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Wauford N, Patel A, Tordoff J, Enghuus C, Jin A, Toppen J, Kemp ML, Weiss R. Synthetic symmetry breaking and programmable multicellular structure formation. Cell Syst 2023; 14:806-818.e5. [PMID: 37689062 PMCID: PMC10919224 DOI: 10.1016/j.cels.2023.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 04/14/2023] [Accepted: 08/02/2023] [Indexed: 09/11/2023]
Abstract
During development, cells undergo symmetry breaking into differentiated subpopulations that self-organize into complex structures.1,2,3,4,5 However, few tools exist to recapitulate these behaviors in a controllable and coupled manner.6,7,8,9 Here, we engineer a stochastic recombinase genetic switch tunable by small molecules to induce programmable symmetry breaking, commitment to downstream cell fates, and morphological self-organization. Inducers determine commitment probabilities, generating tunable subpopulations as a function of inducer dosage. We use this switch to control the cell-cell adhesion properties of cells committed to each fate.10,11 We generate a wide variety of 3D morphologies from a monoclonal population and develop a computational model showing high concordance with experimental results, yielding new quantitative insights into the relationship between cell-cell adhesion strengths and downstream morphologies. We expect that programmable symmetry breaking, generating precise and tunable subpopulation ratios and coupled to structure formation, will serve as an integral component of the toolbox for complex tissue and organoid engineering.
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Affiliation(s)
- Noreen Wauford
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Akshay Patel
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jesse Tordoff
- Program in Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Casper Enghuus
- Department of Microbiology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Andrew Jin
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Jack Toppen
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Melissa L Kemp
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Ron Weiss
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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2
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Abstract
Transgenic technology allows a gene of interest to be introduced into the genome of a laboratory animal and provides an extremely powerful tool to dissect the molecular mechanisms of disease. Transgenic mouse models made by microinjection of DNA into zygotic pronuclei, in particular, have been widely used by the genetics community for over 35 years. However, up till 5 years ago, it remained a rather crude approach: injected sequences randomly insert in multiple copies as concatemers, and they can be mutagenic and have variable, ectopic, or silenced expression depending on the site of integration, a phenomenon called position effects. As a result, multiple lines are required in order to confirm appropriate transgene expression. This can be partially overcome by flanking transgenes with insulator sequences to protect the transgene from influence of surrounding regulatory elements. Large (<300 kb) BAC-based transgenic vectors have also been shown to be more resistant to position effects. However, animals carrying extra copies of fairly large regions of the genome could have unpredictable phenotypes.These problems can be overcome by targeting the transgene to a specific chromosomal locus via homologous recombination in embryonic stem (ES) cells. However, this method is significantly more laborious and time consuming, as it involves creation of modified ES cells and mouse chimeras, as well as eventual germline transmission of the transgene.Here, I describe an integrase-based approach, trademarked as "TARGATT™" (target attP), to produce site-specific transgenic mice via pronuclear microinjection, whereby an intact single-copy transgene can be inserted into predetermined chromosomal loci with high efficiency (up to 40%), and faithfully transmitted through generations. This system allows high-level global transgene expression or tissue-specific expression depending on the promoter used, or inducible expression such as induced by tetracycline or doxycycline. Using this approach, site-specific transgenic mice can be generated as fast as in 3 months. The technique presented here greatly facilitates murine transgenesis and precise structure/function dissection of mammalian gene function and regulation in vivo.
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Abstract
The discovery of new gene editing tools in the past several years has moved the transgenic field to a new level. The traditional random transgenesis method by pronuclear microinjection has been largely replaced by targeted or site-specific transgenic technologies without the need of homologous recombination in embryonic stem (ES) cells. In this chapter, I describe detailed protocols of an integrase-based approach, trademarked as "TARGATT™" (target attP), to produce site-specific transgenic mice via pronuclear microinjection, whereby an intact single-copy transgene can be inserted into a predetermined chromosomal locus with high efficiency (up to 40%), and faithfully transmitted through generations. This system allows high-level global transgene expression or tissue-specific expression depending on the promoter used, or inducible expression such as induced by tetracycline or doxycycline. Using this approach, site-specific transgenic mice can be generated as fast as in 3 months. The technique presented here greatly facilitates murine transgenesis and precise structure/function dissection of mammalian gene function and regulation in vivo.
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Sekhavati MH, Hosseini SM, Tahmoorespur M, Ghaedi K, Jafarpour F, Hajian M, Dormiani K, Nasr-Esfahani MH. PhiC31-based Site-Specific Transgenesis System for Production of Transgenic Bovine Embryos by Somatic Cell Nuclear Transfer and Intracytoplasmic Sperm Injection. CELL JOURNAL 2018; 20:98-107. [PMID: 29308625 PMCID: PMC5759686 DOI: 10.22074/cellj.2018.4385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 03/01/2017] [Indexed: 01/10/2023]
Abstract
OBJECTIVES The Streptomyces phage phiC31 integrase offers a sequence-specific method of transgenesis with a robust long-term gene expression. PhiC31 has been successfully developed in a variety of tissues and organs for purpose of in vivo gene therapy. The objective of the present experiment was to evaluate PhiC31-based site-specific transgenesis system for production of transgenic bovine embryos by somatic cell nuclear transfer and intracytoplasmic sperm injection. MATERIALS AND METHODS In this experimental study, the application of phiC31 integrase system was evaluated for generating transgenic bovine embryos by somatic cell nuclear transfer (SCNT) and sperm mediated gene transfer (SMGT) approaches. RESULTS PhiC31 integrase mRNA and protein was produced in vitro and their functionality was confirmed. Seven phiC31 recognizable bovine pseudo attachment sites of phage (attP) sites were considered for evaluation of site specific recombination. The accuracy of these sites was validated in phic31 targeted bovine fibroblasts using polymerase chain reaction (PCR) and sequencing. The efficiency and site-specificity of phiC31 integrase system was also confirmed in generated transgenic bovine embryo which successfully obtained using SCNT and SMGT technique. CONCLUSIONS The results showed that both SMGT and SCNT-derived embryos were enhanced green fluorescent protein (EGFP) positive and phiC31 integrase could recombine the reporter gene in a site specific manner. These results demonstrate that attP site can be used as a proper location to conduct site directed transgenesis in both mammalian cells and embryos in phiC31 integrase system when even combinaed to SCNT and intracytoplasmic sperm injection (ICSI) method.
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Affiliation(s)
| | - Sayed Morteza Hosseini
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | | | - Kamran Ghaedi
- Department of Biology, Facualty of Sciences, Uneversity of Isfahan, Isfahan, Iran
- Department of Cellular Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Farnoosh Jafarpour
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Mehdi Hajian
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Kyanoosh Dormiani
- Department of Cellular Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Mohammad Hossain Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.
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5
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Fani Maleki A, Sekhavati MH. Application of phiC31 integrase system in stem cells biology and technology: a review. FRONTIERS IN LIFE SCIENCE 2018. [DOI: 10.1080/21553769.2018.1447516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Adham Fani Maleki
- Embryonic and Stem Cell Biology and Biotechnology Research Group, Institute of Biotechnology, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mohammad Hadi Sekhavati
- Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
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6
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Blastocyst Formation Rate and Transgene Expression are Associated with Gene Insertion into Safe and Non-Safe Harbors in the Cattle Genome. Sci Rep 2017; 7:15432. [PMID: 29133827 PMCID: PMC5684190 DOI: 10.1038/s41598-017-15648-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 10/23/2017] [Indexed: 12/02/2022] Open
Abstract
Integration target site is the most important factor in successful production of transgenic animals. However, stable expression of transgene without disturbing the function of the host genome depends on promoter methylation, transgene copy number and transcriptional activity in integration regions. Recently, new genome-editing tools have made much progress, however little attention has been paid to the identification of genomic safe harbors. The aim of the present study was to evaluate the effect of insertion site, promoter and copy number of transgene on the production of embryos from cattle fibroblast cells following somatic cell nuclear transfer (SCNT). So, three donor vectors were constructed with EGFP gene under control of different promoters. Each vector was integrated into safe and non-safe harbors in the genome using phiC31 integrase. Transgenic clones with a single copy of each vector were isolated. Each clone was analyzed to find site and frequency of integration, expression level and promoter methylation before SCNT, as well as transgene expression level and blastocyst formation rate after SCNT. The data obtained demonstrated that BF5, as a safe harbor, not only showed a stable expression, but also the rate of in vitro-produced embryos from BF5-clones are similar to that of non-transfected cells.
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7
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Bosch P, Forcato DO, Alustiza FE, Alessio AP, Fili AE, Olmos Nicotra MF, Liaudat AC, Rodríguez N, Talluri TR, Kues WA. Exogenous enzymes upgrade transgenesis and genetic engineering of farm animals. Cell Mol Life Sci 2015; 72:1907-29. [PMID: 25636347 PMCID: PMC11114025 DOI: 10.1007/s00018-015-1842-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 01/15/2015] [Accepted: 01/16/2015] [Indexed: 01/14/2023]
Abstract
Transgenic farm animals are attractive alternative mammalian models to rodents for the study of developmental, genetic, reproductive and disease-related biological questions, as well for the production of recombinant proteins, or the assessment of xenotransplants for human patients. Until recently, the ability to generate transgenic farm animals relied on methods of passive transgenesis. In recent years, significant improvements have been made to introduce and apply active techniques of transgenesis and genetic engineering in these species. These new approaches dramatically enhance the ease and speed with which livestock species can be genetically modified, and allow to performing precise genetic modifications. This paper provides a synopsis of enzyme-mediated genetic engineering in livestock species covering the early attempts employing naturally occurring DNA-modifying proteins to recent approaches working with tailored enzymatic systems.
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Affiliation(s)
- Pablo Bosch
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Diego O. Forcato
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Fabrisio E. Alustiza
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Ana P. Alessio
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Alejandro E. Fili
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - María F. Olmos Nicotra
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Ana C. Liaudat
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Nancy Rodríguez
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Fco-Qcas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba Republic of Argentina
| | - Thirumala R. Talluri
- Friedrich-Loeffler-Institute, Institute of Farm Animal Genetics, Biotechnology, 31535 Neustadt, Germany
| | - Wilfried A. Kues
- Friedrich-Loeffler-Institute, Institute of Farm Animal Genetics, Biotechnology, 31535 Neustadt, Germany
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8
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Abstract
In recent years, application of serine integrases for genomic engineering has increased in popularity. The factor-independence and unidirectionality of these large serine recombinases makes them well suited for reactions such as site-directed vector integration and cassette exchange in a wide variety of organisms. In order to generate information that might be useful for altering the specificity of serine integrases and to improve their efficiency, we tested a hybridization strategy that has been successful with several small serine recombinases. We created chimeras derived from three characterized members of the serine integrase family, phiC31, phiBT1, and TG1 integrases, by joining their amino- and carboxy-terminal portions. We found that several phiBT1-phiC31 (BC) and phiC31-TG1 (CT) hybrid integrases are active in E. coli. BC chimeras function on native att-sites and on att-sites that are hybrids between those of the two donor enzymes, while CT chimeras only act on the latter att-sites. A BC hybrid, BC{−1}, was also active in human HeLa cells. Our work is the first to demonstrate chimeric serine integrase activity. This analysis sheds light on integrase structure and function, and establishes a potentially tractable means to probe the specificity of the thousands of putative large serine recombinases that have been revealed by bioinformatics studies.
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Affiliation(s)
- Alfonso P Farruggio
- Department of Genetics, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5120, USA
| | - Michele P Calos
- Department of Genetics, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5120, USA
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9
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Grandchamp N, Altémir D, Philippe S, Ursulet S, Pilet H, Serre MC, Lenain A, Serguera C, Mallet J, Sarkis C. Hybrid lentivirus-phiC31-int-NLS vector allows site-specific recombination in murine and human cells but induces DNA damage. PLoS One 2014; 9:e99649. [PMID: 24956106 PMCID: PMC4067480 DOI: 10.1371/journal.pone.0099649] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 05/17/2014] [Indexed: 12/27/2022] Open
Abstract
Gene transfer allows transient or permanent genetic modifications of cells for experimental or therapeutic purposes. Gene delivery by HIV-derived lentiviral vector (LV) is highly effective but the risk of insertional mutagenesis is important and the random/uncontrollable integration of the DNA vector can deregulate the cell transcriptional activity. Non Integrative Lentiviral Vectors (NILVs) solve this issue in non-dividing cells, but they do not allow long term expression in dividing cells. In this context, obtaining stable expression while avoiding the problems inherent to unpredictable DNA vector integration requires the ability to control the integration site. One possibility is to use the integrase of phage phiC31 (phiC31-int) which catalyzes efficient site-specific recombination between the attP site in the phage genome and the chromosomal attB site of its Streptomyces host. Previous studies showed that phiC31-int is active in many eukaryotic cells, such as murine or human cells, and directs the integration of a DNA substrate into pseudo attP sites (pattP) which are homologous to the native attP site. In this study, we combined the efficiency of NILV for gene delivery and the specificity of phiC31-int for DNA substrate integration to engineer a hybrid tool for gene transfer with the aim of allowing long term expression in dividing and non-dividing cells preventing genotoxicity. We demonstrated the feasibility to target NILV integration in human and murine pattP sites with a dual NILV vectors system: one which delivers phiC31-int, the other which constitute the substrate containing an attB site in its DNA sequence. These promising results are however alleviated by the occurrence of significant DNA damages. Further improvements are thus required to prevent chromosomal rearrangements for a therapeutic use of the system. However, its use as a tool for experimental applications such as transgenesis is already applicable.
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Affiliation(s)
- Nicolas Grandchamp
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
- Biosource, Paris, France
| | - Dorothée Altémir
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
| | - Stéphanie Philippe
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
- Biosource, Paris, France
| | - Suzanna Ursulet
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
- Biosource, Paris, France
| | - Héloïse Pilet
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
- Biosource, Paris, France
| | - Marie-Claude Serre
- Laboratoire de Virologie Moléculaire et Structurale, Gif-sur-Yvette, France
| | - Aude Lenain
- Commissariat à l'Energie Atomique, Laboratoire de Radiobiologie et Oncologie, Fontenay-aux-Roses, France
| | - Che Serguera
- Molecular Imaging Research Center - Modélisation des biothérapies, Fontenay-aux-Roses, France
| | - Jacques Mallet
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
| | - Chamsy Sarkis
- Unit of Biotechnology and Biotherapy, Centre de recherche de l'Institut du Cerveau et de la Moelle Epinière, Pierre-and-Marie-Curie University/Institut National de la Santé et de la Recherche Médicale, Paris, France
- NewVectys, Villebon-sur-Yvette, France
- * E-mail:
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10
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Ma H, Ma Q, Lu Y, Wang J, Hu W, Gong Z, Cai L, Huang Y, Huang SZ, Zeng F. PhiC31 integrase induces efficient site-specific recombination in the Capra hircus genome. DNA Cell Biol 2014; 33:484-91. [PMID: 24754538 DOI: 10.1089/dna.2013.2124] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Streptomyces phage φC31 integrase induces efficient site-specific recombination capable of integrating exogenous genes at pseudo attP sites in human, mouse, rat, rabbit, sheep, Drosophila, and bovine genomes. However, the φC31-mediated recombination between attB and the corresponding pseudo attP sites has not been investigated in Capra hircus. Here, we identified eight pseudo attP sites located in the intron or intergenic regions of the C. hircus genome, and demonstrated different levels of foreign gene expression after φC31 integrase-mediated integration. These pseudo attP sites share similar sequences with each other and with pseudo attP sites in other mammalian genomes, and these are associated with a neighboring consensus motif found in other genomes. The application of the φC31 integrase system in C. hircus provides a new option for genetic engineering of this economically important goat species.
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Affiliation(s)
- Haiyan Ma
- 1 Shanghai Institute of Medical Genetics, Shanghai Children's Hospital, Shanghai Jiao Tong University , Shanghai, People's Republic of China
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11
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Improved site-specific recombinase-based method to produce selectable marker- and vector-backbone-free transgenic cells. Sci Rep 2014; 4:4240. [PMID: 24577484 PMCID: PMC3937794 DOI: 10.1038/srep04240] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 02/06/2014] [Indexed: 12/30/2022] Open
Abstract
PhiC31 integrase-mediated gene delivery has been extensively used in gene therapy and animal transgenesis. However, random integration events are observed in phiC31-mediated integration in different types of mammalian cells; as a result, the efficiencies of pseudo attP site integration and evaluation of site-specific integration are compromised. To improve this system, we used an attB-TK fusion gene as a negative selection marker, thereby eliminating random integration during phiC31-mediated transfection. We also excised the selection system and plasmid bacterial backbone by using two other site-specific recombinases, Cre and Dre. Thus, we generated clean transgenic bovine fetal fibroblast cells free of selectable marker and plasmid bacterial backbone. These clean cells were used as donor nuclei for somatic cell nuclear transfer (SCNT), indicating a similar developmental competence of SCNT embryos to that of non-transgenic cells. Therefore, the present gene delivery system facilitated the development of gene therapy and agricultural biotechnology.
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12
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Chen-Tsai RY, Jiang R, Zhuang L, Wu J, Li L, Wu J. Genome editing and animal models. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s11434-013-0032-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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13
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Zhu F, Gamboa M, Farruggio AP, Hippenmeyer S, Tasic B, Schüle B, Chen-Tsai Y, Calos MP. DICE, an efficient system for iterative genomic editing in human pluripotent stem cells. Nucleic Acids Res 2013; 42:e34. [PMID: 24304893 PMCID: PMC3950688 DOI: 10.1093/nar/gkt1290] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
To reveal the full potential of human pluripotent stem cells, new methods for rapid, site-specific genomic engineering are needed. Here, we describe a system for precise genetic modification of human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). We identified a novel human locus, H11, located in a safe, intergenic, transcriptionally active region of chromosome 22, as the recipient site, to provide robust, ubiquitous expression of inserted genes. Recipient cell lines were established by site-specific placement of a ‘landing pad’ cassette carrying attP sites for phiC31 and Bxb1 integrases at the H11 locus by spontaneous or TALEN-assisted homologous recombination. Dual integrase cassette exchange (DICE) mediated by phiC31 and Bxb1 integrases was used to insert genes of interest flanked by phiC31 and Bxb1 attB sites at the H11 locus, replacing the landing pad. This system provided complete control over content, direction and copy number of inserted genes, with a specificity of 100%. A series of genes, including mCherry and various combinations of the neural transcription factors LMX1a, FOXA2 and OTX2, were inserted in recipient cell lines derived from H9 ESC, as well as iPSC lines derived from a Parkinson’s disease patient and a normal sibling control. The DICE system offers rapid, efficient and precise gene insertion in ESC and iPSC and is particularly well suited for repeated modifications of the same locus.
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Affiliation(s)
- Fangfang Zhu
- Department of Genetics, Stanford University, Stanford, CA 94305, USA, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA, Howard Hughes Medical Institute and Department of Biology, Stanford University, Stanford, CA 94305, USA, Parkinson's Institute and Clinical Center, Sunnyvale, CA 94085, USA and Stanford Transgenic Research Facility, Stanford University, Stanford, CA 94305, USA
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14
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Bi Y, Liu X, Zhang L, Shao C, Ma Z, Hua Z, Zhang L, Li L, Hua W, Xiao H, Wei Q, Zheng X. Pseudo attP sites in favor of transgene integration and expression in cultured porcine cells identified by Streptomyces phage phiC31 integrase. BMC Mol Biol 2013; 14:20. [PMID: 24010979 PMCID: PMC3844521 DOI: 10.1186/1471-2199-14-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/27/2013] [Indexed: 12/30/2022] Open
Abstract
Phage PhiC31 integrase integrates attB-containing plasmid into pseudo attP site in eukaryotic genomes in a unidirectional site-specific manner and maintains robust transgene expression. Few studies, however, explore its potential in livestock. This study aims to discover the molecular basis of PhiC31 integrase-mediated site-specific recombination in pig cells. We show that PhiC31 integrase can mediate site-specific transgene integration into the genome of pig kidney PK15 cells. Intramolecular recombination in pig PK15 cell line occurred at maximum frequency of 82% with transiently transfected attB- and attP-containing plasmids. An optimal molar ratio of pCMV-Int to pEGFP-N1-attB at 5:1 was observed for maximum number of cell clones under drug selection. Four candidate pseudo attP sites were identified by TAIL-PCR from those cell clones with single-copy transgene integration. Two of them gave rise to higher integration frequency occurred at 33%. 5′ and 3′ junction PCR showed that transgene integration mediated by PhiC31 integrase was mono-allelic. Micro- deletion and insertion were observed by sequencing the integration border, indicating that double strand break was induced by the recombination. We then constructed rescue reporter plasmids by ABI-REC cloning of the four pseudo attP sites into pBCPB + plasmid. Transfection of these rescue plasmids and pCMV-Int resulted in expected intramolecular recombination between attB and pseudo attP sites. This proved that the endogenous pseudo attP sites were functional substrates for PhiC31 integrase-mediated site-specific recombination. Two pseudo attP sites maintained robust extracellular and intracellular EGFP expression. Alamar blue assay showed that transgene integration into these specific sites had little effect on cell proliferation. This is the first report to document the potential use of PhiC31 integrase to mediate site-specific recombination in pig cells. Our work established an ideal model to study the position effect of identical transgene located in diverse chromosomal contexts. These findings also form the basis for targeted pig genome engineering and may be used to produce genetically modified pigs for agricultural and biomedical uses.
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Affiliation(s)
- Yanzhen Bi
- Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Science, Wuhan 430064, China.
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15
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Ou H, Huang Y, Ma Q, Ren Z, Huang S, Zeng F, Zeng Y. A highly efficient site-specific integration strategy using combination of homologous recombination and the ΦC31 integrase. J Biotechnol 2013; 167:427-32. [DOI: 10.1016/j.jbiotec.2013.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/29/2013] [Accepted: 08/02/2013] [Indexed: 10/26/2022]
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Mosimann C, Puller AC, Lawson KL, Tschopp P, Amsterdam A, Zon LI. Site-directed zebrafish transgenesis into single landing sites with the phiC31 integrase system. Dev Dyn 2013; 242:949-963. [PMID: 23723152 PMCID: PMC3775328 DOI: 10.1002/dvdy.23989] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2013] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Linear DNA-based and Tol2-mediated transgenesis are powerful tools for the generation of transgenic zebrafish. However, the integration of multiple copies or transgenes at random genomic locations complicates comparative transgene analysis and makes long-term transgene stability unpredictable with variable expression. Targeted, site-directed transgene integration into pre-determined genomic loci can circumvent these issues. The phiC31 integrase catalyzes the unidirectional recombination reaction between heterotypic attP and attB sites and is an efficient platform for site-directed transgenesis. RESULTS We report the implementation of the phiC31 integrase-mediated attP/attB recombination for site-directed zebrafish transgenics of attB-containing transgene vectors into single genomic attP landing sites. We generated Tol2-based single-insertion attP transgenic lines and established their performance in phiC31 integrase-catalyzed integration of an attB-containing transgene vector. We found stable germline transmission into the next generation of an attB reporter transgene in 34% of all tested animals. We further characterized two functional attP landing site lines and determined their genomic location. Our experiments also demonstrate tissue-specific transgene applications as well as long-term stability of phiC31-mediated transgenes. CONCLUSIONS Our results establish phiC31 integrase-controlled site-directed transgenesis into single, genomic attP sites as space-, time-, and labor-efficient zebrafish transgenesis technique. The described reagents are available for distribution to the zebrafish community.
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Affiliation(s)
- Christian Mosimann
- Howard Hughes Medical Institute, Boston, MA 02115, USA
- Stem Cell Program, Children’s Hospital Boston, Boston, MA 02115, USA
- Division of Hematology/Oncology, Children’s Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Ann-Christin Puller
- Howard Hughes Medical Institute, Boston, MA 02115, USA
- Stem Cell Program, Children’s Hospital Boston, Boston, MA 02115, USA
- Division of Hematology/Oncology, Children’s Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Katy L. Lawson
- Howard Hughes Medical Institute, Boston, MA 02115, USA
- Stem Cell Program, Children’s Hospital Boston, Boston, MA 02115, USA
- Division of Hematology/Oncology, Children’s Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Patrick Tschopp
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Adam Amsterdam
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02319, USA
| | - Leonard I. Zon
- Howard Hughes Medical Institute, Boston, MA 02115, USA
- Stem Cell Program, Children’s Hospital Boston, Boston, MA 02115, USA
- Division of Hematology/Oncology, Children’s Hospital Boston, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA
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Yu Y, Wang Y, Tong Q, Liu X, Su F, Quan F, Guo Z, Zhang Y. A site-specific recombinase-based method to produce antibiotic selectable marker free transgenic cattle. PLoS One 2013; 8:e62457. [PMID: 23658729 PMCID: PMC3641042 DOI: 10.1371/journal.pone.0062457] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 03/21/2013] [Indexed: 12/24/2022] Open
Abstract
Antibiotic selectable marker genes have been widely used to generate transgenic animals. Once transgenic animals have been obtained, the selectable marker is no longer necessary but raises public concerns regarding biological safety. The aim of this study was to prepare competent antibiotic selectable marker free transgenic cells for somatic cell nuclear transfer (SCNT). PhiC31 intergrase was used to insert a transgene cassette into a "safe harbor" in the bovine genome. Then, Cre recombinase was employed to excise the selectable marker under the monitoring of a fluorescent double reporter. By visually tracking the phenotypic switch from red to green fluorescence, antibiotic selectable marker free cells were easily detected and sorted by fluorescence-activated cell sorting. For safety, we used phiC31 mRNA and cell-permeant Cre protein in this study. When used as donor nuclei for SCNT, these safe harbor integrated marker-free transgenic cells supported a similar developmental competence of SCNT embryos compared with that of non-transgenic cells. After embryo transfer, antibiotic selectable marker free transgenic cattle were generated and anti-bacterial recombinant human β-defensin-3 in milk was detected during their lactation period. Thus, this approach offers a rapid and safe alternative to produce antibiotic selectable marker free transgenic farm animals, thereby making it a valuable tool to promote the healthy development and welfare of transgenic farm animals.
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Affiliation(s)
- Yuan Yu
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Yongsheng Wang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Qi Tong
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Xu Liu
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Feng Su
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Fusheng Quan
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Zekun Guo
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
| | - Yong Zhang
- Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi, People’s Republic of China
- * E-mail:
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Zhang J, Zhao J, Jiang WJ, Shan XW, Yang XM, Gao JG. Conditional gene manipulation: Cre-ating a new biological era. J Zhejiang Univ Sci B 2012; 13:511-24. [PMID: 22761243 DOI: 10.1631/jzus.b1200042] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To solve the problem of embryonic lethality in conventional gene knockouts, site-specific recombinase (SSR) systems (Cre-loxP, Flp-FRT, and ΦC31) have been used for tissue-specific gene knockout. With the combination of an SSR system and inducible gene expression systems (tetracycline and tamoxifen), stage-specific knockout and transgenic expression can be achieved. The application of this "SSR+inducible" conditional tool to genomic manipulation can be extended in various ways. Alternatives to conditional gene targeting, such as conditional gene trapping, multipurpose conditional alleles, and conditional gene silencing, have been developed. SSR systems can also be used to construct precise disease models with point mutations and chromosomal abnormalities. With these exciting achievements, we are moving towards a new era in which the whole genome can be manipulated as we wish.
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Affiliation(s)
- Jian Zhang
- School of Life Science, Shandong University, Jinan, China
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20
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ΦC31 integrase mediates efficient site-specific integration in sheep fibroblasts. Biosci Biotechnol Biochem 2012; 76:2093-5. [PMID: 23132571 DOI: 10.1271/bbb.120439] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ΦC31 integrase, a site-specific recombinase, can effectively mediate the integration of foreign genes bearing an attB sequence into pseudo attP sites of genomes in human, mouse, and Drosophila cells. In this study, we measured ΦC31 integrase-mediated homologous recombination between attB and pseudo attP sites in sheep cells. The integration efficiency of the EGFP expression cassette with the attB sequence increased at least 2-fold in sheep fibroblasts. Three pseudo-attP sites were identified in the sheep genome, located in the intergenic regions on chromosomes 4, 13, and 7 respectively. Moreover, the transgene that was integrated at the three pseudo attP sites exhibited high levels of expression. Our study indicates that the ΦC31 integrase system provides an efficient integration tool for genetic engineering of the sheep genome.
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21
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Xie F, Ma Q, Jiang S, Ren Z, Wang J, Huang S, Zeng F, Zeng Y. Adjusting the attB site in donor plasmid improves the efficiency of ΦC31 integrase system. DNA Cell Biol 2012; 31:1335-40. [PMID: 22489575 DOI: 10.1089/dna.2011.1590] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
ΦC31 integrase, a site-specific recombinase, can catalyze integration of circular DNA bearing attB site into pseudo attP sites in mammalian genomes. However, the integration efficiency mediated by integrase is relatively low. Our study centered on the investigation of the impact of the position, orientation, and number of attBs in the donor plasmid on the efficiency of ΦC31 integrase system. Donor plasmids bearing various types of attBs (including forward and reverse directions, tandem, and intersperse) and reporter enhanced green fluorescent protein (EGFP) were constructed. The plasmids plus helper plasmid encoding integrase were co-transfected into HeLa cells. After G418 selection, the resistant cell colonies were counted for calculating chromosomal integration frequency. EGFP expression was detected by fluorescence-activated cell sorter and enzyme-linked immunosorbent assay analysis. The results showed that efficiency of integration mediated by integrase accounted for 70% ± 7.1% of total integration events in the transfected HeLa cells. Compared with a forward orientation of attB in donor plasmid, a reverse direction of attB or interspersed attBs showed 1.5- or 2.8-fold increase in integration efficiency, respectively, while tandem attBs in donor plasmids caused a decreased efficiency of integration. We conclude that the adjustment of attB sites in donor plasmids may be of value for gene therapy and routine genetic engineering by using ΦC31 integrase system.
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Affiliation(s)
- Fei Xie
- Shanghai Institute of Medical Genetics, Children's Hospital of Shanghai, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China
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22
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Qu L, Ma Q, Zhou Z, Ma H, Huang Y, Huang S, Zeng F, Zeng Y. A profile of native integration sites used by φC31 integrase in the bovine genome. J Genet Genomics 2012; 39:217-24. [PMID: 22624883 DOI: 10.1016/j.jgg.2012.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 03/07/2012] [Accepted: 03/30/2012] [Indexed: 11/24/2022]
Abstract
The Streptomyces phage φC31 integrase can efficiently target attB-bearing transgenes to endogenous pseudo attP sites within mammalian genomes. To better understand the activity of φC31 integrase in the bovine genome, DNA sequences of 44 integration events were analyzed, and 32 pseudo attP sites were identified. The majority of these sites share a sequence motif that contains inverted repeats and has similarities to wild-type attP site. Genomic DNA flanking these sites typically contained repetitive sequence elements, such as short and long interspersed repetitive elements. These sequence features indicate that DNA sequence recognition plays an important role in guiding φC31-mediated site-specific integration. In addition, BF27 integration hotspot sites were identified in the bovine genome, which accounted for 13.6% of all isolated integration events and mapped to an intron of the deleted in liver cancer 1 (DLC1) gene. Also we found that the pseudo attP sites in the bovine genome had other features in common with those in the human genome. This study represents the first time that the sequence features of pseudo attP sites in the bovine genome were analyzed. We conclude that this site-specific integrase system has great potential for applied modifications of the bovine genome.
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Affiliation(s)
- Lijuan Qu
- Shanghai Institute of Medical Genetics, Children's Hospital of Shanghai, Shanghai Jiao Tong University School of Medicine, 24/1400 West Beijing Road, Shanghai 200040, China
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Establishment of an improved high-efficiency thermal asymmetric interlaced PCR for identification of genomic integration sites mediated by phiC31 integrase. World J Microbiol Biotechnol 2011; 28:1295-9. [PMID: 22805850 DOI: 10.1007/s11274-011-0877-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022]
Abstract
Streptomyces phage phiC31 integrase is widely used to mediate the integration of exogenous genes into host genomes for gene therapy and genomic modification, as it autonomously performs efficient, unidirectional, site-specific integration into pseudo attP sites of the host genome. Although pseudo attP sites are rarely found within exons, it is necessary to map their precise locations to avoid the risk of insertion mutagenesis. High-efficiency thermal asymmetric interlaced PCR (hiTAIL-PCR) is a technique that has been developed to recover genomic sequences that flank insertion tags. We have found, however, that this technique is poorly efficient, as it amplifies many non-specific targets and frequently does not generate sufficient product for downstream analysis. Therefore, we have modified the hiTAIL-PCR procedure and re-designed the random primers. As a result, both the amount and specificity of the reaction product were enhanced for each integration site. Restriction analysis of known sequences within the integrated vector, which co-amplified with the flanking genomic sequences, validated 90% of these bands for sequencing. In contrast, only 30% of the bands produced by previous hiTAIL-PCR could be validated. Compared with the original hiTAIL-PCR, our improved hiTAIL-PCR procedure identified phiC31 integration sites more accurately and efficiently.
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[Construction of the oocyte-specific expressing phiC31 integrase vector pZP3-INT and its expression in mouse oocytes]. YI CHUAN = HEREDITAS 2009; 31:595-9. [PMID: 19586858 DOI: 10.3724/sp.j.1005.2009.00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Streptomyces phage phiC31 integrase is a site-specific recombinase, which can catalyze site-specific, unidirectional recombination between the attP site and attB site. To explore whether it can be used to mediate the recombination of specific gene in oocytes, GV-stage oocytes were collected from 3-week-old Kunming White mice by puncturing antral follocles with a sharp needle, and micro-injected with oocyte-specific expressing phiC31 integrase vector pZP3-INT and site -specific recombination detection vector pBCPB+. phiC31 integrase mRNA were detected by RT-PCR and the recombination of pBCPB+ was evaluated by PCR in mouse oocytes at 48 h after injection. Both can get corresponding bands. These results indicated that the expression of phiC31 integrase can be driven by ZP3 promoter efficiently and phiC31 integrase can mediate the site-specific recombination between attP site and attB site in mouse GV-stage oocytes. It could be a powerful tool for the study of recombination of specific gene in mouse oocytes and would provide an alternative way for the mouse oocyte genome manipulation.
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25
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Fu Q, Jia S, Sun Z, Tian F, Du J, Zhou Y, Wang Y, Wang X, Zhan L. φC31 integrase and liver-specific regulatory elements confer high-level, long-term expression of firefly luciferase in mouse liver. Biotechnol Lett 2009; 31:1151-7. [DOI: 10.1007/s10529-009-9996-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/16/2009] [Accepted: 03/19/2009] [Indexed: 01/28/2023]
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26
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Ou HL, Huang Y, Qu LJ, Xu M, Yan JB, Ren ZR, Huang SZ, Zeng YT. A phiC31 integrase-mediated integration hotspot in favor of transgene expression exists in the bovine genome. FEBS J 2009; 276:155-63. [PMID: 19019083 DOI: 10.1111/j.1742-4658.2008.06762.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
phiC31 integrase, a site-specific recombinase, can effectively mediate foreign genes bearing an attB sequence integrated into pseudo attP sites. We have previously identified two pseudo attP sites, BpsF1 and BpsM1 from the bovine genome. In this study, two new pseudo attP sites, BF4 and BF10, were discovered using half-nested inverse PCR from cow fibroblasts. The genomic locations of these two pseudo attP sites were identified by direct sequencing and a BLAST search, and it was confirmed that they reside at positions 4q31 and 10q35 by fluorescence in situ hybridization analysis. Subsequently, the distinct integration frequencies of the four pseudo attP sites were examined. The BF4 site was identified as a hotspot where site-specific integration occurred in most of the cell clones examined, accounting for 74% (42/57) of the integration; much more than the integration frequency for BF10 (7%; 4/57), BpsF1 (7%; 4/57) and BpsM1 (0/57). Interestingly, similar to other hotspots identified in the human and mouse genomes, in which transgenes integrated at hotspots result in high expression, the GFP gene integrated at hotspot BF4 was expressed at high levels in cow fibroblasts, as confirmed by fluorescence microscopy and FACS analysis. Furthermore, ELISA showed that the expression level of the GFP gene integrated at the BF4 site averaged approximately 328 microg x mg(-1), which is more than twofold higher than that integrated at the BF10 site. This study suggests that somatic cells carrying a desired gene integrated at the BF4 site can be used as nuclear donors to generate valuable transgenic animals by nuclear transfer.
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Affiliation(s)
- Hai-Long Ou
- Shanghai Institute of Medical Genetics, Shanghai Jiao Tong University, China
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Thyagarajan B, Liu Y, Shin S, Lakshmipathy U, Scheyhing K, Xue H, Ellerström C, Strehl R, Hyllner J, Rao MS, Chesnut JD. Creation of engineered human embryonic stem cell lines using phiC31 integrase. Stem Cells 2007; 26:119-26. [PMID: 17962703 DOI: 10.1634/stemcells.2007-0283] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
It has previously been shown that the phage-derived phiC31 integrase can efficiently target native pseudo-attachment sites in the genome of various species in cultured cells, as well as in vivo. To demonstrate its utility in human embryonic stem cells (hESC), we have created hESC-derived clones containing expression constructs. Variant human embryonic stem cell lines BG01v and SA002 were used to derive lines expressing a green fluorescent protein (GFP) marker under control of either the human Oct4 promoter or the EF1alpha promoter. Stable clones were selected by antibiotic resistance and further characterized. The frequency of integration suggested candidate hot spots in the genome, which were mapped using a plasmid rescue strategy. The pseudo-attP profile in hESC differed from those reported earlier in differentiated cells. Clones derived using this method retained the ability to differentiate into all three germ layers, and fidelity of expression of GFP was verified in differentiation assays. GFP expression driven by the Oct4 promoter recapitulated endogenous Oct4 expression, whereas persistent stable expression of GFP expression driven by the EF1alpha promoter was seen. Our results demonstrate the utility of phiC31 integrase to target pseudo-attP sites in hESC and show that integrase-mediated site-specific integration can efficiently create stably expressing engineered human embryonic stem cell clones.
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