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Wang Y, Fu Q, Park SY, Lee YS, Park SY, Lee DY, Yoon S. Decoding cellular mechanism of recombinant adeno-associated virus (rAAV) and engineering host-cell factories toward intensified viral vector manufacturing. Biotechnol Adv 2024; 71:108322. [PMID: 38336188 DOI: 10.1016/j.biotechadv.2024.108322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 01/22/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Recombinant adeno-associated virus (rAAV) is one of the prominent gene delivery vehicles that has opened promising opportunities for novel gene therapeutic approaches. However, the current major viral vector production platform, triple transfection in mammalian cells, may not meet the increasing demand. Thus, it is highly required to understand production bottlenecks from the host cell perspective and engineer the cells to be more favorable and tolerant to viral vector production, thereby effectively enhancing rAAV manufacturing. In this review, we provided a comprehensive exploration of the intricate cellular process involved in rAAV production, encompassing various stages such as plasmid entry to the cytoplasm, plasmid trafficking and nuclear delivery, rAAV structural/non-structural protein expression, viral capsid assembly, genome replication, genome packaging, and rAAV release/secretion. The knowledge in the fundamental biology of host cells supporting viral replication as manufacturing factories or exhibiting defending behaviors against viral production is summarized for each stage. The control strategies from the perspectives of host cell and materials (e.g., AAV plasmids) are proposed as our insights based on the characterization of molecular features and our existing knowledge of the AAV viral life cycle, rAAV and other viral vector production in the Human embryonic kidney (HEK) cells.
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Affiliation(s)
- Yongdan Wang
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Qiang Fu
- Department of Biomedical Engineering and Biotechnology, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - So Young Park
- Department of Pharmaceutical Sciences, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Yong Suk Lee
- Department of Pharmaceutical Sciences, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Seo-Young Park
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Dong-Yup Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Seongkyu Yoon
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, United States of America.
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2
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Fu Q, Polanco A, Lee YS, Yoon S. Critical challenges and advances in recombinant adeno-associated virus (rAAV) biomanufacturing. Biotechnol Bioeng 2023; 120:2601-2621. [PMID: 37126355 DOI: 10.1002/bit.28412] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/27/2023] [Accepted: 04/19/2023] [Indexed: 05/02/2023]
Abstract
Gene therapy is a promising therapeutic approach for genetic and acquired diseases nowadays. Among DNA delivery vectors, recombinant adeno-associated virus (rAAV) is one of the most effective and safest vectors used in commercial drugs and clinical trials. However, the current yield of rAAV biomanufacturing lags behind the necessary dosages for clinical and commercial use, which embodies a concentrated reflection of low productivity of rAAV from host cells, difficult scalability of the rAAV-producing bioprocess, and high levels of impurities materialized during production. Those issues directly impact the price of gene therapy medicine in the market, limiting most patients' access to gene therapy. In this context, the current practices and several critical challenges associated with rAAV gene therapy bioprocesses are reviewed, followed by a discussion of recent advances in rAAV-mediated gene therapy and other therapeutic biological fields that could improve biomanufacturing if these advances are integrated effectively into the current systems. This review aims to provide the current state-of-the-art technology and perspectives to enhance the productivity of rAAV while reducing impurities during production of rAAV.
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Affiliation(s)
- Qiang Fu
- Department of Biomedical Engineering and Biotechnology, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Ashli Polanco
- Department of Chemical Engineering, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Yong Suk Lee
- Department of Pharmaceutical Sciences, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Seongkyu Yoon
- Department of Chemical Engineering, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
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3
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Wang Y, Fu Q, Lee YS, Sha S, Yoon S. Transcriptomic features reveal molecular signatures associated with recombinant adeno-associated virus production in HEK293 cells. Biotechnol Prog 2023; 39:e3346. [PMID: 37130170 DOI: 10.1002/btpr.3346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 03/21/2023] [Accepted: 04/09/2023] [Indexed: 05/04/2023]
Abstract
The development of gene therapies based on recombinant adeno-associated viruses (rAAVs) has grown exponentially, so the current rAAV manufacturing platform needs to be more efficient to satisfy rising demands. Viral production exerts great demand on cellular substrates, energy, and machinery; therefore, viral production relies heavily on the physiology of the host cell. Transcriptomics, as a mechanism-driven tool, was applied to identify significantly regulated pathways and to study cellular features of the host cell for supporting rAAV production. This study investigated the transcriptomic features of two cell lines cultured in their respective media by comparing viral-producing cultures with non-producing cultures over time in parental human embryonic kidney cells (HEK293). The results demonstrate that the innate immune response signaling pathways of host cells (e.g., RIG-I-like receptor signaling pathway, Toll-like receptor signaling pathway, cytosolic DNA sensing pathway, JAK-STAT signaling pathway) were significantly enriched and upregulated. This was accompanied by the host cellular stress responses, including endoplasmic reticulum stress, autophagy, and apoptosis in viral production. In contrast, fatty acid metabolism and neutral amino acid transport were downregulated in the late phase of viral production. Our transcriptomics analysis reveals the cell-line independent signatures for rAAV production and serves as a significant reference for further studies targeting the productivity improvement in the future.
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Affiliation(s)
- Yongdan Wang
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Qiang Fu
- Department of Biomedical Engineering and Biotechnology, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Yong Suk Lee
- Department of Pharmaceutical Sciences, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Sha Sha
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Seongkyu Yoon
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA
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4
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Chung CH, Murphy CM, Wingate VP, Pavlicek JW, Nakashima R, Wei W, McCarty D, Rabinowitz J, Barton E. Production of rAAV by plasmid transfection induces antiviral and inflammatory responses in suspension HEK293 cells. Mol Ther Methods Clin Dev 2023; 28:272-283. [PMID: 36819978 PMCID: PMC9937832 DOI: 10.1016/j.omtm.2023.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 01/13/2023] [Indexed: 01/18/2023]
Abstract
Recombinant adeno-associated virus (rAAV) is a clinically proven viral vector for delivery of therapeutic genes to treat rare diseases. Improving rAAV manufacturing productivity and vector quality is necessary to meet clinical and commercial demand. These goals will require an improved understanding of the cellular response to rAAV production, which is poorly defined. We interrogated the kinetic transcriptional response of HEK293 cells to rAAV production following transient plasmid transfection, under manufacturing-relevant conditions, using RNA-seq. Time-series analyses identified a robust cellular response to transfection and rAAV production, with 1,850 transcripts differentially expressed. Gene Ontology analysis determined upregulated pathways, including inflammatory and antiviral responses, with several interferon-stimulated cytokines and chemokines being upregulated at the protein level. Literature-based pathway prediction implicated multiple pathogen pattern sensors and signal transducers in up-regulation of inflammatory and antiviral responses in response to transfection and rAAV replication. Systematic analysis of the cellular transcriptional response to rAAV production indicates that host cells actively sense vector manufacture as an infectious insult. This dataset may therefore illuminate genes and pathways that influence rAAV production, thereby enabling the rational design of next-generation manufacturing platforms to support safe, effective, and affordable AAV-based gene therapies.
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Affiliation(s)
- Cheng-Han Chung
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA
| | - Christopher M. Murphy
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA
| | - Vincent P. Wingate
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA
| | - Jeffrey W. Pavlicek
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA
| | - Reiko Nakashima
- Pfizer Inc., Worldwide Research, Development and Medical, Simulation and Modeling Sciences, Cambridge, MA 02139, USA
| | - Wei Wei
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA
| | - Douglas McCarty
- Pfizer Inc., Worldwide Research, Development and Medical, Rare Disease Research Unit, Morrisville, NC 27560, USA
| | - Joseph Rabinowitz
- Pfizer Inc., Worldwide Research, Development and Medical, Rare Disease Research Unit, Morrisville, NC 27560, USA
| | - Erik Barton
- Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA,Corresponding author: Erik Barton, Pfizer Inc., Worldwide Research, Development and Medical, Bioprocess Research and Development, Morrisville, NC 27560, USA.
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5
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Jacquet K, Rodrigue MA, Richard DE, Lavoie JN. The adenoviral protein E4orf4: a probing tool to decipher mechanical stress-induced nuclear envelope remodeling in tumor cells. Cell Cycle 2020; 19:2963-2981. [PMID: 33103553 DOI: 10.1080/15384101.2020.1836441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The human adenovirus (Ad) type 2/5 early region 4 (E4) ORF4 protein (E4orf4) exerts a remarkable tumor cell-selective killing activity in mammalian cells. This indicates that E4orf4 can target tumor cell-defining features and is a unique tool to probe cancer cell vulnerabilities. Recently, we found that E4orf4, through an interaction with the polarity protein PAR3, subverts nuclear envelope (NE) remodeling processes in a tumor cell-selective manner. In this Perspective, we outline mechanical signals that modify nuclear dynamics and tumor cell behavior to highlight potential mechanisms for E4orf4's tumoricidal activity. Through an analysis of E4orf4's cellular targets, we define a protein subnetwork that comprises phosphatase systems interconnected to polarity protein hubs, which could contribute to enhanced NE plasticity. We infer that elucidating E4orf4's protein network at a functional level could uncover key mechanisms of NE remodeling that define the tumor cell phenotype.
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Affiliation(s)
- Kévin Jacquet
- Centre de Recherche sur le Cancer de l'Université Laval , Québec, Canada.,Oncology, Centre de Recherche du CHU de Québec-Université Laval , Québec, Canada
| | - Marc-Antoine Rodrigue
- Centre de Recherche sur le Cancer de l'Université Laval , Québec, Canada.,Oncology, Centre de Recherche du CHU de Québec-Université Laval , Québec, Canada
| | - Darren E Richard
- Centre de Recherche sur le Cancer de l'Université Laval , Québec, Canada.,Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval , Québec, Canada.,Endocrinology and Nephrology, Centre de Recherche du CHU de Québec-Université Laval , Québec, Canada
| | - Josée N Lavoie
- Centre de Recherche sur le Cancer de l'Université Laval , Québec, Canada.,Oncology, Centre de Recherche du CHU de Québec-Université Laval , Québec, Canada.,Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, Université Laval , Québec, Canada
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6
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Georgi F, Greber UF. The Adenovirus Death Protein - a small membrane protein controls cell lysis and disease. FEBS Lett 2020; 594:1861-1878. [PMID: 32472693 DOI: 10.1002/1873-3468.13848] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/20/2020] [Accepted: 05/21/2020] [Indexed: 12/16/2022]
Abstract
Human adenoviruses (HAdVs) cause widespread acute and persistent infections. Infections are usually mild and controlled by humoral and cell-based immunity. Reactivation of persistently infected immune cells can lead to a life-threatening disease in immunocompromised individuals, especially children and transplant recipients. To date, no effective therapy or vaccine against HAdV disease is available to the public. HAdV-C2 and C5 are the best-studied of more than 100 HAdV types. They persist in infected cells and release their progeny by host cell lysis to neighbouring cells and fluids, a process facilitated by the adenovirus death protein (ADP). ADP consists of about 100 amino acids and harbours a single membrane-spanning domain. It undergoes post-translational processing in endoplasmic reticulum and Golgi compartments, before localizing to the inner nuclear membrane. Here, we discuss the current knowledge on how ADP induces membrane rupture. Membrane rupture is essential for both progression of disease and efficacy of therapeutic viruses in clinical applications, in particular oncolytic therapy.
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Affiliation(s)
- Fanny Georgi
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Urs F Greber
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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7
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Kleinberger T. Biology of the adenovirus E4orf4 protein: from virus infection to cancer cell death. FEBS Lett 2019; 594:1891-1917. [DOI: 10.1002/1873-3468.13704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/24/2019] [Accepted: 11/25/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Tamar Kleinberger
- Department of Molecular Microbiology the Rappaport Faculty of Medicine Technion –Israel Institute of Technology Haifa Israel
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8
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Wyatt J, Müller MM, Tavassoli M. Cancer Treatment Goes Viral: Using Viral Proteins to Induce Tumour-Specific Cell Death. Cancers (Basel) 2019; 11:E1975. [PMID: 31817939 DOI: 10.3390/cancers11121975] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/04/2019] [Accepted: 12/05/2019] [Indexed: 12/24/2022] Open
Abstract
Cell death is a tightly regulated process which can be exploited in cancer treatment to drive the killing of the tumour. Several conventional cancer therapies including chemotherapeutic agents target pathways involved in cell death, yet they often fail due to the lack of selectivity they have for tumour cells over healthy cells. Over the past decade, research has demonstrated the existence of numerous proteins which have an intrinsic tumour-specific toxicity, several of which originate from viruses. These tumour-selective viral proteins, although from distinct backgrounds, have several similar and interesting properties. Though the mechanism(s) of action of these proteins are not fully understood, it is possible that they can manipulate several cell death modes in cancer exemplifying the intricate interplay between these pathways. This review will discuss our current knowledge on the topic and outstanding questions, as well as deliberate the potential for viral proteins to progress into the clinic as successful cancer therapeutics.
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9
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Nebenzahl-Sharon K, Sharf R, Amer J, Shalata H, Khoury-Haddad H, Sohn SY, Ayoub N, Hearing P, Kleinberger T. An Interaction with PARP-1 and Inhibition of Parylation Contribute to Attenuation of DNA Damage Signaling by the Adenovirus E4orf4 Protein. J Virol 2019; 93:e02253-18. [PMID: 31315986 PMCID: PMC6744226 DOI: 10.1128/jvi.02253-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 07/02/2019] [Indexed: 01/27/2023] Open
Abstract
The adenovirus (Ad) E4orf4 protein was reported to contribute to inhibition of ATM- and ATR-regulated DNA damage signaling during Ad infection and following treatment with DNA-damaging drugs. Inhibition of these pathways improved Ad replication, and when expressed alone, E4orf4 sensitized transformed cells to drug-induced toxicity. However, the mechanisms utilized were not identified. Here, we show that E4orf4 associates with the DNA damage sensor poly(ADP-ribose) polymerase 1 (PARP-1) and that the association requires PARP activity. During Ad infection, PARP is activated, but its activity is not required for recruitment of either E4orf4 or PARP-1 to virus replication centers, suggesting that their association occurs following recruitment. Inhibition of PARP-1 assists E4orf4 in reducing DNA damage signaling during infection, and E4orf4 attenuates virus- and DNA damage-induced parylation. Furthermore, E4orf4 reduces PARP-1 phosphorylation on serine residues, which likely contributes to PARP-1 inhibition as phosphorylation of this enzyme was reported to enhance its activity. PARP-1 inhibition is important to Ad infection since treatment with a PARP inhibitor enhances replication efficiency. When E4orf4 is expressed alone, it associates with poly(ADP-ribose) (PAR) chains and is recruited to DNA damage sites in a PARP-1-dependent manner. This recruitment is required for inhibition of drug-induced ATR signaling by E4orf4 and for E4orf4-induced cancer cell death. Thus, the results presented here demonstrate a novel mechanism by which E4orf4 targets and inhibits DNA damage signaling through an association with PARP-1 for the benefit of the virus and impacting E4orf4-induced cancer cell death.IMPORTANCE Replication intermediates and ends of viral DNA genomes can be recognized by the cellular DNA damage response (DDR) network as DNA damage whose repair may lead to inhibition of virus replication. Therefore, many viruses evolved mechanisms to inhibit the DDR network. We have previously shown that the adenovirus (Ad) E4orf4 protein inhibits DDR signaling, but the mechanisms were not identified. Here, we describe an association of E4orf4 with the DNA damage sensor poly(ADP-ribose) polymerase 1 (PARP-1). E4orf4 reduces phosphorylation of this enzyme and inhibits its activity. PARP-1 inhibition assists E4orf4 in reducing Ad-induced DDR signaling and improves the efficiency of virus replication. Furthermore, the ability of E4orf4, when expressed alone, to accumulate at DNA damage sites and to kill cancer cells is attenuated by chemical inhibition of PARP-1. Our results indicate that the E4orf4-PARP-1 interaction has an important role in Ad replication and in promotion of E4orf4-induced cancer-selective cell death.
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Affiliation(s)
- Keren Nebenzahl-Sharon
- Department of Molecular Microbiology, the Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Rakefet Sharf
- Department of Molecular Microbiology, the Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Jana Amer
- Department of Molecular Microbiology, the Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Hassan Shalata
- Department of Molecular Microbiology, the Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Sook-Young Sohn
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Nabieh Ayoub
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Patrick Hearing
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Tamar Kleinberger
- Department of Molecular Microbiology, the Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
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10
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Wang Q, Huang WR, Chih WY, Chuang KP, Chang CD, Wu Y, Huang Y, Liu HJ. Cdc20 and molecular chaperone CCT2 and CCT5 are required for the Muscovy duck reovirus p10.8-induced cell cycle arrest and apoptosis. Vet Microbiol 2019; 235:151-163. [PMID: 31282373 DOI: 10.1016/j.vetmic.2019.06.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 06/19/2019] [Accepted: 06/22/2019] [Indexed: 01/22/2023]
Abstract
This study demonstrates that the Muscovy duck reovirus (MDRV) p10.8 protein is one of many viral non-structural proteins that induces both cell cycle arrest and apoptosis. The p10.8 but not σC is a nuclear targeting protein that shuttles between the nucleus and the cytoplasm. Our results reveal that p10.8-induced apoptosis in cultured cells occurs by the nucleoporin Tpr/p53-dependent and Fas/caspase 8-mediated pathways. Furthermore, a compelling finding from this study is that the p10.8 and σC proteins of MDRV facilitate CDK2 and CDK4 degradation via the ubiquitin-proteasome pathway. We found that depletion of Cdc20 reversed the p10.8- and σC- mediated CDK4 degradation and p10.8-induced apoptosis, suggesting that Cdc20 plays a critical role in modulating p10.8-mediated cell cycle and apoptosis. Furthermore, we found that depletion of chaperonin-containing tailless complex polypeptide 1 (CCT) 2 and CCT5 reduced the level of Cdc20 and reversed the p10.8- and σC-mediated CDK4 degradation and p10.8-induced apoptosis, indicating that molecular chaperone CCT2 and CCT5 are required for stabilization of Ccd20 for mediating both cell cycle arrest and apoptosis. This study provides mechanistic insights into how p10.8 induces both cell cycle arrest and apoptosis.
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Affiliation(s)
- Quanxi Wang
- College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Wei-Ru Huang
- Institute of Molecular Biology, National Chung Hsing University, Taichung 402, Taiwan
| | - Wan-Yi Chih
- Institute of Molecular Biology, National Chung Hsing University, Taichung 402, Taiwan
| | - Kuo-Pin Chuang
- Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung, 912, Taiwan
| | - Ching-Dong Chang
- Department of Veterinary medicine, National Pingtung University of Science and Technology, Pingtung, 912, Taiwan
| | - Yijian Wu
- College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Yifan Huang
- College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Hung-Jen Liu
- Institute of Molecular Biology, National Chung Hsing University, Taichung 402, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan; Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; Ph. D Program in Translational Medicine, National Chung Hsing University, Taichung 402, Taiwan; Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan.
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11
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Rosen H, Sharf R, Pechkovsky A, Salzberg A, Kleinberger T. Selective elimination of cancer cells by the adenovirus E4orf4 protein in a Drosophila cancer model: a new paradigm for cancer therapy. Cell Death Dis 2019; 10:455. [PMID: 31186403 PMCID: PMC6560070 DOI: 10.1038/s41419-019-1680-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 05/08/2019] [Accepted: 05/16/2019] [Indexed: 01/16/2023]
Abstract
The adenovirus (Ad) E4orf4 protein contributes to efficient progression of virus infection. When expressed alone E4orf4 induces p53- and caspase-independent cell-death, which is more effective in cancer cells than in normal cells in tissue culture. Cancer selectivity of E4orf4-induced cell-death may result from interference with various regulatory pathways that cancer cells are more dependent on, including DNA damage signaling and proliferation control. E4orf4 signaling is conserved in several organisms, including yeast, Drosophila, and mammalian cells, indicating that E4orf4-induced cell-death can be investigated in these model organisms. The Drosophila genetic model system has contributed significantly to the study of cancer and to identification of novel cancer therapeutics. Here, we used the fly model to investigate the ability of E4orf4 to eliminate cancer tissues in a whole organism with minimal damage to normal tissues. We show that E4orf4 dramatically inhibited tumorigenesis and rescued survival of flies carrying a variety of tumors, including highly aggressive and metastatic tumors in the fly brain and eye discs. Moreover, E4orf4 rescued the morphology of adult eyes containing scrib- cancer clones even when expressed at a much later stage than scrib elimination. The E4orf4 partner protein phosphatase 2A (PP2A) was required for inhibition of tumorigenesis by E4orf4 in the system described here, whereas another E4orf4 partner, Src kinase, provided only minimal contribution to this process. Our results suggest that E4orf4 is an effective anticancer agent and reveal a promising potential for E4orf4-based cancer treatments.
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Affiliation(s)
- Helit Rosen
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Rakefet Sharf
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Antonina Pechkovsky
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel.,Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Adi Salzberg
- Department of Genetics and Developmental Biology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel
| | - Tamar Kleinberger
- Department of Molecular Microbiology, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, 3109601, Haifa, Israel.
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12
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Nebenzahl-Sharon K, Shalata H, Sharf R, Amer J, Khoury-Haddad H, Sohn SY, Ayoub N, Hearing P, Kleinberger T. Biphasic Functional Interaction between the Adenovirus E4orf4 Protein and DNA-PK. J Virol 2019; 93:e01365-18. [PMID: 30842317 DOI: 10.1128/JVI.01365-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 02/22/2019] [Indexed: 02/06/2023] Open
Abstract
The adenovirus (Ad) E4orf4 protein contributes to virus-induced inhibition of the DNA damage response (DDR) by reducing ATM and ATR signaling. Consequently, E4orf4 inhibits DNA repair and sensitizes transformed cells to killing by DNA-damaging drugs. Inhibition of ATM and ATR signaling contributes to the efficiency of virus replication and may provide one explanation for the cancer selectivity of cell death induced by the expression of E4orf4 alone. In this report, we investigate a direct interaction of E4orf4 with the DDR. We show that E4orf4 physically associates with the DNA-dependent protein kinase (DNA-PK), and we demonstrate a biphasic functional interaction between these proteins, wherein DNA-PK is required for ATM and ATR inhibition by E4orf4 earlier during infection but is inhibited by E4orf4 as infection progresses. This biphasic process is accompanied by initial augmentation and a later inhibition of DNA-PK autophosphorylation as well as by colocalization of DNA-PK with early Ad replication centers and distancing of DNA-PK from late replication centers. Moreover, inhibition of DNA-PK improves Ad replication more effectively when a DNA-PK inhibitor is added later rather than earlier during infection. When expressed alone, E4orf4 is recruited to DNA damage sites in a DNA-PK-dependent manner. DNA-PK inhibition reduces the ability of E4orf4 to induce cancer cell death, likely because E4orf4 is prevented from arriving at the damage sites and from inhibiting the DDR. Our results support an important role for the E4orf4-DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.IMPORTANCE Several DNA viruses evolved mechanisms to inhibit the cellular DNA damage response (DDR), which acts as an antiviral defense system. We present a novel mechanism by which the adenovirus (Ad) E4orf4 protein inhibits the DDR. E4orf4 interacts with the DNA damage sensor DNA-PK in a biphasic manner. Early during infection, E4orf4 requires DNA-PK activity to inhibit various branches of the DDR, whereas it later inhibits DNA-PK itself. Furthermore, although both E4orf4 and DNA-PK are recruited to virus replication centers (RCs), DNA-PK is later distanced from late-phase RCs. Delayed DNA-PK inhibition greatly contributes to Ad replication efficiency. When E4orf4 is expressed alone, it is recruited to DNA damage sites. Inhibition of DNA-PK prevents both recruitment and the previously reported ability of E4orf4 to kill cancer cells. Our results support an important role for the E4orf4-DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.
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Tan H, Gao S, Zhuang Y, Dong Y, Guan W, Zhang K, Xu J, Cui J. R-Phycoerythrin Induces SGC-7901 Apoptosis by Arresting Cell Cycle at S Phase. Mar Drugs 2016; 14:E166. [PMID: 27626431 DOI: 10.3390/md14090166] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 09/03/2016] [Accepted: 09/07/2016] [Indexed: 02/04/2023] Open
Abstract
R-Phycoerythrin (R-PE), one of the chemical constituents of red algae, could produce singlet oxygen upon excitation with the appropriate radiation and possibly be used in photodynamic therapy (PDT) for cancer. Documents reported that R-PE could inhibit cell proliferation in HepG2 and A549 cells, which was significative for cancer therapy. This is due to the fact that R-PE could kill cancer cells directly as well as by PDT. However, little is known about the cytotoxicity of R-PE to the SGC-7901 cell. In this study, it has been found that R-PE could inhibit SGC-7901 proliferation and induce cell apoptosis, which was achieved by arresting the SGC-7901 cell at S phase. CyclinA, CDK2 and CDC25A are proteins associated with the S phase, and it was found that R-PE could increase the expression of cyclin A protein and decrease the expression of CDK2 and CDC25A proteins. Thus, it was concluded that R-PE reduced the CDK2 protein activated through decreasing the CDC25A factor, which reduced the formation of Cyclin-CDK complex. The reduction of Cyclin-CDK complex made the SGC-7901 cells arrest at the S phase. Therefore, R-PE induced apoptosis by arresting the SGC-7901 cell at S phase was successful, which was achieved by the expression of the CDC25A protein, which reduced the CDK2 protein actived and the formation of Cyclin-CDK complex.
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Brestovitsky A, Nebenzahl-Sharon K, Kechker P, Sharf R, Kleinberger T. The Adenovirus E4orf4 Protein Provides a Novel Mechanism for Inhibition of the DNA Damage Response. PLoS Pathog 2016; 12:e1005420. [PMID: 26867009 DOI: 10.1371/journal.ppat.1005420] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 01/06/2016] [Indexed: 12/20/2022] Open
Abstract
The DNA damage response (DDR) is a conglomerate of pathways designed to detect DNA damage and signal its presence to cell cycle checkpoints and to the repair machinery, allowing the cell to pause and mend the damage, or if the damage is too severe, to trigger apoptosis or senescence. Various DDR branches are regulated by kinases of the phosphatidylinositol 3-kinase-like protein kinase family, including ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR). Replication intermediates and linear double-stranded genomes of DNA viruses are perceived by the cell as DNA damage and activate the DDR. If allowed to operate, the DDR will stimulate ligation of viral genomes and will inhibit virus replication. To prevent this outcome, many DNA viruses evolved ways to limit the DDR. As part of its attack on the DDR, adenovirus utilizes various viral proteins to cause degradation of DDR proteins and to sequester the MRN damage sensor outside virus replication centers. Here we show that adenovirus evolved yet another novel mechanism to inhibit the DDR. The E4orf4 protein, together with its cellular partner PP2A, reduces phosphorylation of ATM and ATR substrates in virus-infected cells and in cells treated with DNA damaging drugs, and causes accumulation of damaged DNA in the drug-treated cells. ATM and ATR are not mutually required for inhibition of their signaling pathways by E4orf4. ATM and ATR deficiency as well as E4orf4 expression enhance infection efficiency. Furthermore, E4orf4, previously reported to induce cancer-specific cell death when expressed alone, sensitizes cells to killing by sub-lethal concentrations of DNA damaging drugs, likely because it inhibits DNA damage repair. These findings provide one explanation for the cancer-specificity of E4orf4-induced cell death as many cancers have DDR deficiencies leading to increased reliance on the remaining intact DDR pathways and to enhanced susceptibility to DDR inhibitors such as E4orf4. Thus DDR inhibition by E4orf4 contributes both to the efficiency of adenovirus replication and to the ability of E4orf4 to kill cancer cells.
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Gupta SK, Yadav PK, Gandham RK, Sahoo A, Harish D, Singh AK, Tiwari A. Canine parvovirus NS1 protein exhibits anti-tumor activity in a mouse mammary tumor model. Virus Res 2016; 213:289-98. [DOI: 10.1016/j.virusres.2015.12.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/20/2015] [Accepted: 12/21/2015] [Indexed: 01/20/2023]
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Dallaire F, Schreiner S, Blair GE, Dobner T, Branton PE, Blanchette P. The Human Adenovirus Type 5 E4orf6/E1B55K E3 Ubiquitin Ligase Complex Can Mimic E1A Effects on E2F. mSphere 2016; 1:e00014-15. [PMID: 27303679 DOI: 10.1128/mSphere.00014-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 09/29/2015] [Indexed: 01/16/2023] Open
Abstract
During the course of work on the adenovirus E3 ubiquitin ligase formed by the viral E4orf6 and E1B55K proteins, we found, very surprisingly, that expression of these species was sufficient to permit low levels of replication of an adenovirus vector lacking E1A, the central regulator of infection. E1A products uncouple E2F transcription factors from Rb repression complexes, thus stimulating viral gene expression and cell and viral DNA synthesis. We found that the E4orf6/E1B55K ligase mimics these functions. This finding is of significance because it represents an entirely new function for the ligase in regulating adenovirus replication. The human adenovirus E4orf6/E1B55K E3 ubiquitin ligase is well known to promote viral replication by degrading an increasing number of cellular proteins that inhibit the efficient production of viral progeny. We report here a new function of the adenovirus 5 (Ad5) viral ligase complex that, although at lower levels, mimics effects of E1A products on E2F transcription factors. When expressed in the absence of E1A, the E4orf6 protein in complex with E1B55K binds E2F, disrupts E2F/retinoblastoma protein (Rb) complexes, and induces hyperphosphorylation of Rb, leading to induction of viral and cellular DNA synthesis as well as stimulation of early and late viral gene expression and production of viral progeny of E1/E3-defective adenovirus vectors. These new and previously undescribed functions of the E4orf6/E1B55K E3 ubiquitin ligase could play an important role in promoting the replication of wild-type viruses. IMPORTANCE During the course of work on the adenovirus E3 ubiquitin ligase formed by the viral E4orf6 and E1B55K proteins, we found, very surprisingly, that expression of these species was sufficient to permit low levels of replication of an adenovirus vector lacking E1A, the central regulator of infection. E1A products uncouple E2F transcription factors from Rb repression complexes, thus stimulating viral gene expression and cell and viral DNA synthesis. We found that the E4orf6/E1B55K ligase mimics these functions. This finding is of significance because it represents an entirely new function for the ligase in regulating adenovirus replication.
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Mui MZ, Zhou Y, Blanchette P, Chughtai N, Knight JF, Gruosso T, Papadakis AI, Huang S, Park M, Gingras AC, Branton PE. The Human Adenovirus Type 5 E4orf4 Protein Targets Two Phosphatase Regulators of the Hippo Signaling Pathway. J Virol 2015; 89:8855-70. [PMID: 26085163 DOI: 10.1128/JVI.03710-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 06/05/2015] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED When expressed alone at high levels, the human adenovirus E4orf4 protein exhibits tumor cell-specific p53-independent toxicity. A major E4orf4 target is the B55 class of PP2A regulatory subunits, and we have shown recently that binding of E4orf4 inhibits PP2A(B55) phosphatase activity in a dose-dependent fashion by preventing access of substrates (M. Z. Mui et al., PLoS Pathog 9:e1003742, 2013, http://dx.doi.org/10.1371/journal.ppat.1003742). While interaction with B55 subunits is essential for toxicity, E4orf4 mutants exist that, despite binding B55 at high levels, are defective in cell killing, suggesting that other essential targets exist. In an attempt to identify additional targets, we undertook a proteomics approach to characterize E4orf4-interacting proteins. Our findings indicated that, in addition to PP2A(B55) subunits, ASPP-PP1 complex subunits were found among the major E4orf4-binding species. Both the PP2A and ASPP-PP1 phosphatases are known to positively regulate effectors of the Hippo signaling pathway, which controls the expression of cell growth/survival genes by dephosphorylating the YAP transcriptional coactivator. We find here that expression of E4orf4 results in hyperphosphorylation of YAP, suggesting that Hippo signaling is affected by E4orf4 interactions with PP2A(B55) and/or ASPP-PP1 phosphatases. Furthermore, knockdown of YAP1 expression was seen to enhance E4orf4 killing, again consistent with a link between E4orf4 toxicity and inhibition of the Hippo pathway. This effect may in fact contribute to the cancer cell specificity of E4orf4 toxicity, as many human cancer cells rely heavily on the Hippo pathway for their enhanced proliferation. IMPORTANCE The human adenovirus E4orf4 protein has been known for some time to induce tumor cell-specific death when expressed at high levels; thus, knowledge of its mode of action could be of importance for development of new cancer therapies. Although the B55 form of the phosphatase PP2A has long been known as an essential E4orf4 target, genetic analyses indicated that others must exist. To identify additional E4orf4 targets, we performed, for the first time, a large-scale affinity purification/mass spectrometry analysis of E4orf4 binding partners. Several additional candidates were detected, including key regulators of the Hippo signaling pathway, which enhances cell viability in many cancers, and results of preliminary studies suggested a link between inhibition of Hippo signaling and E4orf4 toxicity.
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Abstract
During adenovirus (Ad) replication the Ad E4orf4 protein regulates progression from the early to the late phase of infection. However, when E4orf4 is expressed alone outside the context of the virus it induces a non-canonical mode of programmed cell death, which feeds into known cell death pathways such as apoptosis or necrosis, depending on the cell line tested. E4orf4-induced cell death has many interesting and unique features including a higher susceptibility of cancer cells to E4orf4-induced cell killing compared with normal cells, caspase-independence, a high degree of evolutionary conservation of the signaling pathways, a link to perturbations of the cell cycle, and involvement of two distinct cell death programs, in the nucleus and in the cytoplasm. Several E4orf4-interacting proteins including its major partners, protein phosphatase 2A (PP2A) and Src family kinases, contribute to induction of cell death. The various features of E4orf4-induced cell killing as well as studies to decipher the underlying mechanisms are described here. Many explanations for the cancer specificity of E4orf4-induced cell death have been proposed, but a full understanding of the reasons for the different susceptibility of cancer and normal cells to killing by E4orf4 will require a more detailed analysis of the complex E4orf4 signaling network. An improved understanding of the mechanisms involved in this unique mode of programmed cell death may aid in design of novel E4orf4-based cancer therapeutics.
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Affiliation(s)
- Tamar Kleinberger
- Department of Microbiology, Faculty of Medicine, Technion-Israel Institute of Technology, 1 Efron St., Bat Galim, Haifa 31096, Israel.
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19
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Abstract
UNLABELLED Infection with adenovirus triggers the cellular DNA damage response, elements of which include cell death and cell cycle arrest. Early adenoviral proteins, including the E1B-55K and E4orf3 proteins, inhibit signaling in response to DNA damage. A fraction of cells infected with an adenovirus mutant unable to express the E1B-55K and E4orf3 genes appeared to arrest in a mitotic-like state. Cells infected early in G1 of the cell cycle were predisposed to arrest in this state at late times of infection. This arrested state, which displays hallmarks of mitotic catastrophe, was prevented by expression of either the E1B-55K or the E4orf3 genes. However, E1B-55K mutant virus-infected cells became trapped in a mitotic-like state in the presence of the microtubule poison colcemid, suggesting that the two viral proteins restrict entry into mitosis or facilitate exit from mitosis in order to prevent infected cells from arresting in mitosis. The E1B-55K protein appeared to prevent inappropriate entry into mitosis through its interaction with the cellular tumor suppressor protein p53. The E4orf3 protein facilitated exit from mitosis by possibly mislocalizing and functionally inactivating cyclin B1. When expressed in noninfected cells, E4orf3 overcame the mitotic arrest caused by the degradation-resistant R42A cyclin B1 variant. IMPORTANCE Cells that are infected with adenovirus type 5 early in G1 of the cell cycle are predisposed to arrest in a mitotic-like state in a p53-dependent manner. The adenoviral E1B-55K protein prevents entry into mitosis. This newly described activity for the E1B-55K protein appears to depend on the interaction between the E1B-55K protein and the tumor suppressor p53. The adenoviral E4orf3 protein facilitates exit from mitosis, possibly by altering the intracellular distribution of cyclin B1. By preventing entry into mitosis and by promoting exit from mitosis, these adenoviral proteins act to prevent the infected cell from arresting in a mitotic-like state.
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Affiliation(s)
- Roberta L Turner
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Peter Groitl
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Thomas Dobner
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - David A Ornelles
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
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20
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Abstract
The most prominent ezrin-radixin-moesin protein in hepatocytes is radixin, which is localized primarily at the canalicular microvilli and appears to be important in regulation of cell polarity and in localizing the multidrug resistance-associated protein 2 (Mrp-2) function. Our aim was to investigate how hypoxia affects radixin distribution and Mrp-2 function. We created wild-type and mutant constructs (in adenoviral vectors), which were expressed in WIF-B cells. The cellular distribution of Mrp-2 and radixin was visualized by fluorescence microscopy, and a 5-chloromethylfluorescein diacetate (CMFDA) assay was used to measure Mrp-2 function. Under usual conditions, cells infected with wild-type radixin, nonphosphorylatable radixin-T564A, and radixin-T564D (active phospho-mimicking mutant) were found to be heavily expressed in canalicular membrane compartment vacuoles, typically colocalizing with Mrp-2. In contrast, after hypoxia for 24 h, both endogenous and overexpressed wild-type radixin and the radixin-T564A mutant were found to be translocated to the cytoplasmic space. However, distribution of the radixin-T564D mutant, which mimics constant phosphorylation, was remarkably different, being associated with canalicular membranes even in hypoxic conditions. This dominant-active construct also prevented dissociation of radixin from the plasma membrane. Hypoxia also led to Mrp-2 mislocalization and caused Mrp-2 to be dissociated from radixin; the radixin phospho-mimicking mutant (T564D) abrogated this effect of hypoxia. Finally, hypoxia diminished the secretory response (measured using the CMFDA assay) in WIF-B cells, and the dominant-active construct (radixin-T567D) rescued this phenotype. Taken collectively, these findings suggest that radixin regulates Mrp-2 localization and function in hepatocytes and is important in hypoxic liver injury.
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Affiliation(s)
- Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Don C Rockey
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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Sriskandarajah N, Blanchette P, Kucharski TJ, Teodoro JG, Branton PE. Analysis by live imaging of effects of the adenovirus E4orf4 protein on passage through mitosis of H1299 tumor cells. J Virol 2015; 89:4685-9. [PMID: 25653433 DOI: 10.1128/JVI.03437-14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The adenovirus E4orf4 protein expressed at high levels kills cancer cells but not normal human primary cells. Previous studies suggested that disruption of processes that regulate mitosis may underlie E4orf4 toxicity. Here we have used live imaging to show that E4orf4 induces a slowed defective transit through mitosis, exhibiting a delay or often failure in cytokinesis that may account for an accumulation of G1 tetraploids in the population of dying E4orf4-expressing cells.
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Gupta SK, Gandham RK, Sahoo AP, Tiwari AK. Viral genes as oncolytic agents for cancer therapy. Cell Mol Life Sci 2014; 72:1073-94. [PMID: 25408521 DOI: 10.1007/s00018-014-1782-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 10/29/2014] [Accepted: 11/13/2014] [Indexed: 12/20/2022]
Abstract
Many viruses have the ability to modulate the apoptosis, and to accomplish it; viruses encode proteins which specifically interact with the cellular signaling pathways. While some viruses encode proteins, which inhibit the apoptosis or death of the infected cells, there are viruses whose encoded proteins can kill the infected cells by multiple mechanisms, including apoptosis. A particular class of these viruses has specific gene(s) in their genomes which, upon ectopic expression, can kill the tumor cells selectively without affecting the normal cells. These genes and their encoded products have demonstrated great potential to be developed as novel anticancer therapeutic agents which can specifically target and kill the cancer cells leaving the normal cells unharmed. In this review, we will discuss about the viral genes having specific cancer cell killing properties, what is known about their functioning, signaling pathways and their therapeutic applications as anticancer agents.
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Affiliation(s)
- Shishir Kumar Gupta
- Molecular Biology Lab, Division of Veterinary Biotechnology, Indian Veterinary Research Institute, Izatnagar, Bareilly, 243122, UP, India
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23
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Avital-Shacham M, Sharf R, Kleinberger T. NTPDASE4 gene products cooperate with the adenovirus E4orf4 protein through PP2A-dependent and -independent mechanisms and contribute to induction of cell death. J Virol 2014; 88:6318-28. [PMID: 24672025 DOI: 10.1128/JVI.00381-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED The adenovirus E4orf4 protein induces nonclassical apoptosis in mammalian cells through at least two complementing pathways regulated by the interactions of E4orf4 with protein phosphatase 2A (PP2A) and Src kinases. In Saccharomyces cerevisiae cells, which do not express Src, E4orf4 induces PP2A-dependent toxicity. The yeast Golgi apyrase Ynd1 was found to contribute to E4orf4-mediated toxicity and to interact with the PP2A-B55α regulatory subunit. In addition, a mammalian Ynd1 orthologue, the NTPDASE4 gene product Golgi UDPase, was shown to physically interact with E4orf4. Here we report that knockdown of NTPDASE4 suppressed E4orf4-induced cell death. Conversely, overexpression of the NTPDASE4 gene products Golgi UDPase and LALP70 enhanced E4orf4-induced cell killing. We found that similarly to results obtained in yeast, the apyrase activity of mammalian UDPase was not required for its contribution to E4orf4-induced toxicity. The interaction between E4orf4 and UDPase had two consequences: a PP2A-dependent one, resulting in increased UDPase levels, and a PP2A-independent outcome that led to dissociation of large UDPase-containing protein complexes. The present report extends our findings in yeast to E4orf4-mediated death of mammalian cells, and combined with previous results, it suggests that the E4orf4-NTPDase4 pathway, partly in association with PP2A, may provide an alternative mechanism for the E4orf4-Src pathway to contribute to the cytoplasmic death function of E4orf4. IMPORTANCE The adenovirus E4orf4 protein contributes to regulation of the progression of virus infection from the early to the late phase, and when expressed alone, it induces a unique caspase-independent programmed cell death which is more efficient in cancer cells than in normal cells. The interactions of E4orf4 with cellular proteins that mediate its functions, such as PP2A and Src kinases, are highly conserved in evolution. The results presented here reveal that the NTPDASE4 gene product Golgi UDPase, first discovered to contribute to E4orf4 toxicity in Saccharomyces cerevisiae, associates with E4orf4 and plays a role in induction of cell death in mammalian cells. Details of the functional interaction between E4orf4, PP2A, and the UDPase are described. Identification of the evolutionarily conserved mechanisms underlying E4orf4 activity will increase our understanding of the interactions between the virus and the host cell and will contribute to our grasp of the unique mode of E4orf4-induced cell death.
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Abstract
The adenovirus E4orf4 protein is a multifunctional viral regulator that contributes to temporal regulation of the progression of viral infection. When expressed alone, outside the context of the virus, E4orf4 induces p53-independent cell-death in transformed cells. Oncogenic transformation of primary cells in tissue culture sensitizes them to cell killing by E4orf4, indicating that E4orf4 research may have implications for cancer therapy. It has also been reported that E4orf4 induces a caspase-independent, non-classical apoptotic pathway, which maintains crosstalk with classical caspase-dependent pathways. Furthermore, several E4orf4 activities in the nucleus and in the cytoplasm and various protein partners contribute to cell killing by this viral protein. In the following chapter I summarize the current knowledge of the unique mode of E4orf4-induced cell death and its underlying mechanisms. Although several explanations for the cancer-specificity of E4orf4-induced toxicity have been proposed, a better grasp of the mechanisms responsible for E4orf4-induced cell death is required to elucidate the differential sensitivity of normal and cancer cells to E4orf4.
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Affiliation(s)
- Tamar Kleinberger
- Department of Molecular Microbiology, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, 31096, Israel,
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25
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Mui MZ, Kucharski M, Miron MJ, Hur WS, Berghuis AM, Blanchette P, Branton PE. Identification of the adenovirus E4orf4 protein binding site on the B55α and Cdc55 regulatory subunits of PP2A: Implications for PP2A function, tumor cell killing and viral replication. PLoS Pathog 2013; 9:e1003742. [PMID: 24244166 PMCID: PMC3828177 DOI: 10.1371/journal.ppat.1003742] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 09/18/2013] [Indexed: 11/18/2022] Open
Abstract
Adenovirus E4orf4 protein induces the death of human cancer cells and Saccharomyces cerevisiae. Binding of E4orf4 to the B/B55/Cdc55 regulatory subunit of protein phosphatase 2A (PP2A) is required, and such binding inhibits PP2AB55 activity leading to dose-dependent cell death. We found that E4orf4 binds across the putative substrate binding groove predicted from the crystal structure of B55α such that the substrate p107 can no longer interact with PP2AB55α. We propose that E4orf4 inhibits PP2AB55 activity by preventing access of substrates and that at high E4orf4 levels this inhibition results in cell death through the failure to dephosphorylate substrates required for cell cycle progression. However, E4orf4 is expressed at much lower and less toxic levels during a normal adenovirus infection. We suggest that in this context E4orf4 largely serves to recruit novel substrates such as ASF/SF2/SRSF1 to PP2AB55 to enhance adenovirus replication. Thus E4orf4 toxicity probably represents an artifact of overexpression and does not reflect the evolutionary function of this viral product. The adenovirus E4orf4 protein when expressed alone at high levels induces the death of human cancer cells but not normal primary cells. It also is toxic in the yeast Saccharomyces cerevisiae, which we have used as a model system in some studies. Toxicity induced by the E4orf4 protein is largely dependent on its ability to associate with the highly conserved B/B55/Cdc55 class of regulatory subunits of protein phosphatase 2A (PP2A), of which the mammalian B55α species is best characterized structurally. We showed previously that binding to B55α appears to inhibit PP2A activity against at least some substrates. In the present study, we mapped the E4orf4 binding site on both yeast Cdc55 and mammalian B55α and propose how such binding may inhibit PP2A activity. The implications of E4orf4 binding on PP2A activity are of significant scientific interest in terms of the process by which PP2A recognizes and dephosphorylates its substrates. We also propose that E4orf4 binding in the context of viral replication serves the quite different function of introducing novel substrates for dephosphorylation by the PP2A holoenzyme.
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Affiliation(s)
- Melissa Z. Mui
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Michael Kucharski
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | | | - Woosuk Steve Hur
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | | | - Paola Blanchette
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Philip E. Branton
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
- Department of Oncology, McGill University, Montreal, Quebec, Canada
- The Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada
- * E-mail:
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26
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Boehme KW, Hammer K, Tollefson WC, Konopka-Anstadt JL, Kobayashi T, Dermody TS. Nonstructural protein σ1s mediates reovirus-induced cell cycle arrest and apoptosis. J Virol 2013; 87:12967-79. [PMID: 24067959 DOI: 10.1128/JVI.02080-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Reovirus nonstructural protein σ1s is implicated in cell cycle arrest at the G2/M boundary and induction of apoptosis. However, the contribution of σ1s to these effects in an otherwise isogenic viral background has not been defined. To evaluate the role of σ1s in cell cycle arrest and apoptosis, we used reverse genetics to generate a σ1s-null reovirus. Following infection with wild-type virus, we observed an increase in the percentage of cells in G2/M, whereas the proportion of cells in G2/M following infection with the σ1s-null mutant was unaffected. Similarly, we found that the wild-type virus induced substantially greater levels of apoptosis than the σ1s-null mutant. These data indicate that σ1s is required for both reovirus-induced cell cycle arrest and apoptosis. To define sequences in σ1s that mediate these effects, we engineered viruses encoding C-terminal σ1s truncations by introducing stop codons in the σ1s open reading frame. We also generated viruses in which charged residues near the σ1s amino terminus were replaced individually or as a cluster with nonpolar residues. Analysis of these mutants revealed that amino acids 1 to 59 and the amino-terminal basic cluster are required for induction of both cell cycle arrest and apoptosis. Remarkably, viruses that fail to induce cell cycle arrest and apoptosis also are attenuated in vivo. Thus, identical sequences in σ1s are required for reovirus-induced cell cycle arrest, apoptosis, and pathogenesis. Collectively, these findings provide evidence that the σ1s-mediated properties are genetically linked and suggest that these effects are mechanistically related.
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Cabon L, Sriskandarajah N, Mui MZ, Teodoro JG, Blanchette P, Branton PE. Adenovirus E4orf4 protein-induced death of p53-/- H1299 human cancer cells follows a G1 arrest of both tetraploid and diploid cells due to a failure to initiate DNA synthesis. J Virol 2013; 87:13168-78. [PMID: 24067978 DOI: 10.1128/JVI.01242-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The adenovirus E4orf4 protein selectively kills human cancer cells independently of p53 and thus represents a potentially promising tool for the development of novel antitumor therapies. Previous studies suggested that E4orf4 induces an arrest or a delay in mitosis and that both this effect and subsequent cell death rely largely on an interaction with the B55 regulatory subunit of protein phosphatase 2A. In the present report, we show that the death of human H1299 lung carcinoma cells induced by expression of E4orf4 is typified not by an accumulation of cells arrested in mitosis but rather by the presence of both tetraploid and diploid cells that are arrested in G1 because they are unable to initiate DNA synthesis. We believe that these E4orf4-expressing cells eventually die by various processes, including those resulting from mitotic catastrophe.
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Zou QF, Du JK, Zhang H, Wang HB, Hu ZD, Chen SP, Du Y, Li MZ, Xie D, Zou J, Sun HD, Pu JX, Zeng MS. Anti-tumour activity of longikaurin A (LK-A), a novel natural diterpenoid, in nasopharyngeal carcinoma. J Transl Med 2013; 11:200. [PMID: 23985029 PMCID: PMC3847153 DOI: 10.1186/1479-5876-11-200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 08/16/2013] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Longikaurin A is a natural ent-kaurene diterpenoid isolated from Isodon genus. The ent-kaurene diterpenoids isolated from medicinal plants have been shown to have anti-disease effects. The present study was designed to examine the anti-tumour effects of longikaurin A (LK-A) in nasopharyngeal carcinoma in vitro and in vivo. METHODS Apoptosis and cell cycle arrest were determined by flow cytometry analysis of the cells treated with Longikaurin A. The proteins of apoptosis signaling pathway were detected by western blotting analysis. Finally, we examined whether LK-A exhibits anti-tumour activity in xenograft models. RESULTS Longikaurin A inhibited the cell growth by inducing apoptosis and cell cycle arrest. At low concentrations, longikaurin A induced S phase arrest and at higher concentrations, longikaurin A induced caspase-dependent apoptosis by regulating apoptotic molecules. Finally, longikaurin A significantly inhibited the tumour growth of CNE2 xenografts in vivo and showed no obvious effect on the body weights of the mice. CONCLUSION Our results suggest that Longikaurin A exhibited anti-tumour activity in nasopharyngeal carcinoma in vitro and in vivo.
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Affiliation(s)
- Qing-Feng Zou
- State Key Laboratory of Oncology in South China, Department of Experimental Research, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
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Wong CM, McFall ER, Burns JK, Parks RJ. The role of chromatin in adenoviral vector function. Viruses 2013; 5:1500-15. [PMID: 23771241 PMCID: PMC3717718 DOI: 10.3390/v5061500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 06/01/2013] [Accepted: 06/04/2013] [Indexed: 12/20/2022] Open
Abstract
Vectors based on adenovirus (Ad) are one of the most commonly utilized platforms for gene delivery to cells in molecular biology studies and in gene therapy applications. Ad is also the most popular vector system in human clinical gene therapy trials, largely due to its advantageous characteristics such as high cloning capacity (up to 36 kb), ability to infect a wide variety of cell types and tissues, and relative safety due to it remaining episomal in transduced cells. The latest generation of Ad vectors, helper‑dependent Ad (hdAd), which are devoid of all viral protein coding sequences, can mediate high-level expression of a transgene for years in a variety of species ranging from rodents to non-human primates. Given the importance of histones and chromatin in modulating gene expression within the host cell, it is not surprising that Ad, a nuclear virus, also utilizes these proteins to protect the genome and modulate virus- or vector‑encoded genes. In this review, we will discuss our current understanding of the contribution of chromatin to Ad vector function.
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Affiliation(s)
- Carmen M. Wong
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, K1H 8L6, Canada; E-Mails: (C.M.W.); (E.R.M.); (J.K.B.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Emily R. McFall
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, K1H 8L6, Canada; E-Mails: (C.M.W.); (E.R.M.); (J.K.B.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Joseph K. Burns
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, K1H 8L6, Canada; E-Mails: (C.M.W.); (E.R.M.); (J.K.B.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Robin J. Parks
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, K1H 8L6, Canada; E-Mails: (C.M.W.); (E.R.M.); (J.K.B.)
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
- Department of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-613-737-8123; Fax: +1-613-737-8803
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Pechkovsky A, Lahav M, Bitman E, Salzberg A, Kleinberger T. E4orf4 induces PP2A- and Src-dependent cell death in Drosophila melanogaster and at the same time inhibits classic apoptosis pathways. Proc Natl Acad Sci U S A 2013; 110:E1724-33. [PMID: 23613593 DOI: 10.1073/pnas.1220282110] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The adenovirus E4orf4 protein regulates the progression of viral infection, and when expressed alone in mammalian tissue culture cells it induces protein phosphatase 2A (PP2A)-B55- and Src-dependent cell death, which is more efficient in oncogene-transformed cells than in normal cells. This form of cell death is caspase-independent, although it interacts with classic caspase-dependent apoptosis. PP2A-B55-dependent E4orf4-induced toxicity is highly conserved in evolution from yeast to mammalian cells. In this work we investigated E4orf4-induced cell death in a whole multicellular organism, Drosophila melanogaster. We show that E4orf4 induced low levels of cell killing, caused by both caspase-dependent and -independent mechanisms. Drosophila PP2A-B55 (twins/abnormal anaphase resolution) and Src64B contributed additively to this form of cell death. Our results provide insight into E4orf4-induced cell death, demonstrating that in parallel to activating caspase-dependent apoptosis, E4orf4 also inhibited this form of cell death induced by the proapoptotic genes reaper, head involution defective, and grim. The combination of both induction and inhibition of caspase-dependent cell death resulted in low levels of tissue damage that may explain the inefficient cell killing induced by E4orf4 in normal cells in tissue culture. Furthermore, E4orf4 inhibited JNK-dependent cell killing as well. However, JNK inhibition did not impede E4orf4-induced toxicity and even enhanced it, indicating that E4orf4-induced cell killing is a distinctive form of cell death that differs from both JNK- and Rpr/Hid/Grim-induced forms of cell death.
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Horowitz B, Sharf R, Avital-Shacham M, Pechkovsky A, Kleinberger T. Structure- and modeling-based identification of the adenovirus E4orf4 binding site in the protein phosphatase 2A B55α subunit. J Biol Chem 2013; 288:13718-27. [PMID: 23530045 DOI: 10.1074/jbc.m112.343756] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND The adenovirus E4orf4 protein must bind protein phosphatase 2A (PP2A) for its functions. RESULTS The E4orf4 binding site in PP2A was mapped to the α1,α2 helices of the B55α subunit. CONCLUSION The E4orf4 binding site in PP2A-B55α lies above the substrate binding site and does not overlap it. SIGNIFICANCE A novel functional significance was assigned to the α1,α2 helices of the PP2A-B55α subunit. The adenovirus E4orf4 protein regulates the progression of viral infection and when expressed outside the context of the virus it induces nonclassical, cancer cell-specific apoptosis. All E4orf4 functions known to date require an interaction between E4orf4 and protein phosphatase 2A (PP2A), which is mediated through PP2A regulatory B subunits. Specifically, an interaction with the B55α subunit is required for induction of cell death by E4orf4. To gain a better insight into the E4orf4-PP2A interaction, mapping of the E4orf4 interaction site in PP2A-B55α has been undertaken. To this end we used a combination of bioinformatics analyses of PP2A-B55α and of E4orf4, which led to the prediction of E4orf4 binding sites on the surface of PP2A-B55α. Mutation analysis, immunoprecipitation, and GST pulldown assays based on the theoretical predictions revealed that the E4orf4 binding site included the α1 and α2 helices described in the B55α structure and involved at least three residues located in these helices facing each other. Loss of E4orf4 binding was accompanied by reduced contribution of the B55α mutants to E4orf4-induced cell death. The identified E4orf4 binding domain lies above the previously described substrate binding site and does not overlap it, although its location could be consistent with direct or indirect effects on substrate binding. This work assigns for the first time a functional significance to the α1,α2 helices of B55α, and we suggest that the binding site defined by these helices could also contribute to interactions between PP2A and some of its cellular regulators.
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Affiliation(s)
- Ben Horowitz
- Department of Molecular Microbiology, Faculty of Medicine, Technion-Israel Institute of Technology, Bat Galim, Haifa 31096, Israel
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Brestovitsky A, Sharf R, Mittelman K, Kleinberger T. The adenovirus E4orf4 protein targets PP2A to the ACF chromatin-remodeling factor and induces cell death through regulation of SNF2h-containing complexes. Nucleic Acids Res 2011; 39:6414-27. [PMID: 21546548 PMCID: PMC3159439 DOI: 10.1093/nar/gkr231] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The adenovirus E4 open-reading-frame 4 (E4orf4) protein regulates the progression of viral infection and when expressed individually it induces non-classical apoptosis in transformed cells. Here we show that E4orf4 associates with the ATP-dependent chromatin-remodeling factor ACF that consists of a sucrose non fermenting-2h (SNF2h) ATPase and an Acf1 regulatory subunit. Furthermore, E4orf4 targets protein phosphatase 2A (PP2A) to this complex and to chromatin. Obstruction of SNF2h activity inhibits E4orf4-induced cell death, whereas knockdown of Acf1 results in enhanced E4orf4-induced toxicity in both mammalian and yeast cells, and Acf1 overexpression inhibits E4orf4′s ability to downregulate early adenovirus gene expression in the context of viral infection. Knockdown of the Acf1 homolog, WSTF, inhibits E4orf4-induced cell death. Based on these results we suggest that the E4orf4–PP2A complex inhibits ACF and facilitates enhanced chromatin-remodeling activities of other SNF2h-containing complexes, such as WSTF–SNF2h. The resulting switch in chromatin remodeling determines life versus death decisions and contributes to E4orf4 functions during adenovirus infection.
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Affiliation(s)
- Anna Brestovitsky
- Department of Molecular Microbiology, Faculty of Medicine, Technion - Israel Institute of Technology, Bat Galim, Haifa 31096, Israel
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Abstract
INTRODUCTION The anaphase promoting complex/cyclosome (APC/C) is a ubiquitin ligase involved in regulation of the cell cycle through ubiquitination-dependent substrate proteolysis. Many viral proteins have been shown to interact with the APC/C, derailing cell cycle progression in order to facilitate their own replication. Induction of G(2)/M arrest by viral APC/C inhibition can lead to apoptotic cell death. Some viral proteins cause cytotoxicity specifically in tumour cells, providing evidence that targeting the APC/C could be exploited to selectively eliminate cancer cells. AREAS COVERED In this review, we provide a summary of studies from viral APC/C interactions over the last decade, as well as recent discoveries identifying the APC/C as a promising target in the context of cancer therapy. EXPERT OPINION Current therapeutic strategies inducing mitotic arrest rely on activation of the spindle assembly checkpoint (SAC) for their function. Many cancer cells have a weakened SAC and escape apoptosis through mitotic slippage. Recent evidence has demonstrated that targeting the APC/C, particularly the co-activator Cdc20, might be a better alternative. Tumour cells display greater dependency on APC/C function than normal cells and oncogenic transformation can lead to increased mitotic stress, rendering cancer cells more vulnerable to APC/C inhibition.
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Affiliation(s)
- Linda Smolders
- McGill University, Goodman Cancer Research Centre, Department of Biochemistry, 1160 Pine Avenue West, Room 616, Montreal, Quebec H3A 1A3, Canada
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Mittelman K, Ziv K, Maoz T, Kleinberger T. The cytosolic tail of the Golgi apyrase Ynd1 mediates E4orf4-induced toxicity in Saccharomyces cerevisiae. PLoS One 2010; 5:e15539. [PMID: 21124936 PMCID: PMC2989921 DOI: 10.1371/journal.pone.0015539] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Accepted: 10/13/2010] [Indexed: 11/18/2022] Open
Abstract
The adenovirus E4 open reading frame 4 (E4orf4) protein contributes to regulation of the progression of virus infection. When expressed individually, E4orf4 was shown to induce non-classical transformed cell-specific apoptosis in mammalian cells. At least some of the mechanisms underlying E4orf4-induced toxicity are conserved from yeast to mammals, including the requirement for an interaction of E4orf4 with protein phosphatase 2A (PP2A). A genetic screen in yeast revealed that the Golgi apyrase Ynd1 associates with E4orf4 and contributes to E4orf4-induced toxicity, independently of Ynd1 apyrase activity. Ynd1 and PP2A were shown to contribute additively to E4orf4-induced toxicity in yeast, and to interact genetically and physically. A mammalian orthologue of Ynd1 was shown to bind E4orf4 in mammalian cells, confirming the evolutionary conservation of this interaction. Here, we use mutation analysis to identify the cytosolic tail of Ynd1 as the protein domain required for mediation of the E4orf4 toxic signal and for the interaction with E4orf4. We also show that E4orf4 associates with cellular membranes in yeast and is localized at their cytoplasmic face. However, E4orf4 is membrane-associated even in the absence of Ynd1, suggesting that additional membrane proteins may mediate E4orf4 localization. Based on our results and on a previous report describing a collection of Ynd1 protein partners, we propose that the Ynd1 cytoplasmic tail acts as a scaffold, interacting with a multi-protein complex, whose targeting by E4orf4 leads to cell death.
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Affiliation(s)
- Karin Mittelman
- Department of Molecular Microbiology, Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
| | - Keren Ziv
- Department of Molecular Microbiology, Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
| | - Tsofnat Maoz
- Department of Molecular Microbiology, Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
| | - Tamar Kleinberger
- Department of Molecular Microbiology, Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
- * E-mail:
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Zhang Z, Mui MZ, Chan F, Roopchand DE, Marcellus RC, Blanchette P, Li S, Berghuis AM, Branton PE. Genetic analysis of B55alpha/Cdc55 protein phosphatase 2A subunits: association with the adenovirus E4orf4 protein. J Virol 2011; 85:286-95. [PMID: 21047956 DOI: 10.1128/JVI.01381-10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human adenovirus E4orf4 protein is toxic in both human tumor cells and Saccharomyces cerevisiae. Previous studies indicated that most of this toxicity is dependent on an interaction of E4orf4 protein with the B55 class of regulatory subunits of protein phosphatase 2A (PP2A) and in yeast with the B55 homolog Cdc55. We have found previously that E4orf4 inhibits PP2A activity against at least some substrates. In an attempt to understand the mechanism of this inhibition, we used a genetic approach to identify residues in the seven-bladed β-propeller proteins B55α and Cdc55 required for E4orf4 binding. In both cases, amino-terminal polypeptides composed only of blade 1 and at least part of blade 2 were found to bind E4orf4 and overexpression blocked E4orf4 toxicity in yeast. Furthermore, certain amino acid substitutions in blades 1 and 2 within full-length B55α and Cdc55 resulted in loss of E4orf4 binding. Recent mutational analysis has suggested that segments of blades 1 and 2 present on the top face of B55α form part of the "substrate-binding groove." Additionally, these segments are in close proximity to the catalytic C subunit of the PP2A holoenzyme. Thus, our results are consistent with the hypothesis that E4orf4 binding could affect the access of substrates, resulting in the failure to dephosphorylate some PP2A substrates.
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Lavoie JN, Landry MC, Faure RL, Champagne C. Src-family kinase signaling, actin-mediated membrane trafficking and organellar dynamics in the control of cell fate: lessons to be learned from the adenovirus E4orf4 death factor. Cell Signal 2010; 22:1604-14. [PMID: 20417707 DOI: 10.1016/j.cellsig.2010.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 04/15/2010] [Indexed: 12/15/2022]
Abstract
Evidence has accumulated that there are different modes of regulated cell death, which share overlapping signaling pathways. Cytoskeletal-dependent inter-organellar communication as a result of protein and lipid trafficking in and out of organelles has emerged as a common, key issue in the regulation of cell death modalities. The movement of proteins and lipids between cell compartments is believed to relay death signals in part through modifications of organelles dynamics. Little is known, however, regarding how trafficking is integrated within stress signaling pathways directing organelle-specific remodeling events. In this review, we discuss emerging evidence supporting a role for regulated changes in actin dynamics and intracellular membrane flow. Based on recent findings using the adenovirus E4orf4 death factor as a probing tool to tackle the mechanistic underpinnings that control alternative modes of cell death, we propose the existence of multifunctional platforms at the endosome-Golgi interface regulated by SFK-signaling. These endosomal platforms could be mobilized during cell activation processes to reorganize cellular membranes and promote inter-organelle signaling.
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Affiliation(s)
- Josée N Lavoie
- Centre de Recherche en Cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, CRCHUQ, Québec, Canada.
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Mui MZ, Roopchand DE, Gentry MS, Hallberg RL, Vogel J, Branton PE. Adenovirus protein E4orf4 induces premature APCCdc20 activation in Saccharomyces cerevisiae by a protein phosphatase 2A-dependent mechanism. J Virol 2010; 84:4798-809. [PMID: 20164229 DOI: 10.1128/JVI.02434-09] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Protein phosphatase 2A (PP2A) has been implicated in cell cycle progression and mitosis; however, the complexity of PP2A regulation via multiple B subunits makes its functional characterization a significant challenge. The human adenovirus protein E4orf4 has been found to induce both high Cdk1 activity and the accumulation of cells in G(2)/M in both mammalian and yeast cells, effects which are largely dependent on the B55/Cdc55 regulatory subunit of PP2A. Thus, E4orf4 represents a unique means by which the function of a specific form of PP2A can be delineated in vivo. In Saccharomyces cerevisiae, only two PP2A regulatory subunits exist, Cdc55 and Rts1. Here, we show that E4orf4-induced toxicity depends on a functional interaction with Cdc55. E4orf4 expression correlates with the inappropriate reduction of Pds1 and Scc1 in S-phase-arrested cells. The unscheduled loss of these proteins suggests the involvement of PP2A(Cdc55) in the regulation of the Cdc20 form of the anaphase-promoting complex (APC). Contrastingly, activity of the Hct1 form of the APC is not induced by E4orf4, as demonstrated by the observed stability of its substrates. We propose that E4orf4, being a Cdc55-specific inhibitor of PP2A, demonstrates the role of PP2A(Cdc55) in regulating APC(Cdc20) activity.
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Zeng S, Liu W, Nie FF, Zhao Q, Rong JJ, Wang J, Tao L, Qi Q, Lu N, Li ZY, Guo QL. LYG-202, a new flavonoid with a piperazine substitution, shows antitumor effects in vivo and in vitro. Biochem Biophys Res Commun 2009; 385:551-6. [DOI: 10.1016/j.bbrc.2009.05.099] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Accepted: 05/21/2009] [Indexed: 11/16/2022]
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Landry MC, Sicotte A, Champagne C, Lavoie JN. Regulation of cell death by recycling endosomes and golgi membrane dynamics via a pathway involving Src-family kinases, Cdc42 and Rab11a. Mol Biol Cell 2009; 20:4091-106. [PMID: 19641023 DOI: 10.1091/mbc.e09-01-0057] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Actin dynamics and membrane trafficking influence cell commitment to programmed cell death through largely undefined mechanisms. To investigate how actin and recycling endosome (RE) trafficking can engage death signaling, we studied the death program induced by the adenovirus early region 4 open reading frame 4 (E4orf4) protein as a model. We found that in the early stages of E4orf4 expression, Src-family kinases (SFKs), Cdc42, and actin perturbed the organization of the endocytic recycling compartment and promoted the transport of REs to the Golgi apparatus, while inhibiting recycling of protein cargos to the plasma membrane. The resulting changes in Golgi membrane dynamics that relied on actin-regulated Rab11a membrane trafficking triggered scattering of Golgi membranes and contributed to the progression of cell death. A similar mobilization of RE traffic mediated by SFKs, Cdc42 and Rab11a also contributed to Golgi fragmentation and to cell death progression in response to staurosporine, in a caspase-independent manner. Collectively, these novel findings suggest that diversion of RE trafficking to the Golgi complex through a pathway involving SFKs, Cdc42, and Rab11a plays a general role in death signaling by mediating regulated changes in Golgi dynamics.
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Affiliation(s)
- Marie-Claude Landry
- Centre de Recherche en Cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, Centre de Recherche du Centre Hospitalier Universitaire de Quebec, Québec G1R 2J6, Canada
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Li S, Brignole C, Marcellus R, Thirlwell S, Binda O, McQuoid MJ, Ashby D, Chan H, Zhang Z, Miron MJ, Pallas DC, Branton PE. The adenovirus E4orf4 protein induces G2/M arrest and cell death by blocking protein phosphatase 2A activity regulated by the B55 subunit. J Virol 2009; 83:8340-52. [PMID: 19535438 DOI: 10.1128/JVI.00711-09] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human adenovirus E4orf4 protein is toxic in human tumor cells. Its interaction with the B alpha subunit of protein phosphatase 2A (PP2A) is critical for cell killing; however, the effect of E4orf4 binding is not known. B alpha is one of several mammalian B-type regulatory subunits that form PP2A holoenzymes with A and C subunits. Here we show that E4orf4 protein interacts uniquely with B55 family subunits and that cell killing increases with the level of E4orf4 expression. Evidence suggesting that B alpha-specific PP2A activity, measured in vitro against phosphoprotein substrates, is reduced by E4orf4 binding was obtained, and two potential B55-specific PP2A substrates, 4E-BP1 and p70(S6K), were seen to be hypophosphorylated in vivo following expression of E4orf4. Furthermore, treatment of cells with low levels of the phosphatase inhibitor okadaic acid or coexpression of the PP2A inhibitor I(1)(PP2A) enhanced E4orf4-induced cell killing and G(2)/M arrest significantly. These results suggested that E4orf4 toxicity results from the inhibition of B55-specific PP2A holoenzymes, an idea that was strengthened by an observed growth arrest resulting from treatment of H1299 cells with B alpha-specific RNA interference. We believe that E4orf4 induces growth arrest resulting in cell death by reducing the global level of B55-specific PP2A activity, thus preventing the dephosphorylation of B55-specific PP2A substrates, including those involved in cell cycle progression.
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Miron MJ, Blanchette P, Groitl P, Dallaire F, Teodoro JG, Li S, Dobner T, Branton PE. Localization and importance of the adenovirus E4orf4 protein during lytic infection. J Virol 2009; 83:1689-99. [PMID: 19073741 DOI: 10.1128/JVI.01703-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The human adenovirus type 5 (Ad5) E4orf4 product has been studied extensively although in most cases as expressed from vectors in the absence of other viral products. Thus, relatively little is known about its role in the context of an adenovirus infection. Although considerable earlier work had indicated that the E4orf4 protein is not essential for replication, a recent study using dl359, an Ad5 mutant believed to produce a nonfunctional E4orf4 protein, suggested that E4orf4 is essential for virus growth in primary small-airway epithelial cells (C. O'Shea, et al., EMBO J. 24:1211-1221, 2005). Hence, to examine further the role of E4orf4 during virus infection, we generated for the first time a set of E4orf4 virus mutants in a common Ad5 genetic background. Such mutant viruses included those that express E4orf4 proteins containing various individual point mutations, those defective entirely in E4orf4 expression, and a mutant expressing wild-type E4orf4 fused to the green fluorescent protein. E4orf4 protein was found to localize primarily in nuclear structures shown to be viral replication centers, in nucleoli, and in perinuclear bodies. Importantly, E4orf4 was shown not to be essential for virus growth in either human tumor or primary cells, at least in tissue culture. Unlike E4orf4-null virus, mutant dl359 appeared to exhibit a gain-of-function phenotype that impairs virus growth. The dl359 E4orf4 protein, which contains a large in-frame internal deletion, clustered in aggregates enriched in Hsp70 and proteasome components. In addition, the late viral mRNAs produced by dl359 accumulated abnormally in a nuclear punctate pattern. Altogether, our results indicate that E4orf4 protein is not essential for virus growth in culture and that expression of the dl359 E4orf4 product interferes with viral replication, presumably through interactions with structures in the nucleus.
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Li S, Szymborski A, Miron MJ, Marcellus R, Binda O, Lavoie JN, Branton PE. The adenovirus E4orf4 protein induces growth arrest and mitotic catastrophe in H1299 human lung carcinoma cells. Oncogene 2008; 28:390-400. [PMID: 18955965 DOI: 10.1038/onc.2008.393] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human adenovirus E4orf4 protein, when expressed alone, induces p53-independent death in a wide range of cancer cells. Earlier studies by our groups suggested that although in some cases cell death can be associated with some hallmarks of apoptosis, it is not always affected by caspase inhibitors. Thus it is unlikely that E4orf4-induced cell death occurs uniquely through apoptosis. In the present studies using H1299 human lung carcinoma cells as a model system we found that death is induced in the absence of activation of any of the caspases tested, accumulation of reactive oxygen species, or release of cytochrome c from mitochondria. E4orf4 caused a substantial change in cell morphology, including vigorous membrane blebbing, multiple nuclei in many cells and increased cell volume. Most of these characteristics are not typical of apoptosis, but they are of necrosis. FACS analysis and western blotting for cell cycle markers showed that E4orf4-expressing cells became arrested in G(2)/M and also accumulated high levels of cyclin E. The presence of significant numbers of tetraploid and polyploid cells and some cells with micronuclei suggested that E4orf4 appears to induce death in these cells through a process resulting from mitotic catastrophe.
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Affiliation(s)
- S Li
- Department of Biochemistry, McGill University, McIntyre Medical Building, Montréal, Québec, Canada
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Brown CW, Bell JC. Oncolytic Viruses: A New Weapon to Fight Cancer. J Med Imaging Radiat Sci 2008; 39:115-127. [PMID: 31051886 DOI: 10.1016/j.jmir.2008.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Remission from cancer after viral infection was first noted in the beginning of the 20th century, and with advances in virotherapy and genetic engineering, the advent of an approved viral therapeutic in North America is fast approaching. Mechanisms of tumour selectivity and killing, along with information obtained from clinical trials are reviewed here. Although oncolytic viruses are generally safe and well tolerated, their overall anti-tumour efficacy has varied. This article outlines strategies to improve the efficacy of the oncolytic platform without compromising its impressive safety profile. It will highlight new methods being developed to quantify the activity of oncolytic viruses in real time. Harnessing the factors that control the tumour microenvironment and the immune system are the key to enhancing the oncolytic activity. The purpose of this article is to introduce and provide an overview of the current state of cancer killing of oncolytic viruses. The reader will acquire knowledge of the basic principles of oncolytic viruses and their use in the clinical setting. This review summarizes articles retrieved from Medline using key words such as "virus," "oncolytic virus," "virotherapy," "cancer," and "clinical trials." Review articles published in the English language from 2005 onward were read and corroborating data and conclusions were summarized. When appropriate, cited references were also reviewed and incorporated. The reader is directed to references we found most concise.
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Affiliation(s)
- Christopher W Brown
- Department of Microbiology & Immunology and the Ottawa Health Research Institute, University of Ottawa, Ottawa Regional Cancer Center, Ottawa, Ontario; Division of Orthopaedic Surgery, University of Ottawa, Ottawa Hospital General Campus, Ottawa, Ontario
| | - John C Bell
- Department of Microbiology & Immunology and the Ottawa Health Research Institute, University of Ottawa, Ottawa Regional Cancer Center, Ottawa, Ontario.
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Ben-Israel H, Sharf R, Rechavi G, Kleinberger T. Adenovirus E4orf4 protein downregulates MYC expression through interaction with the PP2A-B55 subunit. J Virol 2008; 82:9381-8. [PMID: 18653458 DOI: 10.1128/JVI.00791-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The adenovirus E4 open reading frame 4 (E4orf4) protein is a multifunctional viral regulator that is involved in the temporal regulation of viral gene expression by modulating cellular and viral genes at the transcription and translation levels and by controlling alternative splicing of adenoviral late mRNAs. When expressed individually, E4orf4 induces apoptosis in transformed cells. Using oligonucleotide microarray analysis, validated by quantitative real time PCR, we found that MYC (also known as c-Myc) is downregulated early after the induction of E4orf4 expression. As a result, Myc protein levels are reduced in E4orf4-expressing cells. MYC downregulation is observed both when E4orf4 is expressed individually and within the context of viral infection. E4orf4 reduces MYC transcription but does not affect transcriptional elongation or RNA stability. An interaction with the PP2A-B55 subunit is required for the downregulation of MYC by E4orf4. Since Myc overexpression was previously shown to inhibit adenovirus replication, the downregulation of Myc by E4orf4 would contribute to efficient virus infection.
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Deng Y, Ni B, Jiang M, Yang D, Li F, Wu Y. Inhibition of proliferation of human Hela cells by small interference RNA against Pokemon gene. Chin J Cancer Res 2008; 20:5-11. [DOI: 10.1007/s11670-008-0005-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Li Y, Wei H, Hsieh TC, Pallas DC. Cdc55p-mediated E4orf4 growth inhibition in Saccharomyces cerevisiae is mediated only in part via the catalytic subunit of protein phosphatase 2A. J Virol 2008; 82:3612-23. [PMID: 18216111 DOI: 10.1128/JVI.02435-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adenovirus early region 4 open reading frame 4 (E4orf4) protein specifically induces p53-independent cell death of transformed but not normal human cells, suggesting that elucidation of its mechanism may provide important new avenues for cancer therapy. Wild-type E4orf4 and mutants that retain cancer cell toxicity also induce growth inhibition in Saccharomyces cerevisiae, which provides a genetically tractable system for studying E4orf4 function. Interaction with the protein phosphatase 2A (PP2A) B regulatory subunit is required for E4orf4's effects, suggesting that E4orf4 may function by regulating B subunit-containing heterotrimeric PP2A holoenzymes (PP2A(BAC)), which consist of a B subunit complexed with the PP2A structural (A) and catalytic (C) subunits. However, it is not known whether E4orf4-induced growth inhibition requires interaction with the PP2A C subunit or whether E4orf4 might have PP2A B subunit-dependent effects that are independent of PP2A(BAC) holoenzyme formation. To test these possibilities in S. cerevisiae, we disrupted the stable formation of PP2A(BAC) heterotrimers and thus E4orf4/C subunit association by PP2A C subunit point mutations or by deletion of the gene for the PP2A methyltransferase, Ppm1p, and assayed for effects on E4orf4-induced growth inhibition. Our results support a model in which E4orf4 mediates growth inhibition and cell killing both through PP2A(BAC) heterotrimers and through a B regulatory subunit-dependent pathway(s) that is independent of stable complex formation with the PP2A C subunit. They also indicate that Ppm1p has a function other than regulating the assembly of PP2A heterotrimers and suggest that selective PP2A trimer inhibitors and PP6 inhibitors may be useful as adjuvant anticancer therapies.
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Wang DM, Zhou Y, Xie HJ, Ma XL, Wang X, Chen H, Huang BR. Cytotoxicity of a recombinant fusion protein of adenovirus early region 4 open reading frame 4 (E4orf4) and human epidermal growth factor on p53-deficient tumor cells. Anticancer Drugs 2007; 17:527-37. [PMID: 16702809 DOI: 10.1097/00001813-200606000-00006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Adenovirus early region 4 open reading frame 4 (E4orf4) protein is a novel cell death factor that selectively induces p53-independent apoptosis in cancer cells, but not in normal human cells. This study presents an approach for inhibiting p53-deficient tumor cell growth by using protein-based E4orf4 that had been genetically fused to epidermal growth factor (EGF) to ensure selective targeting of EGF receptor-overexpressing tumor cells. EGF-E4orf4 enables binding onto the cell surface and is then internalized into Saos-2 cells. The success of the process had been demonstrated by immunofluorescence assay and confocal laser microscopy. After prolonged exposure, E4orf4 remained mostly in the nuclei. EGF-E4orf4 treatment of Saos-2 cells showed dose-dependent cytotoxicity. Nearly 50% of the Saos-2 cells were killed at a concentration of 250 nmol/l. In contrast, EGF-E4orf4 showed no significant inhibitory effect iresn primary cells of human umbilical vein endothelial cells. To confirm the ability of EGF-E4orf4 to induce apoptosis, DNA fragmentation was detected using BrdUTP end-labeling. Flow cytometric analysis revealed a significant increase of apoptotic cells in Saos-2 cells treated with EGF-E4orf4, but not in the case of cells cultured in plain medium (t=0.028, P<0.05). In conclusion, these preliminary results indicate that EGF-E4orf4 could show promise as a new reagent that is more efficient and less toxic in anti-cancer therapy.
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Affiliation(s)
- Dong-Mei Wang
- National Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Matsuzaki Y, Xu Y, Ikegami M, Besnard V, Park KS, Hull WM, Wert SE, Whitsett JA. Stat3 is required for cytoprotection of the respiratory epithelium during adenoviral infection. J Immunol 2006; 177:527-37. [PMID: 16785550 DOI: 10.4049/jimmunol.177.1.527] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The role of Stat3 in the maintenance of pulmonary homeostasis following adenoviral-mediated lung injury was assessed in vivo. Stat3 was selectively deleted from bronchiolar and alveolar epithelial cells in Stat3(DeltaDelta) mice. Although lung histology and function were unaltered by deletion of Stat3 in vivo, Stat3(DeltaDelta) mice were highly susceptible to lung injury caused by intratracheal administration of AV1-GFP, an early (E) region 1- and E3-deleted, nonproliferative adenovirus. Severe airspace enlargement, loss of alveolar septae, and sloughing of the bronchiolar epithelium were observed in Stat3(DeltaDelta) mice as early as 1 day after exposure to the virus. Although surfactant protein A, B, and C content and surfactant protein-B mRNA expression in Stat3(DeltaDelta) mice were similar, TUNEL staining and caspase-3 were increased in alveolar type II epithelial cells of Stat3(DeltaDelta) mice after exposure to virus. RNA microarray analysis of type II epithelial cells isolated from Stat3(DeltaDelta) mice demonstrated significant changes in expression of numerous genes, including those genes regulating apoptosis, supporting the concept that the susceptibility of Stat3-deficient mice to adenovirus was related to the role of Stat3 in the regulation of cell survival. AV1-Bcl-x(L), an E1- and E3-deleted, nonproliferative adenovirus expressing the antiapoptotic protein Bcl-x(L), protected Stat3(DeltaDelta) mice from adenoviral-induced lung injury. Adenoviral infection of the lungs of Stat3-deficient mice was associated with severe injury of the alveolar and bronchiolar epithelium. Thus, Stat3 plays a critical cytoprotective role that is required for epithelial cell survival and maintenance of alveolar structures during the early phases of pulmonary adenoviral infection.
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Affiliation(s)
- Yohei Matsuzaki
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
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Glockzin G, Mantwill K, Jurchott K, Bernshausen A, Ladhoff A, Royer HD, Gansbacher B, Holm PS. Characterization of the recombinant adenovirus vector AdYB-1: implications for oncolytic vector development. J Virol 2006; 80:3904-11. [PMID: 16571807 PMCID: PMC1440461 DOI: 10.1128/jvi.80.8.3904-3911.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Conditionally replicating adenoviruses are a promising new modality for the treatment of cancer. However, early clinical trials demonstrate that the efficacy of current vectors is limited. Interestingly, DNA replication and production of viral particles do not always correlate with virus-mediated cell lysis and virus release depending on the vector utilized for infection. However, we have previously reported that nuclear accumulation of the human transcription factor YB-1 by regulating the adenoviral E2 late promoter facilitates viral DNA replication of E1-deleted adenovirus vectors which are widely used for cancer gene therapy. Here we report the promotion of virus-mediated cell killing as a new function of the human transcription factor YB-1. In contrast to the E1A-deleted vector dl312 the first-generation adenovirus vector AdYB-1, which overexpresses YB-1 under cytomegalovirus promoter control, led to necrosis-like cell death, virus production, and viral release after infection of A549 and U2OS tumor cell lines. Our data suggest that the integration of YB-1 in oncolytic adenoviruses is a promising strategy for developing oncolytic vectors with enhanced potency against different malignancies.
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Affiliation(s)
- Gabriel Glockzin
- Institut fuer Experimentelle Onkologie und Therapieforschung, Technische Universitaet Muenchen, Klinikum rechts der Isar, Ismaninger Str. 22, 81675 Munich, Germany
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Abstract
DNA viruses promote cell cycle progression, stimulate unscheduled DNA synthesis, and present the cell with an extraordinary amount of exogenous DNA. These insults elicit vigorous responses mediated by cellular factors that govern cellular homeostasis. To ensure productive infection, adenovirus has developed means to inactivate these intracellular antiviral responses. Among the challenges to the host cell is the viral DNA genome, which is viewed as DNA damage and elicits a cellular response to inhibit replication. Adenovirus therefore encodes proteins that dismantle the cellular DNA damage machinery. Studying virus-host interactions has yielded insights into the molecular functioning of fundamental cellular mechanisms. In addition, it has suggested ways that viral cytotoxicity can be exploited to offer a selective means of restricted growth in tumor cells as a therapy against cancer. In this review, we discuss aspects of the intracellular response that are unique to adenovirus infection and how adenoviral proteins produced from the early region E4 act to neutralize antiviral defenses, with a particular focus on DNA damage signaling.
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Affiliation(s)
- Matthew D Weitzman
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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