Dataset Information

Proteins ZNF198 and SUZ12 are down-regulated in hepatitis B virus (HBV) X protein-mediated hepatocyte transformation and in HBV replication.

ABSTRACT: Chronic hepatitis B virus (HBV) infection is a major etiologic factor in hepatocellular carcinoma (HCC) pathogenesis, involving effects of chronic liver inflammation and of the weakly oncogenic HBV X protein (pX). pX-mediated hepatocyte transformation requires Polo-like kinase1 (Plk1) activity, but the mechanism is not fully understood. We identified by a genome-wide short hairpin RNA (shRNA) library screen the genes zinc finger, MYM-type 2 (ZNF198) and suppressor of zeste 12 homolog (Drosophila) (SUZ12) whose protein depletion rescues pX-expressing cells from DNA damage-induced apoptosis. ZNF198 and SUZ12 are components of chromatin remodeling complexes and associate with promyelocytic leukemia (PML) nuclear bodies. Knockdown of ZNF198 and SUZ12 by small interfering RNA (siRNA) reduced p53 stability and DNA repair, rescued pX-expressing hepatocytes from DNA damage-induced apoptosis, and increased pX-induced polyploidy and oncogenic transformation, suggesting ZNF198 and SUZ12 have a role in pX-mediated transformation. Interestingly, during pX-mediated transformation the protein but not messenger RNA (mRNA) levels of ZNF198 and SUZ12 progressively decreased, whereas Plk1 levels increased. Inhibition of Plk1 activity restored protein levels of ZNF198 and SUZ12. In addition, transfected Polo-box-domain (PBD) of Plk1 coimmunoprecipitated with ZNF198 and SUZ12, suggesting that these proteins are Plk1 substrates. Elevated Plk1 and reduced protein levels of ZNF198 and SUZ12 were also observed in human liver cancer cell lines derived from HBV-related tumors and in the presence of HBV replication. Importantly, knockdown by siRNA of ZNF198 and SUZ12 enhanced HBV replication.Reduced protein levels of ZNF198 and SUZ12 and elevated Plk1 occur during pX-mediated hepatocyte transformation in human liver cancer cell lines, as well as during HBV replication, underscoring the significance of these genes both in HBV-mediated HCC pathogenesis and HBV replication. We propose Plk1 activity down-regulates ZNF198 and SUZ12, thereby enhancing both HBV replication and pX-mediated oncogenic transformation.

SUBMITTER: Wang WH

PROVIDER: S-EPMC3079326 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Proteins ZNF198 and SUZ12 are down-regulated in hepatitis B virus (HBV) X protein-mediated hepatocyte transformation and in HBV replication.

Wang Wen-Horng WH Studach Leo L LL Andrisani Ourania M OM

Hepatology (Baltimore, Md.) 20110401 4

<h4>Unlabelled</h4>Chronic hepatitis B virus (HBV) infection is a major etiologic factor in hepatocellular carcinoma (HCC) pathogenesis, involving effects of chronic liver inflammation and of the weakly oncogenic HBV X protein (pX). pX-mediated hepatocyte transformation requires Polo-like kinase1 (Plk1) activity, but the mechanism is not fully understood. We identified by a genome-wide short hairpin RNA (shRNA) library screen the genes zinc finger, MYM-type 2 (ZNF198) and suppressor of zeste 12 ...[more]

PMID: 21480320

Similar Datasets

Project description:Chronic hepatitis B virus (HBV) infection is a major risk factor for developing liver cancer, and the HBV X protein (pX) has been implicated as a cofactor in hepatocyte transformation. We have shown that HBV replication as well as in vitro transformation by pX are associated with induction of the mitotic polo-like kinase 1 (Plk1) and down-regulation of the chromatin remodeling components Suz12 and Znf198. Herein, we demonstrate the same inverse relationship between Plk1 and Suz12/Znf198 in liver tumors from X/c-myc bitransgenic mice and woodchuck hepatitis virus (WHV)-infected woodchucks. Employing these animal models and the HBV replicating HepAD38 cells we examined the effect of Suz12/Znf198 down-regulation on gene expression. Genes analyzed include hepatic cancer stem cell markers BAMBI, DKK1,2, DLK1, EpCAM, MYC, and proliferation genes CCNA1, CCND2, IGFII, MCM4-6, PLK1, RPA2, and TYMS. Suz12 occupancy at the promoters of BAMBI, CCND2, DKK2, DLK1, EpCAM, and IGFII was demonstrated by chromatin immunoprecipitation in untransformed hepatocytes, but was markedly reduced in pX-transformed and Suz12 knockdown cells. Accordingly, we refer to these genes as "Suz12 repressed" genes in untransformed hepatocytes. The Suz12 repressed genes and proliferation genes were induced in HBV-replicating HepAD38 cells and, interestingly, they exhibited distinct expression profiles during hepatocellular carcinoma (HCC) progression in X/c-myc bitransgenics. Specifically, CCND2, EpCAM, and IGFII expression was elevated at the proliferative and preneoplastic stages in X/c-myc bitransgenic livers, whereas BAMBI and PLK1 were overexpressed in hepatic tumors from X/c-myc bitransgenics and WHV-infected woodchucks. Importantly, most of these genes were selectively up-regulated in HBV-induced HCCs.The distinct expression profile of the identified Suz12 repressed genes in combination with the proliferation genes hold promise as biomarkers for progression of chronic HBV infection to HCC.

Project description:Background & aimsChronic infection with hepatitis B virus (HBV) progresses through different phases. The first, called the immune-tolerant phase, has been associated with a lack of disease activity. We examined HBV-DNA integration, clonal hepatocyte expansion, HBV antigen expression, and HBV-specific immune responses in patients in the immune-tolerant phase to assess whether this designation is appropriate or if there is evidence of disease activity.MethodsWe studied HBV-DNA integration, clonal hepatocyte expansion, and expression of hepatitis B surface antigen and core antigen in liver tissues from 26 patients with chronic HBV infection (ages, 14-39 y); 9 patients were positive for hepatitis B e antigen (HBeAg) in the immune-tolerant phase and were matched for age with 10 HBeAg-positive patients with active disease and 7 HBeAg-negative patients with active disease. Peripheral blood samples were collected and HBV-specific T cells were quantified for each group.ResultsDetection of HBV antigens differed among groups. However, unexpectedly high numbers of HBV-DNA integrations, randomly distributed among chromosomes, were detected in all groups. Clonal hepatocyte expansion in patients considered immune tolerant also was greater than expected, potentially in response to hepatocyte turnover mediated by HBV-specific T cells, which were detected in peripheral blood cells from patients in all phases of infection.ConclusionsWe measured HBV-specific T cells, HBV-DNA integration, and clonal hepatocyte expansion in different disease phases of young patients with chronic hepatitis B, with emphasis on the so-called immune-tolerant phase. A high level of HBV-DNA integration and clonal hepatocyte expansion in patients considered immune tolerant indicated that hepatocarcinogenesis could be underway-even in patients with early stage chronic HBV infection. Our findings do not support the concepts that this phase is devoid of markers of disease progression or that an immune response has not been initiated. We propose that this early phase be called a high-replication, low-inflammation stage. The timing of therapeutic interventions to minimize further genetic damage to the hepatocyte population should be reconsidered.

Project description:UnlabelledHepatitis B virus (HBV) is a causative agent for chronic liver diseases such as hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). HBx protein encoded by the HBV genome plays crucial roles not only in pathogenesis but also in replication of HBV. Although HBx has been shown to bind to a number of host proteins, the molecular mechanisms by which HBx regulates HBV replication are largely unknown. In this study, we identified jumonji C-domain-containing 5 (JMJD5) as a novel binding partner of HBx interacting in the cytoplasm. DNA microarray analysis revealed that JMJD5-knockout (JMJD5KO) Huh7 cells exhibited a significant reduction in the expression of transcriptional factors involved in hepatocyte differentiation, such as HNF4A, CEBPA, and FOXA3. We found that hydroxylase activity of JMJD5 participates in the regulation of these transcriptional factors. Moreover, JMJD5KO Huh7 cells exhibited a severe reduction in HBV replication, and complementation of HBx expression failed to rescue replication of a mutant HBV deficient in HBx, suggesting that JMJD5 participates in HBV replication through an interaction with HBx. We also found that replacing Gly(135) with Glu in JMJD5 abrogates binding with HBx and replication of HBV. Moreover, the hydroxylase activity of JMJD5 was crucial for HBV replication. Collectively, these results suggest that direct interaction of JMJD5 with HBx facilitates HBV replication through the hydroxylase activity of JMJD5.ImportanceHBx protein encoded by hepatitis B virus (HBV) plays important roles in pathogenesis and replication of HBV. We identified jumonji C-domain-containing 5 (JMJD5) as a novel binding partner to HBx. JMJD5 was shown to regulate several transcriptional factors to maintain hepatocyte function. Although HBx had been shown to support HBV replication, deficiency of JMJD5 abolished contribution of HBx in HBV replication, suggesting that HBx-mediated HBV replication is largely dependent on JMJD5. We showed that hydroxylase activity of JMJD5 in the C terminus region is crucial for expression of HNF4A and replication of HBV. Furthermore, a mutant JMJD5 with Gly(135) replaced by Glu failed to interact with HBx and to rescue the replication of HBV in JMJD5-knockout cells. Taken together, our data suggest that interaction of JMJD5 with HBx facilitates HBV replication through the hydroxylase activity of JMJD5.

Dataset Information

Proteins ZNF198 and SUZ12 are down-regulated in hepatitis B virus (HBV) X protein-mediated hepatocyte transformation and in HBV replication.

Publications

Proteins ZNF198 and SUZ12 are down-regulated in hepatitis B virus (HBV) X protein-mediated hepatocyte transformation and in HBV replication.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets