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Alhaji SY, Ngai SC, Abdullah S. Silencing of transgene expression in mammalian cells by DNA methylation and histone modifications in gene therapy perspective. Biotechnol Genet Eng Rev 2018; 35:1-25. [PMID: 30514178 DOI: 10.1080/02648725.2018.1551594] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DNA methylation and histone modifications are vital in maintaining genomic stability and modulating cellular functions in mammalian cells. These two epigenetic modifications are the most common gene regulatory systems known to spatially control gene expression. Transgene silencing by these two mechanisms is a major challenge to achieving effective gene therapy for many genetic conditions. The implications of transgene silencing caused by epigenetic modifications have been extensively studied and reported in numerous gene delivery studies. This review highlights instances of transgene silencing by DNA methylation and histone modification with specific focus on the role of these two epigenetic effects on the repression of transgene expression in mammalian cells from integrative and non-integrative based gene delivery systems in the context of gene therapy. It also discusses the prospects of achieving an effective and sustained transgene expression for future gene therapy applications.
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Affiliation(s)
- Suleiman Yusuf Alhaji
- a Medical Genetics Laboratory, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences , Universiti Putra Malaysia, UPM , Serdang , Malaysia.,b Department of Human Anatomy , College of Medical Sciences, Abubakar Tafawa Balewa University Bauchi, ATBU , Bauchi , Nigeria
| | - Siew Ching Ngai
- c School of Biosciences, Faculty of Science , University of Nottingham Malaysia , Semenyih , Malaysia
| | - Syahril Abdullah
- a Medical Genetics Laboratory, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences , Universiti Putra Malaysia, UPM , Serdang , Malaysia.,d UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience , Universiti Putra Malaysia, UPM , Serdang , Malaysia
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2
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Lee CS, Bishop ES, Zhang R, Yu X, Farina EM, Yan S, Zhao C, Zeng Z, Shu Y, Wu X, Lei J, Li Y, Zhang W, Yang C, Wu K, Wu Y, Ho S, Athiviraham A, Lee MJ, Wolf JM, Reid RR, He TC. Adenovirus-Mediated Gene Delivery: Potential Applications for Gene and Cell-Based Therapies in the New Era of Personalized Medicine. Genes Dis 2017; 4:43-63. [PMID: 28944281 PMCID: PMC5609467 DOI: 10.1016/j.gendis.2017.04.001] [Citation(s) in RCA: 387] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 04/19/2017] [Indexed: 12/12/2022] Open
Abstract
With rapid advances in understanding molecular pathogenesis of human diseases in the era of genome sciences and systems biology, it is anticipated that increasing numbers of therapeutic genes or targets will become available for targeted therapies. Despite numerous setbacks, efficacious gene and/or cell-based therapies still hold the great promise to revolutionize the clinical management of human diseases. It is wildly recognized that poor gene delivery is the limiting factor for most in vivo gene therapies. There has been a long-lasting interest in using viral vectors, especially adenoviral vectors, to deliver therapeutic genes for the past two decades. Among all currently available viral vectors, adenovirus is the most efficient gene delivery system in a broad range of cell and tissue types. The applications of adenoviral vectors in gene delivery have greatly increased in number and efficiency since their initial development. In fact, among over 2,000 gene therapy clinical trials approved worldwide since 1989, a significant portion of the trials have utilized adenoviral vectors. This review aims to provide a comprehensive overview on the characteristics of adenoviral vectors, including adenoviral biology, approaches to engineering adenoviral vectors, and their applications in clinical and pre-clinical studies with an emphasis in the areas of cancer treatment, vaccination and regenerative medicine. Current challenges and future directions regarding the use of adenoviral vectors are also discussed. It is expected that the continued improvements in adenoviral vectors should provide great opportunities for cell and gene therapies to live up to its enormous potential in personalized medicine.
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Affiliation(s)
- Cody S. Lee
- The University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA
- Laboratory of Craniofacial Biology and Development, Section of Plastic and Reconstructive Surgery, Department of Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Elliot S. Bishop
- Laboratory of Craniofacial Biology and Development, Section of Plastic and Reconstructive Surgery, Department of Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Ruyi Zhang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Xinyi Yu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Evan M. Farina
- The University of Chicago Pritzker School of Medicine, Chicago, IL 60637, USA
- Laboratory of Craniofacial Biology and Development, Section of Plastic and Reconstructive Surgery, Department of Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Shujuan Yan
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Chen Zhao
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Zongyue Zeng
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Yi Shu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Xingye Wu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Jiayan Lei
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Yasha Li
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Wenwen Zhang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Department of Laboratory Medicine and Clinical Diagnostics, The Affiliated Yantai Hospital, Binzhou Medical University, Yantai 264100, China
| | - Chao Yang
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Ke Wu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Ministry of Education Key Laboratory of Diagnostic Medicine, and the Affiliated Hospitals of Chongqing Medical University, Chongqing 400016, China
| | - Ying Wu
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
- Department of Immunology and Microbiology, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Sherwin Ho
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Aravind Athiviraham
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Michael J. Lee
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Jennifer Moriatis Wolf
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Russell R. Reid
- Laboratory of Craniofacial Biology and Development, Section of Plastic and Reconstructive Surgery, Department of Surgery, The University of Chicago Medical Center, Chicago, IL 60637, USA
| | - Tong-Chuan He
- Molecular Oncology Laboratory, Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL 60637, USA
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Low PT, Lai MI, Ngai SC, Abdullah S. Transgene expression from CpG-reduced lentiviral gene delivery vectors in vitro. Gene 2013; 533:451-5. [PMID: 24120896 DOI: 10.1016/j.gene.2013.09.075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 08/07/2013] [Accepted: 09/20/2013] [Indexed: 11/27/2022]
Abstract
Current viral gene delivery vectors for gene therapy are inefficient due to short-lived transgene expression attributed to the cytosine-phosphate-guanine (CpG) motifs in the transgene. Here we assessed the effects of CpG motif reduction in lentiviral (LV) gene delivery context on the level and duration of reporter gene expression in Chinese Hamster Ovary (CHO) cells, Human Immortalized Myelogenous Leukemia (K562) cells and hematopoietic stem cells (HSCs). The cells were transduced with LV carrying Zero-CpG green fluorescent protein (ZGFP) reporter gene, LV/CMV/ZGFP. The GFP expression was compared to its non CpG-depleted GFP reporter gene LV (LV/CMV/GFP) counterpart. The LV/CMV/ZGFP exhibited prolonged transgene expression in CHO cells and HSCs up to 10 days and 14 days, in the respective cells. This effect was not seen in the transduced K562 cells, which may be due to the DNA hypomethylation status of the cancer cell line. Transgene copy number analysis verified that the GFP expression was not from pseudo-transduction and the transgene remained in the genome of the cells throughout the period of the study. The modest positive effects from the LV/CMV/ZGFP suggest that the reduction of CpG in the LV construct was not substantial to generate higher and more prolonged transgene expression.
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Affiliation(s)
- Poh Tee Low
- Medical Genetics Laboratory, Clinical Genetics Unit, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
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Lee SH. Detection of human papillomavirus (HPV) L1 gene DNA possibly bound to particulate aluminum adjuvant in the HPV vaccine Gardasil. J Inorg Biochem 2012; 117:85-92. [PMID: 23078778 DOI: 10.1016/j.jinorgbio.2012.08.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/26/2012] [Accepted: 08/26/2012] [Indexed: 10/28/2022]
Abstract
Medical practitioners in nine countries submitted samples of Gardasil (Merck & Co.) to be tested for the presence of human papillomavirus (HPV) DNA because they suspected that residual recombinant HPV DNA left in the vaccine might have been a contributing factor leading to some of the unexplained post-vaccination side effects. A total of 16 packages of Gardasil were received from Australia, Bulgaria, France, India, New Zealand, Poland, Russia, Spain and the United States. A nested polymerase chain reaction (PCR) method using the MY09/MY11 degenerate primers for initial amplification and the GP5/GP6-based nested PCR primers for the second amplification were used to prepare the template for direct automated cycle DNA sequencing of a hypervariable segment of the HPV L1 gene which is used for manufacturing of the HPV L1 capsid protein by a DNA recombinant technology in vaccine production. Detection of HPV DNA and HPV genotyping of all positive samples were finally validated by BLAST (Basic Local Alignment Search Tool) analysis of a 45-60 bases sequence of the computer-generated electropherogram. The results showed that all 16 Gardasil samples, each with a different lot number, contained fragments of HPV-11 DNA, or HPV-18 DNA, or a DNA fragment mixture from both genotypes. The detected HPV DNA was found to be firmly bound to the insoluble, proteinase-resistant fraction, presumably of amorphous aluminum hydroxyphosphate sulfate (AAHS) nanoparticles used as adjuvant. The clinical significance of these residual HPV DNA fragments bound to a particulate mineral-based adjuvant is uncertain after intramuscular injection, and requires further investigation for vaccination safety.
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Affiliation(s)
- Sin Hang Lee
- Milford Hospital and Milford Molecular Laboratory, 2044 Bridgeport Avenue, Milford, CT 06460, USA.
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5
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Van Opdenbosch N, Favoreel H, Van de Walle GR. Histone modifications in herpesvirus infections. Biol Cell 2012; 104:139-64. [PMID: 22188068 DOI: 10.1111/boc.201100067] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 12/02/2011] [Indexed: 12/13/2022]
Abstract
In eukaryotic cells, gene expression is not only regulated by transcription factors but also by several epigenetic mechanisms including post-translational modifications of histone proteins. There are numerous histone modifications described to date and methylation, acetylation, ubiquitination and phosphorylation are amongst the best studied. In parallel, certain viruses interact with the very same regulatory mechanisms, hereby manipulating the normal epigenetic landscape of the host cell, to fit their own replication needs. This review concentrates on herpesviruses specifically and how they interfere with the histone-modifying enzymes to regulate their replication cycles. Herpesviruses vary greatly with respect to the cell types they infect and the clinical diseases they cause, yet they share various common features including their capacity to encode viral proteins which affect and interfere with the normal functions of histone-modifying enzymes. Studying the epigenetic manipulation/dysregulation of herpesvirus-host interactions not only generates novel insights into the pathogenesis of these viruses but may also have important therapeutic implications.
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Affiliation(s)
- Nina Van Opdenbosch
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium.
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Abstract
Isotope labeling of proteins represents an important and often required tool for the application of nuclear magnetic resonance (NMR) spectroscopy to investigate the structure and dynamics of proteins. Mammalian expression systems have conventionally been considered to be too weak and inefficient for protein expression. However, recent advances have significantly improved the expression levels of these systems. Here, we provide an overview of some of the recent developments in expression strategies for mammalian expression systems in view of NMR investigations.
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Affiliation(s)
- Arpana Dutta
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Krishna Saxena
- Institute for Organic Chemistry and Chemical Biology, Center for, Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Frankfurt, Max-von-Laue-Str.7, Frankfurt am Main, Germany
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance, Johann Wolfgang Goethe-University, Frankfurt, Max-von-Laue-Str.7, Frankfurt am Main, Germany
| | - Judith Klein-Seetharaman
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Lee SH. Detection of human papillomavirus L1 gene DNA fragments in postmortem blood and spleen after Gardasil<sup>®</sup> vaccination—A case report. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/abb.2012.38148] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Huang B, Li T, Alonso-Gonzalez L, Gorre R, Keatley S, Green A, Turner P, Kallingappa PK, Verma V, Oback B. A virus-free poly-promoter vector induces pluripotency in quiescent bovine cells under chemically defined conditions of dual kinase inhibition. PLoS One 2011; 6:e24501. [PMID: 21912700 PMCID: PMC3166309 DOI: 10.1371/journal.pone.0024501] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 08/11/2011] [Indexed: 12/17/2022] Open
Abstract
Authentic induced pluripotent stem cells (iPSCs), capable of giving rise to all cell types of an adult animal, are currently only available in mouse. Here, we report the first generation of bovine iPSC-like cells following transfection with a novel virus-free poly-promoter vector. This vector contains the bovine cDNAs for OCT4, SOX2, KLF4 and c-MYC, each controlled by its own independent promoter. Bovine fibroblasts were cultured without feeders in a chemically defined medium containing leukaemia inhibitory factor (LIF) and inhibitors of MEK1/2 and glycogen synthase kinase-3 signaling (‘2i’). Non-invasive real-time kinetic profiling revealed a different response of bovine vs human and mouse cells to culture in 2i/LIF. In bovine, 2i was necessary and sufficient to induce the appearance of tightly packed alkaline phosphatase-positive iPSC-like colonies. These colonies formed in the absence of DNA synthesis and did not expand after passaging. Following transfection, non-proliferative primary colonies expressed discriminatory markers of pluripotency, including endogenous iPSC factors, CDH1, DPPA3, NANOG, SOCS3, ZFP42, telomerase activity, Tra-1-60/81 and SSEA-3/4, but not SSEA-1. This indicates that they had initiated a self-sustaining pluripotency programme. Bovine iPSC-like cells maintained a normal karyotype and differentiated into derivatives of all three germ layers in vitro and in teratomas. Our study demonstrates that conversion into induced pluripotency can occur in quiescent cells, following a previously undescribed route of direct cell reprogramming. This identifies a major species-specific barrier for generating iPSCs and provides a chemically defined screening platform for factors that induce proliferation and maintain pluripotency of embryo-derived pluripotent stem cells in livestock.
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Affiliation(s)
- Ben Huang
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
| | - Tong Li
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
- Animal Reproduction Institute, Guangxi University, Nanning, China
| | - Lucia Alonso-Gonzalez
- Children's Cancer Research Group, Department of Paediatrics, University of Otago, Christchurch, New Zealand
| | | | - Sarah Keatley
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
| | - Andria Green
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
| | - Pavla Turner
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
| | | | - Vinod Verma
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Björn Oback
- AgResearch, Ruakura Research Centre, Hamilton, New Zealand
- * E-mail:
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Zhu J, Park CW, Sjeklocha L, Kren BT, Steer CJ. High-level genomic integration, epigenetic changes, and expression of sleeping beauty transgene. Biochemistry 2010; 49:1507-21. [PMID: 20041635 DOI: 10.1021/bi9016846] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sleeping Beauty transposon (SB-Tn) has emerged as an important nonviral vector for integrating transgenes into mammalian genomes. We report here a novel dual fluorescent reporter cis SB-Tn system that permitted nonselective fluorescent-activated cell sorting for SB-Tn-transduced K562 erythroid cells. Using an internal ribosome entry site element, the green fluorescent protein (eGFP) was linked to the SB10 transposase gene as an indirect marker for the robust expression of SB10 transposase. Flourescence-activated cell sorting (FACS) by eGFP resulted in significant enrichment (>60%) of cells exhibiting SB-Tn-mediated genomic insertions and long-term expression of a DsRed transgene. The hybrid erythroid-specific promoter of DsRed transgene was verified in erythroid or megakaryocyte differentiation of K562 cells. Bisulfite-mediated genomic analyses identified different DNA methylation patterns between DsRed(+) and DsRed(-) cell clones, suggesting a critical role in transgene expression. Moreover, although the host genomic copy of the promoter element showed no CpG methylation, the same sequence carried by the transgene was markedly hypermethylated. Additional evidence also suggested a role for histone deacetylation in the regulation of DsRed transgene. The presence of SB transgene affected the expression of neighboring host genes at distances >45 kb. Our data suggested that a fluorescent reporter cis SB-Tn system can be used to enrich mammalian cells harboring SB-mediated transgene insertions. The observed epigenetic changes also demonstrated that transgenes inserted by SB could be selectively modified by endogenous factors. In addition, long-range activation of host genes must now be recognized as a potential consequence of an inserted transgene cassette containing enhancer elements.
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Affiliation(s)
- Jianhui Zhu
- Department of Medicine, University of Minnesota Medical School,Minneapolis, Minnesota 55455, USA
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Bauer AP, Leikam D, Krinner S, Notka F, Ludwig C, Längst G, Wagner R. The impact of intragenic CpG content on gene expression. Nucleic Acids Res 2010; 38:3891-908. [PMID: 20203083 PMCID: PMC2896515 DOI: 10.1093/nar/gkq115] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The development of vaccine components or recombinant therapeutics critically depends on sustained expression of the corresponding transgene. This study aimed to determine the contribution of intragenic CpG content to expression efficiency in transiently and stably transfected mammalian cells. Based upon a humanized version of green fluorescent protein (GFP) containing 60 CpGs within its coding sequence, a CpG-depleted variant of the GFP reporter was established by carefully modulating the codon usage. Interestingly, GFP reporter activity and detectable protein amounts in stably transfected CHO and 293 cells were significantly decreased upon CpG depletion and independent from promoter usage (CMV, EF1α). The reduction in protein expression associated with CpG depletion was likewise observed for other unrelated reporter genes and was clearly reflected by a decline in mRNA copy numbers rather than translational efficiency. Moreover, decreased mRNA levels were neither due to nuclear export restrictions nor alternative splicing or mRNA instability. Rather, the intragenic CpG content influenced de novo transcriptional activity thus implying a common transcription-based mechanism of gene regulation via CpGs. Increased high CpG transcription correlated with changed nucleosomal positions in vitro albeit histone density at the two genes did not change in vivo as monitored by ChIP.
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Affiliation(s)
- Asli Petra Bauer
- Institute of Medical Microbiology and Hygiene, Molecular Microbiology & Gene Therapy Unit, University of Regensburg, Regensburg, Germany
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Graham C, Cole S, Laible G. Site-specific modification of the bovine genome using Cre recombinase-mediated gene targeting. Biotechnol J 2009; 4:108-18. [PMID: 19156732 DOI: 10.1002/biot.200800200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cre recombinase (Cre)-mediated targeted insertion of a transgene is a powerful technique that can be used to tailor genomes. When combined with somatic cell nuclear transfer it could offer an efficient way to generate transgenic livestock with site-specific genetic modifications that are free of antibiotic selection markers. We have engineered primary bovine fibroblasts to contain a chromosomal acceptor site with incompatible loxP/lox2272 sites for Cre-mediated cassette exchange and show for the first time that Cre-mediated targeting can be applied in these acceptor cells. Molecular characterization of the resulting cell clones revealed Cre-mediated transgene insertion efficiencies of up to 98% when antibiotic selection was used to identify transgene containing cell clones. Most clonal lines also contained random insertions of the targeting and Cre expression plasmids with only about 10% of the clones being exclusively modified by the intended targeted insertion. This targeting efficiency was sufficient to enable the isolation of correctly targeted clones without the help of antibiotic selection. Therefore, this recombinase-mediated insertion strategy has the potential to produce transgenic cattle from antibiotic selection marker-free somatic cells with transgenes inserted into proven genomic loci ensuring reliable expression levels.
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Anne Ingeborg Myhr, Terje Traavik. The Precautionary Principle Applied to Deliberate Release of Genetically Modified Organisms (GMOs). MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.1080/089106099435790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Rothkötter HJ. Anatomical particularities of the porcine immune system--a physician's view. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:267-272. [PMID: 18775744 DOI: 10.1016/j.dci.2008.06.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 06/30/2008] [Accepted: 06/30/2008] [Indexed: 05/26/2023]
Abstract
In this article the anatomical structure of the porcine immune organs is described. The focus is on their particularities that are related to the use of pigs as an animal model. Key issues of the intrauterine development of the lymphoid organs are presented, such as the specific epithelio-chorial placenta, the appearance of the thymic tissue and the initial development of B cells. The role of the thymus for the development of alpha/beta and gamma/delta T cells and the location of tonsillar tissue in the naso-pharynx, in the oral cavity and at the basis of the tongue are described. The porcine spleen is of interest for surgical techniques to treat splenic trauma adequately. The observation of the inverted lymph node structure of pigs is puzzling and it remains unclear why only few species have this distinct morphological organisation. Based on the functional differences in lymphocyte recirculation observed in pigs, specific lymph cannulation experiments are possible in the porcine immune system. The porcine intestinal lymphoid tissue and the lymphocytes in the mucosal epithelium and lamina propria are of interest for studying the gut immune responses. For use as a model the fact that the pig is a monogastric omnivorous animal represents an advantage, although the porcine ileal Peyer's patch has no obvious anatomical equivalent in man. Based on the detailed knowledge of porcine immune morphology the pig is suitable as model animal for immunology--in addition to the various experimental approaches in physiology, pharmacology, surgery, etc. that are applicable to human medicine.
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Affiliation(s)
- Hermann-Josef Rothkötter
- Institute of Anatomy, Medical Faculty, Otto-von-Guericke-University Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany.
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Bertheau Y, Helbling JC, Fortabat MN, Makhzami S, Sotinel I, Audéon C, Nignol AC, Kobilinsky A, Petit L, Fach P, Brunschwig P, Duhem K, Martin P. Persistence of plant DNA sequences in the blood of dairy cows fed with genetically modified (Bt176) and conventional corn silage. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:509-516. [PMID: 19123817 DOI: 10.1021/jf802262c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
To determine whether plant sequences, including transgenic sequences, are present in animal blood, we tested blood samples from Holstein cows fed with either Bt176 genetically modified corn or conventional corn. We used previously described sensitive real-time PCR assays targeting transgenic sequences (35S promoter and Bt176 specific junction sequence), a monocopy maize-specific sequence (ADH promoter), and two multicopy sequences from plant nucleus (26S rRNA gene) and chloroplast (psaB gene). The presence of Cry1A(b) protein in bovine blood samples was also tested using a sandwich ELISA kit. Our study shows the ability of plant nuclear and/or chloroplast DNA fragments to enter bovine blood circulation. However, maize nuclear DNA, both mono- and multicopy sequences, was less detected than chloroplast DNA, probably because the higher number of chloroplast copies and also possibly because nuclear DNA might be less protected by the nuclear membrane. Despite our data confirm the ability of small (ca.150 bp) plant DNA fragments to cross the intestinal barrier, we were unable to demonstrate clearly the presence of transgenic DNA or proteins in bovine blood. No sample tested positive with the two real-time PCR assays targeting transgenic sequences (35S promoter and Bt176 specific junction sequence). Only faint punctual positive results occurred randomly and were probably due to postsample collection or laboratory contamination or can be considered as artifact as they have never been confirmed. Our data highlight the difficulties to detect transgenic sequences in blood of dairy cows fed genetically modified corn (Bt176) silage. Those results show that in order to meet the consumers' demand of animals fed with GM products there is currently no cost-effective analytical procedure to replace documentary traceability.
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Affiliation(s)
- Y Bertheau
- Agence Française de Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches sur la Qualité des Aliments et les Procédés Agro-Alimentaires, Maisons-Alfort, France.
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15
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Chauhan SS, Seth P, Katara R. Expression of cloned cDNAs in mammalian cells from a cryptic promoter upstream to T7 in pGEM-4Z cloning vector. Mol Cell Biochem 2008; 322:119-25. [DOI: 10.1007/s11010-008-9947-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Accepted: 10/22/2008] [Indexed: 11/29/2022]
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16
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Abreu PA, Dellamora-Ortiz G, Leão-Ferreira LR, Gouveia M, Braggio E, Zalcberg I, Santos DO, Bourguinhon S, Cabral LM, Rodrigues CR, Castro HC. DNA methylation: a promising target for the twenty-first century. Expert Opin Ther Targets 2008; 12:1035-47. [PMID: 18620524 DOI: 10.1517/14728222.12.8.1035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Over the last few years DNA methylation and its involvement in diseases such as cancer has become of great interest for applied research. Since reversal of aberrant DNA methylation may influence the behavior of tumors, the methylation of DNA CpG sites is a potential target for the development of inhibitors for use in cancer treatment. OBJECTIVE/METHODS We briefly review the structural and mechanistic features of DNA methylation, including a structural analysis of the three main human DNA methyltransferases and some (pre)clinical results. RESULTS/CONCLUSION Despite side effects, data obtained to date still support the vision that DNA-methylation, possibly associated with the use of histone deacetylases (HDACs) and/or artificial transcription factors (ATFs), is a promising target for improving anticancer therapy in the 21st century.
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Affiliation(s)
- Paula A Abreu
- Federal Fluminense University, Biology Institute, Department of Celular and Molecular Biology, CEP 24020-150 Niterói, Rio de Janeiro, Brazil
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17
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Lufino MMP, Edser PAH, Wade-Martins R. Advances in high-capacity extrachromosomal vector technology: episomal maintenance, vector delivery, and transgene expression. Mol Ther 2008; 16:1525-38. [PMID: 18628754 DOI: 10.1038/mt.2008.156] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Recent developments in extrachromosomal vector technology have offered new ways of designing safer, physiologically regulated vectors for gene therapy. Extrachromosomal, or episomal, persistence in the nucleus of transduced cells offers a safer alternative to integrating vectors which have become the subject of safety concerns following serious adverse events in recent clinical trials. Extrachromosomal vectors do not cause physical disruption in the host genome, making these vectors safe and suitable tools for several gene therapy targets, including stem cells. Moreover, the high insert capacity of extrachromosomal vectors allows expression of a therapeutic transgene from the context of its genomic DNA sequence, providing an elegant way to express normal splice variants and achieve physiologically regulated levels of expression. Here, we describe past and recent advances in the development of several different extrachromosomal systems, discuss their retention mechanisms, and evaluate their use as expression vectors to deliver and express genomic DNA loci. We also discuss a variety of delivery systems, viral and nonviral, which have been used to deliver episomal vectors to target cells in vitro and in vivo. Finally, we explore the potential for the delivery and expression of extrachromosomal transgenes in stem cells. The long-term persistence of extrachromosomal vectors combined with the potential for stem cell proliferation and differentiation into a wide range of cell types offers an exciting prospect for therapeutic interventions.
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Affiliation(s)
- Michele M P Lufino
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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18
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Krayer von Krauss MP, Kaiser M, Almaas V, van der Sluijs J, Kloprogge P. Diagnosing and prioritizing uncertainties according to their relevance for policy: the case of transgene silencing. THE SCIENCE OF THE TOTAL ENVIRONMENT 2008; 390:23-34. [PMID: 17988720 DOI: 10.1016/j.scitotenv.2007.09.028] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 08/31/2007] [Accepted: 09/07/2007] [Indexed: 04/14/2023]
Abstract
Uncertainty often becomes problematic when science is used to support decision making in the policy process. Scientists can contribute to a more constructive approach to uncertainty by making their uncertainties transparent. In this article, an approach to systematic uncertainty diagnosis is demonstrated on the case study of transgene silencing and GMO risk assessment. Detailed interviews were conducted with five experts on transgene silencing to obtain quantitative and qualitative information on their perceptions of the uncertainty characterising our knowledge of the phenomena. The results indicate that there are competing interpretations of the cause-effect relationships leading to gene silencing (model structure uncertainty). In particular, the roles of post-transcriptional gene silencing, position effects, DNA-DNA interactions, direct-repeat DNA structures, recognition factors and dsRNA and aberrant zRNA are debated. The study highlights several sources of uncertainty beyond the statistical uncertainty commonly reported in risk assessment. The results also reveal a discrepancy between the way in which uncertainties would be prioritized on the basis of the uncertainty analysis conducted, and the way in which they would be prioritized on the basis of expert willingness to pay to eliminate uncertainty. The results also reveal a diversity of expert opinions on the uncertainty characterizing transgene silencing. Because the methodology used to diagnose uncertainties was successful in revealing a broad spectrum of uncertainties as well as a diversity of expert opinion, it is concluded that the methodology used could contribute to increasing transparency and fostering a critical discussion on uncertainty in the decision making process.
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Affiliation(s)
- Martin Paul Krayer von Krauss
- European Centre for Environment and Health, WHO, Regional Office for Europe, Scherfigsvej 8, 2100 Copenhagen Ø, Denmark.
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19
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EL-SANHOTY RAFAATMOHAMEDELSAYEDSOLIMAN, EL-MAGED AFAFDESOKYABD, RAMADAN MOHAMEDFAWZY. SAFETY ASSESSMENT OF GENETICALLY MODIFIED POTATO SPUNTA: DEGRADATION OF DNA IN GASTROINTESTINAL TRACT AND CARRYOVER TO RAT ORGANS. J Food Biochem 2006. [DOI: 10.1111/j.1745-4514.2006.00082.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Papapetrou EP, Zoumbos NC, Athanassiadou A. Genetic modification of hematopoietic stem cells with nonviral systems: past progress and future prospects. Gene Ther 2006; 12 Suppl 1:S118-30. [PMID: 16231044 DOI: 10.1038/sj.gt.3302626] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Serious unwanted complications provoked by retroviral gene transfer into hematopoietic stem cells (HSCs) have recently raised the need for the development and assessment of alternative gene transfer vectors. Within this context, nonviral gene transfer systems are attracting increasing interest. Their main advantages include low cost, ease of handling and large-scale production, large packaging capacity and, most importantly, biosafety. While nonviral gene transfer into HSCs has been restricted in the past by poor transfection efficiency and transient maintenance, in recent years, biotechnological developments are converting nonviral transfer into a realistic approach for genetic modification of cells of hematopoietic origin. Herein we provide an overview of past accomplishments in the field of nonviral gene transfer into hematopoietic progenitor/stem cells and we point at future challenges. We argue that episomally maintained self-replicating vectors combined with physical methods of delivery show the greatest promise among nonviral gene transfer strategies for the treatment of disorders of the hematopoietic system.
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Affiliation(s)
- E P Papapetrou
- Department of Biology, Faculty of Medicine, University of Patras, Patras, Greece
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21
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Jung D, Néron S, Drouin M, Jacques A. Efficient gene transfer into normal human B lymphocytes with the chimeric adenoviral vector Ad5/F35. J Immunol Methods 2005; 304:78-87. [PMID: 16129448 DOI: 10.1016/j.jim.2005.06.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 06/22/2005] [Accepted: 06/24/2005] [Indexed: 11/24/2022]
Abstract
The failure to efficiently introduce genes into normal cells such as human B lymphocytes limits the characterization of their function on cellular growth, differentiation and survival. Recent studies have shown that a new adenoviral vector Ad5/F35 can efficiently transduce human haematopoietic CD34+ progenitor cells. In this study, we compared the gene transfer efficiencies of the Ad5/F35 vector to that of the parental vector Ad5 in human B lymphocytes. Peripheral blood B cells obtained from healthy individuals were cultured in vitro using CD40-CD154 system. Normal B lymphocytes were infected with replication-defectives Ad5 and Ad5/F35, both containing the GFP reporter gene, and transduction efficiencies were monitored by flow cytometry. Ad5 was highly ineffective, infecting only about 5% of human B lymphocytes. In contrast, Ad5/F35 transduced up to 60% of human B lymphocytes and GFP expression could be detected for up to 5 days post infection. Importantly, physiology of B lymphocytes such as proliferation, viability and antibodies secretion were unaffected following Ad5/F35 transduction. Finally, we observed that memory B lymphocytes were more susceptible to Ad5/F35 infection than naïve B lymphocytes. Thus, our results demonstrate that the adenoviral vector Ad5/F35 is an efficient tool for the functional characterization of genes in B lymphopoiesis.
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22
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Williams S, Mustoe T, Mulcahy T, Griffiths M, Simpson D, Antoniou M, Irvine A, Mountain A, Crombie R. CpG-island fragments from the HNRPA2B1/CBX3 genomic locus reduce silencing and enhance transgene expression from the hCMV promoter/enhancer in mammalian cells. BMC Biotechnol 2005; 5:17. [PMID: 15935093 PMCID: PMC1175082 DOI: 10.1186/1472-6750-5-17] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Accepted: 06/03/2005] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The hCMV promoter is very commonly used for high level expression of transgenes in mammalian cells, but its utility is hindered by transcriptional silencing. Large genomic fragments incorporating the CpG island region of the HNRPA2B1 locus are resistant to transcriptional silencing. RESULTS In this report we describe studies on the use of a novel series of vectors combining the HNRPA2B1 CpG island with the hCMV promoter for expression of transgenes in CHO-K1 cells. We show that the CpG island gives at least twenty-fold increases in the levels of EGFP and EPO observed in pools of transfectants, and that transgene expression levels remain high in such pools for more than 100 generations. These novel vectors also allow facile isolation of clonal CHO-K1 cell lines showing stable, high-level transgene expression. CONCLUSION Vectors incorporating the hnRPA2B1 CpG island give major benefits in transgene expression from the hCMV promoter, including substantial improvements in the level and stability of expression. The utility of these vectors for the improved production of recombinant proteins in CHO cells has been demonstrated.
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Affiliation(s)
- Steven Williams
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Tracey Mustoe
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Tony Mulcahy
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Mark Griffiths
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - David Simpson
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Michael Antoniou
- Nuclear Biology Group, Division of Medical and Molecular Genetics, GKT School of Medicine, Kings College London, Guy's Campus, London Bridge, London, SE1 9RT, UK
| | - Alistair Irvine
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Andrew Mountain
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
| | - Robert Crombie
- ML Laboratories PLC-Research Division, MED IC4, Keele University Science and Business Park, Keele, Staffordshire, ST5 5SP, UK
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23
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Aeschbacher K, Messikommer R, Meile L, Wenk C. Bt176 corn in poultry nutrition: physiological characteristics and fate of recombinant plant DNA in chickens. Poult Sci 2005; 84:385-94. [PMID: 15782906 DOI: 10.1093/ps/84.3.385] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A genetically modified Bt176 corn hybrid, which contains an insecticidal protein against the European corn borer, and its conventional, nonmodified counterpart were evaluated in 4 separate trials to verify substantial equivalence in feeding value and animal performance. Thirty-six individually kept laying hens and 3 replicates of 94 broiler chickens each, assigned to 12 cages, were fed 2 different hen and broiler diets containing either 60% conventional or 60% Bt176 corn. The nutrient compositions of the 2 corn hybrids and the 2 corn diets revealed no major differences. Furthermore, metabolism and performance data revealed no significant differences between the birds that received the conventional, nonmodified corn, and those that received the modified corn diets. The detection of the genetic modification, by PCR, in feed obtained from insect-resistant Bt corn, in tissues and products from animals fed Bt corn is described. In all evaluated chicken tissues of muscle, liver, and spleen, the corn-chloroplast ivr gene fragment was amplified. It can be deduced from these findings and from other studies that the transfer of DNA fragments into the body is a normal process that takes place constantly. Nevertheless, no recombinant plant DNA fragments such as recombinant bla or cry1A(b) fragments could be found. Bt-gene specific constructs from the Bt corn were not detected in any of the poultry samples, neither in organs, meat, nor eggs.
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Affiliation(s)
- K Aeschbacher
- Institute of Animal Sciences, Nutrition Biology, ETH Zurich, Switzerland.
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24
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Habel ME, Drouin M, Jung D. Maintenance of Epstein-Barr virus-derived episomal vectors in the murine Sp2/0 myeloma cell line is dependent upon exogenous expression of human EBP2. Biochem Cell Biol 2005; 82:375-80. [PMID: 15181471 DOI: 10.1139/o04-037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vectors carrying the origin of replication (oriP) and driving expression of the EBNA-1 protein from Epstein-Barr virus (EBV) replicate as extrachromosomal episomes in human cells. Whether these vectors can be maintained as episomes in murine cells is still controversial. Here we demonstrate that EBNA-1 expression alone was unable to maintain episomal expression of an EBV-based vector in the murine Sp2/0 cell line. However, we were able to obtain long-term episome maintenance in Sp2/0 cells after exogenously expressing human EBP2 by genetic engineering. Our results provide further evidence for the fundamental role of human EBP2 in episomal maintenance of EBV-based vectors. Moreover, we demonstrate that EBV-based vectors can be successfully used in cells presumably incompetent for episomal maintenance.
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Affiliation(s)
- Marie-Eve Habel
- Héma-Québec, Recherche et développement, Pavillion Héma-Québec, 1009 Route du Vallon, Sainte Foy, QC G1V 4C3, Canada
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25
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Smith KR. Gene transfer in higher animals: theoretical considerations and key concepts. J Biotechnol 2002; 99:1-22. [PMID: 12204554 PMCID: PMC7252021 DOI: 10.1016/s0168-1656(02)00105-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2001] [Revised: 04/12/2002] [Accepted: 04/17/2002] [Indexed: 11/16/2022]
Abstract
Gene transfer technology provides the ability to genetically manipulate the cells of higher animals. Gene transfer permits both germline and somatic alterations. Such genetic manipulation is the basis for animal transgenesis goals and gene therapy attempts. Improvements in gene transfer are required in terms of transgene design to permit gene targeting, and in terms of transfection approaches to allow improved transgene uptake efficiencies.
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Affiliation(s)
- Kevin R Smith
- Division of Life Sciences, University of Abertay, Dundee DD1 1HG, UK.
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26
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Aronson MN, Complainville A, Clérot D, Alcalde H, Katul L, Vetten HJ, Gronenborn B, Timchenko T. In planta protein-protein interactions assessed using a nanovirus-based replication and expression system. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:767-775. [PMID: 12220267 DOI: 10.1046/j.1365-313x.2002.01388.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The multipartite genome of the nanovirus Faba bean necrotic yellows virus, which consists of one gene on each DNA component, was exploited to construct a series of virus-based episomal vectors designed for transient replication and gene expression in plants. This nanovirus based expression system yields high levels of protein which allows isolation of recombinant protein and protein complexes from plant tissues. As examples, we demonstrated in planta interaction between the nanovirus F-box protein Clink and SKP1, a constituent of the ubiquitin-dependent protein turnover pathway. Thus, replicative nanovirus vectors provide a simple and efficient means for in planta characterization of protein-protein interaction.
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Affiliation(s)
- Marie N Aronson
- Institut des Sciences du Végétale, CNRS, 91198 Gif sur Yvette, France
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27
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Harland L, Crombie R, Anson S, deBoer J, Ioannou PA, Antoniou M. Transcriptional regulation of the human TATA binding protein gene. Genomics 2002; 79:479-82. [PMID: 11944977 DOI: 10.1006/geno.2002.6728] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The human TATA binding protein (TBP) locus consists of a functional domain of three closely linkedhousekeeping genes (TBP, PSMB1 (proteasomal C5 subunit), and PDCD2 (programmed cell death-2)) within a 50-kb interval at chromosome position 6q27. Here we demonstrate that a genomic clone spanning the 20-kb TBP gene, with 12 kb 5' and 3' flanking sequences, was fully functional in stable, transfected L-cells harboring a single copy of this transgene, including after long-term (60 day) culture in the absence of drug selective pressure. Furthermore, we were only able to detect DNaseI hypersensitive sites at the TBP and PSMB1 promoters present within this 44-kb fragment. Our data suggest that this 44-kb genomic region possesses genetic regulatory elements that not only drive ubiquitous expression of TBP but also negate chromatin and DNA methylation induced silencing, which is normally associated with transgenes stably integrated into tissue culture cells.
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Affiliation(s)
- Lee Harland
- Nuclear Biology Group, Division of Medical and Molecular Genetics, GKT School of Medicine, 8(th) Floor Guy's Tower, Guy's Hospital, London Bridge, London, SE1 9RT, UK
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28
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Zhou H, Chen WD, Qin X, Lee K, Liu L, Markowitz SD, Gerson SL. MMTV promoter hypomethylation is linked to spontaneous and MNU associated c-neu expression and mammary carcinogenesis in MMTV c-neu transgenic mice. Oncogene 2001; 20:6009-17. [PMID: 11593408 DOI: 10.1038/sj.onc.1204830] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2001] [Revised: 06/29/2001] [Accepted: 07/12/2001] [Indexed: 11/09/2022]
Abstract
The erbB family of receptor tyrosine kinases is frequently implicated in neoplasia. Amplification and overexpression of erbB2/neu has been found in 20 to 40% of human breast cancers. Previous studies using MMTV/c-neu transgenic mice have linked rat neu overexpression to mammary tumor development. In this study, we provide evidence that rat neu overexpression in mammary tumors of MMTV/c-neu transgenic mice is always associated with demethylation of the MMTV promoter, whereas the normal mammary glands of these transgenic mice always contain specific methylated regions of the MMTV promoter. In addition, after exposure to N-methyl-N-nitrosourea (MNU), the latency of mammary tumor development is significantly reduced and again is also associated with MMTV promoter demethylation. Thus, the transition from methylation to hypomethylation of the MMTV promoter induces high-level expression of c-neu and appears to be a prerequisite for transformation from normal to malignant mammary epithelium, either spontaneously or after carcinogen exposure. Expression of transgenic c-neu from the demethylated MMTV promoter appears to be an early event that allows outgrowth of mammary epithelium predisposed to malignant transformation.
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MESH Headings
- Alkylating Agents
- Animals
- Carcinoma/etiology
- Carcinoma/genetics
- Carcinoma/metabolism
- DNA Methylation
- DNA, Viral/genetics
- Female
- Genes, ras
- Lymphoma, T-Cell/etiology
- Mammary Glands, Animal/metabolism
- Mammary Neoplasms, Experimental/etiology
- Mammary Neoplasms, Experimental/genetics
- Mammary Neoplasms, Experimental/metabolism
- Mammary Tumor Virus, Mouse/genetics
- Methylnitrosourea
- Mice
- Mice, Transgenic
- Mutation
- Promoter Regions, Genetic
- RNA, Neoplasm/biosynthesis
- Receptor, ErbB-2/biosynthesis
- Receptor, ErbB-2/genetics
- Receptor, ErbB-3/biosynthesis
- Receptor, ErbB-3/genetics
- Terminal Repeat Sequences
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Affiliation(s)
- H Zhou
- Division of Hematology/Oncology and Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106-4937, USA
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29
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Pan D, Aronovich E, McIvor RS, Whitley CB. Retroviral vector design studies toward hematopoietic stem cell gene therapy for mucopolysaccharidosis type I. Gene Ther 2000; 7:1875-83. [PMID: 11110421 DOI: 10.1038/sj.gt.3301298] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To optimize a gene transfer system for hematopoietic stem cell gene therapy of patients with mucopolysaccharidosis (MPS) type I, 10 retroviral vectors were constructed to express the human alpha-L-iduronidase (IDUA) cDNA. These vectors were designed to evaluate the potential effects of specific promoters, the addition of selectable markers, and the use of multiple promoters versus an internal ribosome entry site for expression of IDUA and selectable maker genes. The effect of vector design was investigated in primary patient fibroblasts (F(MPS)) or murine fibroblast cell lines; while overall comparison of transgene expression was determined in patients' peripheral blood lymphocytes (PBL(MPS)) and CD34+ progenitors (PBPC(MPS)). We observed that the human PGK promoter introduced the highest IDUA activity per 1% relative transgene frequency in F(MPS). Use of the same promoter to separately regulate both the therapeutic gene and a drug-resistance gene resulted in decreased expression of the unselected gene. Co-selection using bicistronic vectors not only increased the number of transductants, but also elevated transgene expression under selective pressure in transgene-positive progenitors. Bicistronic vector LP1CD overcame down-regulation and practically introduced the highest IDUA level in unselected PBL(MPS) and an intermediate level in PBPC(MPS). These studies provide a better understanding of factors contributing to efficient gene expression in hematopoietic cells.
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Affiliation(s)
- D Pan
- Department of Pediatrics, and Institute of Human Genetics, University of Minnesota, Minneapolis 55455, USA
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30
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Van Craenenbroeck K, Vanhoenacker P, Haegeman G. Episomal vectors for gene expression in mammalian cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:5665-78. [PMID: 10971576 DOI: 10.1046/j.1432-1327.2000.01645.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An important reason for preferring mammalian cells for heterologous gene expression is their ability to make authentic proteins containing post-translational modifications similar to those of the native protein. The development of expression systems for mammalian cells has been ongoing for several years, resulting in a wide variety of effective expression vectors. The aim of this review is to highlight episomal expression vectors. Such episomal plasmids are usually based on sequences from DNA viruses, such as BK virus, bovine papilloma virus 1 and Epstein-Barr virus. In this review we will mainly focus on the improvements made towards the usefulness of these systems for gene expression studies and gene therapy.
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31
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Van Craenenbroeck K, Vanhoenacker P, Duchau H, Haegeman G. Molecular integrity and usefulness of episomal expression vectors derived from BK and Epstein-Barr virus. Gene 2000; 253:293-301. [PMID: 10940567 DOI: 10.1016/s0378-1119(00)00242-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
High-level and stable production of a protein of interest is one of the most important parameters when considering the development of an efficient vector system for heterologous gene expression. In order to achieve this goal, we have used episomal vector elements derived from Epstein-Barr virus (EBV) or BK virus (BKV) in combination with the strictly regulated interferon-inducible Mx promoter. Here we demonstrate that EBV-derived vectors replicate efficiently in all cell lines tested (i.e. HEK293, HeLaH21 and Vero), yielding stable transfectants with a high, inducible expression level and almost no background. In contrast, BKV-derived vectors are much more restricted to particular cell types and hampered by DNA rearrangements, which is a serious drawback for use over a longer timespan.
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Affiliation(s)
- K Van Craenenbroeck
- Department of Molecular Biology, University of Gent-VIB, K.L. Ledeganckstraat 35, B-9000, Gent, Belgium
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32
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Abstract
Although lipid-based DNA delivery systems are being assessed in gene therapy clinical trials, many investigators in this field are concerned about the inefficiency of lipid-based gene transfer technology, a criticism directed at all formulations used to enhance transfer of plasmid expression vectors. It is important to recognize that many approaches have been taken to improve transfection efficiency, however because of the complex nature of the formulation technology being developed, it has been extremely difficult to define specific carrier attributes that enhance transfection. We believe that these optimization processes are flawed for two reasons. First, a very defined change in formulation components affects the physical and chemical characteristics of the carrier in many ways. As a consequence, it has not been possible to define structure/activity relationships. Second, the primary endpoint used to assess plasmid delivery has been transgene expression, an activity that is under the control of cellular processes that have nothing to do with delivery. Gene expression following administration of a plasmid expression vector involves a number of critical steps: (i) DNA protection, (ii) binding to a specific cell population, (iii) DNA transfer across the cell membrane, (iv) release of DNA into the cytoplasm, (v) transport through the cell and across the nuclear membrane as well as (vi) transcription and translation of the gene. The objective of this review is to describe lipid-based DNA carrier systems and the attributes believed to be important in regulating the transfection activity of these formulations. Although membrane destabilization activity of the lipid-based carriers plays an important role, we suggest here that a critical element required for efficient transfection is dissociation of lipids bound to the plasmid expression vector following internalization.
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33
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McClarrinon M, Gilkey L, Watral V, Fox B, Bullock C, Fradkin L, Liggitt D, Roche L, Bussey LB, Fox E, Gorman C. In vivo studies of gene expression via transient transgenesis using lipid-DNA delivery. DNA Cell Biol 1999; 18:533-47. [PMID: 10433552 DOI: 10.1089/104454999315088] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As the sequencing of the human genome proceeds, the need for a new screen for in vivo function is becoming apparent. Many investigators are turning to various transgenic models as a means of studying function. However, these approaches are very time consuming, with a transgene-expressing mouse model often taking months to establish. We have developed an efficient system for delivering genes in vivo, which allows the gene product to be studied as early as 24 h after introduction into the mouse model. The delivery system employs a novel cationic lipid, 1-[2-(9-(Z)-octadecenoyloxy)ethyl]-2-(8-(Z)-heptadecenyl)-3- (hydroxyethyl)imidazolinium chloride (DOTIM), and a neutral lipid, cholesterol, complexed with an expression vector containing the reporter gene chloramphenicol acetyl transferase (CAT). After a single intravenous injection of these complexes, several tissues were seen to express the transgene. High, persistent expression in the vascular endothelial cells in the mouse lung was obtained. Delivery of DNA in vivo has been evaluated by quantitative polymerase chain reaction and protein expression by CAT activity assays. In vivo studies showed reproducible expression in more than 500 mice injected via the tail vein. An early peak of expression was followed by lower, but sustained, expression for > 50 days. Transgene expression of CAT could also be identified by immunohistochemistry staining in mouse lung and appeared to be located within the capillaries. The pattern of in vivo expression could be modulated and targeted to specific organs by altering the lipid-DNA formulation. New expression vectors with altered introns and polyadenylation sites further improved expression. The expression reported here may be sufficient in magnitude, duration, and flexibility to be an attractive alternative, in some cases, to establishing transgenic animals by stable gene transfer.
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Schaible UE, Collins HL, Kaufmann SH. Confrontation between intracellular bacteria and the immune system. Adv Immunol 1999; 71:267-377. [PMID: 9917916 DOI: 10.1016/s0065-2776(08)60405-8] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- U E Schaible
- Max-Planck Institute for Infection Biology, Berlin, Germany
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Lopez-Borges S, Gallego MI, Lazo PA. Recurrent integration of papillomavirus DNA within the human 12q14-15 uterine breakpoint region in genital carcinomas. Genes Chromosomes Cancer 1998; 23:55-60. [PMID: 9713997 DOI: 10.1002/(sici)1098-2264(199809)23:1<55::aid-gcc8>3.0.co;2-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genital carcinomas are associated with human papillomaviruses, and the viral DNA is frequently integrated in the host cell genome. Recurrent chromosomal alterations are genetic markers for specific tumor phenotypes. To demonstrate that papillomavirus DNA integration is indeed a recurrent chromosomal aberration, we mapped two independent papillomavirus integration sites in the human 12q14-15 region, one containing HPV16 DNA and the other HPV18 DNA. The two HPV integration sites map approximately 10 kbp from each other within the cosmid LLNL12NCO1-196E1 clone. The integration site corresponding to HPV16 DNA in SK-v cells is proximal to the 5' end of a DNA segment known to be rearranged by integration of HPV18 DNA in another cervical carcinoma cell line, SW756. Both integrations are located in the PAL2 locus within the uterine leiomyoma cluster region of translocation.
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Affiliation(s)
- S Lopez-Borges
- Unidad de Genética y Medicina Molecular (Consejo Superior de Investigaciones Científicas), Centro Nacional de Biología Fundamental, Instituto de Salud Carlos III, Majadahonda, Spain
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Rein T, DePamphilis ML, Zorbas H. Identifying 5-methylcytosine and related modifications in DNA genomes. Nucleic Acids Res 1998; 26:2255-64. [PMID: 9580672 PMCID: PMC147551 DOI: 10.1093/nar/26.10.2255] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Intense interest in the biological roles of DNA methylation, particularly in eukaryotes, has produced at least eight different methods for identifying 5-methylcytosine and related modifications in DNA genomes. However, the utility of each method depends not only on its simplicity but on its specificity, resolution, sensitivity and potential artifacts. Since these parameters affect the interpretation of data, they should be considered in any application. Therefore, we have outlined the principles and applications of each method, quantitatively evaluated their specificity,resolution and sensitivity, identified potential artifacts and suggested solutions, and discussed a paradox in the distribution of m5C in mammalian genomes that illustrates how methodological limitations can affect interpretation of data. Hopefully, the information and analysis provided here will guide new investigators entering this exciting field.
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Affiliation(s)
- T Rein
- National Institute of Child Health and Human Development, Building 6, Room 416, National Institutes of Health, Bethesda, MD 20892-2753, USA
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