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Oropeza CE, Tarnow G, Sridhar A, Taha TY, Shalaby RE, McLachlan A. The Regulation of HBV Transcription and Replication. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1179:39-69. [PMID: 31741333 DOI: 10.1007/978-981-13-9151-4_3] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Hepatitis B virus (HBV) is a major human pathogen lacking a reliable curative therapy. Current therapeutics target the viral reverse transcriptase/DNA polymerase to inhibit viral replication but generally fail to resolve chronic HBV infections. Due to the limited coding potential of the HBV genome, alternative approaches for the treatment of chronic infections are desperately needed. An alternative approach to the development of antiviral therapeutics is to target cellular gene products that are critical to the viral life cycle. As transcription of the viral genome is an essential step in the viral life cycle, the selective inhibition of viral RNA synthesis is a possible approach for the development of additional therapeutic modalities that might be used in combination with currently available therapies. To address this possibility, a molecular understanding of the relationship between viral transcription and replication is required. The first step is to identify the transcription factors that are the most critical in controlling the levels of HBV RNA synthesis and to determine their in vivo role in viral biosynthesis. Mapping studies in cell culture utilizing reporter gene constructs permitted the identification of both ubiquitous and liver-enriched transcription factors capable of modulating transcription from the four HBV promoters. However, it was challenging to determine their relative importance for viral biosynthesis in the available human hepatoma replication systems. This technical limitation was addressed, in part, by the development of non-hepatoma HBV replication systems where viral biosynthesis was dependent on complementation with exogenously expressed transcription factors. These systems revealed the importance of specific nuclear receptors and hepatocyte nuclear factor 3 (HNF3)/forkhead box A (FoxA) transcription factors for HBV biosynthesis. Furthermore, using the HBV transgenic mouse model of chronic viral infection, the importance of various nuclear receptors and FoxA isoforms could be established in vivo. The availability of this combination of systems now permits a rational approach toward the development of selective host transcription factor inhibitors. This might permit the development of a new class of therapeutics to aid in the treatment and resolution of chronic HBV infections, which currently affects approximately 1 in 30 individuals worldwide and kills up to a million people annually.
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Affiliation(s)
- Claudia E Oropeza
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Grant Tarnow
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Abhayavarshini Sridhar
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Taha Y Taha
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Rasha E Shalaby
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.,Department of Microbiology and Immunology, Faculty of Medicine, Tanta University, Egypt, Egypt
| | - Alan McLachlan
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Velmurugan BK, Chang R, Marthandam Asokan S, Chang C, Day C, Lin Y, Lin Y, Kuo W, Huang C. A minireview of E4BP4/NFIL3 in heart failure. J Cell Physiol 2018; 233:8458-8466. [DOI: 10.1002/jcp.26790] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/30/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Bharath Kumar Velmurugan
- Toxicology and Biomedicine Research Group, Faculty of Applied Sciences Ton Duc Thang University Ho Chi Minh City Vietnam
| | - Ruey‐Lin Chang
- College of Chinese Medicine, School of Post‐Baccalaureate Chinese Medicine China Medical University Taichung Taiwan
| | | | - Chih‐Fen Chang
- Department of Internal Medicine, Division of Cardiology Taichung Armed Force Taichung General Hospital Taichung Taiwan
| | | | - Yueh‐Min Lin
- Department of Pathology Changhua Christian Hospital Changhua Taiwan
- Department of Medical Technology, Jen‐Teh Junior College of Medicine Nursing and Management Miaoli Taiwan
| | - Yuan‐Chuan Lin
- Graduate Institute of Basic Medical Science China Medical University Taichung Taiwan
| | - Wei‐Wen Kuo
- Department of Biological Science and Technology China Medical University Taichung Taiwan
| | - Chih‐Yang Huang
- Graduate Institute of Basic Medical Science China Medical University Taichung Taiwan
- Graduate Institute of Chinese Medical Science China Medical University Taichung Taiwan
- Department of Biological Science and Technology Asia University Taichung Taiwan
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3
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Chen BC, Shibu MA, Kuo CH, Shen CY, Chang-Lee SN, Lai CH, Chen RJ, Yao CH, Viswanadha VP, Liu JS, Chen WK, Huang CY. E4BP4 inhibits AngII-induced apoptosis in H9c2 cardiomyoblasts by activating the PI3K-Akt pathway and promoting calcium uptake. Exp Cell Res 2018; 363:227-234. [PMID: 29331388 DOI: 10.1016/j.yexcr.2018.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 01/06/2018] [Accepted: 01/09/2018] [Indexed: 01/28/2023]
Abstract
The bZIP transcription factor E4BP4 is a survival factor that is known to be elevated in diseased heart and promote cell survival. In this study the role of E4BP4 on angiotensin-II (AngII)-induced apoptosis has been examined in in vitro cell model. H9c2 cardiomyoblast cells that overexpressed E4BP4 were exposed to AngII to observe the cardio-protective effects of E4BP4 on hypertension related apoptosis. The results from TUNEL assays revealed that E4BP4 significantly attenuated AngII-induced apoptosis. Further analysis by Western blot and RT-PCR showed that E4BP4 inhibited AngII-induced IGF-II mRNA expression and cleavage of caspase-3 through the PI3K-Akt pathway. In addition, E4BP4 enhanced calcium reuptake into the sacroplasmic reticulum by down-regulating PP2A and by up-regulating the phosphorylation of PKA and PLB proteins. Our findings indicate that E4BP4 functions as a survival factor in cardiomyoblasts by inhibiting IGF-II transcription and by regulating calcium cycling.
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Affiliation(s)
- Bih-Cheng Chen
- School of Post-Baccalaureate Chinese Medicine, China Medical University, Taichung, Taiwan
| | | | - Chia-Hua Kuo
- Laboratory of Exercise Biochemistry, University of Taipei, Taipei, Taiwan
| | - Chia-Yao Shen
- Department of Nursing, Meiho University, Pingtung, Taiwan
| | - Shu Nu Chang-Lee
- Department of Healthcare Administration, Asia University, Taiwan
| | - Chao-Hung Lai
- Division of Cardiology, Department of Internal Medicine, Armed Force Taichung, General Hospital, Taichung 41152, Taiwan
| | - Ray-Jade Chen
- Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chun-Hsu Yao
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | | | - Jian-Shen Liu
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Beigang Hospital, Yunlin County, Taiwan; Department of Emergency Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Wei-Kung Chen
- School of Post-Baccalaureate Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Chih-Yang Huang
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan; Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan; Graduate Institute of Chinese Medical Science, China Medical University, Taichung, Taiwan.
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4
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Keniry M, Dearth RK, Persans M, Parsons R. New Frontiers for the NFIL3 bZIP Transcription Factor in Cancer, Metabolism and Beyond. Discoveries (Craiova) 2014; 2:e15. [PMID: 26539561 PMCID: PMC4629104 DOI: 10.15190/d.2014.7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The bZIP transcription factor NFIL3 (Nuclear factor Interleukin 3 regulated, also known as E4 binding protein 4, E4BP4) regulates diverse biological processes from circadian rhythm to cellular viability. Recently, a host of novel roles have been identified for NFIL3 in immunological signal transduction, cancer, aging and metabolism. Elucidating the signaling pathways that are impacted by NFIL3 and the regulatory mechanisms that it targets, inhibits or activates will be critical for developing a clearer picture of its physiological roles in disease and normal processes. This review will discuss the recent advances and emerging issues regarding NFIL3-mediated transcriptional regulation of CEBPb and FOXO1 activated genes and signal transduction.
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Affiliation(s)
- Megan Keniry
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Robert K Dearth
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Michael Persans
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Ramon Parsons
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave HCSM 6-117, New York, NY 10029, USA
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Reinke AW, Grigoryan G, Keating AE. Identification of bZIP interaction partners of viral proteins HBZ, MEQ, BZLF1, and K-bZIP using coiled-coil arrays. Biochemistry 2010; 49:1985-97. [PMID: 20102225 DOI: 10.1021/bi902065k] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Basic-region leucine-zipper transcription factors (bZIPs) contain a segment rich in basic amino acids that can bind DNA, followed by a leucine zipper that can interact with other leucine zippers to form coiled-coil homo- or heterodimers. Several viruses encode proteins containing bZIP domains, including four that encode bZIPs lacking significant homology to any human protein. We investigated the interaction specificity of these four viral bZIPs by using coiled-coil arrays to assess self-associations as well as heterointeractions with 33 representative human bZIPs. The arrays recapitulated reported viral-human interactions and also uncovered new associations. MEQ and HBZ interacted with multiple human partners and had unique interaction profiles compared to any human bZIPs, whereas K-bZIP and BZLF1 displayed homospecificity. New interactions detected included HBZ with MAFB, MAFG, ATF2, CEBPG, and CREBZF and MEQ with NFIL3. These were confirmed in solution using circular dichroism. HBZ can heteroassociate with MAFB and MAFG in the presence of MARE-site DNA, and this interaction is dependent on the basic region of HBZ. NFIL3 and MEQ have different yet overlapping DNA-binding specificities and can form a heterocomplex with DNA. Computational design considering both affinity for MEQ and specificity with respect to other undesired bZIP-type interactions was used to generate a MEQ dimerization inhibitor. This peptide, anti-MEQ, bound MEQ both stably and specifically, as assayed using coiled-coil arrays and circular dichroism in solution. Anti-MEQ also inhibited MEQ binding to DNA. These studies can guide further investigation of the function of viral and human bZIP complexes.
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Affiliation(s)
- Aaron W Reinke
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Weng YJ, Hsieh DJY, Kuo WW, Lai TY, Hsu HH, Tsai CH, Tsai FJ, Lin DY, Lin JA, Huang CY, Tung KC. E4BP4 is a cardiac survival factor and essential for embryonic heart development. Mol Cell Biochem 2010; 340:187-94. [PMID: 20186462 DOI: 10.1007/s11010-010-0417-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 02/10/2010] [Indexed: 11/29/2022]
Abstract
The bZIP transcription factor E4BP4, has been demonstrated to be a survival factor in pro-B lymphocytes. GATA factors play important roles in transducing the IL-3 survival signal and transactivating the downstream survival gene, E4BP4. In heart, GATA sites are essential for proper transcription of several cardiac genes, and GATA-4 is a mediator of cardiomyocyte survival. However, the role E4BP4 plays in heart is still poorly understood. In this study, Dot-blot hybridization assays using Dig-labeled RNA probes revealed that the E4BP4 gene was expressed in cardiac tissue from several species including, monkey, dog, rabbit, and human. Western blot analysis showed that the E4BP4 protein was consistently present in all of these four species. Furthermore, immunohistochemistry revealed that the E4BP4 protein was overexpressed in diseased heart tissue in comparison with normal heart tissue. In addition, the overexpression of E4BP4 in vitro activated cell survival signaling pathway of cardiomyocytes. At last, siRNA-mediated knock down of E4BP4 in zebrafish resulted in malformed looping of the embryonic heart tube and decreased heart beating. Based on these results, we conclude that E4BP4 plays as a survival factor in heart and E4BP4 is essential for proper embryonic heart development.
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Affiliation(s)
- Yi-Jiun Weng
- Department of Veterinary Medicine, National Chung-Hsing University, No.250, Kuo-Kuang Road, 402 Taichung, Taiwan
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Rothman PB. The transcriptional regulator NFIL3 controls IgE production. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2010; 121:156-171. [PMID: 20697558 PMCID: PMC2917151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Cytokines are essential modulators of the immune response that underlies the inflammatory component of atopic asthma and other allergic diseases, lnterleukin-4 is an important cytokine for the regulation of allergic immune responses. However, the molecular mechanisms that regulate the response of cells to IL-4 are still not completely defined. IL-4 plays an important role in B cell biology. It can regulate B cell differentiation. For example, IL-4 induces immunoglobulin heavy chain class switching to IgE by inducing germline immunoglobulin heavy chain transcription. It also induces expression of CD23 and MHC class II. Further understanding of the mechanisms by which IL-4 mediates these biologic responses may lead to novel mechanisms for therapeutic intervention and control of allergy. To define how different signaling pathways activated by IL-4 regulate gene transcription, we identified many differentially expressed genes by IL-4 stimulation by microarray analysis. NFIL3 (nuclear factor, interleukin 3 regulated) is the most strongly induced transcription factor by IL-4 stimulation in a STAT6-dependent manner. To analyze the role of NFIL3 in the immune system, we have generated NFIL3-deficient mice. NFIL3-deficient mice showed greatly impaired IgE production in response to antigen. NFIL3-deficient B cells fail to produce IgE in response to LPS plus IL-4. These defects may be due to the reduced production of immunoglobulin heavy chain germline epsilon transcripts in the absence of NFIL3. Moreover, NFIL3 KO mice sensitized and challenged with ovalbumin showed reduced airway hyper-responsiveness when compared to wild-type mice. Therefore, we hypothesize that NFIL3 is a critical regulator for IgE production and airway hyper-responsiveness.
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Affiliation(s)
- Paul B Rothman
- Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 212 CMAB, 451 Newton Road, Iowa City, Iowa 52242, USA.
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IL-4-induced transcription factor NFIL3/E4BP4 controls IgE class switching. Proc Natl Acad Sci U S A 2009; 107:821-6. [PMID: 20080759 DOI: 10.1073/pnas.0909235107] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
IL-4 signaling promotes IgE class switching through STAT6 activation and the induction of Ig germ-line epsilon (GLepsilon) transcription. Previously, we and others identified a transcription factor, Nfil3, as a gene induced by IL-4 stimulation in B cells. However, the precise roles of nuclear factor, IL-3-regulated (NFIL3) in IL-4 signaling are unknown. Here, we report that NFIL3 is important for IgE class switching. NFIL3-deficient mice show impaired IgE class switching, and this defect is B-cell intrinsic. The induction of GLepsilon transcripts after LPS and IL-4 stimulation is significantly reduced in NFIL3-deficient B cells. Expression of NFIL3 in NFIL3-deficient B cells restores the impairment of IgE production, and overexpression of NFIL3 in the presence of cycloheximide induces GLepsilon transcripts. Moreover, NFIL3 binds to Iepsilon promoter in vivo. Together, these results identify NFIL3 as a key regulator of IL-4-induced GLepsilon transcription in response to IL-4 and subsequent IgE class switching.
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Williams V, Brichler S, Radjef N, Lebon P, Goffard A, Hober D, Fagard R, Kremsdorf D, Dény P, Gordien E. Hepatitis delta virus proteins repress hepatitis B virus enhancers and activate the alpha/beta interferon-inducible MxA gene. J Gen Virol 2009; 90:2759-2767. [PMID: 19625466 DOI: 10.1099/vir.0.011239-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Co-infection and superinfection of hepatitis B virus (HBV) with hepatitis delta virus (HDV) leads to suppression of HBV replication both in patients and in animal and cellular models. The mechanisms behind this inhibition have not previously been explored fully. HBV replication is governed by four promoters and two enhancers, Enh1 and Enh2. Repression of these enhancers has been reported to be one of the main mechanisms of HBV inhibition. Moreover, in a previous study, it has been demonstrated that alpha interferon (IFN-alpha)-inducible MxA protein inhibits HBV replication. HDV encodes two proteins, p24 and p27. p27 was shown to activate several heterologous promoters, including HBV promoters. In an attempt to analyse the mechanisms of HBV inhibition by HDV, the question was raised whether HDV proteins could act directly by repressing HBV enhancers, and/or indirectly by activating the MxA gene. This issue was addressed in a co-transfection model in Huh-7 cells, using p24- or p27-expressing plasmids along with Enh1, Enh2, HBV and MxA promoter-luciferase constructs. Enh1 and Enh2 were strongly repressed, by 60 and 80 % and 40 and 60 %, by p24 and p27, respectively. In addition, p27 was responsible for threefold activation of the MxA promoter and potentiation of IFN-alpha on this promoter. MxA mRNA quantification and a virus yield reduction assay confirmed these results. In conclusion, this study shows that HDV proteins inhibit HBV replication by trans-repressing its enhancers and by trans-activating the IFN-alpha-inducible MxA gene.
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Affiliation(s)
- Virginie Williams
- INSERM U845, Faculté de Médecine de Necker, Université Paris 5, France
- Service de Bactériologie, Virologie, Hygiène, Associé au Centre National de Référence des Hépatites B, C et Delta, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
| | - Ségolène Brichler
- INSERM U845, Faculté de Médecine de Necker, Université Paris 5, France
- Service de Bactériologie, Virologie, Hygiène, Associé au Centre National de Référence des Hépatites B, C et Delta, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
| | - Nadjia Radjef
- Service de Bactériologie, Virologie, Hygiène, Associé au Centre National de Référence des Hépatites B, C et Delta, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
| | - Pierre Lebon
- Laboratoire de Virologie, Hôpital Saint Vincent de Paul, Université Paris 5, France
| | - Anne Goffard
- Service de Virologie, UPRES EA 3610 Faculté de Médecine, Université Lille 2, Centre Hospitalier Régional et Universitaire de Lille, France
| | - Didier Hober
- Service de Virologie, UPRES EA 3610 Faculté de Médecine, Université Lille 2, Centre Hospitalier Régional et Universitaire de Lille, France
| | - Remi Fagard
- Laboratoire de Biochimie, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
| | - Dina Kremsdorf
- INSERM U845, Faculté de Médecine de Necker, Université Paris 5, France
| | - Paul Dény
- INSERM U871, Lyon, France
- Service de Bactériologie, Virologie, Hygiène, Associé au Centre National de Référence des Hépatites B, C et Delta, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
| | - Emmanuel Gordien
- INSERM U845, Faculté de Médecine de Necker, Université Paris 5, France
- Service de Bactériologie, Virologie, Hygiène, Associé au Centre National de Référence des Hépatites B, C et Delta, Hôpital Avicenne, Assistance Publique des Hôpitaux de Paris, Université Paris 13, Faculté de Bobigny, France
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Lin YC, Hsu EC, Ting LP. Repression of hepatitis B viral gene expression by transcription factor nuclear factor-kappaB. Cell Microbiol 2009; 11:645-60. [DOI: 10.1111/j.1462-5822.2008.01280.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Hung CS, Lin YL, Wu CI, Huang CJ, Ting LP. Suppression of hepatitis B viral gene expression by phosphoinositide 5-phosphatase SKIP. Cell Microbiol 2009; 11:37-50. [DOI: 10.1111/j.1462-5822.2008.01235.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Silvestris F, Cafforio P, De Matteo M, Calvani N, Frassanito MA, Dammacco F. Negative regulation of the osteoblast function in multiple myeloma through the repressor gene E4BP4 activated by malignant plasma cells. Clin Cancer Res 2008; 14:6081-91. [PMID: 18829486 DOI: 10.1158/1078-0432.ccr-08-0219] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE To explore the pathogenetic mechanisms that suppress the osteoblast function in multiple myeloma because osteogenesis results in defective new bone formation and repair. EXPERIMENTAL DESIGN Microarray gene analysis revealed the overexpression of E4BP4, a transcriptional repressor gene, in normal osteoblasts cocultured with myeloma cells that were releasing the parathyroid hormone-related protein (PTHrP). Thus, the effect of E4BP4 was assessed in PTHrP-stimulated osteoblasts by measuring the RNA levels of both Runx2 and Osterix as major osteoblast transcriptional activators. Because E4BP4 is a negative regulator of the cyclooxygenase-2 (COX-2) pathway that drives the expression of both Runx2 and Osterix, these factors were investigated after prostaglandin E(2) treatment to overcome the COX-2 defect as well as in E4BP4-silenced osteoblasts. Finally, E4BP4, PTHrP, Osterix, and osteocalcin levels were measured in vivo in patients with bone disease together with the E4BP4 protein in bone biopsies. RESULTS E4BP4 was specifically induced by PTHrP and inhibited both Runx2 and Osterix, whereas E4BP4-silenced osteoblasts expressed functional levels of both factors. The prostaglandin E(2) treatment of E4BP4-up-regulated osteoblasts promptly restored Runx2 and Osterix activities, suggesting that integrity of COX-2 pathway is essential for their transcription. Down-regulation of Osterix by E4BP4 was confirmed in vivo by its inverse levels in osteoblasts from myeloma patients with increased serum PTHrP, whose bone biopsies expressed the E4BP4 protein. CONCLUSIONS Our data support the role of E4BP4 as osteoblast transcriptional repressor in inhibiting both Runx2 and Osterix in myeloma bone disease and correlate its effect with the increased PTHrP activity.
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Affiliation(s)
- Franco Silvestris
- Department of Internal Medicine and Clinical Oncology, University of Bari Medical School, Piazza Giulio Cesare 11, Bari, Italy.
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Helgeson SC, Schmutz SM. Genetic variation in the pro-melanin-concentrating hormone gene affects carcass traits in Bos taurus cattle. Anim Genet 2008; 39:310-5. [DOI: 10.1111/j.1365-2052.2008.01717.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Hines RN. The ontogeny of drug metabolism enzymes and implications for adverse drug events. Pharmacol Ther 2008; 118:250-67. [PMID: 18406467 DOI: 10.1016/j.pharmthera.2008.02.005] [Citation(s) in RCA: 250] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
Profound changes in drug metabolizing enzyme (DME) expression occurs during development that impacts the risk of adverse drug events in the fetus and child. A review of our current knowledge suggests individual hepatic DME ontogeny can be categorized into one of three groups. Some enzymes, e.g., CYP3A7, are expressed at their highest level during the first trimester and either remain at high concentrations or decrease during gestation, but are silenced or expressed at low levels within one to two years after birth. SULT1A1 is an example of the second group of DME. These enzymes are expressed at relatively constant levels throughout gestation and minimal changes are observed postnatally. ADH1C is typical of the third DME group that are not expressed or are expressed at low levels in the fetus, usually during the second or third trimester. Substantial increases in enzyme levels are observed within the first one to two years after birth. Combined with our knowledge of other physiological factors during early life stages, knowledge regarding DME ontogeny has permitted the development of robust physiological based pharmacokinetic models and an improved capability to predict drug disposition in pediatric patients. This review will provide an overview of DME developmental expression patterns and discuss some implications of the data with regards to drug therapy. Common themes emerging from our current knowledge also will be discussed. Finally, the review will highlight gaps in knowledge that will be important to advance this field.
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Affiliation(s)
- Ronald N Hines
- Department of Pediatrics, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, WI 53226-4801, USA.
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15
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The possible interaction of CDA14 and protein elongation factor 1α. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:312-8. [DOI: 10.1016/j.bbapap.2007.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 10/03/2007] [Accepted: 10/03/2007] [Indexed: 12/24/2022]
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16
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Hsu EC, Lin YC, Hung CS, Huang CJ, Lee MY, Yang SC, Ting LP. Suppression of hepatitis B viral gene expression by protein-tyrosine phosphatase PTPN3. J Biomed Sci 2007; 14:731-44. [PMID: 17588219 DOI: 10.1007/s11373-007-9187-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 06/03/2007] [Indexed: 10/23/2022] Open
Abstract
Protein-tyrosine phosphatase PTPN3 is a membrane-associated non-receptor protein-tyrosine phosphatase. PTPN3 contains a N-terminal FERM domain, a middle PDZ domain, and a C-terminal phosphatase domain. Upon co-expression of PTPN3, the level of human hepatitis B viral (HBV) RNAs, 3.5 kb, 2.4/2.1 kb, and 0.7 kb transcribed from a replicating HBV expression plasmid is significantly reduced in human hepatoma HuH-7 cells. When the expression of endogenous PTPN3 protein is diminished by specific small interfering RNA, the expression of HBV genes is enhanced, indicating that the endogenous PTPN3 indeed plays a suppressive role on HBV gene expression. PTPN3 can interact with HBV core protein. The interaction is mediated via the PDZ domain of PTPN3 and the carboxyl-terminal last four amino acids of core. Either deletion of PDZ domain of PTPN3 or substitution of PDZ ligand in core has no effect on PTPN3-mediated suppression. These results clearly show that the interaction of PTPN3 with core is not required for PTPN3 suppressive effect. Mutation of (359)serine and (835)serine of 14-3-3beta binding sites to alanine, which slightly reduces the interaction with 14-3-3beta, does not influence the PTPN3 effect. In contrast, mutation of the invariant (842)cysteine residue in phosphatase domain to serine, which makes the phosphatase activity inactive, does not change its subcellular localization and interaction with core or 14-3-3beta, but completely abolishes PTPN3-mediated suppression. Furthermore, deletion of FERM domain does not affect the phosphatase activity or interaction with 14-3-3beta, but changes the subcellular localization from cytoskeleton-membrane interface to cytoplasm and nucleus, abolishes binding to core, and diminishes the PTPN3 effect on HBV gene expression. Taken together, these results demonstrate that the phosphatase activity and FERM domain of PTPN3 are essential for its suppression of HBV gene expression.
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MESH Headings
- Carcinoma, Hepatocellular/metabolism
- Cells, Cultured
- Fluorescent Antibody Technique
- Gene Expression Regulation, Viral
- Gene Silencing
- Genes, Viral
- Hepatitis B virus/genetics
- Hepatitis B virus/metabolism
- Humans
- Liver Neoplasms/metabolism
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatase, Non-Receptor Type 3/analysis
- Protein Tyrosine Phosphatase, Non-Receptor Type 3/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 3/metabolism
- Suppression, Genetic
- Transfection
- Tumor Cells, Cultured
- Viral Core Proteins/genetics
- Viral Core Proteins/metabolism
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Affiliation(s)
- En-Chi Hsu
- Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Pei-Tou, Taipei 11221, Taiwan, ROC
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17
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Pan XB, Wei L, Chen HS, Liu F, Gao Y. Liver-derived cell lines QSG-7701 and HepG2 support different HBV replication patterns. Arch Virol 2007; 152:1159-73. [PMID: 17308979 DOI: 10.1007/s00705-006-0927-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2006] [Accepted: 12/12/2006] [Indexed: 01/10/2023]
Abstract
Hepatitis B virus (HBV) infection is currently still a worldwide heath concern. In our study, we compared HBV replication patterns in two liver-derived cell lines, QSG-7701 and HepG2. Viral markers of HBV replication in culture medium and cells were analyzed after transfection of these cells with plasmid pUC18-HBV1.2 into. We showed that QSG-7701 cells could support more stable and a higher level of HBV replication than HepG2 cells. Gene expression profiles of QSG-7701 and HepG2 cells by microarray analysis showed that many genes were differentially expressed between these two cell lines, including those that are related to the HBV life cycle. The global gene expression profile of these two cell types provides some clues to explain how different HBV replication is achieved. QSG-7701 cells offer a new opportunity for basic research on HBV virus-host interactions.
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Affiliation(s)
- X B Pan
- Peking University Hepatology Institute, Peking University People's Hospital, Beijing, P.R. China
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18
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Abstract
Period2 (Per2) is an essential component of the mammalian clock mechanism and robust circadian expression of Per2 is essential for the maintenance of circadian rhythms. Although recent studies have shown that the circadian E2 enhancer (a non-canonical E-box) accounts for most of the circadian transcriptional drive of mPer2, little is known about the other cis-elements of mPer2 oscillatory transcription. Here, we examined the contribution of E4BP4 to Per2 mRNA oscillation in the cell-autonomous clock. Knockdown experiments of E4BP4 in both Northern blots and real-time luciferase assays suggested that endogenous E4BP4 negatively regulates Per2 mRNA oscillation. Sequence analysis revealed two putative E4BP4-binding sites (termed A-site and B-site) on mammalian Per2 promoter regions. Luciferase assays with mutant constructs showed that a novel E4BP4-binding site (B-site) is responsible for E4BP4-mediated transcriptional repression of Per2. Furthermore, chromatin immunoprecipitation assays in vivo showed that the peak of E4BP4 binding to the B-site on the Per2 promoter almost matched the trough of Per2 mRNA expression. Importantly, real-time luciferase assays showed that the B-site in addition to the E2 enhancer is required for robust circadian expression of Per2 in the cell-autonomous clock. These findings indicated that E4BP4 is required for the negative regulation of mammalian circadian clocks.
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Affiliation(s)
- Tomoya Ohno
- Clock Cell Biology, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)Tsukuba 305-8566, Japan
- Graduate School of Life and Environmental Sciences, University of TsukubaTsukuba 305-8576, Japan
| | - Yoshiaki Onishi
- Clock Cell Biology, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)Tsukuba 305-8566, Japan
| | - Norio Ishida
- Clock Cell Biology, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST)Tsukuba 305-8566, Japan
- Graduate School of Life and Environmental Sciences, University of TsukubaTsukuba 305-8576, Japan
- To whom correspondence should be addressed at Clock Cell Biology, National Institute of Advanced Industrial Science and Technology, Central 6-5, 1-1-1 Higashi, Tsukuba 305-8566, Japan. Tel: +81 298 61 6053; Fax: +81 298 61 9499;
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19
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Yang CY, Kuo TH, Ting LP. Human hepatitis B viral e antigen interacts with cellular interleukin-1 receptor accessory protein and triggers interleukin-1 response. J Biol Chem 2006; 281:34525-36. [PMID: 16973626 DOI: 10.1074/jbc.m510981200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Human hepatitis B virus (HBV) can cause acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HBV e antigen (HBeAg), a secreted protein and not required for viral replication, is thought to play an immunoregulatory role during viral infection. However, the functional involvement of HBeAg in host immune response has not been fully elucidated. We report in this study that HBeAg can bind to interleukin-1 receptor accessory protein (IL-1RAcP). Interleukin-1 (IL-1) plays an important role in inflammation and regulation of immune response, and membrane form of IL-1RAcP (mIL-1RAcP) is an essential component of trimeric IL-1/IL-1 receptor/mIL-1RAcP complex. We show that glutathione S-transferase- or polyhistidine-tagged recombinant HBeAg can interact with endogenous mIL-1RAcP in vitro. Purified (His)6-HBeAg added in the culture medium can interact with overexpressed FLAG-tagged mIL-1RAcP in vivo. Indirect immunofluorescence and confocal microscopy show that HBeAg colocalizes with mIL-1RAcP on the cell surface. Furthermore, HBeAg is able to induce the interaction of IL-1 receptor I (IL-1RI) with mIL-1RAcP and trigger the recruitment of adaptor protein myeloid differentiation factor 88 (MyD88) to the IL-1RI/mIL-1RAcP complex. Assembly and activation of IL-1RI/mIL-1RAcP signaling complex by HBeAg can activate downstream NF-kappaB pathway through IkappaB degradation, induce NF-kappaB-dependent luciferase expression, and induce the expression of IL-1-responsive genes. Silencing of IL-1RAcP by small interfering RNA dramatically abolishes HBeAg-mediated NF-kappaB activation. These results demonstrate that HBeAg can trigger host IL-1 response by binding to mIL-1RAcP. The interaction of HBeAg with mIL-1RAcP may play an important role in modulating host immune response in acute and chronic HBV infection.
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Affiliation(s)
- Chih-Yung Yang
- Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Pei-Tou, Taipei 11221, Taiwan
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20
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Hough C, Cuthbert CD, Notley C, Brown C, Hegadorn C, Berber E, Lillicrap D. Cell type-specific regulation of von Willebrand factor expression by the E4BP4 transcriptional repressor. Blood 2004; 105:1531-9. [PMID: 15498853 DOI: 10.1182/blood-2002-10-3093] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanisms of tissue-restricted patterns of von Willebrand factor (VWF) expression involve activators and repressors that limit expression to endothelial cells and megakaryocytes. The relative transcriptional activity of the proximal VWF promoter was assessed in VWF-producing and -nonproducing cells, and promoter activity was highest in endothelial cells followed by megakaryocytes. Only basal VWF promoter activity was seen in nonendothelial cells. Here we identify a negative response element located at nucleotides (nts) +96/+105 and demonstrate, using chromatin immunoprecipitation (ChIP) analysis, that in vivo this sequence interacts with the E4BP4 transcriptional repressor. Differences in size and relative abundance of nuclear E4BP4 were observed. In HepG2 cells, low levels of larger forms of E4BP4 are present that directly interact with the negative response element. In VWF-expressing cells, high levels of smaller forms predominate with no evidence of direct DNA binding. However, in endothelial cells, mutation of the VWF E4BP4 binding motif not only restores but also further elevates VWF promoter activity, suggesting that E4BP4 may be part of a coordinated binding complex. These observations implicate this binding motif in repressing both activated and basal levels of VWF transcription by different cell type-specific mechanisms, and support the hypothesis that E4BP4 sequesters negative regulators of transcription, thereby enhancing activated gene expression.
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Affiliation(s)
- Christine Hough
- The Department of Pathology and Molecular Medicine, Richardson Laboratories, Queen's University, Kingston, ON, Canada, K7L 3N6
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21
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Junghans D, Chauvet S, Buhler E, Dudley K, Sykes T, Henderson CE. The CES-2-related transcription factor E4BP4 is an intrinsic regulator of motoneuron growth and survival. Development 2004; 131:4425-34. [PMID: 15306565 DOI: 10.1242/dev.01313] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The regulation of neuronal growth and survival during development requires interplay between extrinsic and intrinsic factors. Among the latter,transcription factors play a key role. In the nematode, the transcription factor CES-2 predisposes neurosecretory motoneurons to death, whereas E4BP4(NFIL3), one of its vertebrate homologs, regulates survival of pro-B lymphocytes. We show that E4BP4 is expressed by embryonic rat and chicken motoneurons in vivo, with levels being highest in neurons that survive the period of naturally occurring cell death. Overexpression of E4BP4 by electroporation of purified motoneurons in culture protected them almost completely against cell death triggered by removal of neurotrophic factors or activation of death receptors. Moreover, E4BP4 strongly enhanced neuronal cell size and axonal growth. Axons of motoneurons transfected with E4BP4 were 3.5-fold longer than control neurons grown on laminin; this effect required the activity of PI3 kinase. In vivo, overexpression of E4BP4 in chicken embryos reduced the number of dying motoneurons by 45%. Our results define E4BP4 as a novel intrinsic regulator of motoneuron growth and survival. Pathways regulated by E4BP4 are of potential interest both for understanding neuromuscular development and for promoting neuronal survival and regeneration in pathological situations.
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Affiliation(s)
- Dirk Junghans
- INSERM UMR623, Developmental Biology Institute of Marseille, CNRS, INSERM, Université Méditerranée, Campus de Luminy, Case 907, 13288 MARSEILLE Cedex 09, France
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22
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Lin SJ, Shu PY, Chang C, Ng AK, Hu CP. IL-4 suppresses the expression and the replication of hepatitis B virus in the hepatocellular carcinoma cell line Hep3B. THE JOURNAL OF IMMUNOLOGY 2004; 171:4708-16. [PMID: 14568946 DOI: 10.4049/jimmunol.171.9.4708] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
IL-4 has been known as a Th2 cytokine and can act on B cells, T cells, and monocytes. In this study we demonstrate that IL-4Rs are expressed on human hepatocellular carcinoma (HCC) cells. We found that IL-4 suppresses hepatitis B surface Ag (HBsAg) mRNA and HBsAg production in the Hep3B cell line, which contains an integrated hepatitis B virus (HBV) genome and constitutively secretes HBsAg. When Hep3B cells are further transfected with the plasmid pHBV3.6 that contains >1 U of HBV genome, IL-4 could suppress the production of all HBV RNA and secreted HBsAg and hepatitis B virus e Ag. Furthermore, an endogenous DNA polymerase activity assay shows a decrease in HBV DNA after IL-4 treatment. Using luciferase reporter assays we have demonstrated that IL-4 could suppress the activity of the surface promoter II and the core promotor (CP). To delineate how IL-4 suppressed the transcription of HBV genes, we have examined the effect of IL-4 on the expression of transcription factors that are known to bind to the core upstream regulatory sequence, which colocalizes with enhancer II of the HBV genome. Our results demonstrate that IL-4 suppresses the expression of C/EBPalpha. Furthermore, overexpression of C/EBPalpha blocked 43 and 30% of the IL-4-mediated suppression of CP activity and IL-4-induced suppression of pregenomic RNA, respectively. Finally, we have demonstrated that mutations affecting the C/EBPalpha-binding sites on core upstream regulatory sequence/enhancer II completely abolish the IL-4-mediated suppression of CP activity. Thus, down-regulation of C/EBPalpha may be involved in the anti-HBV effect of IL-4 in Hep3B cells.
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MESH Headings
- Antiviral Agents/metabolism
- Antiviral Agents/pharmacology
- Binding Sites/genetics
- Binding Sites/immunology
- CCAAT-Enhancer-Binding Protein-alpha/biosynthesis
- CCAAT-Enhancer-Binding Protein-alpha/genetics
- CCAAT-Enhancer-Binding Protein-alpha/physiology
- CCAAT-Enhancer-Binding Protein-beta/biosynthesis
- CCAAT-Enhancer-Binding Protein-beta/genetics
- Carcinoma, Hepatocellular/immunology
- Carcinoma, Hepatocellular/virology
- Cell Line, Transformed
- Cell Line, Tumor
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- G-Box Binding Factors
- Gene Expression Regulation, Viral/immunology
- Hepatitis B Surface Antigens/biosynthesis
- Hepatitis B Surface Antigens/genetics
- Hepatitis B e Antigens/biosynthesis
- Hepatitis B e Antigens/genetics
- Hepatitis B virus/genetics
- Hepatitis B virus/immunology
- Hepatitis B virus/physiology
- Humans
- Interleukin-4/metabolism
- Interleukin-4/pharmacology
- Liver Neoplasms/immunology
- Liver Neoplasms/virology
- Promoter Regions, Genetic/immunology
- Protein Subunits/biosynthesis
- Protein Subunits/genetics
- RNA Stability/immunology
- RNA, Viral/biosynthesis
- Receptors, Interleukin-4/biosynthesis
- Receptors, Interleukin-4/genetics
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transcription, Genetic/immunology
- Transfection
- Viral Proteins/biosynthesis
- Viral Proteins/genetics
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Sue-Jane Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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23
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Ozkurt IC, Tetradis S. Parathyroid hormone-induced E4BP4/NFIL3 down-regulates transcription in osteoblasts. J Biol Chem 2003; 278:26803-9. [PMID: 12743120 DOI: 10.1074/jbc.m212652200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parathyroid hormone (PTH), a major regulator of bone metabolism, activates the PTHR1 receptor on the osteoblast plasma membrane to initiate signaling and induce transcription of primary response genes. Subsequently, primary genes with transcriptional activity regulate expression of downstream PTH targets. We have identified the adenovirus E4 promoter-binding protein/nuclear factor regulated by IL-3 (E4bp4) as a PTH-induced primary gene in osteoblasts. E4BP4 is a basic leucine zipper (bZIP) transcription factor that represses or activates transcription in non-osteoblastic cells. We report here that PTH rapidly and transiently induced E4bp4 mRNA in osteoblastic cells and that this induction did not require protein synthesis. PTH also induced E4BP4 protein synthesis and E4BP4 binding to a consensus but not to a mutant E4BP4 response element (EBPRE). E4BP4 overexpression inhibited an EBPRE-containing promoter-reporter construct, whereas PTH treatment attenuated activity of the same construct in primary mouse osteoblasts. Finally, E4BP4 overexpression inhibited PTH-induced activity of a cyclooxygenase-2 promoter-reporter construct. Our data suggest a role for E4BP4 in attenuation of PTH target gene transcription in osteoblasts.
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Affiliation(s)
- Ibrahim C Ozkurt
- Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, California 90095-1668, USA
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24
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Schüttler CG, Fiedler N, Schmidt K, Repp R, Gerlich WH, Schaefer S. Suppression of hepatitis B virus enhancer 1 and 2 by hepatitis C virus core protein. J Hepatol 2002; 37:855-62. [PMID: 12445429 DOI: 10.1016/s0168-8278(02)00296-9] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND/AIMS Epidemiological studies have shown that coinfection or superinfection with hepatitis B virus (HBV) and C virus (HCV) frequently leads to the suppression of hepatitis B virus replication. The mechanism of this phenomenon is still unclear. Shih et al. [J Virol 1993;67:5823] reported a direct suppression of HBV replication by the core protein of HCV. The target structure of HCV core protein in this system remained unclear. METHODS As HCV core protein has been shown to influence expression from transcriptional elements, we studied whether HCV core protein altered the activity of the two HBV enhancers 1 and 2. Luciferase vectors for HBV enhancers 1 or 2 were cotransfected with expression constructs for HCV core protein in murine and human hepatocyte lines. RESULTS Full-length HCV core protein suppressed the HBV enhancer 1 up to 11-fold, the enhancer 2 3-4-fold. Suppression of HBV enhancer 1 by HCV core from genotype 1b was stronger than by HCV core of genotypes 3a or 1a. Carboxyterminally truncated core proteins had lower or no suppression activity. CONCLUSIONS These data suggest that HCV core protein may directly repress transcription of the HBV RNAs. This trans-repression may contribute to suppression of HBV replication in patients coinfected with both viruses.
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Affiliation(s)
- Christian G Schüttler
- Institut für Medizinische Virologie Justus-Liebig-Universität, Frankfurter Strasse 107, D-35392 Giessen, Germany
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25
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Abstract
E4BP4, a mammalian basic leucine zipper (bZIP) transcription factor, was first identified through its ability to bind and repress viral promoter sequences. Subsequently, E4BP4 and homologues in other species have been implicated in a diverse range of processes including commitment to cell survival versus apoptosis, the anti-inflammatory response and, most recently, in the mammalian circadian oscillatory mechanism. In some of these cases at least, E4BP4 appears to act antagonistically with members of the related PAR family of transcription factors with which it shares DNA-binding specificity. This diversity of function is mirrored by the regulatory pathways impinging on E4BP4, which include regulation by ras via the lymphokine IL-3 in murine B-cells, by thyroid hormone during Xenopus tail resorption, by glucocorticoids in murine fibroblasts and by calcium in rat smooth muscle cells. This article will cover the unfolding role/s of and regulation of E4BP4, E4BP4-like proteins and PAR factors in species as diverse as mouse and C. elegans.
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Affiliation(s)
- Ian G Cowell
- Department of Gene Expression and Development, The Roslin Institute (Edinburgh), Roslin, Midlothian. Scotland EH25 9PS.
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26
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Tang H, McLachlan A. Mechanisms of inhibition of nuclear hormone receptor-dependent hepatitis B virus replication by hepatocyte nuclear factor 3beta. J Virol 2002; 76:8572-81. [PMID: 12163577 PMCID: PMC136416 DOI: 10.1128/jvi.76.17.8572-8581.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nuclear hormone receptors hepatocyte nuclear factor 4 (HNF4) and the retinoid X alpha (RXRalpha) plus the peroxisome proliferator-activated receptor alpha (PPARalpha) heterodimer support hepatitis B virus (HBV) replication in nonhepatoma cells. Hepatocyte nuclear factor 3 (HNF3) inhibits nuclear hormone receptor-mediated viral replication. Inhibition of HBV replication by HNF3beta is associated with the preferential reduction in the level of the pregenomic RNA compared with that of precore RNA. Hepatitis B e antigen (HBeAg), encoded by the precore RNA, mediates part of the inhibition of viral replication by HNF3beta. The amino-terminal transcriptional activation domain of HNF3beta is essential for the inhibition of HBV replication. The activation of transcription by HNF3 from HBV promoters downstream from the nucleocapsid promoter appears to contribute indirectly to the reduction in the steady-state level of 3.5-kb HBV RNA, possibly by interfering with the elongation rate of these transcripts. Therefore, transcriptional interference mediated by HNF3 may also regulate HBV RNA synthesis and viral replication.
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Affiliation(s)
- Hong Tang
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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27
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Abstract
The precise modulation of hepatitis B virus (HBV) gene expression is essential for replication of the virus. HBV sequences are transcribed under the control of the preC/pregenomic, S1, S2 and X promoters. With the exception of S1, all the HBV promoters lack the orthodox TATA box motifs required for the formation of the transcription initiation complex, and as such they represent a unique model of transcription initiation elements. The presence of two enhancer sequences and negative regulatory elements in the HBV genome further augments the controlled synthesis of HBV- RNA. All these transcription cis-elements are embedded within protein coding regions of the genome. This feature demonstrates the remarkable ability of the virus to maximize the function of its small genome. HBV transcription control elements also display a preference for liver-specific or liver-enriched trans-factors, which contributes to the liver tropism of the virus. This review outlines the major HBV transcription regulatory elements and highlights the reliance of accurate HBV gene modulation on the complex interplay between several trans-acting factors and their corresponding cis- motifs in the viral genome.
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Affiliation(s)
- Naazneen Moolla
- Hepatitis B virus Research Programme, Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School, 7 York Road, Parktown 2193, South Africa
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28
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Yu YL, Chiang YJ, Yen JJY. GATA factors are essential for transcription of the survival gene E4bp4 and the viability response of interleukin-3 in Ba/F3 hematopoietic cells. J Biol Chem 2002; 277:27144-53. [PMID: 12023274 DOI: 10.1074/jbc.m200924200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
E4bp4, a member of the basic region/leucine zipper transcription factor superfamily, is up-regulated by the interleukin-3 (IL-3) signaling pathway and plays an important role in the anti-apoptotic response of IL-3. In this study, we demonstrated that E4bp4 is regulated by IL-3 mainly at the transcriptional level. Promoter analysis revealed that a GATA motif downstream of a major transcription initiation site is essential for E4bp4 expression in the IL-3-dependent Ba/F3 cell line. Gel shift assays demonstrated that both GATA-1 and GATA-2 proteins bind to the E4bp4 GATA site in vitro, and the chromatin immunoprecipitation assay further confirmed the in vivo binding of GATA-1 to the E4bp4 promoter. Overexpression of GATA-1 alone transactivates the E4bp4 reporter, whereas transactivation of the E4bp4 reporter by GATA-2 is dependent on the stimulation of IL-3. Last, we demonstrated that alteration of GATA-1 binding to the GATA site by stably overexpressing GATA-1 or a GATA-1 mutant containing only the DNA-binding domain not only modulates the expression of the E4bp4 gene but also influences apoptosis induced by IL-3 removal. Taken together, our results suggest that the GATA factors play an important role in transducing the survival signal of IL-3, and one of their cellular targets is E4bp4.
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Affiliation(s)
- Yung-Luen Yu
- Graduate Institute of Life Sciences, National Defense Medical Center, Academia Sinica, No. 128, Sec. 2, Yen-Jiou-Yuan Road, Taipei, 115 Taiwan
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29
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Sun CT, Lo WY, Wang IH, Lo YH, Shiou SR, Lai CK, Ting LP. Transcription repression of human hepatitis B virus genes by negative regulatory element-binding protein/SON. J Biol Chem 2001; 276:24059-67. [PMID: 11306577 DOI: 10.1074/jbc.m101330200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A negative regulatory element (NRE) is located immediately upstream of the upstream regulatory sequence of core promoter and second enhancer of human hepatitis B virus (HBV). NRE represses the transcription activation function of the upstream regulatory sequence of core promoter and the second enhancer. In this study, we described the cloning and characterization of an NRE-binding protein (NREBP) through expression cloning. NREBP cDNA is 8266 nucleotides in size and encodes a protein of 2386 amino acids with a predicted molecular mass of 262 kDa. Three previously described cDNAs, DBP-5, SONB, and SONA, are partial sequence and/or alternatively spliced forms of NREBP. The genomic locus of the NREBP/SON gene is composed of 13 exons and 12 introns. The endogenous NREBP protein is localized in the nucleus of human hepatoma HuH-7 cells. Antibody against NREBP protein can specifically block the NRE binding activity present in fractionated nuclear extracts in gel shifting assays, indicating that NREBP is the endogenous nuclear protein that binds to NRE sequence. By polymerase chain reaction-assisted binding site selection assay, we determined that the consensus sequence for NREBP binding is GA(G/T)AN(C/G)(A/G)CC. Overexpression of NREBP enhances the repression of the HBV core promoter activity via NRE. Overexpression of NREBP can also repress the transcription of HBV genes and the production of HBV virions in a transient transfection system that mimics the viral infection in vivo.
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Affiliation(s)
- C T Sun
- Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Shih-Pai, Taipei 112, Taiwan, Republic of China
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30
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Nishimura Y, Tanaka T. Calcium-dependent activation of nuclear factor regulated by interleukin 3/adenovirus E4 promoter-binding protein gene expression by calcineurin/nuclear factor of activated T cells and calcium/calmodulin-dependent protein kinase signaling. J Biol Chem 2001; 276:19921-8. [PMID: 11262393 DOI: 10.1074/jbc.m010332200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An increase in the intracellular Ca(2+) concentration controls a diverse range of cell functions, including gene expression, apoptosis, adhesion, motility, and proliferation. We have investigated Ca(2+) regulation of gene expression in rat aortic smooth muscle cells. We found that the expression of nuclear factor regulated by interleukin 3 (NFIL3)/adenovirus E4 promoter-binding protein (E4BP4)/basic region/leucine zipper (bZIP) type of a transcription factor that has a very important function in cell survival, was activated by thapsigargin (TG). This activation was inhibited by chelation of extra- or intracellular Ca(2+), suggesting that the induction by TG was dependent on the elevation of [Ca(2+)](i). Specific inhibition of calcineurin or calcium/calmodulin-dependent protein kinase (CaM kinase) by chemical means impaired the TG-induced NFIL3/E4BP4 expression. Expression of dominant negative forms of calcineurin or nuclear factor of activated T cells (NFAT) inhibited the induction of NFIL3/E4BP4 mRNA by TG. These results suggest that intracellular Ca(2+) plays a critical role in regulating gene expression of NFIL3/E4BP4 by calcineurin/NFAT and CaM kinase signaling in vascular smooth muscle cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Basic-Leucine Zipper Transcription Factors
- Calcineurin/physiology
- Calcium/physiology
- Calcium-Calmodulin-Dependent Protein Kinases/antagonists & inhibitors
- Calcium-Calmodulin-Dependent Protein Kinases/metabolism
- Cells, Cultured
- DNA, Complementary
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Enzyme Inhibitors/pharmacology
- G-Box Binding Factors
- Gene Expression Regulation/physiology
- Lymphocyte Activation
- Molecular Sequence Data
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/enzymology
- Muscle, Smooth, Vascular/metabolism
- NFATC Transcription Factors
- Nuclear Proteins
- Phosphoprotein Phosphatases/antagonists & inhibitors
- Rats
- Sequence Homology, Amino Acid
- Signal Transduction
- T-Lymphocytes/enzymology
- T-Lymphocytes/metabolism
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transcription, Genetic/physiology
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Affiliation(s)
- Y Nishimura
- Department of Molecular and Cellular Pharmacology, Mie University School of Medicine, Edobashi, Tsu, Mie 514-8507, Japan
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Ishida H, Ueda K, Ohkawa K, Kanazawa Y, Hosui A, Nakanishi F, Mita E, Kasahara A, Sasaki Y, Hori M, Hayashi N. Identification of multiple transcription factors, HLF, FTF, and E4BP4, controlling hepatitis B virus enhancer II. J Virol 2000; 74:1241-51. [PMID: 10627534 PMCID: PMC111458 DOI: 10.1128/jvi.74.3.1241-1251.2000] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hepatitis B virus (HBV) enhancer II (EnII) is a hepatotropic cis element which is responsible for the hepatocyte-specific gene expression of HBV. Multiple transcription factors have been demonstrated to interact with this region. In this study, the region from HBV nucleotides (nt) 1640 to 1663 in EnII was demonstrated to be essential for enhancer activity and to be another target sequence of putative transcription factors. To elucidate the factors which bind to this region, we used a yeast one-hybrid screening system and cloned three transcription factors, HLF, FTF, and E4BP4, from a human adult liver cDNA library. All of these factors had binding affinity to the sequence from nt 1640 to 1663. Investigation of the effects of these factors on transcriptional regulation revealed that HLF and FTF had stimulatory activity on nt 1640 to 1663, whereas E4BP4 had a suppressing effect. FTF coordinately activated both 3. 5-kb RNA and 2.4/2.1-kb RNA transcription in a transient transfection assay with an HBV expression vector. HLF, however, activated only 3.5-kb RNA transcription, and in primer extension analysis, HLF strongly stimulated the synthesis of pregenome RNA compared to precore RNA. Thus, FTF stimulated the activity of the second enhancer, while HLF stimulated the activity of the core upstream regulatory sequence, which affects only the core promoter, and had a dominant effect on the pregenome RNA synthesis.
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Affiliation(s)
- H Ishida
- Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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