Hepatitis B virus pX interacts with HBXAP, a PHD finger protein to coactivate transcription

UBR7 E3 Ligase Suppresses Interferon-β Mediated Immune Signaling by Targeting Sp110 in Hepatitis B Virus-Induced Hepatocellular Carcinoma

A newly discovered E3 ubiquitin ligase, UBR7, plays a crucial role in histone H2BK120 monoubiquitination. Here, we report a novel function of UBR7 in promoting hepatitis B virus (HBV) pathogenesis, which further leads to HBV-induced hepatocellular carcinoma (HCC). Transcriptomics analysis from HCC patients revealed the deregulation of UBR7 in cancer. Remarkably, targeting UBR7, particularly its catalytic function, led to a significant decrease in viral copy numbers. We also identified the speckled family protein Sp110 as an important substrate of UBR7. Notably, Sp110 has been previously shown to be a resident of promyelocytic leukemia nuclear bodies (PML-NBs), where it remains SUMOylated, and during HBV infection, it undergoes deSUMOylation and exits the PML body. We observed that UBR7 ubiquitinates Sp110 at critical residues within its SAND domain. Sp110 ubiquitination downregulates genes in the type I interferon response pathway. Comparative analysis of RNA-Seq from the UBR7/Sp110 knockdown data set confirmed that the IFN-β signaling pathway gets deregulated in HCC cells in the presence of HBV. Single-cell RNA-Seq analysis of patient samples further confirmed the inverse correlation between the expression of Sp110/UBR7 and the inflammation score. Notably, silencing of UBR7 induces IRF7 phosphorylation, thereby augmenting interferon (IFN)-β and the downstream interferon-stimulated genes (ISGs). Further, wild-type but not the ubiquitination-defective mutant of Sp110 could be recruited to the type I interferon response pathway genes. Our study establishes a new function of UBR7 in non-histone protein ubiquitination, promoting viral persistence, and has important implications for the development of therapeutic strategies targeting HBV-induced HCC.

Genome-Wide Meta-Analysis Identifies Multiple Novel Rare Variants to Predict Common Human Infectious Diseases Risk

Infectious diseases still threaten global human health, and host genetic factors have been indicated as determining risk factors for observed variations in disease susceptibility, severity, and outcome. We performed a genome-wide meta-analysis on 4624 subjects from the 10,001 Dalmatians cohort, with 14 infection-related traits. Despite a rather small number of cases in some instances, we detected 29 infection-related genetic associations, mostly belonging to rare variants. Notably, the list included the genes CD28, INPP5D, ITPKB, MACROD2, and RSF1, all of which have known roles in the immune response. Expanding our knowledge on rare variants could contribute to the development of genetic panels that could assist in predicting an individual's life-long susceptibility to major infectious diseases. In addition, longitudinal biobanks are an interesting source of information for identifying the host genetic variants involved in infectious disease susceptibility and severity. Since infectious diseases continue to act as a selective pressure on our genomes, there is a constant need for a large consortium of biobanks with access to genetic and environmental data to further elucidate the complex mechanisms behind host-pathogen interactions and infectious disease susceptibility.

RNR-R2 Upregulation by a Short Non-Coding Viral Transcript

DNA viruses require dNTPs for replication and have developed different strategies to increase intracellular dNTP pools. Hepatitis B virus (HBV) infects non-dividing cells in which dNTPs are scarce and the question is how viral replication takes place. Previously we reported that the virus induces the DNA damage response (DDR) pathway culminating in RNR-R2 expression and the generation of an active RNR holoenzyme, the key regulator of dNTP levels, leading to an increase in dNTPs. How the virus induces DDR and RNR-R2 upregulation is not completely known. The viral HBx open reading frame (ORF) was believed to trigger this pathway. Unexpectedly, however, we report here that the production of HBx protein is dispensable. We found that a small conserved region of 125 bases within the HBx ORF is sufficient to upregulate RNR-R2 expression in growth-arrested HepG2 cells and primary human hepatocytes. The observed HBV mRNA embedded regulatory element is named ERE. ERE in isolation is sufficient to activate the ATR-Chk1-E2F1-RNR-R2 DDR pathway. These findings demonstrate a non-coding function of HBV transcripts to support its propagation in non-cycling cells.

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.

RSF1 requires CEBP/β and hSNF2H to promote IL-1β-mediated angiogenesis: the clinical and therapeutic relevance of RSF1 overexpression and amplification in myxofibrosarcomas

Myxofibrosarcoma is genetically complex and lacks effective nonsurgical treatment strategies; thus, elucidation of novel molecular drivers is urgently needed. Reanalyzing public myxofibrosarcoma datasets, we identified mRNA upregulation and recurrent gain of RSF1 and characterized this chromatin remodeling gene. Myxofibrosarcoma cell lines were employed to elucidate the oncogenic mechanisms of RSF1 by genetic manipulation and two IL-1β-neutralizing antibodies (RD24, P2D7KK), highlighting the regulatory basis and targetability of downstream IL-1β-mediated angiogenesis. Tumor samples were assessed for RSF1, IL-1β, and microvascular density (MVD) by immunohistochemistry and for RSF1 gene status by FISH. In vivo, RSF1-silenced and P2D7KK-treated xenografts were analyzed for tumor-promoting effects and the IL-1β-linked therapeutic relevance of RSF1, respectively. In vitro, RSF1 overexpression promoted invasive and angiogenic phenotypes with a stronger proangiogenic effect. RT-PCR profiling identified IL1B as a top-ranking candidate upregulated by RSF1. RSF1 required hSNF2H and CEBP/β to cotransactivate the IL1B promoter, which increased the IL1B mRNA level, IL-1β secretion and angiogenic capacity. Angiogenesis induced by RSF1-upregulated IL-1β was counteracted by IL1B knockdown and both IL-1β-neutralizing antibodies. Clinically, RSF1 overexpression was highly associated with RSF1 amplification, IL-1β overexpression, increased MVD and higher grades (all P ≤ 0.01) and independently predicted shorter disease-specific survival (P = 0.019, hazard ratio: 4.556). In vivo, both RSF1 knockdown and anti-IL-1β P2D7KK (200 μg twice weekly) enabled significant growth inhibition and devascularization in xenografts. In conclusion, RSF1 overexpression, partly attributable to RSF1 amplification, contributes a novel proangiogenic function by partnering with CEBP/β to cotransactivate IL1B, highlighting its prognostic, pathogenetic, and therapeutic relevance in myxofibrosarcomas.

RSF-1 overexpression determines cancer progression and drug resistance in cervical cancer

BACKGROUND

Remodeling spacing factor 1 (RSF-1/HBXAP) has been linked to a variety of cancer types, however, its roles and the therapeutic potential are not clear in cervical cancer.

METHODS

RSF-1 expression in cancer tissues was analyzed by immunohistochemical staining followed by statistical analysis with SPSS. Anti-RSF-1 studies were performed by treating cells with specific siRNA or a dominant mutant form (RSF-D4).

RESULTS

RSF-1 expression correlates with cancer progression that strongly-positive staining can be found in 67.7% carcinomas and 66.7% CIN lesions, but none in normal tissues. Such overexpression also associated with increased tumor size, poor differentiation, higher nodal metastasis and advanced clinical stages. Kaplan- Meier analysis confirmed that cancer patients with high RSF-1 levels exhibited a significantly shorter survival time than those with low RSF-1 levels. Downregulation of RSF-1 by siRNA silencing or RSF-D4 reduced cell growth and increased drug sensitivity toward paclitaxel treatment in HeLa cells.

CONCLUSIONS

RSF-1 participates in the tumor progression of cervical cancer and could be considered as an early prognostic marker for cancer development and clinical outcome. Therapies based on anti-RSF-1 activity may be beneficial for patients with RSF-1 overexpression in their tumors.

Host transcription factor Speckled 110 kDa (Sp110), a nuclear body protein, is hijacked by hepatitis B virus protein X for viral persistence

Promyelocytic leukemia nuclear bodies (PML-NB) are sub-nuclear organelles that are the hub of numerous proteins. DNA/RNA viruses often hijack the cellular factors resident in PML-NBs to promote their proliferation in host cells. Hepatitis B virus (HBV), belonging to Hepadnaviridae family, remains undetected in early infection as it does not induce the innate immune response and is known to be the cause of several hepatic diseases leading to cirrhosis and hepatocellular carcinoma. The association of PML-NB proteins and HBV is being addressed in a number of recent studies. Here, we report that the PML-NB protein Speckled 110 kDa (Sp110) is SUMO1-modified and undergoes a deSUMOylation-driven release from the PML-NB in the presence of HBV. Intriguingly, Sp110 knockdown significantly reduced viral DNA load in the culture supernatant by activation of the type I interferon-response pathway. Furthermore, we found that Sp110 differentially regulates several direct target genes of hepatitis B virus protein X (HBx), a viral co-factor. Subsequently, we identified Sp110 as a novel interactor of HBx and found this association to be essential for the exit of Sp110 from the PML-NB during HBV infection and HBx recruitment on the promoter of these genes. HBx, in turn, modulates the recruitment of its associated transcription cofactors p300/HDAC1 to these co-regulated genes, thereby altering the host gene expression program in favor of viral persistence. Thus, we report a mechanism by which HBV can evade host immune response by hijacking the PML-NB protein Sp110, and therefore, we propose it to be a novel target for antiviral therapy.

MicroRNA-154 as a prognostic factor in bladder cancer inhibits cellular malignancy by targeting RSF1 and RUNX2

Recent studies have demonstrated that microRNA-154 (miR-154) is involved in tumorigenesis, progression, invasion and metastasis in several types of human cancer. However, whether it plays a role in bladder cancer (BC) is unclear. The aim of the present study was to determine miR-154 levels in human BC tissues and investigate the correlation between miR-154 levels and clinicopathological characteristics as well as patient outcome. Using RT-qPCR, we found that the expression levels of miR-154 were significantly lower in BC tissues compared to adjacent normal tissues. We also demonstrated that downregulation of miR-154 was associated with advanced clinicopathological features and worse prognoses for patients with BC. Using a variety of integrated approaches, we demonstrated that both runt-related transcription factor 2 (RUNX2) and remodeling and spacing factor 1 (RSF1) were miR-154 targets. Notably, there was an inverse correlation between RSF1, RUNX2 and miR-154 expression in BC tissues. The biological functions of miR-154 were examined in vitro using Cell Counting Kit-8 (CCK-8), wound healing, and Transwell assays with T24 human bladder carcinoma cells transfected with miR-154 mimics or negative controls. These assays demonstrated that miR-154 significantly suppressed proliferation, migration and invasion of T24 cells (P<0.05). Furthermore, overexpression of RSF1 and RUNX2 rescued miR-154-induced inhibition of these aggressive behaviors. Our results indicated that miR-154, and its downstream targets RSF1 and RUNX2, are promising options for future BC therapies.

Accurately mapping the location of the binding site for the interaction between hepatitis B virus X protein and cytochrome c oxidase III

The hepatitis B virus (HBV) X protein (HBx) plays an important pathogenetic role in hepatocarcinoma tumorigenesis. As HBx does not have the ability to bind to double-stranded DNA (dsDNA), protein-protein interaction is crucial for HBx functions. In a previous study, we screened a novel HBx-interacting protein, the cytochrome c oxidase subunit III (COXIII). In the present study, we aimed to accurately map the location of the binding site for the interaction of HBx with COXIII. Two fragments of HBx mutants (X1 aa1-72 and X2 aa1-117) were amplified by polymerase chain reaction (PCR) and separately inserted into the pAS2-1 plasmid. PCR and gene sequencing confirmed the correct insertion of the mutant fragments in the plasmid. The tanscription of the mutant fragments in yeast cells was demonstrated by RT-PCR and western blot analysis confirmed that they were accurately translated into fusion proteins. Hybridization on solid medium and the detection of β-galactosidase (β-gal) activity indicated that the binding site for the interaction between HBx and COXIII was located between aa72 and aa117. Specific interactions between the HBxX2 protein and COXIII were verified by co-immunoprecipitation. To the best of our knowledge, this is the first study showing to demonstrate that aa72-117 in HBx is the key region for binding with COXIII.

RSF1 is a positive regulator of NF-κB-induced gene expression required for ovarian cancer chemoresistance

Overexpression or amplification of the RSF1 gene has been associated with poor prognosis in various human cancers, including ovarian cancer. In previous work, RSF1 was identified as an amplified gene that facilitated the development of paclitaxel-resistant ovarian cancer. In the present study, we further demonstrated that RSF1 expression inversely correlated with paclitaxel response in patients with ovarian cancer and the mouse xenograft model. In addition, RSF1-overexpressing paclitaxel-resistant ovarian cancer cell lines were found to express elevated levels of genes regulated by NF-κB, including some involved with the evasion of apoptosis (CFLAR, XIAP, BCL2, and BCL2L1) and inflammation (PTGS2). In addition, ectopic expression of RSF1 using Tet-off inducible SKOV3 cells significantly enhanced NF-κB-dependent gene expression and transcriptional activation of NF-κB. An RSF1 knockdown using short hairpin RNAs suppressed these same pathways. Moreover, pretreatment with NF-κB inhibitors or downregulation of NF-κB-regulated gene expression considerably enhanced paclitaxel sensitivity in RSF1-overexpressing OVCAR3 and/or RSF1-induced SKOV3 cells. A coimmunoprecipitation assay revealed that RSF1 interacts with NF-κB and CREB-binding protein, a ubiquitous coactivator for NF-κB. Recruitment of RSF1 to the NF-κB binding element in the PTGS2 and XIAP promoters was demonstrated by the chromatin immunoprecipitation assay. Furthermore, hSNF2H, a well-known binding partner of RSF1, was partially involved in the interaction between RSF1 and NF-κB. Taken together, these data suggest that RSF1 may function as a coactivator for NF-κB, consequently augmenting expression of genes necessary for the development of chemoresistance in ovarian cancer cells.

Using proteomics to identify the HBx interactome in hepatitis B virus: how can this inform the clinic?

Hepatitis B virus (HBV) is a small and enveloped DNA virus, of which chronic infection is the main risk factor of liver cirrhosis and hepatocellular carcinoma. Hepatitis B virus X protein (HBx) is a multifunctional protein encoded by HBV genome, which have significant effects on HBV replication and pathogenesis. Through directly interacting with cellular proteins, HBx is capable to promote HBV replication, regulate transcription of host genes, disrupt protein degradation, modulate signaling pathway, manipulate cell death and deregulate cell cycle. In this review, we briefly discuss the diversified effects of HBx-interactome and their potential clinical significances.

Expression of cytokines in mouse hepatitis B virus X gene-transfected model

The expression profile in the mouse hepatitis B virus X (HBx)-transfected model was investigated in order to lay a foundation for further study on the implication of cytokines expression in hepatitis B virus (HBV) infection. Hydrodynamic injection method via the tail vein was used to establish the animal HBx-transfected model. By using microassay, the differential expression of gene in each group was analyzed, which was further confirmed by using real-time PCR and semi-quantitative PCR. Most of chemokine genes such as Ccl2, Ccl5, Ccl9, MIG and IP-10 were up-regulated in the HBx-transfected mouse model versus the control mice, which was coincided with the microarray results. Western blotting and immunohistochemistry were applied to detect the expression of MIG and IP-10 in the liver tissues. Simultaneously, ELISA was adopted to measure the content of IFN-γ in the liver tissues. DNA microassay revealed that the expression of 611 genes changed in HBx-transfected mice as compared with that in pCMV-tag2B-transfected mice, and most of the screened chemokines were up-regulated (including MIG and IP-10). Additionally, IFN-γ protein levels were increased by 20.7% (P<0.05) in pCMV-tag2B-HBx-transfected mice as compared with the untreated mice. IFN-γ protein levels were reduced by 53.9% (P<0.05) in pCMV-tag2B-transfected mice as compared with the untreated mice, which was consistent with the up-regulation of MIG and IP-10. It was suggested HBx transfection could induce the expression of MIG and IP-10 in the liver tissues, which might play the roles in HBV-related liver immunity and cytokines-mediated antiviral effect.

HBxAPα/Rsf-1-mediated HBx-hBubR1 interactions regulate the mitotic spindle checkpoint and chromosome instability

Hepatitis B virus (HBV) X protein (HBx), encoded by the HBV genome, is involved in the development of HBV-mediated liver cancer, whose frequency is highly correlated with chromosomal instability (CIN). We reported previously that HBx induces mitotic checkpoint dysfunction by targeting the human serine/threonine kinase BubR1 (hBubR1). However, the underlying mechanism remained unresolved. Here, we show that HBx protein-associated protein α (HBxAPα)/Rsf-1 associates with hBubR1 and HBx in the chromatin fraction during mitosis. Depletion of HBxAPα/Rsf-1 abolished the interaction between HBx and hBubR1, indicating that HBxAPα/Rsf-1 mediates these interactions. Knockdown of HBxAPα/Rsf-1 with small interfering RNA did not affect the recruitment of hBubR1 to kinetochores; however, it did significantly impair HBx targeting to kinetochores. A deletion mutant analysis revealed that two Kunitz domains of HBx, the Cdc20-binding domain of hBubR1 and full-length of HBxAPα/Rsf-1 were essential for these interactions. Thus, binding of HBx to hBubR1, stabilized by HBxAPα/Rsf-1, significantly attenuated hBubR1 binding to Cdc20 and consequently increased the rate of mitotic aberrations. Collectively, our data show that the HBx impairs hBubR1 function and induces CIN through HBxAPα/Rsf-1, providing a novel mechanism for induction of genomic instability by a viral pathogen in hepatocarcinogenesis.

The HPV E2-Host Protein-Protein Interactions: A Complex Hijacking of the Cellular Network

Over 100 genotypes of human papillomaviruses (HPVs) have been identified as being responsible for unapparent infections or for lesions ranging from benign skin or genital warts to cancer. The pathogenesis of HPV results from complex relationships between viral and host factors, driven in particular by the interplay between the host proteome and the early viral proteins. The E2 protein regulates the transcription, the replication as well as the mitotic segregation of the viral genome through the recruitment of host cell factors to the HPV regulatory region. It is thereby a pivotal factor for the productive viral life cycle and for viral persistence, a major risk factor for cancer development. In addition, the E2 proteins have been shown to engage numerous interactions through which they play important roles in modulating the host cell. Such E2 activities are probably contributing to create cell conditions appropriate for the successive stages of the viral life cycle, and some of these activities have been demonstrated only for the oncogenic high-risk HPV. The recent mapping of E2-host protein-protein interactions with 12 genotypes representative of HPV diversity has shed some light on the large complexity of the host cell hijacking and on its diversity according to viral genotypes. This article reviews the functions of E2 as they emerge from the E2/host proteome interplay, taking into account the large-scale comparative interactomic study.

Rsf-1 (HBXAP) expression is associated with advanced stage and lymph node metastasis in ovarian clear cell carcinoma

Ovarian clear cell carcinoma (CCC) is a unique type of ovarian cancer characterized by distinct clinicopathological and molecular features. CCC is considered to be a highly malignant disease because it is resistant to conventional chemotherapy, and when presented at advanced stages, it has a dismal overall survival. Identifying and characterizing biomarkers associated with its malignant behavior is fundamental toward elucidating the mechanisms underlying its aggressive phenotype. In this study, we performed immunohistochemical analysis on 89 CCCs to assess their expression of Rsf-1 (HBXAP), a chromatin-remodeling gene frequently amplified and overexpressed in several types of human cancer. We found that 73 (82%) of the 89 CCCs expressed Rsf-1 and most importantly, there was a statistically significant correlation between Rsf-1 immunostaining intensity and the 2 disease parameters: advanced stage (P=0.008) and status of retroperitoneal lymph node metastasis (P=0.023). However, there was no correlation between Rsf-1 expression and patient age, peritoneal tumor dissemination, or overall survival. In conclusion, a higher expression level of Rsf-1 is associated with advanced clinical stage and lymph node metastasis in CCC. Our data suggest that Rsf-1 participates in tumor progression in CCC, and indicates that the contribution of Rsf-1 to disease aggressiveness deserves further study.

Detecting protein-protein interactions in vesicular stomatitis virus using a cytoplasmic yeast two hybrid system

Protein-protein interactions play an important role in many virus-encoded functions and in virus-host interactions. While a "classical" yeast two-hybrid system (Y2H) is one of the most common techniques to detect such interactions, it has a number of limitations, including a requirement for the proteins of interest to be relocated to the nucleus. Modified Y2H, such as the Sos recruitment system (SRS), which detect interactions occurring in the cytoplasm rather than the nucleus, allow proteins from viruses replicating in the cytoplasm to be tested in a more natural context. In this study, a SRS was used to detect interactions involving proteins from vesicular stomatitis virus (VSV), a prototypic non-segmented negative strand RNA (NNS) virus. All five full-length VSV proteins, as well as several truncated proteins, were screened against each other. Using the SRS, most interactions demonstrated previously involving VSV phosphoprotein, nucleocapsid (N) and large polymerase proteins were confirmed independently, while difficulties were encountered using the membrane associated matrix and glycoproteins. A human cDNA library was also screened against VSV N protein and one cellular protein, SFRS18, was identified which interacted with N in this context. The system presented can be redesigned easily for studies in other less tractable NNS viruses.

Ethanol Extract from Ampelopsis sinica Root Exerts Anti-Hepatitis B Virus Activity via Inhibition of p53 Pathway In Vitro

Ampelopsis sinica root is widely used in Chinese folk medicine for treating liver disorders caused by the hepatitis B virus (HBV). The present study was performed in order to investigate the anti-HBV activity and mechanisms of the ethanol extract from A. sinica root (EASR) in vitro. The antiviral activity of EASR was examined by detecting the levels of HBsAg, HBeAg and extracellular HBV DNAs in stable HBV-producing human hepatoblastoma HepG2 2.2.15 cells. We found that EASR effectively suppressed the secretion of HBsAg and HBeAg from HepG2 2.2.15 cells in a dose-dependent manner, and it also suppressed the amount of extracellular HBV DNA. After EASR treatment, the percentage of apoptotic cells was found to be significantly higher than that of control by flow cytometric analysis. A luciferase reporter gene assay was used to determine the effects of EASR on the activities of HBV promoters and intracellular signaling pathways. The results showed that EASR selectively inhibited the activities of HBV promoters (Cp, S1p and Fp) and the p53 signaling pathway in HepG2 cells significantly. These data indicate that EASR exerts anti-HBV effects via inhibition of HBV promoters and the p53-associated signaling pathway, which helps to elucidate the mechanism underlying the potential therapeutic value of EASR.

Hepatitis B virus protein X-induced expression of the CXC chemokine IP-10 is mediated through activation of NF-kappaB and increases migration of leukocytes

Interferon-gamma inducible protein 10 (IP-10) involves inflammatory cell recruitment and cellular immune damage during virus infection. Although an increase of the peripheral IP-10 level is known in HBV-infected patients, the molecular basis of HBV infection inducing IP-10 expression has remained elusive. In the present study, we demonstrate that hepatitis B virus protein X (HBx) increases IP-10 expression in a dose-dependent manner. Transfection of the HBx-expressing vector into HepG2 cells results in nuclear translocation of NF-kappaB, which directly binds the promoter of IP-10 at positions from -122 to -113, thus facilitating transcription. The addition of the NF-kappaB inhibitor blocks the effect of HBx on IP-10 induction. In parallel, increase of NF-kappaB subunits p65 and p50 in HepG2 cells also augments IP-10 expression. Furthermore, we show that HBx induces activation of NF-kappaB through the TRAF2/TAK1 signaling pathway, leading to up-regulation of IP-10 expression. As a consequence, up-regulation of IP-10 may mediate the migration of peripheral blood leukocytes in a NF-kappaB-dependent manner. In conclusion, we report a novel molecular mechanism of HBV infection inducing IP-10 expression, which involves viral protein HBx affecting NF-kappaB pathway, leading to transactivation of the IP-10 promoter. Our study provides insight into the migration of leukocytes in response to HBV infection, thus causing immune pathological injury of liver.

Pathogenesis of ovarian cancer: clues from selected overexpressed genes

Ovarian cancer is the most malignant gynecologic neoplasm. Although new chemotherapeutic agents have improved patients' 5-year survival rate, the overall mortality of ovarian cancer has remained largely unchanged in the past several decades. The main reason for the lack of success in effectively treating ovarian cancer is our limited understanding of its etiology and the very few molecular diagnostic markers and therapeutic targets known so far. Identification and characterization of ovarian cancer-associated genes are fundamental for unveiling the pathogenesis of its initiation and progression, especially the development of recurrent diseases. As there are a vast number of genes for which molecular genetic changes and aberrant gene expression have been reported in ovarian cancer, this review will only focus on summarizing those exemplified genes that have been demonstrated to have biological functions in promoting ovarian cancer development and potential clinical significance. The genes to be discussed include nuclear proteins (Notch3, HBXAP [Rsf-1], NAC1 and NFkappaB), cytoplasmic proteins (fatty acid synthase and apolipoprotein E) and cell surface/secretory proteins (mucin-4, mesothelin, claudin, HLA-G, kallikrein and folate receptor and osteopontin). Since the study of ovarian cancer-associated genes is complicated by several factors unique to ovarian cancer, we will also present our views on the limitations and challenges of current ovarian cancer research.

Hepatitis B virus X gene is implicated in liver carcinogenesis

Hepatitis B virus (HBV) is a small hepatotropic and highly species-specific enveloped DNA virus. The carcinogenicity of this virus has become focused on the X gene and its coded X protein. The X protein itself is unable to bind to DNA directly, but works as a potent transcriptional activator through multiple cis-acting elements and mediates several signal transduction cascades. Two regions of the X protein, aa.61-69 and aa.105-140, are found essential for the viral replication and expression as well. These functions interacting with transcription factors and signaling cascades are acting cooperatively to cause cell proliferation. Furthermore, the association of X protein with mitochondria causes loss of the mitochondrial membrane potential and subsequently causes cell death, the function of which is attributed to the aa.68-104 region of X protein. As a result, the X protein has two independent proliferative and cell death-promoting activities. Liver cancer has been shown to result from a series of mutations in specific oncogenes and tumor suppressor genes. In a recent study, X protein stimulates ROS generation in the mitochondria due to collapse of the membrane potential and increases the mutation frequency, that evokes malignant transformation. Inflammation as a result of HBV infection is concerned to cause DNA damage. In the past 10years, the possibility that several viral proteins directly engaged in the DNA damage has increased to some extent. From an evolutionary viewpoint, it is noteworthy that several arrangement proteins have been found in viruses. Thus, there is some clue that a small amount of X protein acts as an arrangement protein for HBV replication dependent upon cellular DNA damage due to generated ROS as an amplified signal.

Active establishment of centromeric CENP-A chromatin by RSF complex

Centromeres are chromosomal structures required for equal DNA segregation to daughter cells, comprising specialized nucleosomes containing centromere protein A (CENP-A) histone, which provide the basis for centromeric chromatin assembly. Discovery of centromere protein components is progressing, but knowledge related to their establishment and maintenance remains limited. Previously, using anti-CENP-A native chromatin immunoprecipitation, we isolated the interphase-centromere complex (ICEN). Among ICEN components, subunits of the remodeling and spacing factor (RSF) complex, Rsf-1 and SNF2h proteins, were found. This paper describes the relationship of the RSF complex to centromere structure and function, demonstrating its requirement for maintenance of CENP-A at the centromeric core chromatin in HeLa cells. The RSF complex interacted with CENP-A chromatin in mid-G1. Rsf-1 depletion induced loss of centromeric CENP-A, and purified RSF complex reconstituted and spaced CENP-A nucleosomes in vitro. From these data, we propose the RSF complex as a new factor actively supporting the assembly of CENP-A chromatin.

Functional analysis of 11q13.5 amplicon identifies Rsf-1 (HBXAP) as a gene involved in paclitaxel resistance in ovarian cancer

The chromosome 11q13.5 locus is frequently amplified in several types of human cancer. We have previously shown that 11q13.5 amplification was associated with significantly shorter overall survival in ovarian cancer patients, but the molecular mechanisms of how amplification of this locus contributes to disease aggressiveness remain unclear. Because ovarian cancer mortality is primarily related to resistance of chemotherapeutic agents, we screened the top six candidate genes within this amplicon for their contribution to drug resistance. Rsf-1 (also known as HBXAP) was found to be the only gene in which gene knockdown sensitized tumor cells to paclitaxel. Rsf-1 has been known to interact with hSNF2H to form an ISWI chromatin remodeling complex. We found that Rsf-1 was up-regulated in paclitaxel-resistant ovarian cancer cell lines, and Rsf-1 immunoreactivity in primary ovarian carcinoma tissues correlated with in vitro paclitaxel resistance. Ectopic expression of Rsf-1 significantly enhanced paclitaxel resistance in ovarian cancer cells. Down-regulation of hSNF2H or disruption of hSNF2H and Rsf-1 interaction enhanced paclitaxel sensitivity in tumor cells with Rsf-1 up-regulation. Rsf-1 expression altered expression in several genes and activated certain signaling pathways that may contribute to drug resistance. In conclusion, our results suggest that Rsf-1 is the major gene within the 11q13.5 amplicon that contributes to paclitaxel resistance, and the formation of the Rsf-1/hSNF2H complex is required for inducing this phenotype.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers

Background: Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.

Methods: Published reports relevant to use of tumor markers for 5 cancer sites—testicular, prostate, colorectal, breast, and ovarian—were critically reviewed.

Results: For testicular cancer, α-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. α-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is &lt;10 μg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node–negative patients. CA15-3/BR27–29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer.

Conclusions: Implementation of these recommendations should encourage optimal use of tumor markers.

The roles of human sucrose nonfermenting protein 2 homologue in the tumor-promoting functions of Rsf-1

Rsf-1 interacts with human sucrose nonfermenting protein 2 homologue (hSNF2H) to form a chromatin remodeling complex that participates in several biological processes. We have previously shown that Rsf-1 gene amplification was associated with the most aggressive type of ovarian cancer and cancer cells with Rsf-1 overexpression depended on Rsf-1 to survive. In this report, we determine if formation of the Rsf-1/hSNF2H complex could be one of the mechanisms contributing to tumor cell survival and growth in ovarian carcinomas. Based on immunohistochemistry, we found that Rsf-1 and hSNF2H were co-upregulated in ovarian cancer tissues. Ectopic expression of Rsf-1 in SKOV3 ovarian cancer cells with undetectable endogenous Rsf-1 expression enhanced hSNF2H protein levels and promoted SKOV3 tumor growth in a mouse xenograft model. Our studies also indicated that induction of Rsf-1 expression affected the molecular partnership of hSNF2H and translocated hSNF2H into nuclei where it colocalized with Rsf-1. Furthermore, analysis of Rsf-1 deletion mutants showed that the Rsf-D4 fragment contained the hSNF2H binding site based on coimmunoprecipitation and in vitro competition assays. As compared with other truncated mutants, expression of Rsf-D4 resulted in remarkable growth inhibition in ovarian cancer cells with Rsf-1 gene amplification and overexpression, but not in those without detectable Rsf-1 expression. The above findings suggest that interaction between Rsf-1 and hSNF2H may define a survival signal in those tumors overexpressing Rsf-1.

Amplification of 11q13 in ovarian carcinoma

Amplification at the 11q13 locus is commonly observed in breast, ovarian, head and neck, oral, and esophageal cancer. Studies of this region led to the identification of multiple amplicons containing several potential oncogenes including EMSY, PAK1, RSF1, and GAB2. Here, we investigate the amplification of the above four genes and their prognostic significance in histologically and clinically defined subsets of ovarian cancer. Amplification of all four genes was assessed by fluorescent in situ hybridization in tissue microarrays containing 538 clinically annotated ovarian carcinomas with 12 years of follow-up data. Overall, for the entire cohort, EMSY was amplified in 44 (16%) of 269 cases, PAK1 was amplified in 38 (15%) of 255 cases, RSF1 was amplified in 37 (12%) of 310 cases, and GAB2 was amplified in 41 (16%) of 255 cases. Amplification of EMSY, PAK1, RSF1, and GAB2 were all highly correlated with each other and with a serous histology. Univariate survival analysis showed that tumors with EMSY and RSF1 amplification were associated with a significantly worse outcome. A molecular inversion probe array was then used to study the 11q13 amplicon in 33 high grade serous carcinomas. The core of the amplicon mapped to a 6-Mb region encompassing EMSY, PAK1, RSF1, and GAB2. However, a second more telomeric amplicon was also observed for which no candidate genes have been identified. In summary, amplification of these four putative oncogenes from 11q13 in early ovarian cancer is associated with a serous histology and in the case of EMSY and RSF1 a poor outcome. These findings support the hypothesis that the11q13 amplicon in ovarian cancer is likely driven by a cassette of genes rather than by a single oncogene. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Expression of the chromatin remodeling factor Rsf-1 is down-regulated in breast carcinoma effusions

We recently identified Rsf-1, a chromatin-remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma, and demonstrated that its expression in carcinoma cells in effusions is associated with poor prognosis. In the present study, we assessed the clinical significance of Rsf-1 overexpression in breast carcinoma effusions. Formalin-fixed paraffin-embedded sections from 47 effusions were analyzed for Rsf-1 expression by immunohistochemistry. Matched primary tumors (n = 30) and solid metastases (n = 26) from 30 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for association with clinicopathologic parameters and survival. Rsf-1 protein expression was found in carcinoma cells in 34 (72%) of 47 effusions, 24 (80%) of 30 primary carcinomas, and 24 (92%) of 26 metastases. Rsf-1 immunoreactivity in effusions showed no association with HER-2 or hormone receptor status. Rsf-1 expression level was significantly lower in effusions compared with primary tumors (P = .026 and P = .011 for extent and intensity, respectively) and lymph node metastases (P = .023 and P = .013 for extent and intensity, respectively). Staining extent and intensity were both significantly lower in breast compared with ovarian carcinoma effusions (P = .001 for extent, P < .001 for intensity). Rsf-1 expression showed no association with survival. In conclusion, in contrast to ovarian carcinoma, Rsf-1 expression is down-regulated in breast carcinoma cells in effusions compared with the solid counterparts and has no prognostic role at this anatomic site.

Viral hepatocarcinogenesis: from infection to cancer

Hepatocellular carcinoma (HCC) is a worldwide health issue that has started receiving attention but is still poorly understood. However, the hepatitis B virus (HBV) and the hepatitis C virus (HCV) are known to be two major causative agents of HCC. They differ in their modes of infection, their treatment options, their genomes and their carcinogenic abilities. However, both share a link with HCC through alterations of the host genome. In order to continue in our search for the mechanisms behind viral hepatocarcinogenesis, the individual entities (HBV, HCV, HCC and host), their natural history, treatment options and genomic properties must be further understood. Additionally, an understanding of the genomics, the link between the entities, is crucial for the success of the ongoing search for therapeutic options for HCC. Similar to most types of cancer, hepatocarcinogenesis is a multistep process involving different genetic alterations that ultimately lead to malignant transformation of the hepatocyte. As technology advances and research continues, the genetic changes and influences among these entities will prove essential to improved diagnostic and therapeutic options. It remains a challenge to provide a clear picture of the connection between virus and cancer. We review (i) the epidemiological link between HBV/HCV infection to HCC; (ii) prevention and control of chronic hepatitis B or C in reducing HCC risk; and (iii) genetic characters of viruses and hosts and the mechanisms associated with HCC susceptibilities, with the intention of providing a direction for future research and treatment.

Expression of the chromatin remodeling factor Rsf-1 is upregulated in ovarian carcinoma effusions and predicts poor survival

OBJECTIVE

We recently identified Rsf-1, a chromatin remodeling gene, as a potential oncogene that is frequently amplified and overexpressed in ovarian serous carcinoma. However, its clinical role in ovarian cancer effusions is not clear. In the present study, we assessed the clinical significance of Rsf-1 overexpression in ovarian carcinoma effusions.

METHODS

Formalin-fixed paraffin-embedded sections from 168 effusions (134 peritoneal, 34 pleural) were analyzed for Rsf-1 expression using immunocytochemistry. Matched primary tumors (n=48) and solid metastases (n=73) from 48 patients were additionally studied. Rsf-1 expression in tumor cells in effusions was analyzed for possible association with clinicopathologic parameters and survival.

RESULTS

Rsf-1 protein expression was found in carcinoma cells in 157/168 (93%) effusions. Of these, 70 (45%) stained weakly and 87 (55%) strongly. Specimens from patients diagnosed with FIGO stage IV disease had higher staining score (extent x intensity) compared with stage III tumors (P=0.008). Rsf-1 expression level was significantly lower in primary tumors and solid metastases (P<0.001 for extent, intensity and score). Univariate survival analysis for 59 patients with post-chemotherapy recurrence effusions demonstrated a significant association between higher Rsf-1 staining and shorter overall survival (OS; P=0.009 for staining extent and intensity, P=0.02 for staining score). FIGO stage was the only clinical parameter associated with OS in this group (P=0.032). In Cox analysis, Rsf-1 expression (P=0.022 for staining extent and intensity, P=0.045 for staining score) and FIGO stage (P=0.035) were independent predictors of shorter survival.

CONCLUSIONS

Rsf-1 is frequently expressed and upregulated in ovarian carcinoma cells in effusions and is a novel prognostic marker for patients with post-chemotherapy recurrent disease. The above findings support a role of Rsf-1 in mediating disease progression and aggressive clinical behavior in this subset of ovarian carcinoma patients.

Gene expression analysis in HBV transgenic mouse liver: a model to study early events related to hepatocarcinogenesis

Hepatitis B virus (HBV) is one of the major etiological factors responsible for the development of hepatocellular carcinoma (HCC). We used a transgenic mouse, containing HBV sequences, as a model system to unravel the molecular mechanisms of hepatocarcinogenesis induced by HBV. We chose this animal model because it consistently develops liver cancer after intermediate steps that mimic the natural history of HBV infection in humans. In this study, we focus our attention on the early events leading to liver cancer. We compared the gene expression profile of 3-month-old transgenic mice with that of 3-month-old wild-type (wt) animals. In the transgenic mouse, microarray data analysis showed a total of 45 significantly differentially expressed genes, 25 highly expressed (fold change > or =2; P = 0.0025), and 20 downregulated (fold change < or =0.5; P = 0.0025). These genes belong to several different functional categories such as the regulation of immunological response, transcription, intracellular calcium ion mobilization, regulation of cell cycle and proliferation, NF-kappab signal transduction cascades, and apoptosis. In particular, the upregulation of the antiapoptotic gene NuprI and the downregulation of the proapoptotic gene Bnip3 were found. This observation was supported by an in vitro apoptosis assay that showed downregulation of apoptosis in hepatocytes of HBV transgenic mouse compared with wt mice treated with staurosporine. In conclusion, our experimental approach allowed identification of new genes modulated by HBV and showed that the apoptotic process was deregulated in transgenic mouse hepatocytes. These data shed light on one possible mechanism by which HBV induces hepatocarcinogenesis.

A novel hepatitis B virus X-interactive protein: cytochrome C oxidase III

BACKGROUND

Hepatitis B virus-encoded X protein has been shown to be capable of activating many different viral and cellular promoters through protein-protein interactions and to contribute to the development of hepatocellular carcinoma. As its mechanism has not yet been identified unequivocally, the aim of the present study was to screen the cellular proteins that can interact with X protein.

METHODS

The yeast two-hybrid system was used to screen the X-interactive protein. False positive clones were eliminated by segregation analysis, and then putative positive clones were amplified, sequenced and analyzed with bioinformatics. A mating experiment was performed to confirm the binding of putative proteins to X protein in the yeast cells. The specific interaction between X protein and putative proteins in mammalian cells was verified by coimmunoprecipitation.

RESULTS

The hepatitis B virus X-interactive protein recovered from a human liver cDNA library was cytochrome C oxidase III. The specific interaction between protein X and cytochrome C oxidase III was verified by mating experiment and coimmunoprecipitation of COS7 cell lysates expressing both proteins.

CONCLUSION

These data support the speculation that cytochrome C oxidase III is a novel functional target of hepatitis B virus X protein in cells.

Amplification of a chromatin remodeling gene, Rsf-1/HBXAP, in ovarian carcinoma

A genomewide technology, digital karyotyping, was used to identify subchromosomal alterations in ovarian cancer. Amplification at 11q13.5 was found in three of seven ovarian carcinomas, and amplicon mapping delineated a 1.8-Mb core of amplification that contained 13 genes. FISH analysis demonstrated amplification of this region in 13.2% of high-grade ovarian carcinomas but not in any of low-grade carcinomas or benign ovarian tumors. Combined genetic and transcriptome analyses showed that Rsf-1 (HBXAPalpha) was the only gene that demonstrated consistent overexpression in all of the tumors harboring the 11q13.5 amplification. Patients with Rsf-1 amplification or overexpression had a significantly shorter overall survival than those without. Overexpression of Rsf-1 gene stimulated cell proliferation and transform nonneoplastic cells by conferring serum-independent and anchorage-independent growth. Furthermore, Rsf-1 gene knockdown inhibited cell growth in OVCAR3 cells, which harbor Rsf-1 amplification. Taken together, these findings indicate an important role of Rsf-1 amplification in ovarian cancer.

CECR2, a protein involved in neurulation, forms a novel chromatin remodeling complex with SNF2L

Chromatin remodeling complexes play critical roles in development. Here we describe a transcription factor, CECR2, which is involved in neurulation and chromatin remodeling. CECR2 shows complex alternative splicing, but all variants contain DDT and bromodomain motifs. A mutant mouse line was generated from an embryonic stem cell line containing a genetrap within Cecr2. Reporter gene expression demonstrated Cecr2 expression to be predominantly neural in the embryo. Mice homozygous for the Cecr2 genetrap-induced mutation show a high penetrance of the neural tube defect exencephaly, the human equivalent of anencephaly, in a strain-dependent fashion. Biochemical isolation of CECR2 revealed the presence of this protein as a component of a novel heterodimeric complex termed CECR2-containing remodeling factor (CERF). CERF comprises CECR2 and the ATP-dependent chromatin remodeler SNF2L, a mammalian ISWI ortholog expressed predominantly in the central nervous system. CERF is capable of remodeling chromatin in vitro and displays an ATP hydrolyzing activity that is stimulated by nucleosomes. Together, these data identify a novel chromatin remodeling complex with a critical role in neurulation.

Evaluation of nuclear factor-kappaB, urokinase-type plasminogen activator, and HBx and their clinicopathological significance in hepatocellular carcinoma

PURPOSE

Nuclear factor kappaB (NF-kappaB) signaling pathway is an important regulating pathway in human diseases and cancers. One of its downstream target genes is urokinase plasminogen activator (uPA), which is involved in cancer invasion and metastasis. The purpose of this study was to evaluate NF-kappaB activation, uPA up-regulation, and hepatitis B viral X protein (HBx) expression in human hepatocellular carcinoma (HCC) and to assess their clinicopathological significance.

EXPERIMENTAL DESIGN

We evaluated NF-kappaB activation, expression of uPA, and presence of HBx in 32 human HCCs. Their clinicopathological significance was assessed by correlation with the clinicopathological features. Aberrant NF-kappaB signaling pathway and uPA up-regulation mediated by HBx were also analyzed in vitro.

RESULTS

We found that NF-kappaB activation and uPA up-regulation were frequently (56% and 59%, respectively) observed in HCCs, and particularly in HBx-positive HCCs. NF-kappaB activation and uPA overexpression were closely associated with one another (P < 0.0001). Furthermore, both activation of NF-kappaB and up-regulation of uPA were significantly associated with a more aggressive tumor behavior in terms of venous invasion, direct liver invasion, and absence of tumor encapsulation. In vitro, NF-kappaB activation was induced by HBx transfection in HepG2 cells through inhibitor of nuclear factor-kappaB kinase beta (IKKbeta). HBx also up-regulated uPA and enhanced cell invasion synergistically with IKKbeta.

CONCLUSIONS

The data indicate that NF-kappaB dysregulation and uPA overexpression may lead to a more aggressive tumor behavior in HCC. In addition, our data suggest that IKKbeta plays a critical role in the HBx-activated NF-kappaB signaling pathway.

Comparative physical maps of the human and mouse Meckel syndrome critical regions

Meckel syndrome (MKS-OMIM 24900) is an autosomal recessive disease characterized by cystic kidneys, occipital encephalocele, polydactyly, and fibrotic changes of the liver, typically resulting in postnatal death. A Meckel syndrome critical region (MKS1) maps to human Chromosome (Chr) 17, in a region of homology to mouse Chr 11. Here we report the comparison of human Chr 17q23 with mouse Chr 11. We have generated physical maps of the human and mouse MKS1 critical regions. Additionally, we have created a transcript map of the MKS1 critical region in both species. By comparing these physical maps, we observe a high degree of similarity in gene order in the human and mouse Meckel syndrome critical regions. We have also examined the expression patterns of genes in the MKS1 region to assess their potential as MKS1 candidates. Finally, we have analyzed genes present in the other Meckel syndrome critical regions, MKS2 and MKS3, to determine whether any of the candidate genes for the three MKS loci have similar gene functions or are members of a common biological pathway.

Cytochrome C oxidase III interacts with hepatitis B virus X protein in vivo by yeast two-hybrid system

AIM: To screen and identify the proteins which interact with hepatitis B virus (HBV) X protein in hepatocytes by yeast two-hybrid system and to explore the effects of X protein in the development of hepatocellular carcinoma (HCC).

METHODS: With HBV X gene amplified by polymerase chain reaction (PCR), HBV X bait plasmid, named pAS2-1-X, was constructed by yeast-two hybridization system3 and verified by auto-sequencing assay. pAS2-1-X was transformed into the yeast AH109, and X-BD fusion protein expressed in the yeast cells was detected by Western blotting. The yeast cells cotransformed with pAS2-1-X and normal human liver cDNA library were grown in selective SC/-trp-leu-his-ade medium. The second screen was performed with β-gal activity detection, and false positive clones were eliminated by segregation analysis, true positive clones were amplified, sequenced and analyzed with bioinformatics. Mating experiment was peformed to confirm the binding of putative proteins to X protein in the yeast cells.

RESULTS: Bait plasmid pAS2-1-X was successfully constructed and pAS2-1-X correctly expressed BD-X fusion protein in yeast AH109. One hundred and three clones grew in the selective SC/-trp-leu-his-ade medium, and only one clone passed through β-gal activity detection and segregation analysis. The inserted cDNA fragment showed high homology with Homo sapiens cytochrome C oxidase III (cox III). Furthermore, mating experiment identified that the binding of cox III to X protein was specific.

CONCLUSION: cox III protein is a novel protein that can interact with X protein in vivo by yeast two-hybrid system, and may contribute to the development of HCC through the interaction with X protein.

Functional interaction between nuclear matrix-associated HBXAP and NF-kappaB

Hepatitis B virus X-associated protein (HBXAP) is a plant homeodomain (PHD) finger-containing protein implicated in transcription regulation. However, the underlying molecular mechanism remains to be defined. Here, we show that HBXAP represses NF-kappaB-mediated gene activation in a dose-dependent manner. Our results showed that HBXAP and NF-kappaB colocalize to the nuclear matrix with specific physical interaction between them. HBXAP may depend on its nuclear matrix localization for its repression of NF-kappaB-mediated gene repression. A specific nuclear matrix targeting sequence of HBXAP was identified. The sequence is included in a region encompassing amino acids 688-722 that could form a coiled-coil structure. The 18-amino acid stretch lies at the core of that structure. The present results showed that either the coiled-coil conformation or the PHD finger domain is crucial for the transcription repression activity of HBXAP on NF-kappaB-mediated gene activation. Taken together, our results suggest that HBXAP may function as a negative regulator for TNF-alpha-induced, NF-kappaB-mediated gene activation.

Systematic genome-wide approach to positional candidate cloning for identification of novel human disease genes

BACKGROUND

Recent large-scale genome projects afford a unique opportunity to identify many novel disease genes and thereby better understand the genetic basis of human disease. Functional Annotation of Mouse (FANTOM) 2, the largest mouse transcriptome project yet, provides a wealth of data on novel genes, splice variants and non-coding RNA, and provides a unique opportunity to identify novel human disease genes.

AIMS

To demonstrate the power of combining the FANTOM 2 cDNA dataset with a positional candidate approach and bioinformatics analysis to identify genes underlying human genetic disease.

RESULTS

By mapping all FANTOM 2 cDNA to the human genome, we were able to identify mouse clones that co-localised on the human genome with mapped but uncloned human disease loci. By this method we identified mouse and corresponding human genes mapping within the loci of 100 different human genetic diseases (mapped interval of <5 cM). Of particular interest was the elucidation through FANTOM 2 novel mouse gene data of candidate human genes for the following: (i) developmental -disorders: neural tube defect, Meckel syndrome, Wolf--Hirschhorn syndrome and keratosis follicularis spinulosa decalvans cum ophiasi; (ii) neurological disorders: benign familial infantile convulsions 3, early-onset cerebellar ataxia with retained tendon reflexes, infantile-onset spinocerebellar ataxia and vacuolar neuro-myopathy and (iii) cancer-related syndromes: tylosis with oesophageal cancer and low-grade B-cell chronic lymphatic leukaemia.

CONCLUSIONS

The FANTOM 2 data will dramatically accelerate efforts to identify genes underlying human disease. It will also facilitate the creation of transgenic mouse models to help elucidate the function of potential human disease genes.

Proteomics analysis of the centromere complex from HeLa interphase cells: UV-damaged DNA binding protein 1 (DDB-1) is a component of the CEN-complex, while BMI-1 is transiently co-localized with the centromeric region in interphase

CENP-A, a centromere-specific histone H3, is conserved throughout eukaryotes, and formation of CENP-A chromatin defines the active centromere region. Here, we report the isolation of CENP-A chromatin from HeLa interphase nuclei by chromatin immunoprecipitation using anti-CENP-A monoclonal antibody, and systematic identification of its components by mass spectrometric analyses. The isolated chromatin contained CENP-B, CENP-C, CENP-H, CENP-I/hMis 6 and hMis 12 as well as CENP-A, suggesting that the isolated chromatin may represent the centromere complex (CEN-complex). Mass spectrometric analyses of the CEN-complex identified approximately 40 proteins, including the previously reported centromere proteins and the proteins of unknown function. In addition, we unexpectedly identified a series of proteins previously reported to be related to functions other than chromosome segregation, such as uvDDB-1, XAP8, hSNF2H, FACTp180, FACTp80/SSRP1, polycomb group proteins (BMI-1, RING1, RNF2, HPC3 and PHP2), KNL5 and racGAP. We found that uvDDB-1 was actually localized to the centromeric region throughout cell cycle, while BMI-1 was transiently co-localized with the centromeres in interphase. These results give us new insights into the architecture, dynamics and function of centromeric chromatin in interphase nuclei, which might reflect regulation of cell proliferation and differentiation.

Functional analysis of the subunits of the chromatin assembly factor RSF

The human ISWI-containing factor RSF (for remodeling and spacing factor) is composed of two subunits: the ATPase hSNF2H and p325 (Rsf-1), a protein encoded by a novel human gene. We previously showed that RSF mediates nucleosome deposition and generates regularly spaced nucleosome arrays. Here we report the characterization of the largest subunit of RSF, Rsf-1. We found that Rsf-1 is a highly acidic protein containing a plant homology domain. The present study includes the cloning of Rsf-1, the preparation of recombinant RSF, and the dissection of the role of each subunit in the chromatin assembly reaction. The sequence of the gene for Rsf-1 includes a recently characterized cDNA, HBXAP; postulated to be involved in the transcriptional regulation of the hepatitis B virus. HBXAP actually contains a 252-amino-acid truncation of the amino terminus of Rsf-1. Finally, comparison of HBXAP and Rsf-1 properties shows that they are functionally different.

Genetic polymorphisms in IL-10 and IL-12b allele promoter regions in Chinese patients of Han nationality with HBV infection

AIM

To investigate the association of genetic susceptibility to hepatitis B virus infection and disease progression with the allelic polymorphisms of IL-10 and IL-12b promoter regions in Chinese Han population.

METHODS

Two groups of indigenous Chinese subjects (314 subjects in total) were recruited in this study. Group 1 included 104 unrelated patients with chronic hepatitis B virus infection and 76 unrelated healthy donors. Group 2 contained 134 related subjects from seven HBV-infected pedigrees of Han ethnic origin. Total genomic DNA samples were purified from the 1.5 ml of peripheral blood of all participated individuals by using the QIAgen purification DNA kit. Genotyping of IL10-5'A and IL12-5'C alleles was performed by means of PCR-RFLP (restriction fragment length polymorphism) and further proved by direct DNA sequencing. All data were statistically analyzed by using SAS software.

RESULTS

IL10-5'A mutant frequency in unrelated healthy subjects was 41.9% compared with 42.1% in unrelated HBV-infected patients, while IL12-5'C mutant frequency was 64.6% and 55.8% among healthy individuals and HBV-infected patients, respectively. No significant difference was found among the unrelated healthy individuals and unrelated HBV-infected patients. In related individuals from the seven HBV-infected pedigrees, the mutant frequency of IL12-5'C allele was found to be identical to that in unrelated healthy and HBV-infected patients, but the mutant frequency of IL10-5'A allele(19.5%) was significantly different from that(42.0%) in unrelated group (P<0.01).

CONCLUSION

The polymorphisms of IL10-5'A and IL12-5'C allele promoter regions were not correlated with hepatitis B virus infection and disease progression among unrelated subjects, but there was a significantly lower mutant frequency of IL10-5'A allele among related subjects.

N/A

N/A

Hepatitis B virus X protein induces cell death by causing loss of mitochondrial membrane potential

The hepatitis B virus X protein (HBx) has been implicated in the carcinogenicity of this virus as a causative factor by means of its transactivation function in development of hepatocellular carcinoma. However, we and others have recently reported that HBx is located in mitochondria and causes subsequent cell death (Takada, S., Shirakata, Y., Kaneniwa, N., and Koike, K. (1999) Oncogene 18, 6965-6973; Rahmani, Z., Huh, K. W., Lasher, R., and Siddiqui, A. (2000) J. Virol. 74, 2840-2846). In this study, we, therefore, examined the mechanism of HBx-related cell death. Using enhanced green fluorescent protein (EGFP) fusion constructs of HBx, the region required for its mitochondrial localization was mapped to amino acids (aa) 68-117, which is essential for cell death but inactive for transactivation function. In vitro binding analysis supported the notion that the recombinant HBx associates with isolated mitochondria through the region of aa 68-117 without causing redistribution of cytochrome c and apoptosis-inducing factor (AIF). A cytochemical analysis revealed that mitochondrial membrane potential was decreased by HBx association with mitochondria, suggesting that HBx induces dysfunction of permeability transition pore (PTP) complex. Furthermore, PTP inhibitors, reactive oxygen species (ROS) scavengers and Bcl-xL, which are known to stabilize mitochondrial membrane potential, prevented HBx-induced cell death. Collectively, the present results suggest that location of HBx in mitochondria of hepatitis B virus-infected cells causes loss of mitochondrial membrane potential and subsequently induces mitochondria-dependent cell death.

Inhibition of hepatitis B virus expression and replication by RNA interference

RNA interference (RNAi) is the process of sequence-specific gene silencing, initiated by double-stranded RNA (dsRNA) that is homologous in sequence to the target gene. Because it has been shown that RNAi can be accomplished in cultured mammalian cells by introducing small interfering RNAs (siRNAs), much effort has been invested in exploiting this phenomenon for experimental and therapeutic means. In this study, we present a series of experiments showing a significant reduction in hepatitis B virus (HBV) transcripts and proteins in cell culture, as well as in the viral replicative forms, induced by siRNA-producing vectors. The antiviral effect is sequence-specific and does not depend on active viral replication. In conclusion, our data suggest that RNAi may provide a powerful therapeutic tool, acting both on replication-competent and on replication-incompetent HBV.