1
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Wang Z, Chen C, Ge X. Large T antigen mediated target gene replication improves site-specific recombination efficiency. Front Bioeng Biotechnol 2024; 12:1377167. [PMID: 38737535 PMCID: PMC11082406 DOI: 10.3389/fbioe.2024.1377167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/11/2024] [Indexed: 05/14/2024] Open
Abstract
With advantages of high-fidelity, monoclonality and large cargo capacity, site-specific recombination (SSR) holds great promises for precise genomic modifications. However, broad applications of SSR have been hurdled by low integration efficiency, and the amount of donor DNA available in nucleus for SSR presents as a limiting factor. Inspired by the DNA replication mechanisms observed in double-stranded DNA virus SV40, we hypothesized that expression of SV40 large T antigen (TAg) can increase the copy number of the donor plasmid bearing an SV40 origin, and in consequence promote recombination events. This hypothesis was tested with dual recombinase-mediated cassette exchange (RMCE) in suspension 293F cells. Results showed that TAg co-transfection significantly enhanced SSR in polyclonal cells. In the monoclonal cell line carrying a single landing pad at an identified genomic locus, 12% RMCE efficiency was achieved, and such improvement was indeed correlated with donor plasmid amplification. The developed TAg facilitated RMCE (T-RMCE) was exploited for the construction of large libraries of >107 diversity, from which GFP variants with enhanced fluorescence were isolated. We expect the underlying principle of target gene amplification can be applicable to other SSR processes and gene editing approaches in general for directed evolution and large-scale genomic screening in mammalian cells.
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Affiliation(s)
- Zening Wang
- Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, United States
- Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA, United States
| | - Chuan Chen
- Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA, United States
| | - Xin Ge
- Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX, United States
- Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA, United States
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2
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Zhang C, Chang F, Miao H, Fu Y, Tong X, Feng Y, Zheng W, Ma X. Construction and application of a multifunctional CHO cell platform utilizing Cre/ lox and Dre/ rox site-specific recombination systems. Front Bioeng Biotechnol 2023; 11:1320841. [PMID: 38173869 PMCID: PMC10761530 DOI: 10.3389/fbioe.2023.1320841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
During the development of traditional Chinese hamster ovary (CHO) cell lines, target genes randomly integrate into the genome upon entering the nucleus, resulting in unpredictable productivity of cell clones. The characterization and screening of high-yielding cell lines is a time-consuming and expensive process. Site-specific integration is recognized as an effective approach for overcoming random integration and improving production stability. We have designed a multifunctional expression cassette, called CDbox, which can be manipulated by the site-specific recombination systems Cre/lox and Dre/rox. The CDbox expression cassette was inserted at the Hipp11(H11) locus hotspot in the CHO-K1 genome using CRISPR/Cas9 technology, and a compliant CHO-CDbox cell platform was screened and obtained. The CHO-CDbox cell platform was transformed into a pool of EGFP-expressing cells using Cre/lox recombinase-mediated cassette exchange (RMCE) in only 2 weeks, and this expression remained stable for at least 75 generations without the need for drug stress. Subsequently, we used the Dre/rox system to directly eliminate the EGFP gene. In addition, two practical applications of the CHO-CDbox cell platform were presented. The first was the quick construction of the Pembrolizumab antibody stable expression strain, while the second was a protocol for the integration of surface-displayed and secreted antibodies on CHO cells. The previous research on site-specific integration of CHO cells has always focused on the single functionality of insertion of target genes. This newly developed CHO cell platform is expected to offer expanded applicability for protein production and gene function studies.
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Affiliation(s)
- Chen Zhang
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Feng Chang
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Hui Miao
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Yunhui Fu
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Xikui Tong
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
| | - Yu Feng
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Wenyun Zheng
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, Shanghai, China
| | - Xingyuan Ma
- State Key Laboratory of Bioreactor Engineering, School of Biotechnology, East China University of Science and Technology, Shanghai, China
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3
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Amiri S, Adibzadeh S, Ghanbari S, Rahmani B, Kheirandish MH, Farokhi-Fard A, Dastjerdeh MS, Davami F. CRISPR-interceded CHO cell line development approaches. Biotechnol Bioeng 2023; 120:865-902. [PMID: 36597180 DOI: 10.1002/bit.28329] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 11/28/2022] [Accepted: 01/02/2023] [Indexed: 01/05/2023]
Abstract
For industrial production of recombinant protein biopharmaceuticals, Chinese hamster ovary (CHO) cells represent the most widely adopted host cell system, owing to their capacity to produce high-quality biologics with human-like posttranslational modifications. As opposed to random integration, targeted genome editing in genomic safe harbor sites has offered CHO cell line engineering a new perspective, ensuring production consistency in long-term culture and high biotherapeutic expression levels. Corresponding the remarkable advancements in knowledge of CRISPR-Cas systems, the use of CRISPR-Cas technology along with the donor design strategies has been pushed into increasing novel scenarios in cell line engineering, allowing scientists to modify mammalian genomes such as CHO cell line quickly, readily, and efficiently. Depending on the strategies and production requirements, the gene of interest can also be incorporated at single or multiple loci. This review will give a gist of all the most fundamental recent advancements in CHO cell line development, such as different cell line engineering approaches along with donor design strategies for targeted integration of the desired construct into genomic hot spots, which could ultimately lead to the fast-track product development process with consistent, improved product yield and quality.
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Affiliation(s)
- Shahin Amiri
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Setare Adibzadeh
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Samaneh Ghanbari
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Behnaz Rahmani
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad H Kheirandish
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
- Department of Medical Biotechnology, School of Advanced Technologies, Tehran University of Medical Sciences, Tehran, Iran
| | - Aref Farokhi-Fard
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Mansoureh S Dastjerdeh
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Fatemeh Davami
- Department of Medical Biotechnology, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
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4
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Targeted integration in CHO cells using CRIS-PITCh/Bxb1 recombinase-mediated cassette exchange hybrid system. Appl Microbiol Biotechnol 2023; 107:769-783. [PMID: 36536089 PMCID: PMC9763083 DOI: 10.1007/s00253-022-12322-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/27/2022] [Accepted: 11/30/2022] [Indexed: 12/24/2022]
Abstract
Recombinant Chinese hamster ovary (CHO) cell line development for complex biotherapeutic production is conventionally based on the random integration (RI) approach. Due to the lack of control over the integration site and copy number, RI-generated cell pools are always coupled with rigorous screening to find clones that satisfy requirements for production titers, quality, and stability. Targeted integration into a well-defined genomic site has been suggested as a possible strategy to mitigate the drawbacks associated with RI. In this work, we employed the CRISPR-mediated precise integration into target chromosome (CRIS-PITCh) system in combination with the Bxb1 recombinase-mediated cassette exchange (RMCE) system to generate an isogenic transgene-expressing cell line. We successfully utilized the CRIS-PITCh system to target a 2.6 kb Bxb1 landing pad with homology arms as short as 30 bp into the upstream region of the S100A gene cluster, achieving a targeting efficiency of 10.4%. The platform cell line (PCL) with a single copy of the landing pad was then employed for the Bxb1-mediated landing pad exchange with an EGFP encoding cassette to prove its functionality. Finally, to accomplish the main goal of our cell line development method, the PCL was applied for the expression of a secretory glycoprotein, human recombinant soluble angiotensin-converting enzyme 2 (hrsACE2). Taken together, on-target, single-copy, and stable expression of the transgene over long-term cultivation demonstrated our CRIS-PITCh/RMCE hybrid approach might possibly improve the cell line development process in terms of timeline, specificity, and stability. KEY POINTS: • CRIS-PITCh system is an efficient method for single copy targeted integration of the landing pad and generation of platform cell line • Upstream region of the S100A gene cluster of CHO-K1 is retargetable by recombinase-mediated cassette exchange (RMCE) approach and provides a stable expression of the transgene • CRIS-PITCh/Bxb1 RMCE hybrid system has the potential to overcome some limitations of the random integration approach and accelerate the cell line development timeline.
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5
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Marx N, Eisenhut P, Weinguny M, Klanert G, Borth N. How to train your cell - Towards controlling phenotypes by harnessing the epigenome of Chinese hamster ovary production cell lines. Biotechnol Adv 2022; 56:107924. [PMID: 35149147 DOI: 10.1016/j.biotechadv.2022.107924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 02/03/2022] [Accepted: 02/04/2022] [Indexed: 11/24/2022]
Abstract
Recent advances in omics technologies and the broad availability of big datasets have revolutionized our understanding of Chinese hamster ovary cells in their role as the most prevalent host for production of complex biopharmaceuticals. In consequence, our perception of this "workhorse of the biopharmaceutical industry" has successively shifted from that of a nicely working, but unknown recombinant protein producing black box to a biological system governed by multiple complex regulatory layers that might possibly be harnessed and manipulated at will. Despite the tremendous progress that has been made to characterize CHO cells on various omics levels, our understanding is still far from complete. The well-known inherent genetic plasticity of any immortalized and rapidly dividing cell line also characterizes CHO cells and can lead to problematic instability of recombinant protein production. While the high mutational frequency has been a focus of CHO cell research for decades, the impact of epigenetics and its role in differential gene expression has only recently been addressed. In this review we provide an overview about the current understanding of epigenetic regulation in CHO cells and discuss its significance for shaping the cell's phenotype. We also look into current state-of-the-art technology that can be applied to harness and manipulate the epigenetic network so as to nudge CHO cells towards a specific phenotype. Here, we revise current strategies on site-directed integration and random as well as targeted epigenome modifications. Finally, we address open questions that need to be investigated to exploit the full repertoire of fine-tuned control of multiplexed gene expression using epigenetic and systems biology tools.
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Affiliation(s)
- Nicolas Marx
- University of Natural Resources and Life Sciences, Vienna, Austria
| | - Peter Eisenhut
- Austrian Centre for Industrial Biotechnology GmbH, Vienna, Austria
| | - Marcus Weinguny
- University of Natural Resources and Life Sciences, Vienna, Austria; Austrian Centre for Industrial Biotechnology GmbH, Vienna, Austria
| | - Gerald Klanert
- Austrian Centre for Industrial Biotechnology GmbH, Vienna, Austria
| | - Nicole Borth
- University of Natural Resources and Life Sciences, Vienna, Austria; Austrian Centre for Industrial Biotechnology GmbH, Vienna, Austria.
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6
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Shin S, Kim SH, Lee JS, Lee GM. Streamlined Human Cell-Based Recombinase-Mediated Cassette Exchange Platform Enables Multigene Expression for the Production of Therapeutic Proteins. ACS Synth Biol 2021; 10:1715-1727. [PMID: 34133132 DOI: 10.1021/acssynbio.1c00113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A platform, based on targeted integration of transgenes using recombinase-mediated cassette exchange (RMCE) coupled with CRISPR/Cas9, is increasingly being used for the development of mammalian cell lines that produce therapeutic proteins, because of reduced clonal variation and predictable transgene expression. However, low efficiency of the RMCE process has hampered its application in multicopy or multisite integration of transgenes. To improve RMCE efficiency, nuclear transport of RMCE components such as site-specific recombinase and donor plasmid was accelerated by incorporation of nuclear localization signal and DNA nuclear-targeting sequence, respectively. Consequently, the efficiency of RMCE in dual-landing pad human embryonic kidney 293 (HEK293) cell lines harboring identical or orthogonal pairs of recombination sites at two well-known human safe harbors (AAVS1 and ROSA26 loci), increased 6.7- and 8.1-fold, respectively. This platform with enhanced RMCE efficiency enabled simultaneous integration of transgenes at the two sites using a single transfection without performing selection and enrichment processes. The use of a homotypic dual-landing pad HEK293 cell line capable of incorporating the same transgenes at two sites resulted in a 2-fold increase in the transgene expression level compared to a single-landing pad HEK293 cell line. In addition, the use of a heterotypic dual-landing pad HEK293 cell line, which can incorporate transgenes for a recombinant protein at one site and an effector transgene for cell engineering at another site, increased recombinant protein production. Overall, a streamlined RMCE platform can be a versatile tool for mammalian cell line development by facilitating multigene expression at genomic safe harbors.
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Affiliation(s)
- Seunghyeon Shin
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Su Hyun Kim
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Jae Seong Lee
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Republic of Korea
| | - Gyun Min Lee
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
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7
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Dias MM, Vidigal J, Sequeira DP, Alves PM, Teixeira AP, Roldão A. Insect High FiveTM cell line development using site-specific flipase recombination technology. G3-GENES GENOMES GENETICS 2021; 11:6274903. [PMID: 33982066 PMCID: PMC8763235 DOI: 10.1093/g3journal/jkab166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 05/24/2021] [Indexed: 11/14/2022]
Abstract
Insect Trichoplusia ni High FiveTM (Hi5) cells have been widely explored for production of heterologous proteins, traditionally mostly using the lytic baculovirus expression vector system (BEVS), and more recently using virus-free transient gene expression systems. Stable expression in such host cells would circumvent the drawbacks associated with both systems when it comes to scale-up and implementation of more efficient high-cell density process modes for the manufacturing of biologics. In this work, we combined Flipase (Flp) recombinase-mediated cassette exchange (RMCE) with fluorescence-activated cell sorting (FACS) for generating a stable master clonal Hi5 cell line with the flexibility to express single or multiple proteins of interest from a tagged genomic locus. The 3-step protocol herein implemented consisted of (i) introducing the RMCE docking cassette into the cell genome by random integration followed by selection in Hygromycin B and FACS (Hi5-tagging population), (ii) eliminating cells tagged in loci with low recombination efficiency by transfecting the tagging population with an eGFP-containing target cassette followed by selection in G418 and FACS (Hi5-RMCE population), and (iii) isolation of pure eGFP-expressing cells by FACS and expansion to suspension cultures (Hi5-RMCE master clone). Exchangeability of the locus in the master clone was demonstrated in small-scale suspension cultures by replacing the target cassette by one containing a single protein (i.e. iCherry, as an intracellular protein model) or two proteins (i.e. influenza HA and M1 for virus-like particles production, as an extracellular protein model). Overall, the stable insect Hi5 cell platform herein assembled has the potential to assist and accelerate biologics development.
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Affiliation(s)
- Mafalda M Dias
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal
| | - João Vidigal
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal
| | - Daniela P Sequeira
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal.,Department of Molecular Life Sciences, University of Zurich, 8057 Zurich, Switzerland
| | - Paula M Alves
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal
| | - Ana P Teixeira
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal.,ETH Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 - Basel, Switzerland
| | - António Roldão
- IBET, Instituto de Biologia Experimental e Tecnológica, 2780-901 Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-901 Oeiras, Portugal
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8
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Feary M, Moffat MA, Casperson GF, Allen MJ, Young RJ. CHOK1SV GS-KO SSI expression system: A combination of the Fer1L4 locus and glutamine synthetase selection. Biotechnol Prog 2021; 37:e3137. [PMID: 33609084 DOI: 10.1002/btpr.3137] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/03/2021] [Accepted: 02/07/2021] [Indexed: 12/11/2022]
Abstract
There are an ever-increasing number of biopharmaceutical candidates in clinical trials fueling an urgent need to streamline the cell line development process. A critical part of the process is the methodology used to generate and screen candidate cell lines compatible with GMP manufacturing processes. The relatively large amount of clone phenotypic variation observed from conventional "random integration" (RI)-based cell line construction is thought to be the result of a combination of the position variegation effect, genome plasticity and clonal variation. Site-specific integration (SSI) has been used by several groups to temper the influence of the position variegation effect and thus reduce variability in expression of biopharmaceutical candidates. Following on from our previous reports on the application of the Fer1L4 locus for SSI in CHOK1SV (10E9), we have combined this locus and a CHOK1SV glutamine synthetase knockout (GS-KO) host to create an improved expression system. The host, CHOK1SV GS-KO SSI (HD7876), was created by homology directed integration of a targetable landing pad flanked with incompatible Frt sequences in the Fer1L4 gene. The targeting vector contains a promoterless GS expression cassette and monoclonal antibody (mAb) expression cassettes, flanked by Frt sites compatible with equivalent sites flanking the landing pad in the host cell line. SSI clones expressing four antibody candidates, selected in a streamlined cell line development process, have mAb titers which rival RI (1.0-4.5 g/L) and robust expression stability (100% of clones stable through the 50 generation "manufacturing window" which supports commercial manufacturing at 12,000 L bioreactor scale).
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Affiliation(s)
- Marc Feary
- R&D Cell Engineering, Lonza Biologics, Little Chesterford, UK
| | - Mark A Moffat
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Chesterfield, MO, 63017, USA
| | - Gerald F Casperson
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Chesterfield, MO, 63017, USA
| | - Martin J Allen
- Cell Line Development, Biotherapeutics Pharmaceutical Sciences, Pfizer Inc., Chesterfield, MO, 63017, USA
| | - Robert J Young
- R&D Cell Engineering, Lonza Biologics, Little Chesterford, UK
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9
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Srirangan K, Loignon M, Durocher Y. The use of site-specific recombination and cassette exchange technologies for monoclonal antibody production in Chinese Hamster ovary cells: retrospective analysis and future directions. Crit Rev Biotechnol 2020; 40:833-851. [DOI: 10.1080/07388551.2020.1768043] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kajan Srirangan
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Martin Loignon
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Yves Durocher
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, Québec, Canada
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10
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Site-specific chromosomal gene insertion: Flp recombinase versus Cas9 nuclease. Sci Rep 2017; 7:17771. [PMID: 29259215 PMCID: PMC5736728 DOI: 10.1038/s41598-017-17651-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/24/2017] [Indexed: 12/16/2022] Open
Abstract
Site-specific recombination systems like those based on the Flp recombinase proved themselves as efficient tools for cell line engineering. The recent emergence of designer nucleases, especially RNA guided endonucleases like Cas9, has considerably broadened the available toolbox for applications like targeted transgene insertions. Here we established a recombinase-mediated cassette exchange (RMCE) protocol for the fast and effective, drug-free isolation of recombinant cells. Distinct fluorescent protein patterns identified the recombination status of individual cells. In derivatives of a CHO master cell line the expression of the introduced transgene of interest could be dramatically increased almost 20-fold by subsequent deletion of the fluorescent protein gene that provided the initial isolation principle. The same master cell line was employed in a comparative analysis using CRISPR/Cas9 for transgene integration in identical loci. Even though the overall targeting efficacy was comparable, multi-loci targeting was considerably more effective for Cas9-mediated transgene insertion when compared to RMCE. While Cas9 is inherently more flexible, our results also alert to the risk of aberrant recombination events around the cut site. Together, this study points at the individual strengths in performance of both systems and provides guidance for their appropriate use.
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11
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Vidigal J, Fernandes B, Dias MM, Patrone M, Roldão A, Carrondo MJT, Alves PM, Teixeira AP. RMCE-based insect cell platform to produce membrane proteins captured on HIV-1 Gag virus-like particles. Appl Microbiol Biotechnol 2017; 102:655-666. [DOI: 10.1007/s00253-017-8628-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/03/2017] [Accepted: 11/05/2017] [Indexed: 12/20/2022]
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12
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Baumann M, Gludovacz E, Sealover N, Bahr S, George H, Lin N, Kayser K, Borth N. Preselection of recombinant gene integration sites enabling high transcription rates in CHO cells using alternate start codons and recombinase mediated cassette exchange. Biotechnol Bioeng 2017; 114:2616-2627. [DOI: 10.1002/bit.26388] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/13/2017] [Accepted: 07/19/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Martina Baumann
- Austrian Centre of Industrial Biotechnology (ACIB); Graz Austria
| | | | | | - Scott Bahr
- MilliporeSigma (SAFC); St. Louis Minnesota
| | | | - Nan Lin
- MilliporeSigma (SAFC); St. Louis Minnesota
| | | | - Nicole Borth
- Austrian Centre of Industrial Biotechnology (ACIB); Graz Austria
- University of Natural Resources and Life Sciences (BOKU); Vienna Austria
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13
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Mayrhofer P, Mader A, Kratzer B, Reinhart D, Steinfellner W, Sommeregger W, Kunert R. Identification of bottlenecks in antibody expression using targeted gene integration. BMC Proc 2015. [PMCID: PMC4685356 DOI: 10.1186/1753-6561-9-s9-p7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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14
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Chen C, Li N, Zhao Y, Hang H. Coupling recombinase-mediated cassette exchange with somatic hypermutation for antibody affinity maturation in CHO cells. Biotechnol Bioeng 2015; 113:39-51. [PMID: 26235363 DOI: 10.1002/bit.25541] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 10/07/2014] [Accepted: 11/17/2014] [Indexed: 02/06/2023]
Abstract
Heterologous expression of activation-induced cytidine deaminase (AID) can induce somatic hypermutation (SHM) for genes of interest in various cells, and several research groups (including ours) have successfully improved antibody affinity in mammalian or chicken cells using AID-induced SHM. These affinity maturation systems are time-consuming and inefficient. In this study, we developed an antibody affinity maturation platform in Chinese hamster ovary (CHO) cells by coupling recombinase-mediated cassette exchange (RMCE) with SHM. Stable CHO cell clones containing a single copy puromycin resistance gene (PuroR) expression cassette flanked by recombination target sequences (FRT and loxP) being able to highly express a gene of interest placed in the cassette were developed. The PuroR gene was replaced with an antibody gene by RMCE, and the antibody was displayed on the cell surface. Cells displaying antibodies on their membrane were transfected with the AID gene, and mutations of the antibody gene were accumulated by AID-mediated hypermutation during cell proliferation followed by flow cytometric cell sorting for cells bearing antibody mutants with improved affinity. Affinity improvements were detected after only one round of cell sorting and proliferation, mutant clones with 15-fold affinity improvement were isolated within five rounds of maturation (within 2 months). CHO cells are fast growing, stress-resistant and produce antibody with glycosylations suitable for therapy. Our antibody-evolution platform based on CHO cells makes antibody-affinity maturation more efficient and is especially convenient for therapeutic antibody affinity improvement.
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Affiliation(s)
- Chuan Chen
- Key Laboratory for Protein and Peptide Pharmaceuticals, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Nan Li
- Key Laboratory for Protein and Peptide Pharmaceuticals, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yun Zhao
- Key Laboratory for Protein and Peptide Pharmaceuticals, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Haiying Hang
- Key Laboratory for Protein and Peptide Pharmaceuticals, National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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15
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Accurate comparison of antibody expression levels by reproducible transgene targeting in engineered recombination-competent CHO cells. Appl Microbiol Biotechnol 2014; 98:9723-33. [PMID: 25158835 PMCID: PMC4231286 DOI: 10.1007/s00253-014-6011-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/30/2014] [Accepted: 08/01/2014] [Indexed: 11/23/2022]
Abstract
Over the years, Chinese hamster ovary (CHO) cells have emerged as the major host for expressing biotherapeutic proteins. Traditional methods to generate high-producer cell lines rely on random integration(s) of the gene of interest but have thereby left the identification of bottlenecks as a challenging task. For comparison of different producer cell lines derived from various transfections, a system that provides control over transgene expression behavior is highly needed. This motivated us to develop a novel “DUKX-B11 F3/F” cell line to target different single-chain antibody fragments into the same chromosomal target site by recombinase-mediated cassette exchange (RMCE) using the flippase (FLP)/FLP recognition target (FRT) system. The RMCE-competent cell line contains a gfp reporter fused to a positive/negative selection system flanked by heterospecific FRT (F) variants under control of an external CMV promoter, constructed as “promoter trap”. The expression stability and FLP accessibility of the tagged locus was demonstrated by successive rounds of RMCE. As a proof of concept, we performed RMCE using cassettes encoding two different anti-HIV single-chain Fc fragments, 3D6scFv-Fc and 2F5scFv-Fc. Both targeted integrations yielded homogenous cell populations with comparable intracellular product contents and messenger RNA (mRNA) levels but product related differences in specific productivities. These studies confirm the potential of the newly available “DUKX-B11 F3/F” cell line to guide different transgenes into identical transcriptional control regions by RMCE and thereby generate clones with comparable amounts of transgene mRNA. This new host is a prerequisite for cell biology studies of independent transfections and transgenes.
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16
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Turan S, Qiao J, Madden S, Benham C, Kotz M, Schambach A, Bode J. Expanding Flp-RMCE options: the potential of Recombinase Mediated Twin-Site Targeting (RMTT). Gene 2014; 546:135-44. [DOI: 10.1016/j.gene.2014.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 06/02/2014] [Indexed: 01/02/2023]
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17
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Shi L, Chen X, Tang W, Li Z, Liu J, Gao F, Sang J. Combination of FACS and homologous recombination for the generation of stable and high-expression engineered cell lines. PLoS One 2014; 9:e91712. [PMID: 24646904 PMCID: PMC3960159 DOI: 10.1371/journal.pone.0091712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 02/14/2014] [Indexed: 11/30/2022] Open
Abstract
Traditionally, cell line generation requires several months and involves screening of over several hundred cell clones for high productivity before dozens are selected as candidate cell lines. Here, we have designed a new strategy for the generation of stable and high-expression cell lines by combining homologous recombination (HR) and fluorescence-activated cell sorting (FACS). High expression was indicated by the expression of secreted green fluorescent protein (SEGFP). Parental cell lines with the highest expression of SEGFP were then selected by FACS and identified by stability analysis. Consequently, HR vectors were constructed using the cassette for SEGFP as the HR region. After transfecting the HR vector, the cells with negative SEGFP expression were enriched by FACS. The complete exchange between SEGFP and target gene (TNFR-Fc) cassettes was demonstrated by DNA analysis. Compared with the traditional method, by integrating the cassette containing the gene of interest into the pre-selected site, the highest producing cells secreted a more than 8-fold higher titer of target protein. Hence, this new strategy can be applied to isolated stable cell lines with desirable expression of any gene of interest. The stable cell lines can rapidly produce proteins for researching protein structure and function and are even applicable in drug discovery.
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Affiliation(s)
- Lei Shi
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China
- R&D Department, AutekBio, Inc., Beijing, China
| | - Xuesi Chen
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China
| | | | - Zhenyi Li
- R&D Department, AutekBio, Inc., Beijing, China
| | - Jin Liu
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China
| | - Feng Gao
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China
- R&D Department, AutekBio, Inc., Beijing, China
- * E-mail: (JS); (FG)
| | - Jianli Sang
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China
- * E-mail: (JS); (FG)
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18
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Torres R, Garcia A, Jimenez M, Rodriguez S, Ramirez JC. An integration-defective lentivirus-based resource for site-specific targeting of an edited safe-harbour locus in the human genome. Gene Ther 2014; 21:343-52. [DOI: 10.1038/gt.2014.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/25/2013] [Accepted: 12/20/2013] [Indexed: 12/29/2022]
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19
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Production of rotavirus core-like particles in Sf9 cells using recombinase-mediated cassette exchange. J Biotechnol 2014; 171:34-8. [DOI: 10.1016/j.jbiotec.2013.11.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 11/20/2013] [Accepted: 11/25/2013] [Indexed: 11/16/2022]
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20
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Vidigal J, Fernandes F, Coroadinha AS, Teixeira AP, Alves PM. Insect cell line development using FLP-mediated cassette exchange technology. Methods Mol Biol 2014; 1104:15-27. [PMID: 24297406 DOI: 10.1007/978-1-62703-733-4_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Traditional cell line development is quite laborious and time-consuming as it is based on the random integration of the gene of interest which leads to unpredictable expression behavior. In opposition, recombinase-mediated cassette exchange systems represent a powerful genetic engineering approach, allowing site-specific insertion of recombinant genes into pre-tagged genomic loci with superior expression characteristics, thus bypassing the need for extensive clone screening and shortening the development timelines. Such systems have not been widely implemented in insect cell lines used for the production of recombinant proteins most commonly through the baculovirus expression vector system. Herein, it is provided the protocol for the implementation of a FLP-mediated cassette exchange system in Spodoptera frugiperda Sf 9 cells, in order to grant a flexible cell line for the stable production of recombinant proteins.
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Affiliation(s)
- João Vidigal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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21
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Vidigal J, Dias MM, Fernandes F, Patrone M, Bispo C, Andrade C, Gardner R, Carrondo MJ, Alves PM, Teixeira AP. A cell sorting protocol for selecting high-producing sub-populations of Sf9 and High Five™ cells. J Biotechnol 2013; 168:436-9. [DOI: 10.1016/j.jbiotec.2013.10.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/10/2013] [Accepted: 10/15/2013] [Indexed: 10/26/2022]
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22
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Almo SC, Garforth SJ, Hillerich BS, Love JD, Seidel RD, Burley SK. Protein production from the structural genomics perspective: achievements and future needs. Curr Opin Struct Biol 2013; 23:335-44. [PMID: 23642905 PMCID: PMC4163025 DOI: 10.1016/j.sbi.2013.02.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/18/2013] [Accepted: 02/18/2013] [Indexed: 01/31/2023]
Abstract
Despite a multitude of recent technical breakthroughs speeding high-resolution structural analysis of biological macromolecules, production of sufficient quantities of well-behaved, active protein continues to represent the rate-limiting step in many structure determination efforts. These challenges are only amplified when considered in the context of ongoing structural genomics efforts, which are now contending with multi-domain eukaryotic proteins, secreted proteins, and ever-larger macromolecular assemblies. Exciting new developments in eukaryotic expression platforms, including insect and mammalian-based systems, promise enhanced opportunities for structural approaches to some of the most important biological problems. Development and implementation of automated eukaryotic expression techniques promises to significantly improve production of materials for structural, functional, and biomedical research applications.
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Affiliation(s)
- Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States.
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23
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24
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Recombinase-mediated cassette exchange (RMCE) — A rapidly-expanding toolbox for targeted genomic modifications. Gene 2013. [DOI: 10.1016/j.gene.2012.11.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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25
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Kober L, Zehe C, Bode J. Development of a novel ER stress based selection system for the isolation of highly productive clones. Biotechnol Bioeng 2012; 109:2599-611. [DOI: 10.1002/bit.24527] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 03/24/2012] [Accepted: 04/03/2012] [Indexed: 12/27/2022]
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26
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Wilke S, Groebe L, Maffenbeier V, Jäger V, Gossen M, Josewski J, Duda A, Polle L, Owens RJ, Wirth D, Heinz DW, van den Heuvel J, Büssow K. Streamlining homogeneous glycoprotein production for biophysical and structural applications by targeted cell line development. PLoS One 2011; 6:e27829. [PMID: 22174749 PMCID: PMC3235087 DOI: 10.1371/journal.pone.0027829] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 10/26/2011] [Indexed: 11/19/2022] Open
Abstract
Studying the biophysical characteristics of glycosylated proteins and solving their three-dimensional structures requires homogeneous recombinant protein of high quality.We introduce here a new approach to produce glycoproteins in homogenous form with the well-established, glycosylation mutant CHO Lec3.2.8.1 cells. Using preparative cell sorting, stable, high-expressing GFP 'master' cell lines were generated that can be converted fast and reliably by targeted integration via Flp recombinase-mediated cassette exchange (RMCE) to produce any glycoprotein. Small-scale transient transfection of HEK293 cells was used to identify genetically engineered constructs suitable for constructing stable cell lines. Stable cell lines expressing 10 different proteins were established. The system was validated by expression, purification, deglycosylation and crystallization of the heavily glycosylated luminal domains of lysosome-associated membrane proteins (LAMP).
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Affiliation(s)
- Sonja Wilke
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Lothar Groebe
- Department of Experimental Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Vitali Maffenbeier
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Volker Jäger
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Manfred Gossen
- Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
- Berlin-Brandenburg Centre for Regenerative Therapies (BCRT), Berlin, Germany
| | - Jörn Josewski
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Agathe Duda
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Lilia Polle
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Raymond J. Owens
- Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Oxford, United Kingdom
- Oxford Protein Production Facility UK, The Research Complex at Harwell, Rutherford Appleton Laboratory Harwell Science and Innovation Campus, Oxfordshire, United Kingdom
| | - Dagmar Wirth
- Department of Gene Regulation and Differentiation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Dirk W. Heinz
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Joop van den Heuvel
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Konrad Büssow
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
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27
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Turan S, Bode J. Site‐specific recombinases: from tag‐and‐target‐ to tag‐and‐exchange‐based genomic modifications. FASEB J 2011; 25:4088-107. [DOI: 10.1096/fj.11-186940] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Soeren Turan
- Institute for Experimental Hematology, Hannover Medical School Hannover Germany
| | - Juergen Bode
- Institute for Experimental Hematology, Hannover Medical School Hannover Germany
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28
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Torres R, García A, Payá M, Ramirez JC. Non-integrative lentivirus drives high-frequency cre-mediated cassette exchange in human cells. PLoS One 2011; 6:e19794. [PMID: 21625434 PMCID: PMC3100306 DOI: 10.1371/journal.pone.0019794] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 04/05/2011] [Indexed: 12/21/2022] Open
Abstract
Recombinase mediated cassette exchange (RMCE) is a two-step process leading to genetic modification in a specific genomic target sequence. The process involves insertion of a docking genetic cassette in the genome followed by DNA transfer of a second cassette flanked by compatible recombination signals and expression of the recombinase. Major technical drawbacks are cell viability upon transfection, toxicity of the enzyme, and the ability to target efficiently cell types of different origins. To overcome such drawbacks, we developed an RMCE assay that uses an integrase-deficient lentivirus (IDLV) vector in the second step combined with promoterless trapping of double selectable markers. Additionally, recombinase expression is self-limiting as a result of the exchangeable reaction, thus avoiding toxicity. Our approach provides proof-of-principle of a simple and novel strategy with expected wide applicability modelled on a human cell line with randomly integrated copies of a genetic landing pad. This strategy does not present foreseeable limitations for application to other cell systems modified by homologous recombination. Safety, efficiency, and simplicity are the major advantages of our system, which can be applied in low-to-medium throughput strategies for screening of cDNAs, non-coding RNAs during functional genomic studies, and drug screening.
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Affiliation(s)
- Raul Torres
- Viral Vector Technical Unit, Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Aida García
- Viral Vector Technical Unit, Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Monica Payá
- Viral Vector Technical Unit, Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Juan C. Ramirez
- Viral Vector Technical Unit, Fundación Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
- * E-mail:
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29
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A genome-wide analysis of FRT-like sequences in the human genome. PLoS One 2011; 6:e18077. [PMID: 21448289 PMCID: PMC3063242 DOI: 10.1371/journal.pone.0018077] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 02/24/2011] [Indexed: 11/19/2022] Open
Abstract
Efficient and precise genome manipulations can be achieved by the
Flp/FRT system of site-specific DNA recombination.
Applications of this system are limited, however, to cases when target sites for
Flp recombinase, FRT sites, are pre-introduced into a genome
locale of interest. To expand use of the Flp/FRT system in
genome engineering, variants of Flp recombinase can be evolved to recognize
pre-existing genomic sequences that resemble FRT and thus can
serve as recombination sites. To understand the distribution and sequence
properties of genomic FRT-like sites, we performed a
genome-wide analysis of FRT-like sites in the human genome
using the experimentally-derived parameters. Out of 642,151 identified
FRT-like sequences, 581,157 sequences were unique and
12,452 sequences had at least one exact duplicate. Duplicated
FRT-like sequences are located mostly within LINE1, but
also within LTRs of endogenous retroviruses, Alu repeats and other repetitive
DNA sequences. The unique FRT-like sequences were classified
based on the number of matches to FRT within the first four
proximal bases pairs of the Flp binding elements of FRT and the
nature of mismatched base pairs in the same region. The data obtained will be
useful for the emerging field of genome engineering.
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30
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Turan S, Galla M, Ernst E, Qiao J, Voelkel C, Schiedlmeier B, Zehe C, Bode J. Recombinase-Mediated Cassette Exchange (RMCE): Traditional Concepts and Current Challenges. J Mol Biol 2011; 407:193-221. [DOI: 10.1016/j.jmb.2011.01.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 12/18/2022]
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31
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Malchin N, Molotsky T, Borovok I, Voziyanov Y, Kotlyar AB, Yagil E, Kolot M. High efficiency of a sequential recombinase-mediated cassette exchange reaction in Escherichia coli. J Mol Microbiol Biotechnol 2010; 19:117-22. [PMID: 20924197 DOI: 10.1159/000321497] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A comparison between the efficiency of recombinase-mediated cassette exchange (RMCE) reactions catalyzed in Escherichia coli by the site-specific recombinases Flp of yeast and Int of coliphage HK022 has revealed that an Flp-catalyzed RMCE reaction is more efficient than an Int-HK022 catalyzed reaction. In contrast, an RMCE reaction with 1 pair of frt sites and 1 pair of att sites catalyzed in the presence of both recombinases is very inefficient. However, the same reaction catalyzed by each recombinase individually supplied in a sequential order is very efficient, regardless of the order. Atomic force microscopy images of Flp with its DNA substrates show that only 1 pair of recombination sites forms a synaptic complex with the recombinase. The results suggest that the RMCE reaction is sequential.
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Affiliation(s)
- Natalia Malchin
- Department of Biochemistry, Tel Aviv University, Tel Aviv, Israel
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32
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Multiplexing RMCE: Versatile Extensions of the Flp-Recombinase-Mediated Cassette-Exchange Technology. J Mol Biol 2010; 402:52-69. [DOI: 10.1016/j.jmb.2010.07.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 07/07/2010] [Accepted: 07/12/2010] [Indexed: 11/19/2022]
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Abstract
Retroviral particles assemble a few thousand units of the Gag polyproteins. Proteolytic cleavage mediated by the retroviral protease forms the bioactive retroviral protein subunits before cell entry. We hypothesized that this process could be exploited for targeted, transient, and dose-controlled transduction of nonretroviral proteins into cultured cells. We demonstrate that gammaretroviral particles tolerate the incorporation of foreign protein at several positions of their Gag or Gag-Pol precursors. Receptor-mediated and thus potentially cell-specific uptake of engineered particles occurred within minutes after cell contact. Dose and kinetics of nonretroviral protein delivery were dependent upon the location within the polyprotein precursor. Proteins containing nuclear localization signals were incorporated into retroviral particles, and the proteins of interest were released from the precursor by the retroviral protease, recognizing engineered target sites. In contrast to integration-defective lentiviral vectors, protein transduction by retroviral polyprotein precursors was completely transient, as protein transducing retrovirus-like particles could be produced that did not transduce genes into target cells. Alternatively, bifunctional protein-delivering particle preparations were generated that maintained their ability to serve as vectors for retroviral transgenes. We show the potential of this approach for targeted genome engineering of induced pluripotent stem cells by delivering the site-specific DNA recombinase, Flp. Protein transduction of Flp after proteolytic release from the matrix position of Gag allowed excision of a lentivirally transduced cassette that concomitantly expresses the canonical reprogramming transcription factors (Oct4, Klf4, Sox2, c-Myc) and a fluorescent marker gene, thus generating induced pluripotent stem cells that are free of lentivirally transduced reprogramming genes.
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