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Bekker S, Potgieter CA, van Staden V, Theron J. Investigating the Role of African Horse Sickness Virus VP7 Protein Crystalline Particles on Virus Replication and Release. Viruses 2022; 14:2193. [PMID: 36298748 DOI: 10.3390/v14102193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/19/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022] Open
Abstract
African horse sickness is a deadly and highly infectious disease of equids, caused by African horse sickness virus (AHSV). AHSV is one of the most economically important members of the Orbivirus genus. AHSV is transmitted by the biting midge, Culicoides, and therefore replicates in both insect and mammalian cell types. Structural protein VP7 is a highly conserved major core protein of orbiviruses. Unlike any other orbivirus VP7, AHSV VP7 is highly insoluble and forms flat hexagonal crystalline particles of unknown function in AHSV-infected cells and when expressed in mammalian or insect cells. To examine the role of AHSV VP7 in virus replication, a plasmid-based reverse genetics system was used to generate a recombinant AHSV that does not form crystalline particles. We characterised the role of VP7 crystalline particle formation in AHSV replication in vitro and found that soluble VP7 interacted with viral proteins VP2 and NS2 similarly to wild-type VP7 during infection. Interestingly, soluble VP7 was found to form uncharacteristic tubule-like structures in infected cells which were confirmed to be as a result of unique VP7-NS1 colocalisation. Furthermore, it was found that VP7 crystalline particles play a role in AHSV release and yield. This work provides insight into the role of VP7 aggregation in AHSV cellular pathogenesis and contributes toward the understanding of the possible effects of viral protein aggregation in other human virus-borne diseases.
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Siddiqui ZI, Azam SA, Khan WH, Afroz M, Farooqui SR, Amir F, Azmi MI, Anwer A, Khan S, Mehmankhah M, Parveen S, Kazim SN. An in vitro Study on the Role of Hepatitis B Virus X Protein C-Terminal Truncation in Liver Disease Development. Front Genet 2021; 12:633341. [PMID: 33777103 PMCID: PMC7994528 DOI: 10.3389/fgene.2021.633341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/02/2021] [Indexed: 11/13/2022] Open
Abstract
Hepatitis B virus X protein C-terminal 127 amino acid truncation is often found expressed in hepatocellular carcinoma (HCC) tissue samples. The present in vitro study tried to determine the role of this truncation mutant in the hepatitis B-related liver diseases such as fibrosis, cirrhosis, HCC, and metastasis. HBx gene and its 127 amino acid truncation mutant were cloned in mammalian expression vectors and transfected in human hepatoma cell line. Changes in cell growth/proliferation, cell cycle phase distribution, expression of cell cycle regulatory genes, mitochondrial depolarization, and intracellular reactive oxygen species (ROS) level were analyzed. Green fluorescent protein (GFP)-tagged version of HBx and the truncation mutant were also created and the effects of truncation on HBx intracellular expression pattern and localization were studied. Effect of time lapse on protein expression pattern was also analyzed. The truncation mutant of HBx is more efficient in inducing cell proliferation, and causes more ROS production and less mitochondrial depolarization as compared with wild type (wt) HBx. In addition, gene expression is altered in favor of carcinogenesis in the presence of the truncation mutant. Furthermore, mitochondrial perinuclear aggregation is achieved earlier in the presence of the truncation mutant. Therefore, HBx C-terminal 127 amino acid truncation might be playing important roles in the development of hepatitis B-related liver diseases by inducing cell proliferation, altering gene expression, altering mitochondrial potential, inducing mitochondrial clustering and oxidative stress, and changing HBx expression pattern.
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Affiliation(s)
- Zaheenul Islam Siddiqui
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.,Department of Microbiology, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Syed Ali Azam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Wajihul Hasan Khan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Masarrat Afroz
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Sabihur Rahman Farooqui
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Fatima Amir
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Md Iqbal Azmi
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Ayesha Anwer
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Saniya Khan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Mahboubeh Mehmankhah
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Shama Parveen
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Syed Naqui Kazim
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
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Yoo YS, Park YJ, Lee HS, Oanh NTK, Cho MY, Heo J, Lee ES, Cho H, Park YY, Cho H. Mitochondria ubiquitin ligase, MARCH5 resolves hepatitis B virus X protein aggregates in the liver pathogenesis. Cell Death Dis 2019; 10:938. [PMID: 31819032 DOI: 10.1038/s41419-019-2175-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 11/26/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022]
Abstract
Infection of hepatitis B virus (HBV) increase the incidence of chronic liver disease and hepatocellular carcinoma (HCC). The hepatitis B viral x (HBx) protein encoded by the HBV genome contributes to the pathogenesis of HCC and thus, negative regulation of HBx is beneficial for the alleviation of the disease pathogenesis. MARCH5 is a mitochondrial E3 ubiquitin ligase and here, we show that high MARCH5 expression levels are correlated with improved survival in HCC patients. MARCH5 interacts with HBx protein mainly accumulated in mitochondria and targets it for degradation. The N-terminal RING domain of MARCH5 was required for the interaction with HBx, and MARCH5H43W lacking E3 ligase activity failed to reduce HBx protein levels. High expression of HBx results in the formation of protein aggregates in semi-denaturing detergent agarose gels and MARCH5 mediates the elimination of protein aggregates through the proteasome pathway. HBx-induced ROS production, mitophagy, and cyclooxygenase-2 gene expression were suppressed in the presence of high MARCH5 expression. These results suggest MARCH5 as a target for alleviating HBV-mediated liver disease.
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Lee AR, Lim KH, Park ES, Kim DH, Park YK, Park S, Kim DS, Shin GC, Kang HS, Won J, Sim H, Ha YN, Jae B, Choi SI, Kim KH. Multiple Functions of Cellular FLIP Are Essential for Replication of Hepatitis B Virus. J Virol 2018; 92:e00339-18. [PMID: 29875248 DOI: 10.1128/JVI.00339-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 05/24/2018] [Indexed: 02/06/2023] Open
Abstract
Hepatitis B virus (HBV) infection is a leading cause of liver diseases; however, the host factors which facilitate the replication and persistence of HBV are largely unidentified. Cellular FLICE inhibitory protein (c-FLIP) is a typical antiapoptotic protein. In many cases of liver diseases, the expression level of c-FLIP is altered, which affects the fate of hepatocytes. We previously found that c-FLIP and its cleaved form interact with HBV X protein (HBx), which is essential for HBV replication, and regulate diverse cellular signals. In this study, we investigated the role of endogenous c-FLIP in HBV replication and its underlying mechanisms. The knockdown of endogenous c-FLIP revealed that this protein regulates HBV replication through two different mechanisms. (i) c-FLIP interacts with HBx and protects it from ubiquitin-dependent degradation. The N-terminal DED1 domain of c-FLIP is required for HBx stabilization. (ii) c-FLIP regulates the expression or stability of hepatocyte nuclear factors (HNFs), which have critical roles in HBV transcription and maintenance of hepatocytes. c-FLIP regulates the stability of HNFs through physical interactions. We verified our findings in three HBV infection systems: HepG2-NTCP cells, differentiated HepaRG cells, and primary human hepatocytes. In conclusion, our results identify c-FLIP as an essential factor in HBV replication. c-FLIP regulates viral replication through its multiple effects on viral and host proteins that have critical roles in HBV replication.IMPORTANCE Although the chronic hepatitis B virus (HBV) infection still poses a major health concern, the host factors which are required for the replication of HBV are largely uncharacterized. Our studies identify cellular FLICE inhibitory protein (c-FLIP) as an essential factor in HBV replication. We found the dual roles of c-FLIP in regulation of HBV replication: c-FLIP interacts with HBx and enhances its stability and regulates the expression or stability of hepatocyte nuclear factors which are essential for transcription of HBV genome. Our findings may provide a new target for intervention in persistent HBV infection.
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Abstract
Hepatocyte apoptosis plays important roles in both the removal of external microorganisms and the occurrence and development of liver diseases. Different conditions, such as virus infection, fatty liver disease, hepatic ischemia reperfusion, and drug-induced liver injury, are accompanied by hepatocyte apoptosis. This review summarizes recent research on the mechanism of hepatocyte apoptosis involving the classical extrinsic and intrinsic apoptotic pathways, endoplasmic reticulum stress, and oxidative stress-induced apoptosis. We emphasized the major causes of apoptosis according to the characteristics of different liver diseases. Several concerns regarding future research and clinical application are also raised.
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Affiliation(s)
- Lei Cao
- Research Center on Aging and Medicine, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xi-Bing Quan
- Research Center on Aging and Medicine, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Wen-Jiao Zeng
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Xiao-Ou Yang
- Department of Gastroenterology, Peking Union Medical College Hospital, Beijing, China
| | - Ming-Jie Wang
- Research Center on Aging and Medicine, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, China
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Minor MM, Slagle BL. Hepatitis B virus HBx protein interactions with the ubiquitin proteasome system. Viruses 2014; 6:4683-702. [PMID: 25421893 DOI: 10.3390/v6114683] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 11/16/2014] [Accepted: 11/20/2014] [Indexed: 01/04/2023] Open
Abstract
The hepatitis B virus (HBV) causes acute and chronic hepatitis, and the latter is a major risk factor for the development of hepatocellular carcinoma (HCC). HBV encodes a 17-kDa regulatory protein, HBx, which is required for virus replication. Although the precise contribution(s) of HBx to virus replication is unknown, many viruses target cellular pathways to create an environment favorable for virus replication. The ubiquitin proteasome system (UPS) is a major conserved cellular pathway that controls several critical processes in the cell by regulating the levels of proteins involved in cell cycle, DNA repair, innate immunity, and other processes. We summarize here the interactions of HBx with components of the UPS, including the CUL4 adaptor DDB1, the cullin regulatory complex CSN, and the 26S proteasome. Understanding how these protein interactions benefit virus replication remains a challenge due to limited models in which to study HBV replication. However, studies from other viral systems that similarly target the UPS provide insight into possible strategies used by HBV.
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Abstract
Recent evidence suggests that proliferating cells polarize damaged proteins during mitosis to protect one cell from aging, and that the structural conformation of damaged proteins mediates their toxicity. We report that the growth, resistance to stress, and differentiation characteristics of a cancer cell line (PC12) with an inducible Huntingtin (Htt) fused to enhanced green fluorescent protein (GFP) are dependent on the conformation of Htt. Cell progeny containing inclusion bodies have a longer cell cycle and increased resistance to stress than those with diffuse Htt. Using live imaging, we demonstrate that asymmetric division resulting from a cell containing a single inclusion body produces sister cells with different fates. The cell that receives the inclusion body has decreased proliferation and increased differentiation compared with its sister cell without Htt. This is the first report that reveals a functional consequence of the asymmetric division of damaged proteins in mammalian cells, and we suggest that this is a result of inclusion body-induced proteasome impairment.
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Affiliation(s)
- Mary Rose Bufalino
- Department of Medical Biophysics; University of Toronto; Toronto, Ontario, Canada
| | - Derek van der Kooy
- Department of Medical Biophysics; University of Toronto; Toronto, Ontario, Canada; Department of Molecular Genetics; University of Toronto; Toronto, Ontario, Canada
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Lim KH, Kim KH, Choi SI, Park ES, Park SH, Ryu K, Park YK, Kwon SY, Yang SI, Lee HC, Sung IK, Seong BL. RPS3a over-expressed in HBV-associated hepatocellular carcinoma enhances the HBx-induced NF-κB signaling via its novel chaperoning function. PLoS One 2011; 6:e22258. [PMID: 21857917 PMCID: PMC3156704 DOI: 10.1371/journal.pone.0022258] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Accepted: 06/18/2011] [Indexed: 12/15/2022] Open
Abstract
Hepatitis B virus (HBV) infection is one of the major causes of hepatocellular carcinoma (HCC) development. Hepatitis B virus X protein (HBx) is known to play a key role in the development of hepatocellular carcinoma (HCC). Several cellular proteins have been reported to be over-expressed in HBV-associated HCC tissues, but their role in the HBV-mediated oncogenesis remains largely unknown. Here, we explored the effect of the over-expressed cellular protein, a ribosomal protein S3a (RPS3a), on the HBx-induced NF-κB signaling as a critical step for HCC development. The enhancement of HBx-induced NF-κB signaling by RPS3a was investigated by its ability to translocate NF-κB (p65) into the nucleus and the knock-down analysis of RPS3a. Notably, further study revealed that the enhancement of NF-κB by RPS3a is mediated by its novel chaperoning activity toward physiological HBx. The over-expression of RPS3a significantly increased the solubility of highly aggregation-prone HBx. This chaperoning function of RPS3a for HBx is closely correlated with the enhanced NF-κB activity by RPS3a. In addition, the mutational study of RPS3a showed that its N-terminal domain (1–50 amino acids) is important for the chaperoning function and interaction with HBx. The results suggest that RPS3a, via extra-ribosomal chaperoning function for HBx, contributes to virally induced oncogenesis by enhancing HBx-induced NF-κB signaling pathway.
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Affiliation(s)
- Keo-Heun Lim
- Department of Biotechnology, College of Life science and Biotechnology, Yonsei University, Seoul, Korea
| | - Kyun-Hwan Kim
- Department of Pharmacology, IBST, Konkuk University School of Medicine, Seoul, Korea
- Research Institute of Medical Sciences, Konkuk University, Seoul, Korea
- * E-mail: (BLS); (K-HK)
| | - Seong Il Choi
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, Korea
| | - Eun-Sook Park
- Department of Pharmacology, IBST, Konkuk University School of Medicine, Seoul, Korea
| | - Seung Hwa Park
- Department of Anatomy and Center for Cancer Research and Diagnostic Medicine, IBST, Konkuk University School of Medicine, Seoul, Korea
| | - Kisun Ryu
- Department of Biotechnology, College of Life science and Biotechnology, Yonsei University, Seoul, Korea
| | - Yong Kwang Park
- Department of Pharmacology, IBST, Konkuk University School of Medicine, Seoul, Korea
| | - So Young Kwon
- Department of Internal Medicine, IBST, Konkuk University School of Medicine, Seoul, Korea
| | - Sung-Il Yang
- Department of Pharmacology, IBST, Konkuk University School of Medicine, Seoul, Korea
- Research Institute of Medical Sciences, Konkuk University, Seoul, Korea
| | - Han Chu Lee
- Department of Internal Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
| | - In-Kyung Sung
- Department of Internal Medicine, IBST, Konkuk University School of Medicine, Seoul, Korea
| | - Baik L. Seong
- Department of Biotechnology, College of Life science and Biotechnology, Yonsei University, Seoul, Korea
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, Korea
- * E-mail: (BLS); (K-HK)
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Keasler VV, Hodgson AJ, Madden CR, Slagle BL. Hepatitis B virus HBx protein localized to the nucleus restores HBx-deficient virus replication in HepG2 cells and in vivo in hydrodynamically-injected mice. Virology 2009; 390:122-9. [PMID: 19464721 DOI: 10.1016/j.virol.2009.05.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2009] [Revised: 04/10/2009] [Accepted: 05/02/2009] [Indexed: 12/12/2022]
Abstract
Identifying the requirements for the regulatory HBx protein in hepatitis B virus (HBV) replication is an important goal. A plasmid-based HBV replication assay was used to evaluate whether HBx subcellular localization influences its ability to promote virus replication, as measured by real time PCR quantitation of viral capsid-associated DNA. HBx targeted to the nucleus by a nuclear localization signal (NLS-HBx) was able to restore HBx-deficient HBV replication, while HBx containing a nuclear export signal (NES-HBx) was not. Both NLS-HBx and NES-HBx were expressed at similar levels (by immunoprecipitation and Western blotting), and proper localization of the signal sequence-tagged proteins was confirmed by deconvolution microscopy using HBx, NLS-HBx, and NES-HBx proteins fused to GFP. Importantly, these findings were confirmed in vivo by hydrodynamic injection into mice. Our results demonstrate that in these HBV replication assays, at least one function of HBx requires its localization to the nucleus.
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Affiliation(s)
- Victor V Keasler
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030-3411, USA
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Abstract
The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural protein that, after postranslation modification, is secreted and constitutes the "e" antigen (HBeAg); ORF P, which encodes the viral polymerase (polyprotein with DNA polymerase activity, reverse transcriptase and RNAase), and ORF X, which encodes a protein that acts as a multifunctional regulator for both the viral and cell cycles. HBV has a mutation rate of 1.4-3.2 x 105 substitutions/nucleotide/year. As a result of this variability, the virus circulates as a complex mixture of genetic variants, constituting a semi-species, that evolves throughout the infection depending on the evolutionary pressure of factors such as the immune response and antiviral treatments. Based on this variability, HBV has been classified into 8 genotypes (A-H) defined by a difference of more than 8% in the sequences of the complete viral genome. This variability is also responsible for HBV resistance to antiviral treatments with nucleotide and nucleoside analogs. Diagnosis of HBV infection includes determination of virological markers: viral antigens (HBsAg, HBeAg), specific antibodies (anti-HBc, anti-HBe, anti-HBs) and study of HBV-DNA for its detection and quantification and determination of genotypes and viral variants.
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Fiedler N, Quant E, Fink L, Sun J, Schuster R, Gerlich WH, Schaefer S. Differential effects on apoptosis induction in hepatocyte lines by stable expression of hepatitis B virus X protein. World J Gastroenterol 2006; 12:4673-82. [PMID: 16937438 PMCID: PMC4087832 DOI: 10.3748/wjg.v12.i29.4673] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: Hepatitis B virus protein X (HBx) has been shown to be weakly oncogenic in vitro. The transforming activities of HBx have been linked with the inhibition of several functions of the tumor suppressor p53. We have studied whether HBx may have different effects on p53 depending on the cell type.
METHODS: We used the human hepatoma cell line HepG2 and the immortalized murine hepatocyte line AML12 and analyzed stably transfected clones which expressed physiological amounts of HBx. P53 was induced by UV irradiation.
RESULTS: The p53 induction by UV irradiation was unaffected by stable expression of HBx. However, the expression of the cyclin kinase inhibitor p21waf/cip/sdi which gets activated by p53 was affected in the HBx transformed cell line AML12-HBx9, but not in HepG2. In AML-HBx9 cells, p21waf/cip/sdi-protein expression and p21waf/cip/sdi transcription were deregulated. Furthermore, the process of apoptosis was affected in opposite ways in the two cell lines investigated. While stable expression of HBx enhanced apoptosis induced by UV irradiation in HepG2-cells, apoptosis was decreased in HBx transformed AML12-HBx9. P53 repressed transcription from the HBV enhancer I, when expressed from expression vectors or after induction of endogenous p53 by UV irradiation. Repression by endogenous p53 was partially reversible by stably expressed HBx in both cell lines.
CONCLUSION: Stable expression of HBx leads to deregulation of apoptosis induced by UV irradiation depending on the cell line used. In an immortalized hepatocyte line HBx acted anti-apoptotic whereas expression in a carcinoma derived hepatocyte line HBx enhanced apoptosis.
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Affiliation(s)
- Nicola Fiedler
- Abt. Virologie, Institut fur Medizinische Mikrobiologie, Schillingallee 70, Universitat Rostock, D-18055 Rostock, Germany
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Gupta P, Aggarwal N, Batra P, Mishra S, Chaudhuri TK. Co-expression of chaperonin GroEL/GroES enhances in vivo folding of yeast mitochondrial aconitase and alters the growth characteristics of Escherichia coli. Int J Biochem Cell Biol 2006; 38:1975-85. [PMID: 16822698 DOI: 10.1016/j.biocel.2006.05.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 05/19/2006] [Accepted: 05/23/2006] [Indexed: 11/22/2022]
Abstract
Over last two decades many researchers have demonstrated the mechanisms of how the Escherichia coli chaperonin GroEL and GroES work in the binding and folding of different aggregation prone substrate proteins both in vivo and in vitro. However, preliminary aspects, such as influence of co-expressing GroEL and GroES on the over expression of other recombinant proteins in E. coli cells and subsequent growth aspects, as well as the conditions for optimum production of recombinant proteins in presence of recombinant chaperones have not been properly investigated. In the present study we have demonstrated the temperature dependent growth characteristics of E. coli cells, which are over expressing recombinant aconitase and how the co-expression of E. coli chaperonin GroEL and GroES influence the growth rate of the cells and in vivo folding of recombinant aconitase. Presence of co-expressed GroEL reduces the aconitase over-expression drastically; however, exogenous GroEL & GroES together compensate this reduction. For the aconitase over-expressing cells the growth rate decreases by 30% at 25 degrees C when compared with the M15 E. coli cells, however, there is an increase of 20% at 37 degrees C indicating the participation of endogenous chaperonin in the folding of a fraction of over expressed aconitase. However, in presence of co-expressed GroEL and GroES the growth rate of aconitase producing cells was enhanced by 30% at 37 degrees C confirming the assistance of exogenous chaperone system for the folding of recombinant aconitase. Optimum in vivo folding of aconitase requires co-production of complete E. coli chaperonin machinery GroEL and GroES together.
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Affiliation(s)
- Parul Gupta
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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Noh EJ, Jung HJ, Jeong G, Choi KS, Park HJ, Lee CH, Lee JS. Subcellular localization and transcriptional repressor activity of HBx on p21WAF1/Cip1 promoter is regulated by ERK-mediated phosphorylation. Biochem Biophys Res Commun 2004; 319:738-45. [PMID: 15184045 DOI: 10.1016/j.bbrc.2004.05.047] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Indexed: 01/14/2023]
Abstract
The protein encoded by the hepatitis B viral X-gene, HBx, is essential for viral infection and has been shown to regulate gene transcription and the Ras signaling pathway including Raf, MEK, and ERK. To better understand regulatory mechanism of HBx functions, we investigated whether ERK1/2-induced phosphorylation of HBx regulates its transcriptional activity on p21(WAF1/Cip1) promoter. HBx-genotype A (WT1) and its modified HBx (WT2; (38)SSPSPS(43) in WT1 was substituted by (38)PPSSPS(43) in HBx-genotype F) were phosphorylated by ERK1/2 in vitro, although their Ser --> Ala constructs, SA1 (S(43) of WT1 to A) and SA2 (S(41) of WT2 to A), were not. HBx WT1 and WT2, but not SA2, repressed transcription from the p21(WAF1/Cip1) promoter. This repression was blocked by treatment with PD98059, an inhibitor of MEK, or by overexpression of dominant negative MEK1. Furthermore, WT1 and WT2 localized predominantly in the nucleus, whereas SA1 and SA2 localized to the cytoplasm, suggesting that the subcellular localization of HBx is controlled by its phosphorylation. Overall, our findings provide insight that ERK1/2-mediated phosphorylation of HBx regulates HBx function and localization, and may contribute to dysregulation of cell cycle progression leading to hepatocarcinogenesis in HBV-infected cells.
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Affiliation(s)
- Eun Joo Noh
- Research Institute, National Cancer Center, Republic of Korea
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Chen HY, Tang NH, Zhang SJ, Chen ZX, Wang XZ. Construction of hepatitis B virus X gene expression vector in eucaryotic cells and its transfection in HL-7702 cells. Shijie Huaren Xiaohua Zazhi 2004; 12:614-617. [DOI: 10.11569/wcjd.v12.i3.614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To establish a human hepatocyte cell line which can express hepatitis B virus (HBV) X gene.
METHODS: HBV X gene was obtained through PCR techn-ology. After A-tailing added, X gene was connected into vector PUCmT. Vector PUCmT-X and PcDNA3 were digested with EcoRI and HindIII. The fragments of X and PcDNA3 were connected to establish reconstituted plasmid PcDNA3-X. Then PcDNA3-X and PcDNA3 were transfected into HL-7702 cells by lipid-mediated transfection. After selected with G418, HL-7702/HBx cells were analysed by the reverse transcription-PCR to confirm the steady expression of X gene in HL-7702.
RESULTS: Reconstituted plasmid PcDNA3-X included the anticipated fragment of HBV X gene was proved by auto-sequencing assay. RT-PCR analysis showed that reconstituted plasmid PcDNA3-X could express the X protein efficiently in HL-7702 cells.
CONCLUSION: Hepatocyte can express HBV X gene, which is an ideal model to study the effect of HBV X gene on the development of hepatitis and hepatocelular carcinoma.
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