Involvement of androgen receptor and glucose-regulated protein 78 kDa in human hepatocarcinogenesis.

Previous studies demonstrated that androgen receptor (AR) is expressed in human hepatocellular carcinoma (HCC), one of the male-dominant diseases. Glucose-regulated protein 78 kDa (GRP78/Bip), which has a role in cancer development, is one of the androgen response genes in prostate cell lines. The aim of this study was to investigate the impact of AR on endoplasmic reticulum (ER)-stress signaling in human hepatoma. AR and GRP78 expressions were examined in human liver tissue panels. Human hepatoma cells stably expressing short hairpin RNA targeting AR and cells over-expressing AR were generated. The expressions of ER-stress molecules and AR were measured by real-time RT-PCR and Western blotting. The effect of AR on ER-stress responsive gene expression was examined by reporter assay. Strong positive correlation between AR mRNA and GRP78 mRNA was observed in stage I/II-HCCs. AR enhanced ER-stress responsive element activities and GRP78 expression, and regulated ER-stress response in hepatocytes. Sorafenib strongly induced significant apoptosis in HepG2 cells by the inhibition of AR and inhibition of the downstream GRP78. AR seems a co-regulator of GRP78 especially in earlier-stage HCC. AR plays a critical role in controlling ER-stress, providing new therapeutic options against HCC.

Ultra-deep sequencing analysis of the hepatitis A virus 5'-untranslated region among cases of the same outbreak from a single source.

Hepatitis A virus (HAV) is a causative agent of acute viral hepatitis for which an effective vaccine has been developed. Here we describe ultra-deep pyrosequences (UDPSs) of HAV 5'-untranslated region (5'UTR) among cases of the same outbreak, which arose from a single source, associated with a revolving sushi bar. We determined the reference sequence from HAV-derived clone from an attendant by the Sanger method. Sixteen UDPSs from this outbreak and one from another sporadic case were compared with this reference. Nucleotide errors yielded a UDPS error rate of < 1%. This study confirmed that nucleotide substitutions of this region are transition mutations in outbreak cases, that insertion was observed only in non-severe cases, and that these nucleotide substitutions were different from those of the sporadic case. Analysis of UDPSs detected low-prevalence HAV variations in 5'UTR, but no specific mutations associated with severity in these outbreak cases. To our surprise, HAV strains in this outbreak conserved HAV IRES sequence even if we performed analysis of UDPSs. UDPS analysis of HAV 5'UTR gave us no association between the disease severity of hepatitis A and HAV 5'UTR substitutions. It might be more interesting to perform ultra-deep sequencing of full length HAV genome in order to reveal possible unknown genomic determinants associated with disease severity. Further studies will be needed.

[Pulmonary nocardiosis associated with the treatment of severe liver injury].

Nocardia infection is a fatal complication in compromised hosts and is often associated with a poor prognosis. Here we report the case of a 42-year-old man with acute liver injury treated with steroids who developed pulmonary nocardiosis. Pulmonary computed tomography was performed followed by bronchoscopy, which confirmed the diagnosis of pulmonary nocardiosis. This facilitated expedient and successful treatment of the pulmonary infection. Computed tomography is a useful tool for screening respiratory tract infection in immunocompromised patients, such as those with acute liver injury.

Different effects of three interferons L on Toll-like receptor-related gene expression in HepG2 cells.

IFNL1 (IL29), IFNL2 (IL28A) and IFNL3 (IL28B) might play important roles in anti-viral defense. IFNL3 genotypes have been shown to be associated with hepatitis C spontaneous and treatment-induced viral clearance. The effects of IFNL1, IFNL2 and IFNL3 on innate immunity including Toll-like receptor (TLR)-related pathway in human hepatocytes were examined. After G418 screening, we established the human hepatoma stable cell lines HepG2-IL28A, HepG2-IL28B, and HepG2-IL29, expressing IFNL2, IFNL3, and IFNL1 in conditioned medium, respectively, and a control cell line, HepG2-pcDNA3.1. We performed real-time RT-PCR to investigate 84 Toll-like receptor-related gene expressions in triplicate and, using ddCt methods, compared these gene expressions in each cell line. IFNL2, IFNL3 and IFNL1 were respectively detected by ELISA in HepG2-IL28A, HepG2-IL28B and HepG2-IL29. Compared to HepG2-pcDNA3.1 cells, 17 (20.2%), 11 (13.0%) and 16 genes (19.0%) were up-regulated 1.5-fold or more (p<0.05); 10 (11.9%), 2 (2.3%) and 10 genes (11.9%) were 1.5-fold or more down-regulated (p<0.05) in HepG2-IL28A, HepG2-IL28B and HepG2-IL29, respectively. EIF2AK2 and SARM1 were up-regulated among all cells. Of interest, TLR3, TLR4 and related molecules CXCL10 (IP10), IL6, EIF2K2, IFNB1, and IRF1, important genes in the progression of HCV-related pathogenesis and antiviral activities against HCV, in HepG2-IL28B, presented different profiles from those of HepG2-IL28A and HepG2-IL29. IFNL3 induces interferon-stimulated genes (ISGs) that are reportedly associated with the progression of HCV-related pathogenesis and antiviral activities against HCV. IFNL is a powerful modulator of innate immune response and it is supposed that the 3 IFNLs may play different roles in the antiviral activity against HBV and HCV.

Alanine aminotransferase elevation during peginterferon alpha-2a or alpha-2b plus ribavirin treatment.

Alanine aminotransferase (ALT) elevation was occassionally observed during the treatment with combination peginterferon alpha plus ribavirin. Two forms of peginterferon are currently available as a standard of care with or without direct-acting antivirals against hepatitis C virus (HCV). Until the appearance of interferon-sparing regimen, peginterferon alpha plus ribavirin will play a central role in the eradication of HCV. In the present study, we compared ALT elevations in response to peginterferon alpha-2a plus ribavirin or peginterferon alpha-2b plus ribavirin in HCV genotype-1-infected patients. There were no significant differences in ALT elevations between treatments with the two peginterferons, but in a comparison of the proportions of patients with transient ALT elevation from baseline between the two groups, transient ALT elevation was observed more in sustained virological response (SVR) patients treated with peginterferon alpha-2a than with peginterferon alpha-2b. However, no patients discontinued treatment due to ALT elevation. Patients with transient ALT elevation from baseline during the treatment had less favorable IL28B rs8099917 genotype in the peginterferon alpha-2b group. Patients achieving SVR tended to have lower ALT levels, although some had persistent ALT elevation during treatment. In conclusion, clinicians should pay attention to possible ALT elevation during the treatment of chronic hepatitis C patients.

Peginterferon Alfa-2a plus ribavirin in Japanese patients infected with hepatitis C virus genotype 2 who failed previous interferon therapy.

Some patients infected with hepatitis C virus (HCV) genotype 2 could be cured with treatment shorter than 24 weeks using peginterferon plus ribavirin, but there are still treatment-refractory patients. Direct-acting antivirals (DAAs) are not currently available for HCV genotype 2 patients, different from genotype 1 patients, in clinical practice. We investigated 29 HCV genotype 2-infected Japanese patients who had been previously treated and failed to clear HCV. We retreated them with peginterferon alfa-2a plus ribavirin and measured HCV RNA level to assess the efficacy and safety of this treatment in patients who had failed previous therapy. We found that retreatment of HCV genotype 2-infected Japanese patients with peginterferon alfa-2a plus ribavirin for 24-48 weeks led to 60 to 66.6% sustained virological response (SVR) in patients previously treated with (peg-)interferon monotherapy and to 69.9% SVR in relapsers previously treated with peginterferon plus ribavirin. Attention should be paid to certain patients with unique features. Selection of patients according to their previous treatment could lead to optimal therapy in HCV genotype 2 treatment-experienced patients.

Spatial configuration of hepatitis E virus antigenic domain.

Hepatitis E virus (HEV) is a human pathogen that causes acute hepatitis. When an HEV capsid protein containing a 52-amino-acid deletion at the C terminus and a 111-amino-acid deletion at the N terminus is expressed in insect cells, the recombinant HEV capsid protein can self-assemble into a T=1 virus-like particle (VLP) that retains the antigenicity of the native HEV virion. In this study, we used cryoelectron microscopy and image reconstruction to show that anti-HEV monoclonal antibodies bind to the protruding domain of the capsid protein at the lateral side of the spikes. Molecular docking of the HEV VLP crystal structure revealed that Fab224 covered three surface loops of the recombinant truncated second open reading frame (ORF2) protein (PORF2) at the top part of the spike. We also determined the structure of a chimeric HEV VLP and located the inserted B-cell tag, an epitope of 11 amino acids coupled to the C-terminal end of the recombinant ORF2 protein. The binding site of Fab224 appeared to be distinct from the location of the inserted B-cell tag, suggesting that the chimeric VLP could elicit immunity against both HEV and an inserted foreign epitope. Therefore, the T=1 HEV VLP is a novel delivery system for displaying foreign epitopes at the VLP surface in order to induce antibodies against both HEV and the inserted epitope.

Biological and immunological characteristics of hepatitis E virus-like particles based on the crystal structure.

Hepatitis E virus (HEV) is a causative agent of acute hepatitis. The crystal structure of HEV-like particles (HEV-LP) consisting of capsid protein was determined at 3.5-A resolution. The capsid protein exhibited a quite different folding at the protruding and middle domains from the members of the families of Caliciviridae and Tombusviridae, while the shell domain shared the common folding. Tyr-288 at the 5-fold axis plays key roles in the assembly of HEV-LP, and aromatic amino acid residues are well conserved among the structurally related viruses. Mutational analyses indicated that the protruding domain is involved in the binding to the cells susceptive to HEV infection and has some neutralization epitopes. These structural and biological findings are important for understanding the molecular mechanisms of assembly and entry of HEV and also provide clues in the development of preventive and prophylactic measures for hepatitis E.

Structure of hepatitis E virion-sized particle reveals an RNA-dependent viral assembly pathway.

Hepatitis E virus (HEV) induces acute hepatitis in humans with a high fatality rate in pregnant women. There is a need for anti-HEV research to understand the assembly process of HEV native capsid. Here, we produced a large virion-sized and a small T=1 capsid by expressing the HEV capsid protein in insect cells with and without the N-terminal 111 residues, respectively, for comparative structural analysis. The virion-sized capsid demonstrates a T=3 icosahedral lattice and contains RNA fragment in contrast to the RNA-free T=1 capsid. However, both capsids shared common decameric organization. The in vitro assembly further demonstrated that HEV capsid protein had the intrinsic ability to form decameric intermediate. Our data suggest that RNA binding is the extrinsic factor essential for the assembly of HEV native capsids.

Pathogenesis of lipid metabolism disorder in hepatitis C: polyunsaturated fatty acids counteract lipid alterations induced by the core protein.

BACKGROUND & AIMS: Disturbance in lipid metabolism is one of the features of chronic hepatitis C, being a crucial determinant of the progression of liver fibrosis. Experimental studies have revealed that the core protein of hepatitis C virus (HCV) induces steatosis. METHODS: The activities of fatty acid metabolizing enzymes were determined by analyzing the fatty acid compositions in HepG2 cells with or without core protein expression. RESULTS: There was a marked accumulation of triglycerides in core-expressing HepG2 cells. While the oleic/stearic acid (18:1/18:0) and palmitoleic/palmitic acid ratio (16:1/16:0) were comparable in both the core-expressing and the control cells, there was a marked accumulation of downstream product, 5,8,11-eicosatrienoic acid (20:3(n-9)) in the core-expressing HepG2 cells. The addition of eicosatetraynoic acid, which inhibits delta-6 desaturase activity which is inherently high in HepG2 cells, led to a marked accumulation of oleic and palmitoleic acids in the core-expressing cells, showing that delta-9 desaturase was activated by the core protein. Eicosapentaenoic acid (20:5(n-3)) or arachidonic acid (20:4(n-6)) administration significantly decreased delta-9 desaturase activity, the concentration of 20:3(n-9), and triglyceride accumulation. This lipid metabolism disorder was associated with NADH accumulation due to mitochondrial dysfunction, and was reversed by the addition of pyruvate through NADH utilization. CONCLUSIONS: The fatty acid enzyme, delta-9 desaturase, was activated by HCV core protein and polyunsaturated fatty acids counteracted this impact of the core protein on lipid metabolism. These results may open up new insights into the mechanism of lipid metabolism disorder associated with HCV infection and provide clues for the development of new therapeutic devices.

Structural requirements of virion-associated cholesterol for infectivity, buoyant density and apolipoprotein association of hepatitis C virus.

Our earlier study has demonstrated that hepatitis C virus (HCV)-associated cholesterol plays a key role in virus infectivity. In this study, the structural requirement of sterols for infectivity, buoyant density and apolipoprotein association of HCV was investigated further. We removed cholesterol from virions with methyl ß-cyclodextrin, followed by replenishment with 10 exogenous cholesterol analogues. Among the sterols tested, dihydrocholesterol and coprostanol maintained the buoyant density of HCV and its infectivity, and 7-dehydrocholesterol restored the physical appearance of HCV, but suppressed its infectivity. Other sterol variants with a 3ß-hydroxyl group or with an aliphatic side chain did not restore density or infectivity. We also provide evidence that virion-associated cholesterol contributes to the interaction between HCV particles and apolipoprotein E. The molecular basis for the effects of different sterols on HCV infectivity is discussed.

Production of infectious hepatitis C virus by using RNA polymerase I-mediated transcription.

In this study, we used an RNA polymerase I (Pol I) transcription system for development of a reverse genetics protocol to produce hepatitis C virus (HCV), which is an uncapped positive-strand RNA virus. Transfection with a plasmid harboring HCV JFH-1 full-length cDNA flanked by a Pol I promoter and Pol I terminator yielded an unspliced RNA with no additional sequences at either end, resulting in efficient RNA replication within the cytoplasm and subsequent production of infectious virions. Using this technology, we developed a simple replicon trans-packaging system, in which transient transfection of two plasmids enables examination of viral genome replication and virion assembly as two separate steps. In addition, we established a stable cell line that constitutively produces HCV with a low mutation frequency of the viral genome. The effects of inhibitors of N-linked glycosylation on HCV production were evaluated using this cell line, and the results suggest that certain step(s), such as virion assembly, intracellular trafficking, and secretion, are potentially up- and downregulated according to modifications of HCV envelope protein glycans. This Pol I-based HCV expression system will be beneficial for a high-throughput antiviral screening and vaccine discovery programs.

[Leprosy in a chimpanzee].

Leprosy is suspected to develop after a long period of latency following infection with Mycobacterium leprae (M. leprae) during infancy, but definitive proof has been lacking. We found a rare case of leprosy in a chimpanzee (Pan troglodytes) born in West Africa (Sierra Leone) and brought to Japan around 2 years of age. At 31, the ape started exhibiting pathognomic signs of leprosy. Pathological diagnosis, skin smear, serum anti-phenolic glycolipid-I (PGL-I) antibody, and by PCR analysis demonstrated lepromatous leprosy. Single-nucleotide polymorphism (SNP) analysis verified the West African origin of the bacilli. This occurrence suggests the possibility of leprosy being endemic among wild chimpanzees in West Africa, potentially posing a zoonotic risk.

E6AP ubiquitin ligase mediates ubiquitin-dependent degradation of peroxiredoxin 1.

E6-associated protein (E6AP) is a cellular ubiquitin protein ligase that mediates ubiquitylation and degradation of tumor suppressor p53 in conjunction with the high-risk human papillomavirus E6 protein. We previously reported that E6AP targets annexin A1 protein for ubiquitin-dependent proteasomal degradation. To gain a better understanding of the physiological function of E6AP, we have been seeking to identify novel substrates of E6AP. Here, we identified peroxiredoxin 1 (Prx1) as a novel E6AP-binding protein using a tandem affinity purification procedure coupled with mass spectrometry. Prx1 is a 25-kDa member of the Prx family, a ubiquitous family of antioxidant peroxidases that regulate many cellular processes through intracellular oxidative signal transduction pathways. Immunoprecipitation analysis showed that E6AP binds Prx1 in vivo. Pull-down experiments showed that E6AP binds Prx1 in vitro. Ectopic expression of E6AP enhanced the degradation of Prx1 in vivo. In vivo and in vitro ubiquitylation assays revealed that E6AP promoted polyubiquitylation of Prx1. RNAi-mediated downregulation of endogenous E6AP increased the level of endogenous Prx1 protein. Taken together, our data suggest that E6AP mediates the ubiquitin-dependent proteasomal degradation of Prx1. Our findings raise a possibility that E6AP may play a role in regulating Prx1-dependent intracellular oxidative signal transduction pathways.

Proteasomal turnover of hepatitis C virus core protein is regulated by two distinct mechanisms: a ubiquitin-dependent mechanism and a ubiquitin-independent but PA28gamma-dependent mechanism.

We have previously reported on the ubiquitylation and degradation of hepatitis C virus core protein. Here we demonstrate that proteasomal degradation of the core protein is mediated by two distinct mechanisms. One leads to polyubiquitylation, in which lysine residues in the N-terminal region are preferential ubiquitylation sites. The other is independent of the presence of ubiquitin. Gain- and loss-of-function analyses using lysineless mutants substantiate the hypothesis that the proteasome activator PA28gamma, a binding partner of the core, is involved in the ubiquitin-independent degradation of the core protein. Our results suggest that turnover of this multifunctional viral protein can be tightly controlled via dual ubiquitin-dependent and -independent proteasomal pathways.

Involvement of creatine kinase B in hepatitis C virus genome replication through interaction with the viral NS4A protein.

Persistent infection with hepatitis C virus (HCV) is a major cause of chronic liver diseases. The aim of this study was to identify host cell factor(s) participating in the HCV replication complex (RC) and to clarify the regulatory mechanisms of viral genome replication dependent on the host-derived factor(s) identified. By comparative proteome analysis of RC-rich membrane fractions and subsequent gene silencing mediated by RNA interference, we identified several candidates for RC components involved in HCV replication. We found that one of these candidates, creatine kinase B (CKB), a key ATP-generating enzyme that regulates ATP in subcellular compartments of nonmuscle cells, is important for efficient replication of the HCV genome and propagation of infectious virus. CKB interacts with HCV NS4A protein and forms a complex with NS3-4A, which possesses multiple enzyme activities. CKB upregulates both NS3-4A-mediated unwinding of RNA and DNA in vitro and replicase activity in permeabilized HCV replicating cells. Our results support a model in which recruitment of CKB to the HCV RC compartment, which has high and fluctuating energy demands, through its interaction with NS4A is important for efficient replication of the viral genome. The CKB-NS4A association is a potential target for the development of a new type of antiviral therapeutic strategy.

Tacrolimus ameliorates metabolic disturbance and oxidative stress caused by hepatitis C virus core protein: analysis using mouse model and cultured cells.

Hepatic steatosis and insulin resistance are factors that aggravate the progression of liver disease caused by hepatitis C virus (HCV) infection. In the pathogenesis of liver disease and metabolic disorders in HCV infection, oxidative stress due to mitochondrial respiratory chain dysfunction plays a pivotal role. Tacrolimus (FK506) is supposed to protect mitochondrial respiratory function. We studied whether tacrolimus affects the development of HCV-associated liver disease using HCV core gene transgenic mice, which develop hepatic steatosis, insulin resistance, and hepatocellular carcinoma. Administration of tacrolimus to HCV core gene transgenic mice three times per week for 3 months led to a significant reduction in the amounts of lipid in the liver as well as in serum insulin. Tacrolimus treatment also ameliorated oxidative stress and DNA damage in the liver of the core gene transgenic mice. Tacrolimus administration reproduced these effects in a dose-dependent manner in HepG2 cells expressing the core protein. The intrahepatic level of tumor necrosis factor-alpha, which may be a key molecule for the pathogenesis in HCV infection, was significantly decreased in tacrolimus-treated core gene transgenic mice. Tacrolimus thus reversed the effect of the core protein in the pathogenesis of HCV-associated liver disease. These results may provide new therapeutic tools for chronic hepatitis C, in which oxidative stress and abnormalities in lipid and glucose metabolism contribute to liver pathogenesis.

Proteomics analysis of mitochondrial proteins reveals overexpression of a mitochondrial protein chaperon, prohibitin, in cells expressing hepatitis C virus core protein.

UNLABELLED: The hepatitis C virus (HCV) core protein is involved in viral pathogenesis such as oxidative stress induction and lipid metabolism disturbance, and is primarily located in the cytoplasm and endoplasmic reticulum in association with lipid droplets as well as in the mitochondria. To clarify the impact of the core protein on mitochondria, we analyzed the expression pattern of mitochondrial proteins in core protein-expressing cells by two-dimensional polyacrylamide gel electrophoresis. Several proteins related to the mitochondrial respiratory chain or protein chaperons were identified by mass spectrometry. Among the identified proteins with consistently different expressions, prohibitin, a mitochondrial protein chaperon, was up-regulated not only in core-expressing cells but also in full-genomic replicon cells and livers of core-gene transgenic mice. The stability of prohibitin was increased through interaction with the core protein. Further analysis demonstrated that interaction of prohibitin with mitochondrial DNA-encoded subunits of cytochrome c oxidase (COX) was disturbed by the core protein, resulting in a significant decrease in COX activity. CONCLUSION: The HCV core protein affects the steady-state levels of a subset of mitochondrial proteins including prohibitin, which may lead to an impaired function of the mitochondrial respiratory chain with the overproduction of oxidative stress.

Identification of annexin A1 as a novel substrate for E6AP-mediated ubiquitylation.

E6-associated protein (E6AP) is a cellular ubiquitin protein ligase that mediates ubiquitylation and degradation of p53 in conjunction with the high-risk human papillomavirus E6 proteins. However, the physiological functions of E6AP are poorly understood. To identify a novel biological function of E6AP, we screened for binding partners of E6AP using GST pull-down and mass spectrometry. Here we identified annexin A1, a member of the annexin superfamily, as an E6AP-binding protein. Ectopic expression of E6AP enhanced the degradation of annexin A1 in vivo. RNAi-mediated downregulation of endogenous E6AP increased the levels of endogenous annexin A1 protein. E6AP interacted with annexin A1 and induced its ubiquitylation in a Ca(2+)-dependent manner. GST pull-down assay revealed that the annexin repeat domain III of annexin A1 is important for the E6AP binding. Taken together, our data suggest that annexin A1 is a novel substrate for E6AP-mediated ubiquitylation. Our findings raise the possibility that E6AP may play a role in controlling the diverse functions of annexin A1 through the ubiquitin-proteasome pathway.