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Corrigendum to ‘Akt augments the oncogenic potential of the HBx protein of hepatitis B virus by phosphorylation’. FEBS J 2022; 290:2780-2781. [PMID: 36423325 DOI: 10.1111/febs.16684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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2
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Kim M, Kim M, Salloum S, Qian T, Wong LP, Xu M, Lee Y, Shroff SG, Sadreyev RI, Corey KE, Baumert TF, Hoshida Y, Chung RT. Atorvastatin favorably modulates a clinical hepatocellular carcinoma risk gene signature. Hepatol Commun 2022; 6:2581-2593. [PMID: 35712812 PMCID: PMC9426409 DOI: 10.1002/hep4.1991] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 11/22/2022] Open
Abstract
Lipophilic but not hydrophilic statins have been shown to be associated with reduced risk for hepatocellular carcinoma (HCC) in patients with chronic viral hepatitis. We investigated differential actions of lipophilic and hydrophilic statins and their ability to modulate a clinical prognostic liver signature (PLS) predicting HCC risk in patients with liver disease. Hepatitis C virus (HCV)-infected Huh7.5.1 cells, recently developed as a model to screen HCC chemopreventive agents, were treated with lipophilic statins (atorvastatin and simvastatin) and hydrophilic statins (rosuvastatin and pravastatin), and then analyzed by RNA sequencing and PLS. Lipophilic statins, particularly atorvastatin, more significantly suppressed the HCV-induced high-risk pattern of PLS and genes in YAP and AKT pathway implicated in fibrogenesis and carcinogenesis, compared with the hydrophilic statins. While atorvastatin inhibited YAP activation through the mevalonate pathway, the distinctive AKT inhibition of atorvastatin was mediated by stabilizing truncated retinoid X receptor alpha, which has been known to enhance AKT activation, representing a target for HCC chemoprevention. In addition, atorvastatin modulated the high-risk PLS in an in vitro model of nonalcoholic fatty liver disease (NAFLD). Conclusion: Atorvastatin distinctively inhibits YAP and AKT activation, which are biologically implicated in HCC development, and attenuates a high-risk PLS in an in vitro model of HCV infection and NAFLD. These findings suggest that atorvastatin is the most potent statin to reduce HCC risk in patients with viral and metabolic liver diseases.
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Affiliation(s)
- Myung‐Ho Kim
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
| | - Mi‐Young Kim
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
- Department of GastroenterologyCHA Bundang Medical CenterCHA University School of MedicineSeongnamSouth Korea
- Department of Gastroenterology, Chaum Life CenterCHA University School of MedicineSeoulSouth Korea
| | - Shadi Salloum
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
| | - Tongqi Qian
- Liver Tumor Translational Research ProgramSimmons Comprehensive Cancer CenterDivision of Digestive and Liver DiseasesDepartment of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Lai Ping Wong
- Department of Molecular BiologyMassachusetts General HospitalBostonMassachusettsUSA
- Department of GeneticsHarvard Medical SchoolBostonMassachusettsUSA
| | - Min Xu
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
| | - Yoojin Lee
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
| | - Stuti G. Shroff
- Department of PathologyMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Ruslan I. Sadreyev
- Department of Molecular BiologyMassachusetts General HospitalBostonMassachusettsUSA
- Department of PathologyMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Kathleen E. Corey
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
| | - Thomas F. Baumert
- Institut National de la Santé et de la Recherche MédicaleU1110Institut de Recherche sur les Maladies Virales et HépatiquesStrasbourgFrance
- Pole Hepato‐digestif, IHUStrasbourg University HospitalsStrasbourgFrance
| | - Yujin Hoshida
- Liver Tumor Translational Research ProgramSimmons Comprehensive Cancer CenterDivision of Digestive and Liver DiseasesDepartment of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTexasUSA
| | - Raymond T. Chung
- Liver CenterGastrointestinal DivisionMassachusetts General HospitalBostonMassachusettsUSA
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3
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Lee HW, Choi Y, Lee AR, Yoon CH, Kim KH, Choi BS, Park YK. Hepatocyte Growth Factor-Dependent Antiviral Activity of Activated cdc42-Associated Kinase 1 Against Hepatitis B Virus. Front Microbiol 2022; 12:800935. [PMID: 35003030 PMCID: PMC8733702 DOI: 10.3389/fmicb.2021.800935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 12/06/2021] [Indexed: 01/04/2023] Open
Abstract
Activated cdc42-associated kinase 1 (ACK1) is a well-known non-receptor tyrosine kinase that regulates cell proliferation and growth through activation of cellular signaling pathways, including mitogen-activated protein kinase (MAPK). However, the anti-HBV activity of ACK1 has not been elucidated. This study aimed to investigate the role of ACK1 in the HBV life cycle and the mechanism underlying the anti-HBV activity of ACK1. To examine the antiviral activity of ACK1, we established HepG2-ACK1 cells stably overexpressing ACK1. The HBV life cycle, including HBeAg/HBsAg secretion, HBV DNA/transcription, and enhancer activity, was analyzed in HepG2 and HepG2-ACK1 cells with HBV replication-competent HBV 1.2mer (HBV 1.2). Finally, the anti-HBV activity of ACK1 was examined in an HBV infection system. ACK1 suppressed HBV gene expression and transcription in HepG2 and HepG2-ACK1 cells. Furthermore, ACK1 inhibited HBV replication by decreasing viral enhancer activity. ACK1 exhibited its anti-HBV activity via activation of Erk1/2, which consequently downregulated the expression of HNF4α binding to HBV enhancers. Furthermore, hepatocyte growth factor (HGF) induced ACK1 expression at an early stage. Finally, ACK1 mediated the antiviral effect of HGF in the HBV infection system. These results indicated that ACK1 induced by HGF inhibited HBV replication at the transcriptional level by activating the MAPK-HNF signaling pathway. Our findings suggest that ACK1 is a potentially novel upstream molecule of MAPK-mediated anti-HBV activity.
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Affiliation(s)
- Hye Won Lee
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, National Institute of Infectious Disease, National Institute of Health, Cheongju, South Korea
| | - Yongwook Choi
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, National Institute of Infectious Disease, National Institute of Health, Cheongju, South Korea
| | - Ah Ram Lee
- Department of Precision Medicine, School of Medicine, Sungkyunkwan University, Suwon, South Korea
| | - Cheol-Hee Yoon
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, National Institute of Infectious Disease, National Institute of Health, Cheongju, South Korea
| | - Kyun-Hwan Kim
- Department of Precision Medicine, School of Medicine, Sungkyunkwan University, Suwon, South Korea
| | - Byeong-Sun Choi
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, National Institute of Infectious Disease, National Institute of Health, Cheongju, South Korea
| | - Yong Kwang Park
- Division of Chronic Viral Diseases, Center for Emerging Virus Research, National Institute of Infectious Disease, National Institute of Health, Cheongju, South Korea
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4
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Medhat A, Arzumanyan A, Feitelson MA. Hepatitis B x antigen (HBx) is an important therapeutic target in the pathogenesis of hepatocellular carcinoma. Oncotarget 2021; 12:2421-2433. [PMID: 34853663 PMCID: PMC8629409 DOI: 10.18632/oncotarget.28077] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/04/2021] [Indexed: 12/12/2022] Open
Abstract
Hepatitis B virus (HBV) is a human pathogen that has infected an estimated two billion people worldwide. Despite the availability of highly efficacious vaccines, universal screening of the blood supply for virus, and potent direct acting anti-viral drugs, there are more than 250 million carriers of HBV who are at risk for the sequential development of hepatitis, fibrosis, cirrhosis and hepatocellular carcinoma (HCC). More than 800,000 deaths per year are attributed to chronic hepatitis B. Many different therapeutic approaches have been developed to block virus replication, and although effective, none are curative. These treatments have little or no impact upon the portions of integrated HBV DNA, which often encode the virus regulatory protein, HBx. Although given little attention, HBx is an important therapeutic target because it contributes importantly to (a) HBV replication, (b) in protecting infected cells from immune mediated destruction during chronic infection, and (c) in the development of HCC. Thus, the development of therapies targeting HBx, combined with other established therapies, will provide a functional cure that will target virus replication and further reduce or eliminate both the morbidity and mortality associated with chronic liver disease and HCC. Simultaneous targeting of all these characteristics underscores the importance of developing therapies against HBx.
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Affiliation(s)
- Arvin Medhat
- Department of Molecular Cell Biology, Azad University, North Unit, Tehran, Iran
| | - Alla Arzumanyan
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, PA, USA
| | - Mark A Feitelson
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, PA, USA
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5
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Van Damme E, Vanhove J, Severyn B, Verschueren L, Pauwels F. The Hepatitis B Virus Interactome: A Comprehensive Overview. Front Microbiol 2021; 12:724877. [PMID: 34603251 PMCID: PMC8482013 DOI: 10.3389/fmicb.2021.724877] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 08/17/2021] [Indexed: 12/19/2022] Open
Abstract
Despite the availability of a prophylactic vaccine, chronic hepatitis B (CHB) caused by the hepatitis B virus (HBV) is a major health problem affecting an estimated 292 million people globally. Current therapeutic goals are to achieve functional cure characterized by HBsAg seroclearance and the absence of HBV-DNA after treatment cessation. However, at present, functional cure is thought to be complicated due to the presence of covalently closed circular DNA (cccDNA) and integrated HBV-DNA. Even if the episomal cccDNA is silenced or eliminated, it remains unclear how important the high level of HBsAg that is expressed from integrated HBV DNA is for the pathology. To identify therapies that could bring about high rates of functional cure, in-depth knowledge of the virus' biology is imperative to pinpoint mechanisms for novel therapeutic targets. The viral proteins and the episomal cccDNA are considered integral for the control and maintenance of the HBV life cycle and through direct interaction with the host proteome they help create the most optimal environment for the virus whilst avoiding immune detection. New HBV-host protein interactions are continuously being identified. Unfortunately, a compendium of the most recent information is lacking and an interactome is unavailable. This article provides a comprehensive review of the virus-host relationship from viral entry to release, as well as an interactome of cccDNA, HBc, and HBx.
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Affiliation(s)
- Ellen Van Damme
- Janssen Research & Development, Janssen Pharmaceutical Companies, Beerse, Belgium
| | - Jolien Vanhove
- Janssen Research & Development, Janssen Pharmaceutical Companies, Beerse, Belgium.,Early Discovery Biology, Charles River Laboratories, Beerse, Belgium
| | - Bryan Severyn
- Janssen Research & Development, Janssen Pharmaceutical Companies, Springhouse, PA, United States
| | - Lore Verschueren
- Janssen Research & Development, Janssen Pharmaceutical Companies, Beerse, Belgium
| | - Frederik Pauwels
- Janssen Research & Development, Janssen Pharmaceutical Companies, Beerse, Belgium
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6
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Zhou Q, Yan L, Xu B, Wang X, Sun X, Han N, Tang H, Huang F. Screening of the HBx transactivation domain interacting proteins and the function of interactor Pin1 in HBV replication. Sci Rep 2021; 11:14176. [PMID: 34238995 PMCID: PMC8266847 DOI: 10.1038/s41598-021-93584-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 06/28/2021] [Indexed: 02/05/2023] Open
Abstract
Hepatitis B virus (HBV) X protein (HBx) has been determined to play a crucial role in the replication and transcription of HBV, and its biological functions mainly depend on the interaction with other host proteins. This study aims at screening the proteins that bind to the key functional domain of HBx by integrated proteomics. Proteins that specifically bind to the transactivation domain of HBx were selected by comparing interactors of full-length HBx and HBx-D5 truncation determined by glutathione-S-transferase (GST) pull-down assay combined with mass spectrometry (MS). The function of HBx interactor Pin1 in HBV replication was further investigated by in vitro experiments. In this study, a total of 189 proteins were identified from HepG2 cells that specifically bind to the transactivation domain of HBx by GST pull-down and subsequent MS. After gene ontology (GO) analysis, Pin1 was selected as the protein with the highest score in the largest cluster functioning in protein binding, and also classified into the cluster of proteins with the function of structural molecule activity, which is of great potential to be involved in HBV life cycle. The interaction between Pin1 and HBx has been further confirmed by Ni2+-NTA pulldown assay, co-immunoprecipitation, and immunofluorescence microscopy. HBsAg and HBeAg levels significantly decreased in Pin1 expression inhibited HepG2.2.15 cells. Besides, the inhibition of Pin1 expression in HepG2 cells impeded the restored replication of HBx-deficient HBV repaired by ectopic HBx expression. In conclusion, our study identified Pin1 as an interactor binds to the transactivation domain of HBx, and suggested the potential association between Pin1 and the function of HBx in HBV replication.
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Affiliation(s)
- Qiaoxia Zhou
- Department of Forensic Pathology, West China School of Preclinical and Forensic Medicine, Sichuan University, No. 17 Third Renmin Road North, Chengdu, 610041, People's Republic of China
| | - Libo Yan
- Center of Infectious Diseases, West China Hospital of Sichuan University, No.37 Guo Xue Xiang, Chengdu, 610041, People's Republic of China.,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Baofu Xu
- Department of Forensic Pathology, West China School of Preclinical and Forensic Medicine, Sichuan University, No. 17 Third Renmin Road North, Chengdu, 610041, People's Republic of China.,Xinxiang Key Laboratory of Forensic Science Evidence, School of Forensic Medicine, Xinxiang Medical University, Xinxiang, 453003, People's Republic of China
| | - Xue'er Wang
- Department of Forensic Pathology, West China School of Preclinical and Forensic Medicine, Sichuan University, No. 17 Third Renmin Road North, Chengdu, 610041, People's Republic of China
| | - Xuehong Sun
- Department of Forensic Pathology, West China School of Preclinical and Forensic Medicine, Sichuan University, No. 17 Third Renmin Road North, Chengdu, 610041, People's Republic of China
| | - Ning Han
- Center of Infectious Diseases, West China Hospital of Sichuan University, No.37 Guo Xue Xiang, Chengdu, 610041, People's Republic of China.,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Hong Tang
- Center of Infectious Diseases, West China Hospital of Sichuan University, No.37 Guo Xue Xiang, Chengdu, 610041, People's Republic of China. .,Division of Infectious Diseases, State Key Laboratory of Biotherapy, Sichuan University, Chengdu, 610041, People's Republic of China.
| | - Feijun Huang
- Department of Forensic Pathology, West China School of Preclinical and Forensic Medicine, Sichuan University, No. 17 Third Renmin Road North, Chengdu, 610041, People's Republic of China.
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7
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Jiang Y, Han Q, Zhao H, Zhang J. The Mechanisms of HBV-Induced Hepatocellular Carcinoma. J Hepatocell Carcinoma 2021; 8:435-450. [PMID: 34046368 PMCID: PMC8147889 DOI: 10.2147/jhc.s307962] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/06/2021] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a common malignancy, and the hepatitis B virus (HBV) is its major pathogenic factor. Over the past decades, it has been confirmed that HBV infection could promote disease progression through a variety of mechanisms, ultimately leading to the malignant transformation of liver cells. Many factors have been identified in the pathogenesis of HBV-associated HCC (HBV-HCC), including HBV gene integration, genomic instability caused by mutation, and activation of cancer-promoting signaling pathways. As research in the progression of HBV-HCC progresses, the role of many new mechanisms, such as epigenetics, exosomes, autophagy, metabolic regulation, and immune suppression, is also being continuously explored. The occurrence of HBV-HCC is a complex process caused by interactions across multiple genes and multiple steps, where the synergistic effects of various cancer-promoting mechanisms accelerate the process of disease evolution from inflammation to tumorigenesis. In this review, we aim to provide a brief overview of the mechanisms involved in the occurrence and development of HBV-HCC, which may contribute to a better understanding of the role of HBV in the occurrence and development of HCC.
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Affiliation(s)
- Yu Jiang
- Institute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, People's Republic of China
| | - Qiuju Han
- Institute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, People's Republic of China
| | - Huajun Zhao
- Institute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, People's Republic of China
| | - Jian Zhang
- Institute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, Shandong Province, People's Republic of China
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8
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Phosphorylation of Phylogenetically Conserved Amino Acid Residues Confines HBx within Different Cell Compartments of Human Hepatocarcinoma Cells. Molecules 2021; 26:molecules26051254. [PMID: 33652602 PMCID: PMC7956559 DOI: 10.3390/molecules26051254] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/20/2021] [Accepted: 02/20/2021] [Indexed: 01/05/2023] Open
Abstract
Hepatitis B virus (HBV) is a circular, and partially double-stranded DNA virus. Upon infection, the viral genome is translocated into the cell nucleus, generating the covalently closed circular DNA (cccDNA) intermediate, and forming a mini chromosome. HBV HBx is a small protein displaying multiple roles in HBV-infected cells, and in different subcellular locations. In the nucleus, the HBx protein is required to initiate and maintain viral transcription from the viral mini chromosome. In contrast, HBx also functions in the cytoplasm, where it is able to alter multiple cellular functions such as mitochondria metabolism, apoptosis and signal transduction pathways. It has been reported that in cultured cells, at low expression levels, the HBx protein is localized in the nucleus, whereas at high expression levels, it accumulates in the cytoplasm. This dynamic subcellular distribution of HBx might be essential to exert its multiple roles during viral infection. However, the mechanism that regulates different subcellular localizations of the HBx protein is unknown. We have previously taken a bioinformatics approach to investigate whether HBx might be regulated via post-translational modification, and we have proposed that the multiple nucleocytoplasmic functions of HBx might be regulated by an evolutionarily conserved mechanism via phosphorylation. In the current study, phylogenetically conserved amino acids of HBx with a high potential of phosphorylation were targeted for site-directed mutagenesis. Two conserved serine (Ser25 and Ser41), and one conserved threonine (Thr81) amino acids were replaced by either alanine or aspartic acid residues to simulate an unphosphorylated or phosphorylated state, respectively. Human hepatoma cells were transfected with increasing amounts of the HBx DNA constructs, and the cells were analyzed by fluorescence microscopy. Together, our results show that the nucleocytoplasmic distribution of the HBx protein could be regulated by phosphorylation since some of the modified proteins were mainly confined to distinct subcellular compartments. Remarkably, both HBx Ser41A, and HBx Thr81D proteins were predominantly localized within the nuclear compartment throughout the different expression levels of HBx mutants.
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9
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Nathan KG, Lal SK. The Multifarious Role of 14-3-3 Family of Proteins in Viral Replication. Viruses 2020; 12:E436. [PMID: 32294919 PMCID: PMC7232403 DOI: 10.3390/v12040436] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 02/06/2023] Open
Abstract
The 14-3-3 proteins are a family of ubiquitous and exclusively eukaryotic proteins with an astoundingly significant number of binding partners. Their binding alters the activity, stability, localization, and phosphorylation state of a target protein. The association of 14-3-3 proteins with the regulation of a wide range of general and specific signaling pathways suggests their crucial role in health and disease. Recent studies have linked 14-3-3 to several RNA and DNA viruses that may contribute to the pathogenesis and progression of infections. Therefore, comprehensive knowledge of host-virus interactions is vital for understanding the viral life cycle and developing effective therapeutic strategies. Moreover, pharmaceutical research is already moving towards targeting host proteins in the control of virus pathogenesis. As such, targeting the right host protein to interrupt host-virus interactions could be an effective therapeutic strategy. In this review, we generated a 14-3-3 protein interactions roadmap in viruses, using the freely available Virusmentha network, an online virus-virus or virus-host interaction tool. Furthermore, we summarize the role of the 14-3-3 family in RNA and DNA viruses. The participation of 14-3-3 in viral infections underlines its significance as a key regulator for the expression of host and viral proteins.
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Affiliation(s)
- Kavitha Ganesan Nathan
- School of Science, Monash University, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia;
| | - Sunil K. Lal
- School of Science, Monash University, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia;
- Tropical Medicine & Biology Platform, Monash University, Bandar Sunway, Selangor Darul Ehsan 47500, Malaysia
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10
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Prescott NA, Bram Y, Schwartz RE, David Y. Targeting Hepatitis B Virus Covalently Closed Circular DNA and Hepatitis B Virus X Protein: Recent Advances and New Approaches. ACS Infect Dis 2019; 5:1657-1667. [PMID: 31525994 DOI: 10.1021/acsinfecdis.9b00249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Chronic Hepatitis B virus (HBV) infection remains a worldwide concern and public health problem. Two key aspects of the HBV life cycle are essential for viral replication and thus the development of chronic infections: the establishment of the viral minichromosome, covalently closed circular (ccc) DNA, within the nucleus of infected hepatocytes and the expression of the regulatory Hepatitis B virus X protein (HBx). Interestingly, nuclear HBx redirects host epigenetic machinery to activate cccDNA transcription. In this Perspective, we provide an overview of recent advances in understanding the regulation of cccDNA and the mechanistic and functional roles of HBx. We also describe the progress toward targeting both cccDNA and HBx for therapeutic purposes. Finally, we outline standing questions in the field and propose complementary chemical biology approaches to address them.
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Affiliation(s)
- Nicholas A. Prescott
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Yaron Bram
- Division of Gastroenterology and Hepatology, Department of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, New York 10065, United States
| | - Robert E. Schwartz
- Division of Gastroenterology and Hepatology, Department of Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, New York 10065, United States
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medicine, 1300 York Avenue, New York, New York 10065, United States
| | - Yael David
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medicine, 1300 York Avenue, New York, New York 10065, United States
- Department of Pharmacology, Weill Cornell Medicine, 1300 York Avenue, New York, New York 10065, United States
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11
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Chaturvedi VK, Singh A, Dubey SK, Hetta HF, John J, Singh M. Molecular mechanistic insight of hepatitis B virus mediated hepatocellular carcinoma. Microb Pathog 2019; 128:184-194. [DOI: 10.1016/j.micpath.2019.01.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/30/2018] [Accepted: 01/02/2019] [Indexed: 02/07/2023]
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12
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Molecular Characterization of Near Full-Length Genomes of Hepatitis B Virus Isolated from Predominantly HIV Infected Individuals in Botswana. Genes (Basel) 2018; 9:genes9090453. [PMID: 30205537 PMCID: PMC6162474 DOI: 10.3390/genes9090453] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/27/2018] [Accepted: 09/03/2018] [Indexed: 12/13/2022] Open
Abstract
The World Health Organization plans to eliminate hepatitis B and C Infections by 2030. Therefore, there is a need to study and understand hepatitis B virus (HBV) epidemiology and viral evolution further, including evaluating occult (HBsAg-negative) HBV infection (OBI), given that such infections are frequently undiagnosed and rarely treated. We aimed to molecularly characterize HBV genomes from 108 individuals co-infected with human immunodeficiency virus (HIV) and chronic hepatitis B (CHB) or OBI identified from previous HIV studies conducted in Botswana from 2009 to 2012. Full-length (3.2 kb) and nearly full-length (~3 kb) genomes were amplified by nested polymerase chain reaction (PCR). Sequences from OBI participants were compared to sequences from CHB participants and GenBank references to identify OBI-unique mutations. HBV genomes from 50 (25 CHB and 25 OBI) individuals were successfully genotyped. Among OBI participants, subgenotype A1 was identified in 12 (48%), D3 in 12 (48%), and E in 1 (4%). A similar genotype distribution was observed in CHB participants. Whole HBV genome sequences from Botswana, representing OBI and CHB, were compared for the first time. There were 43 OBI-unique mutations, of which 26 were novel. Future studies using larger sample sizes and functional analysis of OBI-unique mutations are warranted.
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13
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Li C, Lin C, Cong X, Jiang Y. PDK1-WNK1 signaling is affected by HBx and involved in the viability and metastasis of hepatic cells. Oncol Lett 2018; 15:5940-5946. [PMID: 29563998 DOI: 10.3892/ol.2018.8001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 12/22/2017] [Indexed: 01/04/2023] Open
Abstract
Hepatitis B virus (HBV)-encoded X antigen (HBx) contributes to the development of hepatocellular carcinoma (HCC). Although HBx has been implicated in the progression of HCC, its precise function in HBV-associated HCC remains unclear. In the present study, HBx affected 3-phosphoinositide-dependent protein kinase-1 (PDK1) and with-no-lysine (K) kinase (WNK1) signaling, which was identified to be involved in the viability and metastasis of hepatic cells. The phosphorylation of WNK1 was decreased when the hepatic cells were treated with a PDK1 inhibitor. The inhibition of PDK1 activity inhibited the viability and migration of hepatic cells. To the best of our knowledge, the present study is the first to identify the activation of PDK1 in HCC tissues, confirmed using western blot analysis. PDK1-WNK1 signaling may be a potential therapeutic target in HBV-associated liver cancer.
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Affiliation(s)
- Chaoying Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, P.R. China
| | - Cong Lin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, P.R. China
| | - Xianling Cong
- Biobank, China-Japan Union Hospital of Jilin University, Changchun, Jilin 130031, P.R. China
| | - Ying Jiang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, P.R. China
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14
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Chen WS, Liu LC, Yen CJ, Chen YJ, Chen JY, Ho CY, Liu SH, Chen CC, Huang WC. Nuclear IKKα mediates microRNA-7/-103/107/21 inductions to downregulate maspin expression in response to HBx overexpression. Oncotarget 2018; 7:56309-56323. [PMID: 27409165 PMCID: PMC5302916 DOI: 10.18632/oncotarget.10462] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/15/2016] [Indexed: 12/14/2022] Open
Abstract
Maspin is a tumor suppressor that stimulates apoptosis and inhibits metastasis in various cancer types, including hepatocellular carcinoma (HCC). Our previous study has demonstrated that HBx induced microRNA-7, 103, 107, and 21 expressions to suppress maspin expression, leading to metastasis, chemoresistance, and poor prognosis in HCC patients. However, it remains unclear how HBx elicits these microRNA expressions. HBx has been known to induce aberrant activation and nuclear translocation of inhibitor-κB kinase-α (IKKα) to promote HCC progression. In this study, our data further revealed that nuclear IKKα expression was inversely correlated with maspin expression in HBV-associated patients. Nuclear IKKα but not IKKβ reduced maspin protein and mRNA expression, and inhibition of IKKα reverses HBx-mediated maspin downregulation and chemoresistance. In response to HBx overexpression, nuclear IKKα was further demonstrated to induce the gene expressions of microRNA-7, −103, −107, and −21 by directly targeting their promoters, thereby leading to maspin downregulation. These findings indicated nuclear IKKα as a critical regulator for HBx-mediated microRNA induction and maspin suppression, and suggest IKKα as a promising target to improve the therapeutic outcome of HCC patients.
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Affiliation(s)
- Wen-Shu Chen
- Department of Pharmacology, National Taiwan University, Taipei, Taiwan.,Center for Molecular Medicine, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan
| | - Liang-Chih Liu
- Division of Breast Surgery, Department of Surgery, China Medical University Hospital, Taichung, Taiwan.,School of Medicine, China Medical University, Taichung, Taiwan
| | - Chia-Jui Yen
- Internal Medicine, National Cheng-Kung University, Tainan, Taiwan
| | - Yun-Ju Chen
- Department of Medical Research, E-DA Hospital, Kaohsiung, Taiwan.,Department of Biological Science & Technology, I-Shou University, Kaohsiung, Taiwan
| | - Jhen-Yu Chen
- Center for Molecular Medicine, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan.,The Ph.D. Program for Cancer Biology and Drug Discovery, China Medical University, Taichung, Taiwan
| | - Chien-Yi Ho
- Department of Family Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Shu-Hui Liu
- Department of Health Care and Social Work, Yu Da University of Science and Technology, Miaoli, Taiwan
| | - Ching-Chow Chen
- Department of Pharmacology, National Taiwan University, Taipei, Taiwan
| | - Wei-Chien Huang
- Center for Molecular Medicine, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Cancer Biology, China Medical University, Taichung, Taiwan.,The Ph.D. Program for Cancer Biology and Drug Discovery, China Medical University, Taichung, Taiwan.,Department of Biotechnology, Asia University, Taichung, Taiwan
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15
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Ghalali A, Martin-Renedo J, Högberg J, Stenius U. Atorvastatin Decreases HBx-Induced Phospho-Akt in Hepatocytes via P2X Receptors. Mol Cancer Res 2017; 15:714-722. [PMID: 28209758 DOI: 10.1158/1541-7786.mcr-16-0373] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 01/24/2017] [Accepted: 01/25/2017] [Indexed: 11/16/2022]
Abstract
Hepatocellular carcinoma (HCC) is rated as the fifth most common malignancy and third in cancer-related deaths worldwide. Statins, HMG-CoA reductase inhibitors, are potent cholesterol-lowering drugs, and recent epidemiologic evidence suggests that statins prevent aggressive HCC development. Previous experiments revealed that statins downregulate phosphorylated Akt (pAkt). Here, it is demonstrated that atorvastatin decreases nuclear pAkt levels in pancreatic and lung cancer cell lines within minutes, and this rapid effect is mediated by the purinergic P2X receptors. Akt is upregulated by hepatitis viruses and has oncogenic activity in HCC; therefore, we tested the possibility that the P2X-Akt pathway is important for the anticipated anticancer effects of statins in hepatocytes. Atorvastatin decreased hepatitis B virus X protein- and insulin-induced pAkt and pGsk3β (Ser9) levels. Furthermore, Akt-induced lipogenesis was counteracted by atorvastatin, and these statin-induced effects were dependent on P2X receptors. Statin also decreased proliferation and invasiveness of hepatocytes. These data provide mechanistic evidence for a P2X receptor-dependent signaling pathway by which statins decrease pAkt, its downstream phosphorylation target pGsk3β, and lipogenesis in hepatocytes.Implications: The Akt pathway is deregulated and may act as a driver in HCC development; the P2X-Akt signaling pathway may have a role in anticancer effects of statins. Mol Cancer Res; 15(6); 714-22. ©2017 AACR.
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Affiliation(s)
- Aram Ghalali
- Institute of Environment Medicine. Karolinska Institutet, Stockholm, Sweden.
| | | | - Johan Högberg
- Institute of Environment Medicine. Karolinska Institutet, Stockholm, Sweden
| | - Ulla Stenius
- Institute of Environment Medicine. Karolinska Institutet, Stockholm, Sweden
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16
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Lee WP, Lan KH, Li CP, Chao Y, Lin HC, Lee SD. Oncogenic circuit constituted by Ser31-HBx and Akt increases risks of chronic hepatitis and hepatocellular carcinoma. Biochim Biophys Acta Mol Basis Dis 2016; 1862:837-849. [PMID: 26791804 DOI: 10.1016/j.bbadis.2015.12.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 11/29/2015] [Accepted: 12/16/2015] [Indexed: 01/27/2023]
Abstract
The X protein of hepatitis B virus (HBx) has been specifically implicated in the development of hepatocellular carcinoma (HCC). Clinical associations of HBx isoforms with chronic hepatitis and HCC have not been well studied. HBx has two roles in liver cells, namely pro-apoptotic and anti-apoptotic. In this report, we examined the role of Ser31-HBx in HCC and chronic hepatitis. Using the case-control study, we determined risks of chronic hepatitis and HCC conferred by hepatitis B virus (HBV) containing Ser31-HBx that was phosphorylated by Akt. Ser31-HBx isoforms conferred 3.23-fold risk of HCC in male and 3.36-fold risk in female. Ser31 isoforms were associated with 3.12-fold risk of chronic hepatitis and 3.43-fold risk of cirrhosis and also associated with higher HBV viral load and replication efficiency and lower rate of HBe loss. To determine the mechanism, we found that Ser31-HBx constituted an oncogenic circuit with Akt and cooperated with ras to transform NIH3T3 cells in contrast to non-Ser31-HBxs that did not transduce oncogenic signals. Our results give a clue to account for an underlying cause of HBx-mediated hepatocarcinogenesis. It appears that Ser31 phosphorylation of HBx by Akt plays an important role. The current study provides an example of association of HBV genome variations with risks of HCC and chronic hepatitis.
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Affiliation(s)
- Wei-Ping Lee
- Institute of Biochemistry and Molecular Biology, School of Life Sciences, National Yang-Ming University, Taiwan; Department of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan.
| | - Keng-Hsin Lan
- Department of Pharmacology, National Yang-Ming University, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chung-Pin Li
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yee Chao
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Cancer Center, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Han-Chieh Lin
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shou-Dong Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
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17
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Slagle BL, Bouchard MJ. Hepatitis B Virus X and Regulation of Viral Gene Expression. Cold Spring Harb Perspect Med 2016; 6:a021402. [PMID: 26747833 DOI: 10.1101/cshperspect.a021402] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The efficient replication of hepatitis B virus (HBV) requires the HBV regulatory hepatitis B virus X (HBx) protein. The exact contributions of HBx are not fully understood, in part because of the limitations of the assays used for its study. When HBV replication is driven from a plasmid DNA, the contribution of HBx is modest. However, there is an absolute requirement for HBx in assays that recapitulate the infectious virus life cycle. There is much evidence that HBx can contribute directly to HBV replication by acting on viral promoters embedded within protein coding sequences. In addition, HBx may also contribute indirectly by modulating cellular pathways to benefit virus replication. Understanding the mechanism(s) of HBx action during virus replication may provide insight into novel ways to disrupt chronic HBV replication.
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Affiliation(s)
- Betty L Slagle
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030
| | - Michael J Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
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18
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Chen X, Zhang L, Zheng S, Zhang T, Li M, Zhang X, Zeng Z, McCrae MA, Zhao J, Zhuang H, Lu F. Hepatitis B Virus X Protein Stabilizes Cyclin D1 and Increases Cyclin D1 Nuclear Accumulation through ERK-Mediated Inactivation of GSK-3β. Cancer Prev Res (Phila) 2015; 8:455-63. [PMID: 25712050 DOI: 10.1158/1940-6207.capr-14-0384] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 02/09/2015] [Indexed: 01/13/2023]
Abstract
The Hepatitis B virus X protein (HBx) contributes centrally to the pathogenesis of hepatocellular carcinoma (HCC). It has been suggested that the transcriptional activation of cyclin D1 by HBx is implicated in the development of HCC. However, numerous studies have shown that overexpression of cyclin D1 alone is not sufficient to drive oncogenic transformation. Herein, we investigated whether HBx can stabilize cyclin D1 and induce cyclin D1 protein nuclear accumulation, and thereby accelerate hepatocarcinogenesis. The effects of HBx on cyclin D1 stabilization were assessed in cell-based transfection, Western blot, immunoprecipitation, immunocytofluorescence staining, and flow-cytometric assays. The results demonstrated that ectopic expression of HBx in HCC cells could extend the half-life of cyclin D1 protein from 40-60 minutes to 80-110 minutes. HBx stabilized cyclin D1 primarily in the S phase of the cell cycle, in a manner dependent on the inactivation of GSK-3β, which was mediated by ERK activation. HBx also prompted the nuclear accumulation of cyclin D1, and cotransfection of the constitutively active mutant of GSK-3β along with HBx could reverse the nuclear accumulation and subsequent cell proliferation induced by HBx. Further, a positive correlation between HBx and nuclear cyclin D1 level was established in HCC specimens detected by an immunohistochemical assay. Taken together, our results indicated that HBx could stabilize and increase cyclin D1 nuclear accumulation through ERK-mediated inactivation of GSK-3β. This HBx-induced cyclin D1 upregulation might play an important role in HCC development and progression.
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Affiliation(s)
- Xiangmei Chen
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | - Ling Zhang
- Department of Hepatobiliary Surgery, Henan Cancer Hospital, Zhengzhou, P.R. China
| | - Sujun Zheng
- Beijing YouAn hospital, Capital Medical University, Beijing, P.R. China
| | - Ting Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | - Meng Li
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | - Xiaolei Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | - Zhenzhen Zeng
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | | | - Jingmin Zhao
- Department of Pathology, Institute of Infectious Diseases, Beijing 302 Hospital, Beijing, P.R. China
| | - Hui Zhuang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China
| | - Fengmin Lu
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, Beijing, P.R. China.
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19
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Ahuja R, Kapoor NR, Kumar V. The HBx oncoprotein of hepatitis B virus engages nucleophosmin to promote rDNA transcription and cellular proliferation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1783-95. [PMID: 25918010 DOI: 10.1016/j.bbamcr.2015.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 04/10/2015] [Accepted: 04/14/2015] [Indexed: 12/31/2022]
Abstract
The pleiotropic HBx oncoprotein of hepatitis B virus is well known to promote the expression of ribosomal RNAs and several host proteins that are known to support the development and progression of hepatocellular carcinoma (HCC). While overexpression of the nucleolar phosphoprotein, nucleophosmin (NPM), correlates with HCC progression, its upregulation by viral HBx and the resulting impact on perturbed nucleolar functions remain enigmatic. The present study shows that HBx up-regulates NPM levels and hijacks its functions to promote cellular proliferation. We found that HBx expression stabilizes NPM through post-translational modifications. Enhanced CDK2-mediated phosphorylation of NPM at Thr199 upon HBx expression prevented its proteolytic cleavage and provided resistance to apoptosis. Further, HBx directly interacted with the C-terminal domain of NPM and got translocated into the nucleolus where it facilitated the recruitment of RNA polymerase I transcriptional machinery onto the rDNA promoter. Our results indicate that HBx enhances rDNA transcription via a novel regulatory mechanism involving acetylation of NPM and the subsequent depletion of histones from the rDNA promoter. Enhanced production of ribosomal RNA resulting from co-expression of HBx and NPM promoted ribosome biogenesis, cellular proliferation and transformation. Taken together, our study strongly suggests an important role of NPM in mediating the oncogenic effects of HBx and the corresponding nucleolar perturbations induced by this viral oncoprotein.
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Affiliation(s)
- Richa Ahuja
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Neetu Rohit Kapoor
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Vijay Kumar
- Virology Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi 110067, India.
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20
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Zeng Z, Tu J, Cheng J, Yao M, Wu Y, Huang X, Xie X, Zhang X, Lu F, Chen X. Influence of CCND1 G870A polymorphism on the risk of HBV-related HCC and cyclin D1 splicing variant expression in Chinese population. Tumour Biol 2015; 36:6891-900. [PMID: 25851350 PMCID: PMC4644212 DOI: 10.1007/s13277-015-3401-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/26/2015] [Indexed: 01/15/2023] Open
Abstract
The G870A polymorphism in the exon 4/intron 4 boundary of CCND1 gene is thought to influence the generation of two mRNAs (cyclin D1a and cyclin D1b). The "A" allele codes for a truncated variant, cyclin D1b, which may have higher transforming activity. Herein, the tumor relevance of G870A polymorphism, the association between cyclin D1 variant expression and G870A genotype, and the oncogenic potential of cyclin D1 variants in HBV-related hepatocellular carcinoma (HCC) were examined. We found that there is no significant difference of G870A distribution among the HCC, chronic HBV (CHB) infection, cirrhotic CHB, and healthy control groups. Stratification analysis revealed that in younger patients (ages ≤ 50), cirrhotic CHB patients with AA genotype had an increased risk of developing HCC with odds ratio of 1.943 (95 % CI 1.022-3.694, p = 0.0411) as compared with AG/GG genotypes. The two variants were both transcripted from "A" and "G" alleles, and neither cyclin D1a nor D1b production was influenced by G870A genotype in HCC. The expression of both cyclins D1a and D1b decreased in HCC tissues (p = 0.003, p = 0.005), while increased in adjacent nontumor tissues as compared with normal liver tissues (p = 0.045, p = 0.034). Overexpression of cyclin D1a or D1b could promote the cell proliferation and cell-cycle progression in Huh-7 and LO2 cell lines. Collectively, our data suggest that G870A polymorphism has only very limited predictive value for HBV-related HCC. Both cyclins D1a and D1b could promote cell proliferation, which might contribute to the potential oncogenic role of cyclin D1 variants during the precancerous cirrhotic stage of hepatocarcinogenesis.
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Affiliation(s)
- Zhenzhen Zeng
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Jing Tu
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Jin Cheng
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Mingjie Yao
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Yali Wu
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Xiangbo Huang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Xiaomeng Xie
- Department of Epidemiology and Statistics, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Xiaolei Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Fengmin Lu
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China
| | - Xiangmei Chen
- Department of Microbiology and Infectious Disease Center, School of Basic Medical Science, Peking University Health Science Center, 38 Xueyuan Road, Beijing, 100191, China.
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21
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Ji X, Zhang Q, Du Y, Liu W, Li Z, Hou X, Cao G. Somatic mutations, viral integration and epigenetic modification in the evolution of hepatitis B virus-induced hepatocellular carcinoma. Curr Genomics 2015; 15:469-80. [PMID: 25646075 PMCID: PMC4311391 DOI: 10.2174/1389202915666141114213833] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 11/11/2014] [Accepted: 11/14/2014] [Indexed: 02/08/2023] Open
Abstract
Liver cancer in men is the second leading cause of cancer death and hepatocellular carcinoma (HCC) accounts for 70%-85% of the total liver cancer worldwide. Chronic infection with hepatitis B virus (HBV) is the major cause of HCC. Chronic, intermittently active inflammation provides “fertile field” for “mutation, selection, and adaptation” of HBV and the infected hepatocytes, a long-term evolutionary process during HBV-induced carcinogenesis. HBV mutations, which are positively selected by insufficient immunity, can promote and predict the occurrence of HCC. Recently, advanced sequencing technologies including whole genome sequencing, exome sequencing, and RNA sequencing provide opportunities to better under-stand the insight of how somatic mutations, structure variations, HBV integrations, and epigenetic modifications contribute to HCC development. Genomic variations of HCC caused by various etiological factors may be different, but the common driver mutations are important to elucidate the HCC evolutionary process. Genome-wide analyses of HBV integrations are helpful in clarifying the targeted genes of HBV in carcinogenesis and disease progression. RNA sequencing can identify key molecules whose expressions are epigenetically modified during HCC evolution. In this review, we summarized the current findings of next generation sequencings for HBV-HCC and proposed a theory framework of Cancer Evolution and Development based on the current knowledge of HBV-induced HCC to characterize and interpret evolutionary mechanisms of HCC and possible other cancers. Understanding the key viral and genomic variations involved in HCC evolution is essential for generating effective diagnostic, prognostic, and predictive biomarkers as well as therapeutic targets for the interventions of HBV-HCC.
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Affiliation(s)
- Xiaowei Ji
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Qi Zhang
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Yan Du
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Wenbin Liu
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Zixiong Li
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Xiaomei Hou
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
| | - Guangwen Cao
- Department of Epidemiology, Second Military Medical University, Shanghai 200433, China
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22
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Zhang XD, Wang Y, Ye LH. Hepatitis B virus X protein accelerates the development of hepatoma. Cancer Biol Med 2014; 11:182-90. [PMID: 25364579 PMCID: PMC4197427 DOI: 10.7497/j.issn.2095-3941.2014.03.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 06/02/2014] [Indexed: 12/12/2022] Open
Abstract
The chronic infection of hepatitis B virus (HBV) is closely related to the occurrence and development of hepatocellular carcinoma (HCC). Accumulated evidence has shown that HBV X protein (HBx protein) is a multifunctional regulator with a crucial role in hepatocarcinogenesis. However, information on the mechanism by which HBV induces HCC is lacking. This review focuses on the pathological functions of HBx in HBV-induced hepatocarcinogenesis. As a transactivator, HBx can modulate nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transcription factor AP-2. Moreover, HBx can affect regulatory non-coding RNAs (ncRNAs) including microRNAs and long ncRNAs (lncRNAs), such as miRNA-205 and highly upregulated in liver cancer (HULC), respectively. HBx is also involved in epigenetic modification, including methylation and acetylation. HBx interacts with various signal-transduction pathways, such as protein kinase B/Akt, Wnt/β-catenin, signal transducer and activator of transcription, and NF-κB pathways. Moreover, HBx affects cellular fate by shifting the balance toward cell survival. HBx may lead to the loss of apoptotic functions or directly contributes to oncogenesis by achieving transforming functions, which induce hepatocarcinogenesis. Additionally, HBx can modulate apoptosis and immune response by direct or indirect interaction with host factors. We conclude that HBx hastens the development of hepatoma.
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Affiliation(s)
- Xiao-Dong Zhang
- 1 Department of Cancer Research, 2 Department of Biochemistry, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
| | - Yuan Wang
- 1 Department of Cancer Research, 2 Department of Biochemistry, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
| | - Li-Hong Ye
- 1 Department of Cancer Research, 2 Department of Biochemistry, College of Life Sciences, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
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23
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Zheng BY, Fang XF, Zou LY, Huang YH, Chen ZX, Li D, Zhou LY, Chen H, Wang XZ. The co-localization of HBx and COXIII upregulates COX-2 promoting HepG2 cell growth. Int J Oncol 2014; 45:1143-50. [PMID: 24938358 DOI: 10.3892/ijo.2014.2499] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Accepted: 05/27/2014] [Indexed: 11/06/2022] Open
Abstract
HBx is a multifunctional regulator that interacts with host factors to contribute to the development of hepatocellular carcinoma. In this study, to explore the co-localization of HBx and COXIII in HepG2 cells and to investigate the molecular mechanism of HBx in HepG2 cell growth promotion, we first constructed a HepG2 cell line stably expressing the HBx gene in vitro by lentivirus vectors. In addition, we found that HBx co-localized with the inner mitochondrial protein, COXIII, in HepG2 cells by confocal laser scanning microscopy. It led to changes of mitochondrial biogenesis and morphology, including upregulation of COXIII protein expression, increased cytochrome c oxidase activity and higher mitochondrial membrane potential. The upregulation of COX-2 caused by HBx through generation of mitochondrial reactive oxygen species promoted cell growth. Thus, we conclude that co-localization of HBx and COXIII leads to upregulation of COX-2 that promotes HepG2 cell growth. Such a mechanism provides deeper insights into the molecular mechanism of HBV-associated hepatocellular carcinoma.
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Affiliation(s)
- Bi-Yun Zheng
- Graduate School, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Xue-Fen Fang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Lai-Yu Zou
- Department of Infection, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Yue-Hong Huang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Zhi-Xin Chen
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Dan Li
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Lin-Ying Zhou
- Laboratory of Electron Microscopy, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Hao Chen
- Department of Gastroenterology, The Third Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian 350108, P.R. China
| | - Xiao-Zhong Wang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
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24
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Hai H, Tamori A, Kawada N. Role of hepatitis B virus DNA integration in human hepatocarcinogenesis. World J Gastroenterol 2014; 20:6236-6243. [PMID: 24876744 PMCID: PMC4033461 DOI: 10.3748/wjg.v20.i20.6236] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Revised: 12/14/2013] [Accepted: 01/15/2014] [Indexed: 02/06/2023] Open
Abstract
Liver cancer ranks sixth in cancer incidence, and is the third leading cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, which arises from hepatocytes and accounts for approximately 70%-85% of cases. Hepatitis B virus (HBV) frequently causes liver inflammation, hepatic damage and subsequent cirrhosis. Integrated viral DNA is found in 85%-90% of HBV-related HCCs. Its presence in tumors from non-cirrhotic livers of children or young adults further supports the role of viral DNA integration in hepatocarcinogenesis. Integration of subgenomic HBV DNA fragments into different locations within the host DNA is a significant feature of chronic HBV infection. Integration has two potential consequences: (1) the host genome becomes altered (“cis” effect); and (2) the HBV genome becomes altered (“trans” effect). The cis effect includes insertional mutagenesis, which can potentially disrupt host gene function or alter host gene regulation. Tumor progression is frequently associated with rearrangement and partial gain or loss of both viral and host sequences. However, the role of integrated HBV DNA in hepatocarcinogenesis remains controversial. Modern technology has provided a new paradigm to further our understanding of disease mechanisms. This review summarizes the role of HBV DNA integration in human carcinogenesis.
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25
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Xie N, Chen X, Zhang T, Liu B, Huang C. Using proteomics to identify the HBx interactome in hepatitis B virus: how can this inform the clinic? Expert Rev Proteomics 2013; 11:59-74. [PMID: 24308553 DOI: 10.1586/14789450.2014.861745] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
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.
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Affiliation(s)
- Na Xie
- The State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, 610041, P.R. China
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Xu C, Zhou W, Wang Y, Qiao L. Hepatitis B virus-induced hepatocellular carcinoma. Cancer Lett 2013; 345:216-22. [PMID: 23981576 DOI: 10.1016/j.canlet.2013.08.035] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/10/2013] [Accepted: 08/18/2013] [Indexed: 12/12/2022]
Abstract
Many factors are considered to contribute to hepatitis B virus (HBV) associated hepatocellular carcinoma (HCC), including products of HBV, HBV integration and mutation, and host susceptibility. HBV X protein (HBx) can interfere with several signal pathways that associated with cell proliferation and apoptosis, and the impact of HBx C-terminal truncation in the development of HCC has been implicated. Recent studies by advanced sequencing technologies have revealed recurrent HBV DNA integration sites in hepatoma cells and susceptible genes/SNPs play an important role in the pathogenesis of liver cancer. Epigenetic changes, immune and inflammatory factors are also important contributing factors for liver cancer. This mini-review provides an overview on the recent development of HBV induced HCC.
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Affiliation(s)
- Cheng Xu
- Institute for Infectious Diseases, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Wence Zhou
- The Department of General Surgery II, The First Hospital of Lanzhou University, Lanzhou 730000, Gansu Province, China
| | - Yuming Wang
- Institute for Infectious Diseases, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
| | - Liang Qiao
- Storr Liver Unit, University of Sydney, Westmead Millennium Institute, Westmead Hospital, Westmead, NSW 2145, Australia.
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Keating JA, Bhattacharya D, Lim PY, Falk S, Weisblum B, Bernard KA, Sharma M, Kuhn RJ, Striker R. West Nile virus methyltransferase domain interacts with protein kinase G. Virol J 2013; 10:242. [PMID: 23876037 PMCID: PMC3725163 DOI: 10.1186/1743-422x-10-242] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 07/11/2013] [Indexed: 11/10/2022] Open
Abstract
Background The flaviviral nonstructural protein 5 (NS5) is a phosphoprotein, though the precise identities and roles of many specific phosphorylations remain unknown. Protein kinase G (PKG), a cGMP-dependent protein kinase, has previously been shown to phosphorylate dengue virus NS5. Methods We used mass spectrometry to specifically identify NS5 phosphosites. Co-immunoprecipitation assays were used to study protein-protein interactions. Effects on viral replication were measured via replicon system and plaque assay titering. Results We identified multiple sites in West Nile virus (WNV) NS5 that are phosphorylated during a WNV infection, and showed that the N-terminal methyltransferase domain of WNV NS5 can be specifically phosphorylated by PKG in vitro. Expressing PKG in cell culture led to an enhancement of WNV viral production. We hypothesized this effect on replication could be caused by factors beyond the specific phosphorylations of NS5. Here we show for the first time that PKG is also able to stably interact with a viral substrate, WNV NS5, in cell culture and in vitro. While the mosquito-borne WNV NS5 interacted with PKG, tick-borne Langat virus NS5 did not. The methyltransferase domain of NS5 is able to mediate the interaction between NS5 and PKG, and mutating positive residues in the αE region of the methyltransferase interrupts the interaction. These same mutations completely inhibited WNV replication. Conclusions PKG is not required for WNV replication, but does make a stable interaction with NS5. While the consequence of the NS5:PKG interaction when it occurs is unclear, mutational data demonstrates that this interaction occurs in a region of NS5 that is otherwise necessary for replication. Overall, the results identify an interaction between virus and a cellular kinase and suggest a role for a host kinase in enhancing flaviviral replication.
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Affiliation(s)
- Julie A Keating
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA
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Swarnalatha M, Singh AK, Kumar V. Promoter occupancy of MLL1 histone methyltransferase seems to specify the proliferative and apoptotic functions of E2F1 in a tumour microenvironment. J Cell Sci 2013; 126:4636-46. [PMID: 23868976 DOI: 10.1242/jcs.126235] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The E2F family of transcription factors are considered versatile modulators, poised at biological crossroads to execute diverse cellular functions. Despite extensive studies on E2F, the molecular mechanisms that control specific biological functions of the E2F1 transcription factor are still not fully understood. Here we have addressed the molecular underpinnings of paradoxical functions of E2F1 in a tumour microenvironment using the 'X15-myc' oncomouse model of hepatocellular carcinoma. We observed that the HBx oncoprotein of hepatitis B virus regulates E2F1 functions by interfering with its binding to Skp2 E3 ubiquitin ligase. The HBx-Skp2 interaction led to the accumulation of transcriptionally active E2F1 and histone methyltransferase mixed lineage leukemia 1 (MLL1) protein. During early stages of hepatocarcinogenesis, the increased E2F1 activity promoted cellular proliferation by stimulating the genes involved in cell cycle control and replication. However, during the late stages, E2F1 triggered replication-stress-induced DNA damage and sensitized cells to apoptotic death in a p53-independent manner. Interestingly, the different promoter occupancy of MLL1 during the early and late stages of tumour development seemed to specify the proliferative and apoptotic functions of E2F1, through its dynamic interaction with the co-activator CBP or co-repressor Brg1. Thus, the temporally regulated promoter occupancy of histone methyltransferase could be a regulatory mechanism associated with the diverse cellular functions of the E2F family of transcription factors.
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Affiliation(s)
- Manickavinayaham Swarnalatha
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
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Varicella-zoster virus ORF12 protein activates the phosphatidylinositol 3-kinase/Akt pathway to regulate cell cycle progression. J Virol 2012. [PMID: 23192871 DOI: 10.1128/jvi.02395-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) activates the phosphatidylinositol 3-kinase (PI3K)/Akt pathway and alters cell cycle progression, but the viral protein(s) responsible for these activities is unknown. We previously reported that the VZV open reading frame 12 (ORF12) protein triggers phosphorylation of ERK. Here, we demonstrate that the VZV ORF12 protein also activates the PI3K/Akt pathway to regulate cell cycle progression. Transfection of cells with a plasmid expressing the ORF12 protein induced phosphorylation of Akt, which was dependent on PI3K. Infection of cells with wild-type VZV triggered phosphorylation of Akt, while infection with an ORF12 deletion mutant induced less phosphorylated Akt. The activation of Akt by ORF12 protein was associated with its binding to the p85 subunit of PI3K. Infection of cells with wild-type VZV resulted in increased levels of cyclin B1, cyclin D3, and phosphorylated glycogen synthase kinase 3β (GSK-3β), while infection with the ORF12 deletion mutant induced lower levels of these proteins. Wild-type VZV infection reduced the G(1) phase cell population and increased the M phase cell population, while infection with the ORF12 deletion mutant had a reduced effect on the G(1) and M phase populations. Inhibition of Akt activity with LY294002 reduced the G(1) and M phase differences observed in cells infected with wild-type and ORF12 mutant viruses. In conclusion, we have found that the VZV ORF12 protein activates the PI3K/Akt pathway to regulate cell cycle progression. Since VZV replicates in both dividing (e.g., keratinocytes) and nondividing (neurons) cells, the ability of the VZV ORF12 protein to regulate the cell cycle is likely important for VZV replication in various cell types in the body.
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Hernández S, Venegas M, Brahm J, Villanueva RA. The viral transactivator HBx protein exhibits a high potential for regulation via phosphorylation through an evolutionarily conserved mechanism. Infect Agent Cancer 2012; 7:27. [PMID: 23079056 PMCID: PMC3533737 DOI: 10.1186/1750-9378-7-27] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 09/20/2012] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED BACKGROUND Hepatitis B virus (HBV) encodes an oncogenic factor, HBx, which is a multifunctional protein that can induce dysfunctional regulation of signaling pathways, transcription, and cell cycle progression, among other processes, through interactions with target host factors. The subcellular localization of HBx is both cytoplasmic and nuclear. This dynamic distribution of HBx could be essential to the multiple roles of the protein at different stages during HBV infection. Transactivational functions of HBx may be exerted both in the nucleus, via interaction with host DNA-binding proteins, and in the cytoplasm, via signaling pathways. Although there have been many studies describing different pathways altered by HBx, and its innumerable binding partners, the molecular mechanism that regulates its different roles has been difficult to elucidate. METHODS In the current study, we took a bioinformatics approach to investigate whether the viral protein HBx might be regulated via phosphorylation by an evolutionarily conserved mechanism. RESULTS We found that the phylogenetically conserved residues Ser25 and Ser41 (both within the negative regulatory domain), and Thr81 (in the transactivation domain) are predicted to be phosphorylated. By molecular 3D modeling of HBx, we further show these residues are all predicted to be exposed on the surface of the protein, making them easily accesible to these types of modifications. Furthermore, we have also identified Yin Yang sites that might have the potential to be phosphorylated and O-β-GlcNAc interplay at the same residues. CONCLUSIONS Thus, we propose that the different roles of HBx displayed in different subcellular locations might be regulated by an evolutionarily conserved mechanism of posttranslational modification, via phosphorylation.
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Affiliation(s)
- Sergio Hernández
- Laboratorio de Virus Hepatitis, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avda. República 217, 3er piso, Santiago 8370146, Chile
| | - Mauricio Venegas
- Sección de Gastroenterología, Departamento de Medicina, Hospital Clínico Universidad de Chile, Avda. Santos Dumont 999, Independencia, Santiago 8340457, Chile
| | - Javier Brahm
- Sección de Gastroenterología, Departamento de Medicina, Hospital Clínico Universidad de Chile, Avda. Santos Dumont 999, Independencia, Santiago 8340457, Chile
| | - Rodrigo A Villanueva
- Laboratorio de Virus Hepatitis, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avda. República 217, 3er piso, Santiago 8370146, Chile
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