51
|
Wang A, Zhou X. ER Stress, UPR and Virus Infections in Plants. CURRENT RESEARCH TOPICS IN PLANT VIROLOGY 2016. [PMCID: PMC7123154 DOI: 10.1007/978-3-319-32919-2_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
The endoplasmic reticulum (ER) endomembrane is a central site for protein synthesis. Perturbation of ER homeostasis can result in an accumulation of unfolded proteins within the ER lumen, causing ER stress and the unfolded protein response (UPR). In humans, ER stress and UPR are closely associated with a vast number of diseases, including viral diseases. In plants, two arms that govern the UPR signaling network have been described: one that contains two ER membrane–associated transcription factors (bZIP17 and bZIP28) and the other that encompasses a dual protein kinase (RNA-splicing factor IRE1) and its target RNA (bZIP60). Although early studies mainly focus on the essential roles of the UPR in abiotic stresses, the significance of UPR in plant diseases caused by virus infections has recently drawn much attention. This chapter summarizes the latest scenario of ER stress and UPR in virus-infected plant cells, highlights the emerging roles of the IRE1 pathway in virus infections, and outlines exciting future directions to spark more research interest in the UPR field in plants.
Collapse
Affiliation(s)
- Aiming Wang
- London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario Canada
| | - Xueping Zhou
- State Key Laboratory for Biology of Plan, Chinese Academy of Agricultural Sciences, Beijing, China
| |
Collapse
|
52
|
Hepatitis C virus and its protein NS4B activate the cancer-related STAT3 pathway via the endoplasmic reticulum overload response. Arch Virol 2016; 161:2149-59. [PMID: 27180099 DOI: 10.1007/s00705-016-2892-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 05/10/2016] [Indexed: 01/05/2023]
Abstract
Oxidative stress induces the activation of signal transducer and activator of transcription 3 (STAT3), which plays an important role in hepatocellular carcinoma (HCC). We have previously reported that hepatitis C virus (HCV) and its protein NS4B induce the production of reactive oxygen species (ROS) via the endoplasmic reticulum overload response (EOR) in human hepatocytes. Here, we found that NS4B and HCV induce STAT3 activation and stimulate the expression of cancer-related STAT3 target genes, including VEGF, c-myc, MMP-9 and Mcl-1, by EOR in human hepatocytes. Moreover, the cancer-related STAT3 pathway activated by NS4B and HCV via EOR were found to promote human hepatocyte viability. Taken together, these findings revealed that HCV NS4B might contribute to HCC by activating the EOR-mediated cancer-related STAT3 pathway, and this could provide novel insights into HCV-induced HCC.
Collapse
|
53
|
HCV-Induced Oxidative Stress: Battlefield-Winning Strategy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:7425628. [PMID: 27293514 PMCID: PMC4880679 DOI: 10.1155/2016/7425628] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 04/21/2016] [Accepted: 04/26/2016] [Indexed: 02/08/2023]
Abstract
About 150 million people worldwide are chronically infected with hepatitis C virus (HCV). The persistence of the infection is controlled by several mechanisms including the induction of oxidative stress. HCV relies on this strategy to redirect lipid metabolism machinery and escape immune response. The 3β-hydroxysterol Δ24-reductase (DHCR24) is one of the newly discovered host markers of oxidative stress. This protein, as HCV-induced oxidative stress responsive protein, may play a critical role in the pathogenesis of HCV chronic infection and associated liver diseases, when aberrantly expressed. The sustained expression of DHCR24 in response to HCV-induced oxidative stress results in suppression of nuclear p53 activity by blocking its acetylation and increasing its interaction with MDM2 in the cytoplasm leading to its degradation, which may induce hepatocarcinogenesis.
Collapse
|
54
|
Lam P, Cheung F, Tan HY, Wang N, Yuen MF, Feng Y. Hepatoprotective Effects of Chinese Medicinal Herbs: A Focus on Anti-Inflammatory and Anti-Oxidative Activities. Int J Mol Sci 2016; 17:465. [PMID: 27043533 PMCID: PMC4848921 DOI: 10.3390/ijms17040465] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/21/2016] [Accepted: 03/21/2016] [Indexed: 12/12/2022] Open
Abstract
The liver is intimately connected to inflammation, which is the innate defense system of the body for removing harmful stimuli and participates in the hepatic wound-healing response. Sustained inflammation and the corresponding regenerative wound-healing response can induce the development of fibrosis, cirrhosis and eventually hepatocellular carcinoma. Oxidative stress is associated with the activation of inflammatory pathways, while chronic inflammation is found associated with some human cancers. Inflammation and cancer may be connected by the effect of the inflammation-fibrosis-cancer (IFC) axis. Chinese medicinal herbs display abilities in protecting the liver compared to conventional therapies, as many herbal medicines have been shown as effective anti-inflammatory and anti-oxidative agents. We review the relationship between oxidative stress and inflammation, the development of hepatic diseases, and the hepatoprotective effects of Chinese medicinal herbs via anti-inflammatory and anti-oxidative mechanisms. Moreover, several Chinese medicinal herbs and composite formulae, which have been commonly used for preventing and treating hepatic diseases, including Andrographis Herba, Glycyrrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, Lycii Fructus, Coptidis Rhizoma, curcumin, xiao-cha-hu-tang and shi-quan-da-bu-tang, were selected for reviewing their hepatoprotective effects with focus on their anti-oxidative and ant-inflammatory activities. This review aims to provide new insight into how Chinese medicinal herbs work in therapeutic strategies for liver diseases.
Collapse
Affiliation(s)
- Puiyan Lam
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China.
| | - Fan Cheung
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China.
| | - Hor Yue Tan
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China.
| | - Ning Wang
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China.
| | - Man Fung Yuen
- Division of Gastroenterology and Hepatology, Queen Mary Hospital and Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
| | - Yibin Feng
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China.
| |
Collapse
|
55
|
HCV induces transforming growth factor β1 through activation of endoplasmic reticulum stress and the unfolded protein response. Sci Rep 2016; 6:22487. [PMID: 26927933 PMCID: PMC4772380 DOI: 10.1038/srep22487] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 02/12/2016] [Indexed: 12/13/2022] Open
Abstract
HCV replication disrupts normal endoplasmic reticulum (ER) function and activates a signaling network called the unfolded protein response (UPR). UPR is directed by three ER transmembrane proteins including ATF6, IRE1, and PERK. HCV increases TGF-β1 and oxidative stress, which play important roles in liver fibrogenesis. HCV has been shown to induce TGF-β1 through the generation of reactive oxygen species (ROS) and p38 MAPK, JNK, ERK1/2, and NFκB-dependent pathways. However, the relationship between HCV-induced ER stress and UPR activation with TGF-β1 production has not been fully characterized. In this study, we found that ROS and JNK inhibitors block HCV up-regulation of ER stress and UPR activation. ROS, JNK and IRE1 inhibitors blocked HCV-activated NFκB and TGF-β1 expression. ROS, ER stress, NFκB, and TGF-β1 signaling were blocked by JNK specific siRNA. Knockdown IRE1 inhibited JFH1-activated NFκB and TGF-β1 activity. Knockdown of JNK and IRE1 blunted JFH1 HCV up-regulation of NFκB and TGF-β1 activation. We conclude that HCV activates NFκB and TGF-β1 through ROS production and induction of JNK and the IRE1 pathway. HCV infection induces ER stress and the UPR in a JNK-dependent manner. ER stress and UPR activation partially contribute to HCV-induced NF-κB activation and enhancement of TGF-β1.
Collapse
|
56
|
HCV and Oxidative Stress: Implications for HCV Life Cycle and HCV-Associated Pathogenesis. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:9012580. [PMID: 26955431 PMCID: PMC4756209 DOI: 10.1155/2016/9012580] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/14/2016] [Indexed: 12/15/2022]
Abstract
HCV (hepatitis C virus) is a member of the Flaviviridae family that contains a single-stranded positive-sense RNA genome of approximately 9600 bases. HCV is a major causative agent for chronic liver diseases such as steatosis, fibrosis, cirrhosis, and hepatocellular carcinoma which are caused by multifactorial processes. Elevated levels of reactive oxygen species (ROS) are considered as a major factor contributing to HCV-associated pathogenesis. This review summarizes the mechanisms involved in formation of ROS in HCV replicating cells and describes the interference of HCV with ROS detoxifying systems. The relevance of ROS for HCV-associated pathogenesis is reviewed with a focus on the interference of elevated ROS levels with processes controlling liver regeneration. The overview about the impact of ROS for the viral life cycle is focused on the relevance of autophagy for the HCV life cycle and the crosstalk between HCV, elevated ROS levels, and the induction of autophagy.
Collapse
|
57
|
Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine. Int J Mol Sci 2015; 16:30269-308. [PMID: 26694382 PMCID: PMC4691167 DOI: 10.3390/ijms161226225] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 12/02/2015] [Accepted: 12/04/2015] [Indexed: 12/12/2022] Open
Abstract
Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.
Collapse
|
58
|
Douglas DN, Pu CH, Lewis JT, Bhat R, Anwar-Mohamed A, Logan M, Lund G, Addison WR, Lehner R, Kneteman NM. Oxidative Stress Attenuates Lipid Synthesis and Increases Mitochondrial Fatty Acid Oxidation in Hepatoma Cells Infected with Hepatitis C Virus. J Biol Chem 2015; 291:1974-1990. [PMID: 26627833 DOI: 10.1074/jbc.m115.674861] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Indexed: 12/11/2022] Open
Abstract
Cytopathic effects are currently believed to contribute to hepatitis C virus (HCV)-induced liver injury and are readily observed in Huh7.5 cells infected with the JFH-1 HCV strain, manifesting as apoptosis highly correlated with growth arrest. Reactive oxygen species, which are induced by HCV infection, have recently emerged as activators of AMP-activated protein kinase. The net effect is ATP conservation via on/off switching of metabolic pathways that produce/consume ATP. Depending on the scenario, this can have either pro-survival or pro-apoptotic effects. We demonstrate reactive oxygen species-mediated activation of AMP-activated kinase in Huh7.5 cells during HCV (JFH-1)-induced growth arrest. Metabolic labeling experiments provided direct evidence that lipid synthesis is attenuated, and β-oxidation is enhanced in these cells. A striking increase in nuclear peroxisome proliferator-activated receptor α, which plays a dominant role in the expression of β-oxidation genes after ligand-induced activation, was also observed, and we provide evidence that peroxisome proliferator-activated receptor α is constitutively activated in these cells. The combination of attenuated lipid synthesis and enhanced β-oxidation is not conducive to lipid accumulation, yet cellular lipids still accumulated during this stage of infection. Notably, the serum in the culture media was the only available source for polyunsaturated fatty acids, which were elevated (2-fold) in the infected cells, implicating altered lipid import/export pathways in these cells. This study also provided the first in vivo evidence for enhanced β-oxidation during HCV infection because HCV-infected SCID/Alb-uPA mice accumulated higher plasma ketones while fasting than did control mice. Overall, this study highlights the reprogramming of hepatocellular lipid metabolism and bioenergetics during HCV infection, which are predicted to impact both the HCV life cycle and pathogenesis.
Collapse
Affiliation(s)
- Donna N Douglas
- From the Departments of Surgery,; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
| | - Christopher Hao Pu
- From the Departments of Surgery,; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Jamie T Lewis
- From the Departments of Surgery,; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | | | | | - Michael Logan
- Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada; Medical Microbiology and Immunology
| | | | - William R Addison
- Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada; Medical Microbiology and Immunology
| | | | - Norman M Kneteman
- From the Departments of Surgery,; Li Ka Shing Institute of Virology, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| |
Collapse
|
59
|
Song L, Wang Y, Wang J, Yang F, Li X, Wu Y. Trinitrotoluene Induces Endoplasmic Reticulum Stress and Apoptosis in HePG2 Cells. Med Sci Monit 2015; 21:3434-41. [PMID: 26551326 PMCID: PMC4644021 DOI: 10.12659/msm.894169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background This study aims to describe trinitrotoluene (TNT)-induced endoplasmic reticulum stress (ERS) and apoptosis in HePG2 cells. Material/Methods HePG2 cells were cultured in vitro with 0, 6, 12, or 24 μg/ml TNT solution for 12, 24, and 48 h. Western blotting was performed to detect intracellular ERS-related proteins, including glucose-regulated protein (GRP) 78, GRP94, Caspase 4, p-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP). Real-time PCR was used to measure mRNA expression from the respective genes. Results The expressions of ERS-related proteins GRP78 and GRP94 as well as mRNA and protein expression of ERS signaling apoptotic CHOP in the TNT treatment group were significantly increased. In addition, the mRNA and protein expression levels of ERS-induced apoptotic protein Caspase-4 were significantly increased. Flow cytometry revealed that after TNT treatment, the apoptosis rate also significantly increased. Conclusions TNT could increase the expression levels of GRP78, GRP94, Caspase-4, and CHOP in HePG2 cells; this increase in protein expression might be involved in HePG2 apoptosis through the induction of the ERS pathway.
Collapse
Affiliation(s)
- Li Song
- Department of Occupational and Environmental Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang, China (mainland)
| | - Yue Wang
- Department of Occupational and Environmental Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang, China (mainland)
| | - Jun Wang
- Department of Occupational and Environmental Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang, China (mainland)
| | - Fan Yang
- Department of Occupational Poisoning, Heilongjiang Institute of Labor, Health, and Occupational Disease, Harbin, Heilongjiang, China (mainland)
| | - Xiaojun Li
- Department of Occupational and Environmental Health, Heilongjiang Institute of Labor, Health, and Occupational Disease, Harbin, Heilongjiang, China (mainland)
| | - Yonghui Wu
- Department of Occupational and Environmental Health, School of Public Health, Harbin Medical University, Harbin, Heilongjiang, China (mainland)
| |
Collapse
|
60
|
Nasheri N, Ning Z, Figeys D, Yao S, Goto NK, Pezacki JP. Activity-based profiling of the proteasome pathway during hepatitis C virus infection. Proteomics 2015; 15:3815-25. [PMID: 26314548 DOI: 10.1002/pmic.201500169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/28/2015] [Accepted: 08/24/2015] [Indexed: 12/30/2022]
Abstract
Hepatitis C virus (HCV) infection often leads to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. The stability of the HCV proteins is controlled by ubiquitin-dependent and ubiquitin-independent proteasome pathways. Many viruses modulate proteasome function for their propagation. To examine the interrelationship between HCV and the proteasome pathways we employed a quantitative activity-based protein profiling method. Using this approach we were able to quantify the changes in the activity of several proteasome subunits and found that proteasome activity is drastically reduced by HCV replication. The results imply a link between the direct downregulation of the activity of this pathway and chronic HCV infection.
Collapse
Affiliation(s)
- Neda Nasheri
- Life Sciences Division, National Research Council of Canada, Ottawa, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Zhibin Ning
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada
| | - Daniel Figeys
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - Shao Yao
- Department of Chemistry, National University of Singapore, Singapore
| | - Natalie K Goto
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - John Paul Pezacki
- Life Sciences Division, National Research Council of Canada, Ottawa, Canada.,Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| |
Collapse
|
61
|
Khan M, Syed GH, Kim SJ, Siddiqui A. Mitochondrial dynamics and viral infections: A close nexus. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1853:2822-33. [PMID: 25595529 PMCID: PMC4500740 DOI: 10.1016/j.bbamcr.2014.12.040] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/09/2014] [Accepted: 12/25/2014] [Indexed: 12/17/2022]
Abstract
Viruses manipulate cellular machinery and functions to subvert intracellular environment conducive for viral proliferation. They strategically alter functions of the multitasking mitochondria to influence energy production, metabolism, survival, and immune signaling. Mitochondria either occur as heterogeneous population of individual organelles or large interconnected tubular network. The mitochondrial network is highly susceptible to physiological and environmental insults, including viral infections, and is dynamically maintained by mitochondrial fission and fusion. Mitochondrial dynamics in tandem with mitochondria-selective autophagy 'mitophagy' coordinates mitochondrial quality control and homeostasis. Mitochondrial dynamics impacts cellular homeostasis, metabolism, and innate-immune signaling, and thus can be major determinant of the outcome of viral infections. Herein, we review how mitochondrial dynamics is affected during viral infections and how this complex interplay benefits the viral infectious process and associated diseases.
Collapse
Affiliation(s)
- Mohsin Khan
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Gulam Hussain Syed
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Seong-Jun Kim
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Aleem Siddiqui
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
| |
Collapse
|
62
|
Zhang L, Chen H, Brandizzi F, Verchot J, Wang A. The UPR branch IRE1-bZIP60 in plants plays an essential role in viral infection and is complementary to the only UPR pathway in yeast. PLoS Genet 2015; 11:e1005164. [PMID: 25875739 PMCID: PMC4398384 DOI: 10.1371/journal.pgen.1005164] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/22/2015] [Indexed: 12/25/2022] Open
Abstract
The unfolded protein response (UPR) signaling network encompasses two pathways in plants, one mediated by inositol-requiring protein-1 (IRE1)-bZIP60 mRNA and the other by site-1/site-2 proteases (S1P/S2P)-bZIP17/bZIP28. As the major sensor of UPR in eukaryotes, IRE1, in response to endoplasmic reticulum (ER) stress, catalyzes the unconventional splicing of HAC1 in yeast, bZIP60 in plants and XBP1 in metazoans. Recent studies suggest that IRE1p and HAC1 mRNA, the only UPR pathway found in yeast, evolves as a cognate system responsible for the robust UPR induction. However, the functional connectivity of IRE1 and its splicing target in multicellular eukaryotes as well as the degree of conservation of IRE1 downstream signaling effectors across eukaryotes remains to be established. Here, we report that IRE1 and its substrate bZIP60 function as a strictly cognate enzyme-substrate pair to control viral pathogenesis in plants. Moreover, we show that the S1P/S2P-bZIP17/bZIP28 pathway, the other known branch of UPR in plants, does not play a detectable role in virus infection, demonstrating the distinct function of the IRE1-bZIP60 pathway in plants. Furthermore, we provide evidence that bZIP60 and HAC1, products of the enzyme-substrate duet, rather than IRE1, are functionally replaceable to cope with ER stress in yeast. Taken together, we conclude that the downstream signaling of the IRE1-mediated splicing is evolutionarily conserved in yeast and plants, and that the IRE1-bZIP60 UPR pathway not only confers overlapping functions with the other UPR branch in fundamental biology but also may exert a unique role in certain biological processes such as virus-plant interactions.
Collapse
Affiliation(s)
- Lingrui Zhang
- Southern Crop Protection and Food Research, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Hui Chen
- Southern Crop Protection and Food Research, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Federica Brandizzi
- Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Jeanmarie Verchot
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, Oklahoma, United States of America
| | - Aiming Wang
- Southern Crop Protection and Food Research, Agriculture and Agri-Food Canada, London, Ontario, Canada
- * E-mail:
| |
Collapse
|
63
|
Shah SZA, Zhao D, Khan SH, Yang L. Regulatory Mechanisms of Endoplasmic Reticulum Resident IP3 Receptors. J Mol Neurosci 2015; 56:938-948. [PMID: 25859934 DOI: 10.1007/s12031-015-0551-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/23/2015] [Indexed: 11/25/2022]
Abstract
Dysregulated calcium signaling and accumulation of aberrant proteins causing endoplasmic reticulum stress are the early sign of intra-axonal pathological events in many neurodegenerative diseases, and apoptotic signaling is initiated when the stress goes beyond the maximum threshold level of endoplasmic reticulum. The fate of the cell to undergo apoptosis is controlled by Ca2(+) signaling and dynamics at the level of the endoplasmic reticulum. Endoplasmic reticulum resident inositol 1,4,5-trisphosphate receptors (IP3R) play a pivotal role in cell death signaling by mediating Ca2(+) flux from the endoplasmic reticulum into the cytosol and mitochondria. Hence, many prosurvival and prodeath signaling pathways and proteins affect Ca2(+) signaling by directly targeting IP3R channels, which can happen in an IP3R-isoform-dependent manner. Here, in this review, we summarize the regulatory mechanisms of inositol triphosphate receptors in calcium regulation and initiation of apoptosis during unfolded protein response.
Collapse
Affiliation(s)
- Syed Zahid Ali Shah
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Deming Zhao
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Sher Hayat Khan
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China
| | - Lifeng Yang
- State Key Laboratories for Agrobiotechnology, Key Lab of Animal Epidemiology and Zoonosis, Ministry of Agriculture, National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
| |
Collapse
|
64
|
Cellular stress responses in hepatitis C virus infection: Mastering a two-edged sword. Virus Res 2015; 209:100-17. [PMID: 25836277 DOI: 10.1016/j.virusres.2015.03.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 03/21/2015] [Accepted: 03/23/2015] [Indexed: 12/11/2022]
Abstract
Hepatitis C virus (HCV) infection affects chronically more than 150 million humans worldwide. Chronic HCV infection causes severe liver disease and hepatocellular carcinoma. While immune response-mediated events are major players in HCV pathogenesis, the impact that viral replication has on cellular homeostasis is increasingly recognized as a necessary contributor to pathological manifestations of HCV infection such as steatosis, insulin-resistance or liver cancer. In this review, we will briefly overview the different cellular stress pathways that are induced by hepatitis C virus infection, the response that the cell promotes to attempt regaining homeostasis or to induce dysfunctional cell death, and how the virus co-opts these response mechanisms to promote both viral replication and survival of the infected cell. We will review the role of unfolded protein and oxidative stress responses as well as the role of auto- and mitophagy in HCV infection. Finally, we will discuss the recent discovery of a cellular chaperone involved in stress responses, the sigma-1 receptor, as a cellular factor required at the onset of HCV infection and the potential molecular events underlying the proviral role of this cellular factor in HCV infection.
Collapse
|
65
|
Elpek G&O. Angiogenesis and liver fibrosis. World J Hepatol 2015; 7:377-391. [PMID: 25848465 PMCID: PMC4381164 DOI: 10.4254/wjh.v7.i3.377] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 02/06/2023] Open
Abstract
Recent data indicate that hepatic angiogenesis, regardless of the etiology, takes place in chronic liver diseases (CLDs) that are characterized by inflammation and progressive fibrosis. Because anti-angiogenic therapy has been found to be efficient in the prevention of fibrosis in experimental models of CLDs, it is suggested that blocking angiogenesis could be a promising therapeutic option in patients with advanced fibrosis. Consequently, efforts are being directed to revealing the mechanisms involved in angiogenesis during the progression of liver fibrosis. Literature evidences indicate that hepatic angiogenesis and fibrosis are closely related in both clinical and experimental conditions. Hypoxia is a major inducer of angiogenesis together with inflammation and hepatic stellate cells. These profibrogenic cells stand at the intersection between inflammation, angiogenesis and fibrosis and play also a pivotal role in angiogenesis. This review mainly focuses to give a clear view on the relevant features that communicate angiogenesis with progression of fibrosis in CLDs towards the-end point of cirrhosis that may be translated into future therapies. The pathogenesis of hepatic angiogenesis associated with portal hypertension, viral hepatitis, non-alcoholic fatty liver disease and alcoholic liver disease are also discussed to emphasize the various mechanisms involved in angiogenesis during liver fibrogenesis.
Collapse
|
66
|
Chronic hepatitis C virus infection triggers spontaneous differential expression of biosignatures associated with T cell exhaustion and apoptosis signaling in peripheral blood mononucleocytes. Apoptosis 2015; 20:466-80. [DOI: 10.1007/s10495-014-1084-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
67
|
Affiliation(s)
| | - Akihiko Ohshige
- Digestive and Lifestyle Diseases, Kagoshima University Graduate School of Medical and Dental Sciences
| | - Hirofumi Uto
- Center for Digestive and Liver Diseases, Miyazaki Medical Center Hospital
| |
Collapse
|
68
|
Ezzikouri S, Nishimura T, Kohara M, Benjelloun S, Kino Y, Inoue K, Matsumori A, Tsukiyama-Kohara K. Inhibitory effects of Pycnogenol® on hepatitis C virus replication. Antiviral Res 2014; 113:93-102. [PMID: 25446333 DOI: 10.1016/j.antiviral.2014.10.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/24/2014] [Accepted: 10/31/2014] [Indexed: 01/29/2023]
Abstract
Chronic hepatitis C virus (HCV) infection increases the risk of liver cirrhosis and hepatocellular carcinoma. In the last decade, the current standard HCV treatment, pegylated interferon and ribavirin, have limited efficacy and significant side effects. Novel direct acting antivirals show promise, but escape mutants are expected, along with potential side effects. Pycnogenol®, a French maritime pine extract, has been reported to have antioxidant and antiviral effects. Here, we evaluated the effect of Pycnogenol® on HCV replication. Wild-type and protease inhibitor (VX-950; telaprevir)-resistant HCV replicon cells were treated with Pycnogenol®, Pycnogenol® and interferon-alpha, and ribavirin and telaprevir. Pycnogenol® effects on replication were also evaluated in HCV-infected chimeric mice. Pycnogenol® treatment showed antiviral effects without cytotoxicity at doses up to 50 μg/mL. Pycnogenol® in combination with interferon-alpha or ribavirin showed synergistic effects. Moreover, Pycnogenol® inhibited HCV replication in telaprevir-resistant replicon cells; telaprevir and Pycnogenol® acted additively to reduce HCV RNA levels in wild-type HCV replicon cells without significantly increasing cytotoxicity. Pycnogenol® antiviral activity was higher than its components procyanidin and taxifolin. Further, treatment of infected chimeric mice with Pycnogenol® suppressed HCV replication and showed a synergistic effect with interferon-alpha. In addition, Pycnogenol® treatment resulted in dose-dependent reduction of reactive oxygen species in HCV replicon cell lines. Pycnogenol® is a natural product that may be used to improve the efficacy of the current standard antiviral agents and even to eliminate resistant HCV mutants.
Collapse
Affiliation(s)
- Sayeh Ezzikouri
- Virology Unit, Viral Hepatitis Laboratory, Pasteur Institute of Morocco, Casablanca, Morocco; Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan; Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.
| | | | - Michinori Kohara
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Soumaya Benjelloun
- Virology Unit, Viral Hepatitis Laboratory, Pasteur Institute of Morocco, Casablanca, Morocco
| | - Yoichiro Kino
- Chemo-Sero Research Institute, Kikuchi Research Center, Kumamoto, Japan
| | - Kazuaki Inoue
- Division of Gastroenterology, Showa University, Fujigaoka Hospital, Kanagawa, Japan
| | | | - Kyoko Tsukiyama-Kohara
- Transboundary Animal Diseases Centre, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan; Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima, Japan.
| |
Collapse
|
69
|
Lazar C, Uta M, Branza-Nichita N. Modulation of the unfolded protein response by the human hepatitis B virus. Front Microbiol 2014; 5:433. [PMID: 25191311 PMCID: PMC4137222 DOI: 10.3389/fmicb.2014.00433] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 07/31/2014] [Indexed: 12/23/2022] Open
Abstract
During productive viral infection the host cell is confronted with synthesis of a vast amount of viral proteins which must be folded, quality controlled, assembled and secreted, perturbing the normal function of the endoplasmic reticulum (ER). To counteract the ER stress, cells activate specific signaling pathways, designated as the unfolded proteins response (UPR), which essentially increase their folding capacity, arrest protein translation, and degrade the excess of misfolded proteins. This cellular defense mechanism may, in turn, affect significantly the virus life-cycle. This review highlights the current understanding of the mechanisms of the ER stress activation by Human Hepatitis B virus (HBV), a deadly pathogen affecting more than 350 million people worldwide. Further discussion addresses the latest discoveries regarding the adaptive strategies developed by HBV to manipulate the UPR for its own benefits, the controversies in the field and future perspectives.
Collapse
Affiliation(s)
- Catalin Lazar
- Department of Viral Glycoproteins, Institute of Biochemistry of the Romanian Academy Bucharest, Romania
| | - Mihaela Uta
- Department of Viral Glycoproteins, Institute of Biochemistry of the Romanian Academy Bucharest, Romania
| | - Norica Branza-Nichita
- Department of Viral Glycoproteins, Institute of Biochemistry of the Romanian Academy Bucharest, Romania
| |
Collapse
|
70
|
Autophagy in HCV infection: keeping fat and inflammation at bay. BIOMED RESEARCH INTERNATIONAL 2014; 2014:265353. [PMID: 25162004 PMCID: PMC4138948 DOI: 10.1155/2014/265353] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 07/11/2014] [Indexed: 12/14/2022]
Abstract
Hepatitis C virus (HCV) infection is one of the main causes of chronic liver disease. Viral persistence and pathogenesis rely mainly on the ability of HCV to deregulate specific host processes, including lipid metabolism and innate immunity. Recently, autophagy has emerged as a cellular pathway, playing a role in several aspects of HCV infection. This review summarizes current knowledge on the molecular mechanisms that link the HCV life cycle with autophagy machinery. In particular, we discuss the role of HCV/autophagy interaction in dysregulating inflammation and lipid homeostasis and its potential for translational applications in the treatment of HCV-infected patients.
Collapse
|
71
|
Blázquez AB, Escribano-Romero E, Merino-Ramos T, Saiz JC, Martín-Acebes MA. Stress responses in flavivirus-infected cells: activation of unfolded protein response and autophagy. Front Microbiol 2014; 5:266. [PMID: 24917859 PMCID: PMC4042264 DOI: 10.3389/fmicb.2014.00266] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/15/2014] [Indexed: 12/11/2022] Open
Abstract
The Flavivirus is a genus of RNA viruses that includes multiple long known human, animal, and zoonotic pathogens such as Dengue virus, yellow fever virus, West Nile virus, or Japanese encephalitis virus, as well as other less known viruses that represent potential threats for human and animal health such as Usutu or Zika viruses. Flavivirus replication is based on endoplasmic reticulum-derived structures. Membrane remodeling and accumulation of viral factors induce endoplasmic reticulum stress that results in activation of a cellular signaling response termed unfolded protein response (UPR), which can be modulated by the viruses for their own benefit. Concomitant with the activation of the UPR, an upregulation of the autophagic pathway in cells infected with different flaviviruses has also been described. This review addresses the current knowledge of the relationship between endoplasmic reticulum stress, UPR, and autophagy in flavivirus-infected cells and the growing evidences for an involvement of these cellular pathways in the replication and pathogenesis of these viruses.
Collapse
Affiliation(s)
- Ana-Belén Blázquez
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Estela Escribano-Romero
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Teresa Merino-Ramos
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Juan-Carlos Saiz
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain
| | - Miguel A Martín-Acebes
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria Madrid, Spain ; Departamento de Virología y Microbiología, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid Madrid, Spain
| |
Collapse
|
72
|
Endoplasmic reticulum stress links hepatitis C virus RNA replication to wild-type PGC-1α/liver-specific PGC-1α upregulation. J Virol 2014; 88:8361-74. [PMID: 24829353 DOI: 10.1128/jvi.01202-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) causes not only severe liver problems but also extrahepatic manifestations, such as insulin resistance (IR). Wild-type peroxisome proliferator-activated receptor gamma coactivator 1 alpha (WT-PGC-1α) is essential in hepatic gluconeogenesis and has recently been demonstrated to link HCV infection to hepatic insulin resistance (IR). A recent study has characterized a novel human liver-specific PGC-1α (L-PGC-1α) transcript, which is proposed to reflect human adaption to more complex pathways. However, the effect of HCV infection on L-PGC-1α expression and the mechanism by which HCV modulates WT-PGC-1α/L-PGC-1α remain unclear. In this study, we showed that HCV infection upregulated both WT-PGC-1α and L-PGC-1α, which further promoted HCV production. The upregulation of both PGC-1α isoforms depended on HCV RNA replication. By using promoter-luciferase reporters, kinase inhibitors, and dominant negative mutants, we further observed that the HCV-induced upregulation of WT-PGC-1α was mediated by the phosphorylation of cyclic AMP (cAMP)-responsive element-binding protein (CREB), whereas that of L-PGC-1α was mediated by CREB phosphorylation and forkhead box O1 dephosphorylation. Moreover, HCV infection induced endoplasmic reticulum (ER) stress, and pharmacological induction of ER stress upregulated WT-PGC-1α/L-PGC-1α and phosphorylated CREB. In contrast, pharmacological inhibition of HCV-induced ER stress impaired WT-PGC-1α/L-PGC-1α upregulation along with decreased phosphorylated CREB. The correlation of hepatic mPGC-1α with ER stress was further confirmed in mice. Overall, HCV infection upregulates both WT-PGC-1α and L-PGC-1α through an ER stress-mediated, phosphorylated CREB-dependent pathway, and both PGC-1α isoforms promote HCV production in turn. IMPORTANCE HCV causes not only severe liver problems but also extrahepatic manifestations, such as insulin resistance (IR). As a key regulator in energy metabolism, wild-type PGC-1α (WT-PGC-1α), has recently been demonstrated to link HCV infection to hepatic IR. A recent study has characterized a novel human liver-specific PGC-1α (L-PGC-1α), which reflects human adaption to more complex pathways. However, the effect of HCV infection on L-PGC-1α expression and the mechanism by which HCV regulates WT-PGC-1α/L-PGC-1α remain unclear. In this study, we showed that HCV infection upregulated both WT-PGC-1α and L-PGC-1α, which further promoted HCV production. WT-PGC-1α upregulation was mediated by CREB phosphorylation, whereas L-PGC-1α upregulation was mediated by CREB phosphorylation and FoxO1 dephosphorylation. HCV-induced ER stress mediated WT-PGC-1α/L-PGC-1α upregulation and CREB phosphorylation. Overall, this study provides new insights into the mechanism by which HCV upregulates WT-PGC-1α/L-PGC-1α and highlights the novel intervention of HCV-ER stress-PGC-1α signaling for HCV therapy and HCV-induced IR therapy.
Collapse
|
73
|
Clinical Aspects of Hepatitis C Virus Infection. Antiviral Res 2014. [DOI: 10.1128/9781555815493.ch14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
74
|
Cuninghame S, Jackson R, Zehbe I. Hypoxia-inducible factor 1 and its role in viral carcinogenesis. Virology 2014; 456-457:370-83. [PMID: 24698149 DOI: 10.1016/j.virol.2014.02.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/17/2014] [Accepted: 02/26/2014] [Indexed: 01/05/2023]
Abstract
The advent of modern molecular biology has allowed for the discovery of several mechanisms by which oncoviruses promote carcinogenesis. Remarkably, nearly all human oncogenic viruses increase levels of the transcription factor hypoxia-inducible factor 1 (HIF-1). In this review, we highlight HIF-1׳s significance in viral oncogenesis, while providing an in-depth analysis of its activation mechanisms by the following oncoviruses: human papillomaviruses (HPVs), hepatitis B/C viruses (HBV/HCVs), Epstein-Barr virus (EBV), Kaposi׳s sarcoma-associated herpes virus (KSHV), and human T-cell lymphotropic virus (HTLV-1). We discuss virus-induced HIF-1׳s role in transcriptional upregulation of metabolic, angiogenic, and microenvironmental factors that are integral for oncogenesis. Admittedly, conclusive evidence is lacking as to whether activation of HIF-1 target genes is necessary for malignant transformation or merely a result thereof. In addition, a complete understanding of host-virus interactions, the effect of viral genomic variation, and the clinical (and potential therapeutic) relevance of HIF-1 in viral oncogenesis warrant further investigation.
Collapse
Affiliation(s)
- Sean Cuninghame
- Probe Development & Biomarker Exploration, Thunder Bay Regional Research Institute, 980 Oliver Rd, Thunder Bay, Ont., Canada P7B 6V4; Department of Biology, Lakehead University, Thunder Bay, Ont., Canada
| | - Robert Jackson
- Probe Development & Biomarker Exploration, Thunder Bay Regional Research Institute, 980 Oliver Rd, Thunder Bay, Ont., Canada P7B 6V4; Department of Biology, Lakehead University, Thunder Bay, Ont., Canada
| | - Ingeborg Zehbe
- Probe Development & Biomarker Exploration, Thunder Bay Regional Research Institute, 980 Oliver Rd, Thunder Bay, Ont., Canada P7B 6V4; Department of Biology, Lakehead University, Thunder Bay, Ont., Canada.
| |
Collapse
|
75
|
Vespasiani-Gentilucci U, Gallo P, Vincentis AD, Galati G, Picardi A. Hepatitis C virus and metabolic disorder interactions towards liver damage and atherosclerosis. World J Gastroenterol 2014; 20:2825-2838. [PMID: 24659875 PMCID: PMC3961987 DOI: 10.3748/wjg.v20.i11.2825] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/25/2013] [Accepted: 01/05/2014] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) is one of the main causes of liver disease worldwide, and alterations of glucose metabolism have reached pandemic proportions in western countries. However, the frequent coexistence between these two conditions is more than simply coincidental, since HCV can induce insulin resistance through several mechanisms. Indeed, the virus interferes with insulin signaling both directly and indirectly, inducing the production of pro-inflammatory cytokines. Furthermore, the entire viral life cycle has strict interconnections with lipid metabolism, and HCV is responsible for a “viral” steatosis which is frequently superimposed to a “metabolic” one. Several evidences suggest that HCV-induced metabolic disorders contribute both to the evolution of liver fibrosis and, likely, to the progression of the other disorders which are typically associated with altered metabolism, in particular atherosclerosis. In the present review, we will examine in depth the links between HCV infection and insulin resistance, liver steatosis and diabetes, and analyze the impact of these interactions on the progression of liver fibrosis and atherosclerosis. Special attention will be focused on the highly debated topic of the relationship between HCV infection and cardiovascular disease. The available clinical literature on this item will be broadly reviewed and all the mechanisms possibly implied will be discussed.
Collapse
|
76
|
Kawaguchi Y, Mizuta T. Interaction between hepatitis C virus and metabolic factors. World J Gastroenterol 2014; 20:2888-2901. [PMID: 24659880 PMCID: PMC3961972 DOI: 10.3748/wjg.v20.i11.2888] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/15/2013] [Accepted: 01/06/2014] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infection disrupts the normal metabolism processes, but is also influenced by several of the host’s metabolic factors. An obvious and significantly detrimental pathophysiological feature of HCV infection is insulin resistance in hepatic and peripheral tissues. Substantial research efforts have been put forth recently to elucidate the molecular mechanism of HCV-induced insulin resistance, and several cytokines, such as tumor necrosis factor-α, have been identified as important contributors to the development of insulin resistance in the distant peripheral tissues of HCV-infected patients and animal models. The demonstrated etiologies of HCV-induced whole-body insulin resistance include oxidative stress, lipid metabolism abnormalities, hepatic steatosis and iron overload. In addition, myriad effects of this condition have been characterized, including glucose intolerance, resistance to antiviral therapy, progression of hepatic fibrosis, development of hepatocellular carcinoma, and general decrease in quality of life. Metabolic-related conditions and disorders, such as visceral obesity and diabetes mellitus, have been shown to synergistically enhance HCV-induced metabolic disturbance, and are associated with worse prognosis. Yet, the molecular interactions between HCV-induced metabolic disturbance and host-associated metabolic factors remain largely unknown. The diet and lifestyle recommendations for chronic hepatitis C are basically the same as those for obesity, diabetes, and metabolic syndrome. Specifically, patients are suggested to restrict their dietary iron intake, abstain from alcohol and tobacco, and increase their intake of green tea and coffee (to attain the beneficial effects of caffeine and polyphenols). While successful clinical management of HCV-infected patients with metabolic disorders has also been achieved with some anti-diabetic (i.e., metformin) and anti-lipid (i.e., statins) medications, it is recommended that sulfonylurea and insulin be avoided.
Collapse
|
77
|
Verchot J. The ER quality control and ER associated degradation machineries are vital for viral pathogenesis. FRONTIERS IN PLANT SCIENCE 2014; 5:66. [PMID: 24653727 DOI: 10.3389/fpls.2014.00066/abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/07/2014] [Indexed: 05/24/2023]
Abstract
The endoplasmic reticulum (ER) is central to protein production and membrane lipid synthesis. The unfolded protein response (UPR) supports cellular metabolism by ensuring protein quality control in the ER. Most positive strand RNA viruses cause extensive remodeling of membranes and require active membrane synthesis to promote infection. How viruses interact with the cellular machinery controlling membrane metabolism is largely unknown. Furthermore, there is mounting data pointing to the importance of the UPR and ER associated degradation (ERAD) machineries in viral pathogenesis in eukaryotes emerging topic. For many viruses, the UPR is an early event that is essential for persistent infection and benefits virus replication. In addition, many viruses are reported to commandeer ER resident chaperones to contribute to virus replication and intercellular movement. In particular, calreticulin, the ubiquitin machinery, and the 26S proteasome are most commonly identified components of the UPR and ERAD machinery that also regulate virus infection. In addition, researchers have noted a link between UPR and autophagy. It is well accepted that positive strand RNA viruses use autophagic membranes as scaffolds to support replication and assembly. However this topic has yet to be explored using plant viruses. The goal of research on this topic is to uncover how viruses interact with this ER-related machinery and to use this information for designing novel strategies to boost immune responses to virus infection.
Collapse
Affiliation(s)
- Jeanmarie Verchot
- Department of Entomology and Plant Pathology, Oklahoma State University Stillwater, OK, USA
| |
Collapse
|
78
|
Marinho HS, Real C, Cyrne L, Soares H, Antunes F. Hydrogen peroxide sensing, signaling and regulation of transcription factors. Redox Biol 2014; 2:535-62. [PMID: 24634836 PMCID: PMC3953959 DOI: 10.1016/j.redox.2014.02.006] [Citation(s) in RCA: 571] [Impact Index Per Article: 57.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 02/19/2014] [Accepted: 02/21/2014] [Indexed: 12/12/2022] Open
Abstract
The regulatory mechanisms by which hydrogen peroxide (H2O2) modulates the activity of transcription factors in bacteria (OxyR and PerR), lower eukaryotes (Yap1, Maf1, Hsf1 and Msn2/4) and mammalian cells (AP-1, NRF2, CREB, HSF1, HIF-1, TP53, NF-κB, NOTCH, SP1 and SCREB-1) are reviewed. The complexity of regulatory networks increases throughout the phylogenetic tree, reaching a high level of complexity in mammalians. Multiple H2O2 sensors and pathways are triggered converging in the regulation of transcription factors at several levels: (1) synthesis of the transcription factor by upregulating transcription or increasing both mRNA stability and translation; (ii) stability of the transcription factor by decreasing its association with the ubiquitin E3 ligase complex or by inhibiting this complex; (iii) cytoplasm–nuclear traffic by exposing/masking nuclear localization signals, or by releasing the transcription factor from partners or from membrane anchors; and (iv) DNA binding and nuclear transactivation by modulating transcription factor affinity towards DNA, co-activators or repressors, and by targeting specific regions of chromatin to activate individual genes. We also discuss how H2O2 biological specificity results from diverse thiol protein sensors, with different reactivity of their sulfhydryl groups towards H2O2, being activated by different concentrations and times of exposure to H2O2. The specific regulation of local H2O2 concentrations is also crucial and results from H2O2 localized production and removal controlled by signals. Finally, we formulate equations to extract from typical experiments quantitative data concerning H2O2 reactivity with sensor molecules. Rate constants of 140 M−1 s−1 and ≥1.3 × 103 M−1 s−1 were estimated, respectively, for the reaction of H2O2 with KEAP1 and with an unknown target that mediates NRF2 protein synthesis. In conclusion, the multitude of H2O2 targets and mechanisms provides an opportunity for highly specific effects on gene regulation that depend on the cell type and on signals received from the cellular microenvironment. Complexity of redox regulation increases along the phylogenetic tree. Complex regulatory networks allow for a high degree of H2O2 biological plasticity. H2O2 modulates gene expression at all steps from transcription to protein synthesis. Fast response (s) is mediated by sensors with high H2O2 reactivity. Low reactivity H2O2 sensors may mediate slow (h) or localized H2O2 responses.
Collapse
Affiliation(s)
- H. Susana Marinho
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Carla Real
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Luísa Cyrne
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Helena Soares
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Escola Superior de Tecnologia da Saúde de Lisboa, IPL, Lisboa, Portugal
| | - Fernando Antunes
- Departamento de Química e Bioquímica, Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Corresponding author.
| |
Collapse
|
79
|
Hassan I, Gaines KS, Hottel WJ, Wishy RM, Miller SE, Powers LS, Rutkowski DT, Monick MM. Inositol-requiring enzyme 1 inhibits respiratory syncytial virus replication. J Biol Chem 2014; 289:7537-46. [PMID: 24497642 DOI: 10.1074/jbc.m113.510594] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Despite being a major health problem, respiratory syncytial virus (RSV) infections remain without specific therapy. Identification of novel host cellular responses that play a role in the pathogenesis of RSV infection is needed for therapeutic development. The endoplasmic reticulum (ER) stress response is an evolutionarily conserved cellular signaling cascade that has been implicated in multiple biological phenomena, including the pathogenesis of some viral infections. In this study, we investigate the role of the ER stress response in RSV infection using an in vitro A549 cell culture model. We found that RSV infection induces a non-canonical ER stress response with preferential activation of the inositol-requiring enzyme 1 (IRE1) and activated transcription factor 6 (ATF6) pathways with no concomitant significant activation of the protein kinase R-like ER kinase (PERK) pathway. Furthermore, we discovered that IRE1 has an inhibitory effect on RSV replication. Our data characterize, for the first time, the nature of the ER stress response in the setting of RSV infection and identify the IRE1 stress pathway as a novel cellular anti-RSV defense mechanism.
Collapse
Affiliation(s)
- Ihab Hassan
- From the Department of Internal Medicine, Carver College of Medicine and
| | | | | | | | | | | | | | | |
Collapse
|
80
|
Gelley F, Zadori G, Nemes B, Fassan M, Lendvai G, Sarvary E, Doros A, Gerlei Z, Nagy P, Schaff Z, Kiss A. MicroRNA profile before and after antiviral therapy in liver transplant recipients for hepatitis C virus cirrhosis. J Gastroenterol Hepatol 2014; 29:121-7. [PMID: 24033414 DOI: 10.1111/jgh.12362] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/02/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND AIM Management of hepatitis C virus (HCV) recurrence is a major challenge after liver transplantation. Significant dysregulated expression of HCV receptors (i.e. claudin-1, occludin, tetraspanin CD81, scavenger receptor type B1) has been shown recently during HCV infection. This might facilitate hepatocytic entry and reinfection of HCV. MicroRNAs (miRs) play role in the regulation of gene expression. We aimed to characterize miR expression profiles related to HCV infection and antiviral therapy in adult liver transplant recipients, with special emphasis on miRs predicted to target HCV receptors. METHODS Twenty-eight adult liver transplant recipients were enrolled in the study. Paired biopsies were obtained at the time of HCV recurrence and at the end of antiviral treatment. MiRs for HCV receptors were selected using target prediction software. Expression levels of miR-21, miR-23a miR-34a, miR-96, miR-99a*, miR-122, miR-125b, miR-181a-2*, miR-194, miR-195, miR-217, miR-221, and miR-224 were determined by reverse transcription-quantitative polymerase chain reaction. RESULTS miR-99a* and miR-224 expressions were increased in HCV recurrence samples, while miR-21 and miR-194 were decreased in comparison to normal liver tissue. Increased expressions of miR-221, miR-224, and miR-217 were observed in samples taken after antiviral therapy when compared with HCV recurrence samples. High HCV titer at recurrence was associated with higher level of miR-122. CONCLUSIONS Samples at recurrence of HCV and after antiviral therapy revealed distinct HCV-related miR expression profiles, with significant dysregulation of those miRNAs potentially targeting mRNAs of HCV receptors. In particular, miR-194 and miR-21 might be involved in the regulation of HCV receptor proteins' expression during HCV infection and antiviral therapy.
Collapse
Affiliation(s)
- Fanni Gelley
- Department of Transplantation and Surgery, Semmelweis University, Budapest, Hungary
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
81
|
Verchot J. The ER quality control and ER associated degradation machineries are vital for viral pathogenesis. FRONTIERS IN PLANT SCIENCE 2014; 5:66. [PMID: 24653727 PMCID: PMC3949406 DOI: 10.3389/fpls.2014.00066] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/07/2014] [Indexed: 05/19/2023]
Abstract
The endoplasmic reticulum (ER) is central to protein production and membrane lipid synthesis. The unfolded protein response (UPR) supports cellular metabolism by ensuring protein quality control in the ER. Most positive strand RNA viruses cause extensive remodeling of membranes and require active membrane synthesis to promote infection. How viruses interact with the cellular machinery controlling membrane metabolism is largely unknown. Furthermore, there is mounting data pointing to the importance of the UPR and ER associated degradation (ERAD) machineries in viral pathogenesis in eukaryotes emerging topic. For many viruses, the UPR is an early event that is essential for persistent infection and benefits virus replication. In addition, many viruses are reported to commandeer ER resident chaperones to contribute to virus replication and intercellular movement. In particular, calreticulin, the ubiquitin machinery, and the 26S proteasome are most commonly identified components of the UPR and ERAD machinery that also regulate virus infection. In addition, researchers have noted a link between UPR and autophagy. It is well accepted that positive strand RNA viruses use autophagic membranes as scaffolds to support replication and assembly. However this topic has yet to be explored using plant viruses. The goal of research on this topic is to uncover how viruses interact with this ER-related machinery and to use this information for designing novel strategies to boost immune responses to virus infection.
Collapse
Affiliation(s)
- Jeanmarie Verchot
- *Correspondence: Jeanmarie Verchot, Department of Entomology and Plant Pathology, Oklahoma State University, 127 Noble Research Center, Stillwater, OK 74078, USA e-mail:
| |
Collapse
|
82
|
Claus C, Liebert UG. A renewed focus on the interplay between viruses and mitochondrial metabolism. Arch Virol 2013; 159:1267-77. [PMID: 24343264 DOI: 10.1007/s00705-013-1841-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 07/26/2013] [Indexed: 01/26/2023]
Abstract
Mitochondria fulfil several key functions within cellular metabolic and antiviral signalling pathways, including their central role in ATP generation. Viruses, as intracellular parasites, require from their cellular host the building blocks for generation of their viral progeny and the energy that drives viral replication and assembly. While some viruses have adopted ways to manipulate the infected cell such that cellular metabolism supports optimal virus production, other viruses simply exhaust cellular resources. The association of viruses with mitochondria is influenced by several important factors such as speed of the viral replication cycle and viral dependence on cellular enzymes and metabolites. This review will highlight the complex interconnectivity of viral life cycles with the three main mitochondrial metabolic pathways, namely β-oxidation, the tricarboxylic (TCA) cycle, and oxidative phosphorylation. This interconnectivity has the potential to reveal interesting points for antiviral therapy with either prometabolites or antimetabolites and highlights the importance of the viral association with mitochondrial metabolism.
Collapse
Affiliation(s)
- C Claus
- Institute of Virology, University of Leipzig, Johannisallee 30, 04317, Leipzig, Germany,
| | | |
Collapse
|
83
|
Abstract
Hepatocellular carcinoma (HCC) is a major cause of cancer death, and its development is influenced by the status of inflammation and oxidative stress in the liver. Although oxidative stress might induce genetic changes and play a role in HCC development, many epigenetic alterations have also been reported in this type of tumor, suggesting the importance of epigenetic instability in hepatocarcinogenesis. Epigenetic instability results in 2 types of DNA alterations: hypermethylation of the promoter of tumor suppressor genes (TSGs), and hypomethylation of nonpromoter CpG, such as repetitive elements and satellite DNA. The former causes transcriptional inactivation of TSGs, while the latter reportedly induces chromosomal instability and an abnormal activation of oncogenes as well as mobile genetic elements. Oxidative stress could induce epigenetic instability and inactivate TSGs through the recruitment of the polycomb repressive complex to the promoter sequence carrying DNA damage induced by oxidation. Inflammatory cytokines from immune cells also reportedly induce expression of several histone and DNA modulators. On the other hand, DNA oxidation could lead to activation of DNA repair pathways and affect the binding of methyl cytosine-binding protein to DNA, which could cause DNA hypomethylation. The decrease of the level of methyl group donors also contributes to the alteration in the methylation status. These mechanisms should act in concert and induce epigenetic instability, leading to HCC.
Collapse
Affiliation(s)
- Naoshi Nishida
- Department of Gastroenterology and Hepatology, Kinki University School of Medicine, Osakasayama, Japan
| | | |
Collapse
|
84
|
Abstract
Intracellular free Ca(2+) ([Ca(2+)]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca(2+) signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca(2+) signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca(2+) signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca(2+)]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca(2+) signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca(2+) signaling in the liver, and the role of Ca(2+) signaling in liver disease.
Collapse
Affiliation(s)
- Maria Jimena Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | | |
Collapse
|
85
|
Rashad AA, Mahalingam S, Keller PA. Chikungunya virus: emerging targets and new opportunities for medicinal chemistry. J Med Chem 2013; 57:1147-66. [PMID: 24079775 DOI: 10.1021/jm400460d] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chikungunya virus is an emerging arbovirus that is widespread in tropical regions and is spreading quickly to temperate climates with recent epidemics in Africa and Asia and documented outbreaks in Europe and the Americas. It is having an increasingly major impact on humankind, with potentially life-threatening and debilitating arthritis. There is no treatment available, and only in the past 24 months have lead compounds for development as potential therapeutics been reported. This Perspective discusses the chikungunya virus as a significant, new emerging topic for medicinal chemistry, highlighting the key viral target proteins and their molecular functions that can be used in drug design, as well as the most important ongoing developments for anti-chikungunya virus research. It represents a complete picture of the current medicinal chemistry of chikungunya, supporting the development of chemotherapeutics through drug discovery and design targeting this virus.
Collapse
Affiliation(s)
- Adel A Rashad
- Centre for Medicinal Chemistry, School of Chemistry, University of Wollongong , Wollongong, 2522, Australia
| | | | | |
Collapse
|
86
|
Desmosterol and DHCR24: unexpected new directions for a terminal step in cholesterol synthesis. Prog Lipid Res 2013; 52:666-80. [PMID: 24095826 DOI: 10.1016/j.plipres.2013.09.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/25/2013] [Accepted: 09/12/2013] [Indexed: 01/31/2023]
Abstract
3β-Hydroxysterol Δ(24)-reductase (DHCR24) catalyzes the conversion of desmosterol to cholesterol. This ultimate step of cholesterol biosynthesis appears to be remarkable in its diverse functions and the number of diseases it is implicated in from vascular disease to Hepatitis C virus (HCV) infection to cancer to Alzheimer's disease. This review summarizes the present knowledge on the DHCR24 gene, sterol Δ(24)-reductase protein and the regulation of both. In addition, the functions of desmosterol, DHCR24 and their roles in human diseases are discussed. It is apparent that DHCR24 exerts more complex effects than what would be expected based on the enzymatic activity of sterol Δ(24)-reduction alone, such as its influence in modulating oxidative stress. Increasing information about DHCR24 membrane association, processing, enzymatic regulation and interaction partners will provide further fundamental insights into DHCR24 and its many and varied biological roles.
Collapse
|
87
|
Nishimura M, Takaki A, Tamaki N, Maruyama T, Onishi H, Kobayashi S, Nouso K, Yasunaka T, Koike K, Hagihara H, Kuwaki K, Nakamura S, Ikeda F, Iwasaki Y, Tomofuji T, Morita M, Yamamoto K. Serum oxidative-anti-oxidative stress balance is dysregulated in patients with hepatitis C virus-related hepatocellular carcinoma. Hepatol Res 2013; 43:1078-92. [PMID: 23363268 DOI: 10.1111/hepr.12048] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/02/2012] [Accepted: 12/16/2012] [Indexed: 12/21/2022]
Abstract
AIM Oxidative stress is associated with progression of chronic liver disease (CLD). This association is best established in chronic hepatitis C. However, the anti-oxidative state is not well characterized. The objective of the present study was to investigate the balance of oxidative and anti-oxidative stress in CLD patients. METHODS We recruited a study population of 208 patients, including healthy volunteers (HV; n = 15), patients with hepatitis B virus (HBV)-related CLD without or with hepatocellular carcinoma (HBV-non-HCC, n = 25, and HBV-HCC, n = 50, respectively), and patients with hepatitis C virus (HCV)-related CLD without or with HCC (HCV-non-HCC, n = 49, and HCV-HCC, n = 69, respectively). Serum levels of reactive oxygen metabolites (ROM) and anti-oxidative markers (OXY-adsorbent test; OXY) were determined, and the balance of these values was used as the oxidative index. Correlations among ROM, OXY, oxidative index and clinical characteristics were investigated. RESULTS Patients with CLD exhibited elevated ROM and oxidative index compared to HV. Among patients with CLD, HCV positive status correlated with increased ROM. In CLD, HCV-HCC patients exhibited the highest ROM levels. Among HCV-related CLD patients, lower OXY correlated with HCC positive status, but was recovered by eradication of HCC. In HCV-HCC, lower OXY correlated with high PT-INR. CONCLUSION HCV positive CLD patients displayed higher oxidative stress and HCV-HCC patients displayed lower anti-oxidative state. Anti-oxidative state depression was associated with liver reservoir-related data in HCV-HCC and could be reversed with HCC eradication.
Collapse
Affiliation(s)
- Mamoru Nishimura
- Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Department of Gastroenterology, Okayama City Hospital, Okayama, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
88
|
Amako Y, Igloi Z, Mankouri J, Kazlauskas A, Saksela K, Dallas M, Peers C, Harris M. Hepatitis C virus NS5A inhibits mixed lineage kinase 3 to block apoptosis. J Biol Chem 2013; 288:24753-63. [PMID: 23857585 PMCID: PMC3750171 DOI: 10.1074/jbc.m113.491985] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 07/12/2013] [Indexed: 01/28/2023] Open
Abstract
Hepatitis C virus (HCV) infection results in the activation of numerous stress responses including oxidative stress, with the potential to induce an apoptotic state. Previously we have shown that HCV attenuates the stress-induced, p38MAPK-mediated up-regulation of the K(+) channel Kv2.1, to maintain the survival of infected cells in the face of cellular stress. We demonstrated that this effect was mediated by HCV non-structural 5A (NS5A) protein, which impaired p38MAPK activity through a polyproline motif-dependent interaction, resulting in reduction of phosphorylation activation of Kv2.1. In this study, we investigated the host cell proteins targeted by NS5A to mediate Kv2.1 inhibition. We screened a phage-display library expressing the entire complement of human SH3 domains for novel NS5A-host cell interactions. This analysis identified mixed lineage kinase 3 (MLK3) as a putative NS5A interacting partner. MLK3 is a serine/threonine protein kinase that is a member of the MAPK kinase kinase (MAP3K) family and activates p38MAPK. An NS5A-MLK3 interaction was confirmed by co-immunoprecipitation and Western blot analysis. We further demonstrate a novel role of MLK3 in the modulation of Kv2.1 activity, whereby MLK3 overexpression leads to the up-regulation of channel activity. Accordingly, coexpression of NS5A suppressed this stimulation. Additionally we demonstrate that overexpression of MLK3 induced apoptosis, which was also counteracted by NS5A. We conclude that NS5A targets MLK3 with multiple downstream consequences for both apoptosis and K(+) homeostasis.
Collapse
Affiliation(s)
- Yutaka Amako
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences and
| | - Zsofia Igloi
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences and
| | - Jamel Mankouri
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences and
| | - Arunas Kazlauskas
- the Department of Virology, Haartman Institute, University of Helsinki Central Hospital, University of Helsinki and HUSLAB, FI-00014 Helsinki, Finland
| | - Kalle Saksela
- the Department of Virology, Haartman Institute, University of Helsinki Central Hospital, University of Helsinki and HUSLAB, FI-00014 Helsinki, Finland
| | - Mark Dallas
- the Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, United Kingdom and
| | - Chris Peers
- the Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, United Kingdom and
| | - Mark Harris
- From the School of Molecular and Cellular Biology, Faculty of Biological Sciences and
| |
Collapse
|
89
|
Stahl S, Burkhart JM, Hinte F, Tirosh B, Mohr H, Zahedi RP, Sickmann A, Ruzsics Z, Budt M, Brune W. Cytomegalovirus downregulates IRE1 to repress the unfolded protein response. PLoS Pathog 2013; 9:e1003544. [PMID: 23950715 PMCID: PMC3738497 DOI: 10.1371/journal.ppat.1003544] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 06/21/2013] [Indexed: 02/07/2023] Open
Abstract
During viral infection, a massive demand for viral glycoproteins can overwhelm the capacity of the protein folding and quality control machinery, leading to an accumulation of unfolded proteins in the endoplasmic reticulum (ER). To restore ER homeostasis, cells initiate the unfolded protein response (UPR) by activating three ER-to-nucleus signaling pathways, of which the inositol-requiring enzyme 1 (IRE1)-dependent pathway is the most conserved. To reduce ER stress, the UPR decreases protein synthesis, increases degradation of unfolded proteins, and upregulates chaperone expression to enhance protein folding. Cytomegaloviruses, as other viral pathogens, modulate the UPR to their own advantage. However, the molecular mechanisms and the viral proteins responsible for UPR modulation remained to be identified. In this study, we investigated the modulation of IRE1 signaling by murine cytomegalovirus (MCMV) and found that IRE1-mediated mRNA splicing and expression of the X-box binding protein 1 (XBP1) is repressed in infected cells. By affinity purification, we identified the viral M50 protein as an IRE1-interacting protein. M50 expression in transfected or MCMV-infected cells induced a substantial downregulation of IRE1 protein levels. The N-terminal conserved region of M50 was found to be required for interaction with and downregulation of IRE1. Moreover, UL50, the human cytomegalovirus (HCMV) homolog of M50, affected IRE1 in the same way. Thus we concluded that IRE1 downregulation represents a previously undescribed viral strategy to curb the UPR. Viruses abuse the cell's protein synthesis and folding machinery to produce large amounts of viral proteins. This enforced synthesis overloads the cell's capacity and leads to an accumulation of unfolded proteins in the endoplasmic reticulum (ER) resulting in ER stress, which can compromise cell viability. To restore ER homeostasis, cells initiate the unfolded protein response (UPR) to reduce protein synthesis, increase degradation of unfolded proteins, and upregulate chaperone expression for enhanced protein folding. The most conserved branch of the UPR is the signaling pathway activated by the ER stress sensor IRE1. It upregulates ER-associated degradation (ERAD), thereby antagonizing ER stress. Some of the counter-regulatory mechanisms of the UPR are detrimental for viral replication and are, therefore, moderated by viruses. In this study we identified the first viral IRE1 inhibitor: The murine cytomegalovirus M50 protein, which interacts with IRE1 and induces its degradation. By this means, M50 inhibits IRE1 signaling and prevents ERAD upregulation. Interestingly, the M50 homolog in human cytomegalovirus, UL50, also downregulated IRE1 revealing a previously unknown mechanism of viral host cell manipulation.
Collapse
Affiliation(s)
- Sebastian Stahl
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- Division of Viral Infections, Robert Koch Institute, Berlin, Germany
| | - Julia M. Burkhart
- Department of Bioanalytics, ISAS – Leibniz Institute for Analytical Sciences, Dortmund, Germany
| | - Florian Hinte
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Boaz Tirosh
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University, Jerusalem, Israel
| | - Hermine Mohr
- Max von Pettenkofer Institute, Ludwig-Maximilians-Universität München, Munich, Germany
| | - René P. Zahedi
- Department of Bioanalytics, ISAS – Leibniz Institute for Analytical Sciences, Dortmund, Germany
| | - Albert Sickmann
- Department of Bioanalytics, ISAS – Leibniz Institute for Analytical Sciences, Dortmund, Germany
- Medical Proteome Center (MPC), Ruhr-Universität, Bochum, Germany
| | - Zsolt Ruzsics
- Max von Pettenkofer Institute, Ludwig-Maximilians-Universität München, Munich, Germany
- DZIF German Center for Infection Research, Munich, Germany
| | - Matthias Budt
- Division of Viral Infections, Robert Koch Institute, Berlin, Germany
| | - Wolfram Brune
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
- Division of Viral Infections, Robert Koch Institute, Berlin, Germany
- DZIF German Center for Infection Research, Hamburg, Germany
- * E-mail:
| |
Collapse
|
90
|
Kim JKS, Zhu Z, Casale G, Koutakis P, McComb RD, Swanson S, Thompson J, Miserlis D, Johanning JM, Haynatzki G, Pipinos II. Human enterovirus in the gastrocnemius of patients with peripheral arterial disease. J Am Heart Assoc 2013; 2:e000082. [PMID: 23920231 PMCID: PMC3828788 DOI: 10.1161/jaha.113.000082] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background Peripheral arterial disease (PAD) is characterized by myofiber degeneration and loss of function in muscles of the lower limbs. Human enterovirus (HEV) infection has been implicated in the pathogenesis of a number of muscle diseases. However, its association with PAD has not been studied. In this study, we tested the hypothesis that infectious HEV is present in skeletal muscle of patients with PAD and is associated with severity of disease. Methods and Results Gastrocnemius biopsies from 37 patients with PAD and 14 controls were examined for the presence of HEV RNA, viral capsid protein, viral RNA copy number, and viral infectivity. HEV RNA was detected in 54% of the biopsies from patients with PAD but was not detected in muscle biopsies from control patients. This difference in prevalence among PAD and control patients was significant at P<0.001. Viral RNA copy numbers were increased significantly at the later stages of disease; Fontaine Stage IV (105.50 copies/mg muscle wet weight, at P<0.005) and Stage III (104.87 copies/mg, at P<0.010) compared to Stage II (102.50 copies/mg). Viral replication was confirmed by the presence of the negative‐strand of viral RNA in all specimens positive for HEV RNA. Cultures of HeLa and human skeletal muscle cells treated with muscle homogenates showed HEV replication and the presence of HEV capsid protein. Conclusion Our data identified infectious HEV in the gastrocnemius of PAD patients but not in controls. Viral copy number and prevalence of infection were higher in the later stages of disease. Our data point to the need for further studies to determine the contribution of HEV infection to the pathophysiology of PAD.
Collapse
Affiliation(s)
- Julian K S Kim
- Department of Surgery, College of Medicine, University of Nebraska Medical Center, Omaha, NE
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
91
|
Wang T, Weinman SA. Interactions Between Hepatitis C Virus and Mitochondria: Impact on Pathogenesis and Innate Immunity. CURRENT PATHOBIOLOGY REPORTS 2013; 1:179-187. [PMID: 23956955 DOI: 10.1007/s40139-013-0024-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) causes a persistent chronic infection of hepatocytes resulting in progressive fibrosis and carcinogenesis. Abnormalities in mitochondria are prominent features of clinical disease where ultrastructural changes, alterations in electron transport, and excess reactive oxygen species (ROS) production occur. These mitochondrial abnormalities correlate with disease severity and resolve with viral eradication. Multiple viral proteins, particularly core and NS3/4a bind to mitochondria. The core and NS5a proteins primarily cause ER stress, ER Ca2+ release and enhance direct transfer of Ca2+ from ER to mitochondria. This results in electron transport changes, increased ROS production and sensitivity to mitochondrial permeability transition and cell death. The viral protease, NS3/4a, binds to mitochondria as well where it cleaves an important signaling adapter, MAVS, thus preventing viral clearance by endogenous interferon production. This review discusses the mechanisms by which HCV causes mitochondrial changes and consequences of these for disease.
Collapse
Affiliation(s)
- Ting Wang
- Liver Center and Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160
| | | |
Collapse
|
92
|
Hepatitis C virus-induced mitochondrial dysfunctions. Viruses 2013; 5:954-80. [PMID: 23518579 PMCID: PMC3705306 DOI: 10.3390/v5030954] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 03/15/2013] [Accepted: 03/20/2013] [Indexed: 12/15/2022] Open
Abstract
Chronic hepatitis C is characterized by metabolic disorders and a microenvironment in the liver dominated by oxidative stress, inflammation and regeneration processes that lead in the long term to hepatocellular carcinoma. Many lines of evidence suggest that mitochondrial dysfunctions, including modification of metabolic fluxes, generation and elimination of oxidative stress, Ca2+ signaling and apoptosis, play a central role in these processes. However, how these dysfunctions are induced by the virus and whether they play a role in disease progression and neoplastic transformation remains to be determined. Most in vitro studies performed so far have shown that several of the hepatitis C virus (HCV) proteins localize to mitochondria, but the consequences of these interactions on mitochondrial functions remain contradictory, probably due to the use of artificial expression and replication systems. In vivo studies are hampered by the fact that innate and adaptive immune responses will overlay mitochondrial dysfunctions induced directly in the hepatocyte by HCV. Thus, the molecular aspects underlying HCV-induced mitochondrial dysfunctions and their roles in viral replication and the associated pathology need yet to be confirmed in the context of productively replicating virus and physiologically relevant in vitro and in vivo model systems.
Collapse
|
93
|
Interplay between Hepatitis C Virus and Redox Cell Signaling. Int J Mol Sci 2013; 14:4705-21. [PMID: 23443167 PMCID: PMC3634496 DOI: 10.3390/ijms14034705] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 02/13/2013] [Accepted: 02/17/2013] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) infects approximately 3% of the world’s population. Currently licensed treatment of HCV chronic infection with pegylated-interferon-α and ribavirin, is not fully effective against all HCV genotypes and is associated to severe side effects. Thus, development of novel therapeutics and identification of new targets for treatment of HCV infection is necessary. Current opinion is orienting to target antiviral drug discovery to the host cell pathways on which the virus relies, instead of against viral structures. Many intracellular signaling pathways manipulated by HCV for its own replication are finely regulated by the oxido-reductive (redox) state of the host cell. At the same time, HCV induces oxidative stress that has been found to affect both virus replication as well as progression and severity of HCV infection. A dual role, positive or negative, for the host cell oxidized conditions on HCV replication has been reported so far. This review examines current information about the effect of oxidative stress on HCV life cycle and the main redox-regulated intracellular pathways activated during HCV infection and involved in its replication.
Collapse
|
94
|
Presser LD, McRae S, Waris G. Activation of TGF-β1 promoter by hepatitis C virus-induced AP-1 and Sp1: role of TGF-β1 in hepatic stellate cell activation and invasion. PLoS One 2013; 8:e56367. [PMID: 23437118 DOI: 10.1371/journal.pone.0056367] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 01/14/2013] [Indexed: 12/17/2022] Open
Abstract
Our previous studies have shown the induction and maturation of transforming growth factor-beta 1 (TGF-β1) in HCV-infected human hepatoma cells. In this study, we have investigated the molecular mechanism of TGF-β1 gene expression in response to HCV infection. We demonstrate that HCV-induced transcription factors AP-1, Sp1, NF-κB and STAT-3 are involved in TGF-β1 gene expression. Using chromatin immunoprecipitation (ChIP) assay, we further show that AP-1 and Sp1 interact with TGF-b1 promoter in vivo in HCV-infected cells. In addition, we demonstrate that HCV-induced TGF-β1 gene expression is mediated by the activation of cellular kinases such as p38 MAPK, Src, JNK, and MEK1/2. Next, we determined the role of secreted bioactive TGF-β1 in human hepatic stellate cells (HSCs) activation and invasion. Using siRNA approach, we show that HCV-induced bioactive TGF-β1 is critical for the induction of alpha smooth muscle actin (α-SMA) and type 1 collagen, the markers of HSCs activation and proliferation. We further demonstrate the potential role of HCV-induced bioactive TGF-β1 in HSCs invasion/cell migration using a transwell Boyden chamber. Our results also suggest the role of HCV-induced TGF-β1 in HCV replication and release. Collectively, these observations provide insight into the mechanism of TGF-β1 promoter activation, as well as HSCs activation and invasion, which likely manifests in liver fibrosis associated with HCV infection.
Collapse
Affiliation(s)
- Lance D Presser
- Department of Microbiology and Immunology, H.M. Bligh Cancer Research Laboratories, Rosalind Franklin University of Medicine and Science, Chicago Medical School, Chicago, Illinois, USA
| | | | | |
Collapse
|
95
|
Rathore APS, Ng ML, Vasudevan SG. Differential unfolded protein response during Chikungunya and Sindbis virus infection: CHIKV nsP4 suppresses eIF2α phosphorylation. Virol J 2013; 10:36. [PMID: 23356742 PMCID: PMC3605262 DOI: 10.1186/1743-422x-10-36] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 01/11/2013] [Indexed: 12/27/2022] Open
Abstract
Chikungunya (CHIKV) and Sindbis (SINV) are arboviruses belonging to the alphavirus genus within the Togaviridae family. They cause frequent epidemics of febrile illness and long-term arthralgic sequelae that affect millions of people each year. Both viruses replicate prodigiously in infected patients and in vitro in mammalian cells, suggesting some level of control over the host cellular translational machinery that senses and appropriately directs the cell's fate through the unfolded protein response (UPR). The mammalian UPR involves BIP (or GRP78), the master sensor in the endoplasmic reticulum (ER) together with the three downstream effector branches: inositol-requiring ser/thr protein kinase/endonuclease (IRE-1), PKR-like ER resident kinase (PERK) and activating transcription factor 6 (ATF-6). Through careful analysis of CHIKV and SINV infections in cell culture we found that the former selectively activates ATF-6 and IRE-1 branches of UPR and suppresses the PERK pathway. By separately expressing each of the CHIKV proteins as GFP-fusion proteins, we found that non-structural protein 4 (nsP4), which is a RNA-dependent-RNA polymerase, suppresses the serine-51 phosphorylation of eukaryotic translation initiation factor, alpha subunit (eIF2α), which in turn regulates the PERK pathway. This study provides insight into a mechanism by which CHIKV replication responds to overcome the host UPR machinery.
Collapse
Affiliation(s)
- Abhay P S Rathore
- Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, 8-College Road, Singapore 169857, Singapore
| | | | | |
Collapse
|
96
|
Yu JW, Sun LJ, Zhao YH, Kang P, Yan BZ. Inhibition of silent information regulator 1 induces glucose metabolism disorders of hepatocytes and enhances hepatitis C virus replication. Hepatol Int 2013. [DOI: 10.1007/s12072-013-9420-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
97
|
Amelioration of influenza virus-induced reactive oxygen species formation by epigallocatechin gallate derived from green tea. Acta Pharmacol Sin 2012; 33:1533-41. [PMID: 22941291 DOI: 10.1038/aps.2012.80] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIM To study whether epigallocatechin gallate (EGCG), a green tea-derived polyphenol, exerted anti-influenza A virus activity in vitro and in vivo. METHODS Madin-Darby canine kidney (MDCK) cells were tested. The antiviral activity of EGCG in the cells was determined using hemagglutination assay and qPCR. Time of addition assay was performed to determine the kinetics of inhibition of influenza A by EGCG. The level of reactive oxygen species (ROS) were determined with confocal microscopy and flow cytometry. BALB/c mice were treated with EGCG (10, 20 or 40 mg·kg(-1)·d(-1), po) for 5 d. On the 3rd d of the treatment, the mice were infected with influenza A virus. Histopathological changes, lung index and virus titers in the lungs were determined. RESULTS Treatment of influenza A-infected MDCK cells with EGCG (1.25-100 nmol/L) inhibited influenza A replication in a concentration-dependent manner (the ED(50) value was 8.71±1.11 nmol/L). Treatment with EGCG (20 nmol/L) significantly suppressed the increased ROS level in MDCK cells following influenza A infection. In BALB/c mice infected with influenza virus, oral administration of EGCG (40 mg·kg(-1)·d(-1)) dramatically improved the survival rate, decreased the mean virus yields and mitigated viral pneumonia in the lungs, which was equivalent to oral administration of oseltamivir (40 mg·kg(-1)·d(-1)), a positive control drug. CONCLUSION The results provide a molecular basis for development of EGCG as a novel and safe chemopreventive agent for influenza A infection.
Collapse
|
98
|
Kanwal N, Zaidi NUSS, Gomez MK. Non-structural protein NS4B: HCV replication web inducer. ASIAN PACIFIC JOURNAL OF TROPICAL DISEASE 2012. [DOI: 10.1016/s2222-1808(12)60111-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
99
|
Lu MW, Ngou FH, Chao YM, Lai YS, Chen NY, Lee FY, Chiou PP. Transcriptome characterization and gene expression of Epinephelus spp in endoplasmic reticulum stress-related pathway during betanodavirus infection in vitro. BMC Genomics 2012; 13:651. [PMID: 23170826 PMCID: PMC3560219 DOI: 10.1186/1471-2164-13-651] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 10/18/2012] [Indexed: 12/14/2022] Open
Abstract
Background Grouper (Epinephelus spp) is an economically important fish species worldwide. However, viral pathogens such as nervous necrosis virus (NNV) have been causing severe infections in the fish, resulting in great loss in the grouper aquaculture industry. Yet, the understanding of the molecular mechanisms underlying the pathogenicity of NNV is still inadequate, mainly due to insufficient genomic information of the host. Results De novo assembly of grouper transcriptome in the grouper kidney (GK) cells was conducted by using short read sequencing technology of Solexa/Illumina. A sum of 66,582 unigenes with mean length of 603 bp were obtained, and were annotated according to Gene Ontology (GO) and Clusters of Orthologous Groups (COG). In addition, the tag-based digital gene expression (DGE) system was used to investigate the gene expression and pathways associated with NNV infection in GK cells. The analysis revealed endoplasmic reticulum (ER) stress response was prominently affected in NNV-infected GK cells. A further analysis revealed an interaction between the NNV capsid protein and the ER chaperone immunoglobulin heavy-chain binding protein (BiP). Furthermore, exogenous expression of NNV capsid protein was able to induce XBP-1 mRNA splicing in vivo, suggesting a role of the capsid protein in the NNV-induced ER stress. Conclusions Our data presents valuable genetic information for Epinephelus spp., which will benefit future study in this non-model but economically important species. The DGE profile of ER stress response in NNV-infected cells provides information of many important components associated with the protein processing in ER. Specifically, we showed that the viral capsid protein might play an important role in the ER stress response.
Collapse
Affiliation(s)
- Ming-Wei Lu
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
| | | | | | | | | | | | | |
Collapse
|
100
|
Abstract
Hepatitis C virus (HCV) easily establishes chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). During the progression of HCV infections, reactive oxygen species (ROS) are generated, and these ROS then induce significant DNA damage. The role of ROS in the pathogenesis of HCV infection is still not fully understood. Recently, we found that HCV induced the expression of 3β-hydroxysterol Δ24-reductase (DHCR24). We also found that a HCV responsive region is present in the 5′-flanking genomic promoter region of DHCR24 and the HCV responsive region was characterized as (−167/−140). Moreover, the transcription factor Sp1 was found to bind to this region in response to oxidative stress under the regulation of ataxia telangiectasia mutated (ATM) kinase. Overexpression of DHCR24 impaired p53 activity by suppression of acetylation and increased interaction with MDM2. This impairment of p53 suppressed the hydrogen peroxide-induced apoptotic response in hepatocytes. Thus, a target of oxidative stress in HCV infection is DHCR24 through Sp1, which suppresses apoptotic responses and increases tumorigenicity.
Collapse
|