length HBV construct, we showed that FXRalpha also increased synthesis of the viral pregenomic RNA and DNA replication intermediates. The data strongly suggest that FXRalpha is another member of the nuclear receptor superfamily implicated in the regulation of HBV core promoter activity and that bile acids could play an important role in the natural history of HBV infection.
| S-EPMC2573182 | biostudies-literature