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Omar AM, Elfaky MA, Arold ST, Soror SH, Khayat MT, Asfour HZ, Bamane FH, El-Araby ME. 1 H-Imidazole-2,5-Dicarboxamides as NS4A Peptidomimetics: Identification of a New Approach to Inhibit HCV-NS3 Protease. Biomolecules 2020; 10:E479. [PMID: 32245218 PMCID: PMC7175367 DOI: 10.3390/biom10030479] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 12/17/2022] Open
Abstract
The nonstructural (NS) protein NS3/4A protease is a critical factor for hepatitis C virus (HCV) maturation that requires activation by NS4A. Synthetic peptide mutants of NS4A were found to inhibit NS3 function. The bridging from peptide inhibitors to heterocyclic peptidomimetics of NS4A has not been considered in the literature and, therefore, we decided to explore this strategy for developing a new class of NS3 inhibitors. In this report, a structure-based design approach was used to convert the bound form of NS4A into 1H-imidazole-2,5-dicarboxamide derivatives as first generation peptidomimetics. This scaffold mimics the buried amino acid sequence Ile-25` to Arg-28` at the core of NS4A21`-33` needed to activate the NS3 protease. Some of the synthesized compounds (Coded MOC) were able to compete with and displace NS4A21`-33` for binding to NS3. For instance, N5-(4-guanidinobutyl)-N2-(n-hexyl)-1H-imidazole-2,5-dicarboxamide (MOC-24) inhibited the binding of NS4A21`-33` with a competition half maximal inhibitory concentration (IC50) of 1.9 ± 0.12 µM in a fluorescence anisotropy assay and stabilized the denaturation of NS3 by increasing the aggregation temperature (40% compared to NS4A21`-33`). MOC-24 also inhibited NS3 protease activity in a fluorometric assay. Molecular dynamics simulations were conducted to rationalize the differences in structure-activity relationship (SAR) between the active MOC-24 and the inactive MOC-26. Our data show that MOC compounds are possibly the first examples of NS4A peptidomimetics that have demonstrated promising activities against NS3 proteins.
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Affiliation(s)
- Abdelsattar M. Omar
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia; (A.M.O.); (M.T.K.)
- Pharmaceutical Chemistry Department, Faculty of Pharmacy, Al-Azhar University, Nasr City, Cairo 11884, Egypt
| | - Mahmoud A. Elfaky
- Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia;
| | - Stefan T. Arold
- Computational Bioscience Research Center, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955, Saudi Arabia;
| | - Sameh H. Soror
- Center for Scientific Excellence Helwan Structural Biology Research (HSBR), Faculty of Pharmacy, Helwan University, Ain Helwan, Cairo 11795, Egypt;
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Ain Helwan, Cairo 11795, Egypt
| | - Maan T. Khayat
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia; (A.M.O.); (M.T.K.)
| | - Hani Z. Asfour
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Faida H. Bamane
- Department of Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia;
| | - Moustafa E. El-Araby
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia; (A.M.O.); (M.T.K.)
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El-Araby ME, Omar AM, Soror SH, Arold ST, Khayat MT, Asfour HZ, Bamane F, Elfaky MA. Synthetic bulky NS4A peptide variants bind to and inhibit HCV NS3 protease. J Adv Res 2020; 24:251-259. [PMID: 32373358 PMCID: PMC7195562 DOI: 10.1016/j.jare.2020.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 11/03/2019] [Accepted: 01/02/2020] [Indexed: 01/21/2023] Open
Abstract
NS4A is a non-structural multi-tasking small peptide that is essential for HCV maturation and replication. The central odd-numbered hydrophobic residues of NS4A (Val-23‘ to Leu-31‘)i are essential for activating NS3 upon NS3/4A protease complex formation. This study aims to design new specific allosteric NS3/4A protease inhibitors by mutating Val-23‘, Ile-25‘, and Ile-29‘ into bulkier amino acids. Pep-15, a synthetic peptide, showed higher binding affinity towards HCV-NS3 subtype-4 than native NS4A. The Kd of Pep-15 (80.0 ± 8.0 nM) was twice as high as that of native NS4A (169 ± 37 nM). The mutant Pep-15 inhibited the catalytic activity of HCV-NS3 by forming an inactive complex. Molecular dynamics simulations suggested that a cascade of conformational changes occurred, especially in the catalytic triad arrangements, thereby inactivating NS3. A large shift in the position of Ser-139 was observed, leading to loss of critical hydrogen bonding with His-57. Even though this study is not a classic drug discovery study—nor do we propose Pep-15 as a drug candidate—it serves as a stepping stone towards developing a potent inhibitor of hitherto untargeted HCV subtypes.
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Affiliation(s)
- Moustafa E El-Araby
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia
| | - Abdelsattar M Omar
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia.,Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Cairo 11884, Egypt
| | - Sameh H Soror
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, Helwan University, Ain Helwan, P.O. 11795, Cairo, Egypt.,Center for Scientific Excellence Helwan Structural Biology Research (HSBR), Faculty of Pharmacy, Helwan University, Ain Helwan, P.O. 11795, Cairo, Egypt
| | - Stefan T Arold
- King Abdullah University of Science and Technology, Computational Bioscience Research Center, Division of Biological and Environmental Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia
| | - Maan T Khayat
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia
| | - Hani Z Asfour
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Faida Bamane
- Department of Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Mahmoud A Elfaky
- Department of Natural Products and Alternative Medicine, Faculty of Pharmacy, King Abdulaziz University, Alsulaymanyah, Jeddah 21589, Saudi Arabia
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Jittavisutthikul S, Thanongsaksrikul J, Thueng-In K, Chulanetra M, Srimanote P, Seesuay W, Malik AA, Chaicumpa W. Humanized-VHH transbodies that inhibit HCV protease and replication. Viruses 2015; 7:2030-56. [PMID: 25903832 PMCID: PMC4411689 DOI: 10.3390/v7042030] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/12/2015] [Accepted: 04/14/2015] [Indexed: 12/28/2022] Open
Abstract
There is a need for safe and broadly effective anti-HCV agents that can cope with genetic multiplicity and mutations of the virus. In this study, humanized-camel VHHs to genotype 3a HCV serine protease were produced and were linked molecularly to a cell penetrating peptide, penetratin (PEN). Human hepatic (Huh7) cells transfected with the JFH-1 RNA of HCV genotype 2a and treated with the cell penetrable nanobodies (transbodies) had a marked reduction of the HCV RNA intracellularly and in their culture fluids, less HCV foci inside the cells and less amounts of HCV core antigen in culture supernatants compared with the infected cells cultured in the medium alone. The PEN-VHH-treated-transfected cells also had up-regulation of the genes coding for the host innate immune response (TRIF, TRAF3, IRF3, IL-28B and IFN-β), indicating that the cell penetrable nanobodies rescued the host innate immune response from the HCV mediated-suppression. Computerized intermolecular docking revealed that the VHHs bound to residues of the protease catalytic triad, oxyanion loop and/or the NS3 N-terminal portion important for non-covalent binding of the NS4A protease cofactor protein. The so-produced transbodies have high potential for testing further as a candidate for safe, broadly effective and virus mutation tolerable anti-HCV agents.
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Affiliation(s)
- Surasak Jittavisutthikul
- Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Jeeraphong Thanongsaksrikul
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani 12120, Thailand.
| | - Kanyarat Thueng-In
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
| | - Monrat Chulanetra
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Potjanee Srimanote
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani 12120, Thailand.
| | - Watee Seesuay
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Aijaz Ahmad Malik
- Graduate Program in Immunology, Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
| | - Wanpen Chaicumpa
- Laboratory for Research and Technology Development, Department of Parasitology and Center of Excellence on Therapeutic Proteins and Antibody Engineering, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
- Graduate Program in Biomedical Science, Faculty of Allied Health Sciences, Thammasat University, Pathum-thani 12120, Thailand.
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Ban S, Ueda Y, Ohashi M, Matsuno K, Ikeda M, Kato N, Miyachi H. Peroxisome proliferator-activated receptor delta antagonists inhibit hepatitis C virus RNA replication. Bioorg Med Chem Lett 2013; 23:4774-8. [PMID: 23891183 DOI: 10.1016/j.bmcl.2013.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 07/03/2013] [Accepted: 07/05/2013] [Indexed: 12/20/2022]
Abstract
It has been reported that ligand-mediated transcription factor peroxisome proliferator-activated receptor alpha (hPPARα) is involved in hepatitis C virus (HCV) RNA replication, whereas hPPARγ is not, and the effect of hPPARδ is unknown. Here, we show that hPPARδ-selective antagonists effectively inhibit HCV RNA replication. We describe the design, synthesis and pharmacological evaluation of a series of biphenyl-4-carboxylic acid-type hPPARδ antagonists, including previously reported compounds, as candidate anti-HCV agents. A representative compound (4c) dose-dependently inhibited HCV RNA replication (EC50 0.22 μM), while exhibiting relatively weak cytotoxicity to the host cells (CC50 2.5 μM). It also showed an additive and dose-dependent effect on the inhibition of HCV RNA replication by pegylated interferon alpha (Peg-IFNα) alone and by both Peg-IFNα and ribavirin (currently the clinical treatment of choice for HCV infection). Thus, combination of a hPPARδ antagonist with current therapy may improve the efficacy of treatment for HCV infection.
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Affiliation(s)
- Shintaro Ban
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-Naka, Kita-ku, Okayama 700-8530, Japan
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Schultz B, Yang H, Delaney WE. Biochemical evaluation of HCV NS3 protease inhibitors. ACTA ACUST UNITED AC 2012; Chapter 13:Unit13B.7. [PMID: 21898332 DOI: 10.1002/0471141755.ph13b07s54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This unit describes assays for characterizing the potency and mechanism of action of NS3 protease inhibitors. Determination of IC(50) values is described using in vitro expressed and purified NS3 protease. This assay can also be used for the rapid exploration of structure-activity relationships. Another protocol describes using the full-length NS3/4A complexes expressed in HCV replicon cell lines for a rapid alternative method for assessing protease activity without requiring conventional protein expression and purification. A method is then provided for determination of inhibitor K(i), which more accurately assesses the potency of inhibitors compared to the IC(50) assay, particularly for potent inhibitors that reach the sensitivity limit for the basic IC(50) assay. The final protocol describes how to determine the reversibility of inhibitor binding to the enzyme, an important parameter that can affect the pharmacodynamic properties of a compound.
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Martin MM, Condotta SA, Fenn J, Olmstead AD, Jean F. In-cell selectivity profiling of membrane-anchored and replicase-associated hepatitis C virus NS3-4A protease reveals a common, stringent substrate recognition profile. Biol Chem 2011; 392:927-35. [PMID: 21749281 DOI: 10.1515/bc.2011.076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The need to identify anti-Flaviviridae agents has resulted in intensive biochemical study of recombinant nonstructural (NS) viral proteases; however, experimentation on viral protease-associated replication complexes in host cells is extremely challenging and therefore limited. It remains to be determined if membrane anchoring and/or association to replicase-membrane complexes of proteases, such as hepatitis C virus (HCV) NS3-4A, plays a regulatory role in the substrate selectivity of the protease. In this study, we examined trans-endoproteolytic cleavage activities of membrane-anchored and replicase-associated NS3-4A using an internally consistent set of membrane-anchored protein substrates mimicking all known HCV NS3-4A polyprotein cleavage sequences. Interestingly, we detected cleavage of substrates encoding for the NS4B/NS5A and NS5A/NS5B junctions, but not for the NS3/NS4A and NS4A/NS4B substrates. This stringent substrate recognition profile was also observed for the replicase-associated NS3-4A and is not genotype-specific. Our study also reveals that ER-anchoring of the substrate is critical for its cleavage by NS3-4A. Importantly, we demonstrate that in HCV-infected cells, the NS4B/NS5A substrate was cleaved efficiently. The unique ability of our membrane-anchored substrates to detect NS3-4A activity alone, in replication complexes, or within the course of infection, shows them to be powerful tools for drug discovery and for the study of HCV biology.
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Affiliation(s)
- Morgan M Martin
- Department of Microbiology and Immunology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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7
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Condotta SA, Martin MM, Boutin M, Jean F. Detection and in-cell selectivity profiling of the full-length West Nile virus NS2B/NS3 serine protease using membrane-anchored fluorescent substrates. Biol Chem 2010; 391:549-59. [PMID: 20302513 DOI: 10.1515/bc.2010.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Flaviviral NS2B/NS3 heterocomplex serine proteases are a primary target for anti-flavivirus drug discovery. To gain insights into the enzymatic properties and molecular determinants of flaviviral NS2B/NS3 protease substrate specificity in host cells, we developed and applied a novel series of membrane-anchored red-shifted fluorescent protein substrates to detect West Nile virus (WNV) NS2B/NS3 endoproteolytic activity in human cells. The substrate consists of a fluorescent reporter group (DsRed) tethered to the endoplasmic reticulum membrane by a membrane-anchoring domain. Between the two domains is a specific peptide linker that corresponds to the NS2A/NS2B, NS2B/NS3, NS3/NS4A, and NS4B/NS5 protein junctions within the WNV polyprotein precursor. When the protease cleaves the peptide linker, the DsRed reporter group is released, changing its localization in the cell from membrane-bound punctate perinuclear to diffuse cytoplasmic. This change in protein location can be monitored by fluorescent microscopy, and cleavage products can be quantified by Western blotting. Our data demonstrate the robustness of our trans-cleavage fluorescence assay to capture single-cell imaging of membrane-associated WNV NS2B/NS3 endoproteolytic activity and to perform in-cell selectivity profiling of the NS2B/NS3 protease. Our study is the first to provide cellular insights into the biological and enzymatic properties of a prime target for inhibitors of WNV replication.
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Affiliation(s)
- Stephanie A Condotta
- Department of Microbiology and Immunology, Life Sciences Center, the University of British Columbia, Vancouver, Canada
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Critical role of cyclophilin A and its prolyl-peptidyl isomerase activity in the structure and function of the hepatitis C virus replication complex. J Virol 2009; 83:6554-65. [PMID: 19386705 DOI: 10.1128/jvi.02550-08] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Replication of hepatitis C virus (HCV) RNA occurs on intracellular membranes, and the replication complex (RC) contains viral RNA, nonstructural proteins, and cellular cofactors. We previously demonstrated that cyclophilin A (CyPA) is an essential cofactor for HCV infection and the intracellular target of cyclosporine's anti-HCV effect. Here we investigate the mechanism by which CyPA facilitates HCV replication. Cyclosporine treatment specifically blocked the incorporation of NS5B into the RC without affecting either the total protein level or the membrane association of the protein. Other nonstructural proteins or viral RNAs in the RC were not affected. NS5B from the cyclosporine-resistant replicon was resistant to this disruption of RC incorporation. We also isolated membrane fractions from both naïve and HCV-positive cells and found that CyPA is recruited into membrane fractions in HCV-replicating cells via an interaction with RC-associated NS5B, which is sensitive to cyclosporine treatment. Finally, we introduced point mutations in the prolyl-peptidyl isomerase (PPIase) motif of CyPA and demonstrated a critical role of this motif in HCV replication in cDNA rescue experiments. We propose a model in which the incorporation of the HCV polymerase into the RC depends on its interaction with a cellular chaperone protein and in which cyclosporine inhibits HCV replication by blocking this critical interaction and the PPIase activity of CyPA. Our results provide a mechanism of action for the cyclosporine-mediated inhibition of HCV and identify a critical role of CyPA's PPIase activity in the proper assembly and function of the HCV RC.
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Bermúdez-Aguirre AD, Padilla-Noriega L, Zenteno E, Reyes-Leyva J. Identification of Amino Acid Variants in the Hepatitis C Virus Non-Structural Protein 4A. TOHOKU J EXP MED 2009; 218:165-75. [DOI: 10.1620/tjem.218.165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Alejandro Daniel Bermúdez-Aguirre
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México
- Laboratorio de Virología, Centro de Investigaciones Biomédicas de Oriente, Instituto Mexicano del Seguro Social, Hospital General de Zona No. 5
| | - Luis Padilla-Noriega
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México
| | - Edgar Zenteno
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México
- Facultad de Medicina Humana, Universidad Ricardo Palma
| | - Julio Reyes-Leyva
- Laboratorio de Virología, Centro de Investigaciones Biomédicas de Oriente, Instituto Mexicano del Seguro Social, Hospital General de Zona No. 5
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Moriishi K, Matsuura Y. Evaluation systems for anti-HCV drugs. Adv Drug Deliv Rev 2007; 59:1213-21. [PMID: 17720275 DOI: 10.1016/j.addr.2007.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 04/03/2007] [Indexed: 12/31/2022]
Abstract
Development of therapeutics for chronic hepatitis C has been hampered by the lack of an efficient cell culture system and a small animal model for the hepatitis C virus (HCV). An RNA replicon system, in which the HCV genome replicates autonomously in cells, and replication competent viruses derived from an HCV genotype 2a JFH1 strain efficiently propagating in Huh7 cells have been developed, and these systems have contributed to the evaluation of anti-HCV drugs targeted to viral and host proteins involved in the replication of HCV. Several compounds counteracting the viral enzymes, such as RNA polymerase and proteases, and host proteins involved in the lipid synthesis and protein folding are reported to have anti-HCV activities based on assessments using these in vitro systems. Furthermore, a mouse model transplanted with human liver fragments was shown to be capable of replicating HCV and has been used to evaluate the efficacy of antiviral drugs in vivo. In this review, we summarize information regarding systems for studying the HCV life cycle and potential new targets for therapeutic intervention for chronic hepatitis C.
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Affiliation(s)
- Kohji Moriishi
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, 3-1, Yamadaoka, Suita-shi, Osaka 565-0871, Japan
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Abstract
Hepatitis C virus (HCV) is the major causative agent of blood-borne hepatitis. The majority of HCV-infected individuals develop chronic hepatitis, which eventually progresses to liver cirrhosis, and hepatocellular carcinoma. Although the precise mechanisms of entry, replication, assembly, egress and pathogenesis of HCV are largely unknown, information about viral receptor candidates has accumulated by the development of pseudotype viruses and an in vitro replication system of the HCV JFH1 strain. Furthermore, the autonomous RNA replication system based on the artificial viral genome revealed that HCV replicates in the intracellular replication complex composed of viral and host proteins. Recently, an immunosuppress ant, cyclosporin A and inhibitors for sphingolipid synthesis and chaperon were reported to inhibit the replication of HCV by counteracting the interplay between host and viral proteins. This review considers the current knowledge of the host proteins that participate in HCV replication and the possibility of developing novel therapeutics intervention for chronic hepatitis C.
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Affiliation(s)
- Kohji Moriishi
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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Hamill P, Hudson D, Kao RY, Chow P, Raj M, Xu H, Richer MJ, Jean F. Development of a red-shifted fluorescence-based assay for SARS-coronavirus 3CL protease: identification of a novel class of anti-SARS agents from the tropical marine sponge Axinella corrugata. Biol Chem 2006; 387:1063-74. [PMID: 16895476 DOI: 10.1515/bc.2006.131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
SARS-coronavirus (SARS-CoV) encodes a main protease, 3CLpro, which plays an essential role in the viral life cycle and is currently the prime target for discovering new anti-coronavirus agents. In this article, we report our success in developing a novel red-shifted (RS) fluorescence-based assay for 3CLpro and its application for identifying small-molecule anti-SARS agents from marine organisms. We have synthesised and characterised the first generation of a red-shifted internally quenched fluorogenic substrate (RS-IQFS) for 3CLpro based on resonance energy transfer between the donor and acceptor pair CAL Fluor Red 610 and Black Hole Quencher-1 (Km and kcat values of 14 microM and 0.65 min-1). The RS-IQFS primary sequence was selected based on the results of our screening analysis of 3CLpro performed using a series of blue-shifted (BS)-IQFSs corresponding to the 3CLpro-mediated cleavage junctions of the SARS-CoV polyproteins. In contrast to BS-IQFSs, the RS-IQFS was not susceptible to fluorescence interference from coloured samples and allowed for successful screening of marine natural products and identification of a coumarin derivative, esculetin-4-carboxylic acid ethyl ester, a novel 3CLpro inhibitor (IC50=46 microM) and anti-SARS agent (EC50=112 microM; median toxic concentration>800 microM) from the tropical marine sponge Axinella corrugata.
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Affiliation(s)
- Pamela Hamill
- Department of Microbiology and Immunology, Life Sciences Centre, University of British Columbia, 3559-2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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Martin MM, Jean F. Single-cell resolution imaging of membrane-anchored hepatitis C virus NS3/4A protease activity. Biol Chem 2006; 387:1075-80. [PMID: 16895477 DOI: 10.1515/bc.2006.132] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The study of host and viral membrane-associated proteases has been hampered due to a lack of in vivo assays. We report here the development of a cell-based fluorescence assay for detecting hepatitis C virus (HCV) NS3/4A juxtamembrane protease activity. Intracellular membrane-anchored protein substrates were engineered comprising: (1) an endoplasmic reticulum targeting domain, the HCV NS5A N-terminal amphipathic alpha-helix; (2) a NS3/4A-specific cleavage site; and (3) a red fluorescent reporter group, DsRed. The results of our immunofluorescence and Western blotting studies demonstrate that our membrane-bound fluorescent probe was cleaved specifically and efficiently by NS3/4A expressed in human cells.
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Affiliation(s)
- Morgan M Martin
- Department of Microbiology and Immunology, Life Sciences Centre, University of British Columbia, 3559-2350 Health Sciences Mall, Vancouver, V6T 1Z3, Canada
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Hamill P, Richer M, Hudson D, Xu H, Jean F. Novel Blue- and Red-Shifted Internally Quenched Fluorogenic Substrates for Continuous Monitoring of SARS-CoV 3CLpro. UNDERSTANDING BIOLOGY USING PEPTIDES 2006. [PMCID: PMC7120450 DOI: 10.1007/978-0-387-26575-9_167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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