1
|
Zeh N, Schmidt M, Schulz P, Fischer S. The new frontier in CHO cell line development: From random to targeted transgene integration technologies. Biotechnol Adv 2024; 75:108402. [PMID: 38950872 DOI: 10.1016/j.biotechadv.2024.108402] [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: 02/24/2024] [Revised: 06/21/2024] [Accepted: 06/27/2024] [Indexed: 07/03/2024]
Abstract
Cell line development represents a crucial step in the development process of a therapeutic glycoprotein. Chinese hamster ovary (CHO) cells are the most frequently employed mammalian host cell system for the industrial manufacturing of biologics. The predominant application of CHO cells for heterologous recombinant protein expression lies in the relative simplicity of stably introducing ectopic DNA into the CHO host cell genome. Since CHO cells were first used as expression host for the industrial production of biologics in the late 1980s, stable genomic transgene integration has been achieved almost exclusively by random integration. Since then, random transgene integration had become the gold standard for generating stable CHO production cell lines due to a lack of viable alternatives. However, it was eventually demonstrated that this approach poses significant challenges on the cell line development process such as an increased risk of inducing cell line instability. In recent years, significant discoveries of new and highly potent (semi)-targeted transgene integration systems have paved the way for a technological revolution in the cell line development sector. These advanced methodologies comprise the application of transposase-, recombinase- or Cas9 nuclease-mediated site-specific genomic integration techniques, which enable a scarless transfer of the transgene expression cassette into transcriptionally active loci within the host cell genome. This review summarizes recent advancements in the field of transgene integration technologies for CHO cell line development and compare them to the established random integration approach. Moreover, advantages and limitations of (semi)-targeted integration techniques are discussed, and benefits and opportunities for the biopharmaceutical industry are outlined.
Collapse
Affiliation(s)
- Nikolas Zeh
- Cell Line Development, Bioprocess Development Biologicals, Boehringer Ingelheim Pharma GmbH and Co.KG, Biberach an der Riss, Germany
| | - Moritz Schmidt
- Cell Line Development, Bioprocess Development Biologicals, Boehringer Ingelheim Pharma GmbH and Co.KG, Biberach an der Riss, Germany
| | - Patrick Schulz
- Cell Line Development, Bioprocess Development Biologicals, Boehringer Ingelheim Pharma GmbH and Co.KG, Biberach an der Riss, Germany
| | - Simon Fischer
- Cell Line Development, Bioprocess Development Biologicals, Boehringer Ingelheim Pharma GmbH and Co.KG, Biberach an der Riss, Germany.
| |
Collapse
|
2
|
Liu HN, Wang XY, Zou Y, Wu WB, Lin Y, Ji BY, Wang TY. Synthetic enhancers including TFREs improve transgene expression in CHO cells. Heliyon 2024; 10:e26901. [PMID: 38468921 PMCID: PMC10926067 DOI: 10.1016/j.heliyon.2024.e26901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 02/12/2024] [Accepted: 02/21/2024] [Indexed: 03/13/2024] Open
Abstract
The human cytomegalovirus major immediate early gene (CMV) promoter is currently the most preferred promoter for recombinant therapeutic proteins (RTPs) production in CHO cells. To enhance the production of RTPs, five synthetic enhancers including multiple transcription factor regulatory elements (TFREs) were evaluated to enhance recombinant protein level in transient and stably transfected CHO cells. Compared with the control, four elements can enhance the report genes expression under both two transfected states. Further, the function of these four enhancers on human serum albumin (HSA) were investigated. We found that the transient expression can increase by up to 1.5 times, and the stably expression can maximum increase by up to 2.14 times. The enhancement of transgene expression was caused by the boost of their corresponding mRNA levels. Transcriptomics analysis was performed and found that transcriptional activation and cell cycle regulation genes were involved. In conclusion, optimization of enhancers in the CMV promoter could increase the production yield of transgene in transfected CHO cells, which has significance for developing high-yield CHO cell expression system.
Collapse
Affiliation(s)
- Hui-Ning Liu
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
- SanQuan College of Xinxiang Medical University, Xinxiang 453003, China
| | - Xiao-Yin Wang
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Ying Zou
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Xinxiang Medical University, Xinxiang 453003, China
| | - Wen-Bao Wu
- Shanghai Immunocan Biotech Co., LTD, Shanghai 200000, China
| | - Yan Lin
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| | - Bo-Yu Ji
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| | - Tian-Yun Wang
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Xinxiang Medical University, Xinxiang 453003, China
| |
Collapse
|
3
|
Kim SH, Park JH, Shin S, Shin S, Chun D, Kim YG, Yoo J, You WK, Lee JS, Lee GM. Genome-Wide CRISPR/Cas9 Screening Unveils a Novel Target ATF7IP-SETDB1 Complex for Enhancing Difficult-to-Express Protein Production. ACS Synth Biol 2024; 13:634-647. [PMID: 38240694 DOI: 10.1021/acssynbio.3c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
With the emerging novel biotherapeutics that are typically difficult-to-express (DTE), improvement is required for high-yield production. To identify novel targets that can enhance DTE protein production, we performed genome-wide fluorescence-activated cell sorting (FACS)-based clustered regularly interspaced short palindromic repeats (CRISPR) knockout screening in bispecific antibody (bsAb)-producing Chinese hamster ovary (CHO) cells. The screen identified the two highest-scoring genes, Atf7ip and Setdb1, which are the binding partners for H3K9me3-mediated transcriptional repression. The ATF7IP-SETDB1 complex knockout in bsAb-producing CHO cells suppressed cell growth but enhanced productivity by up to 2.7-fold. Decreased H3K9me3 levels and an increased transcriptional expression level of the transgene were also observed. Furthermore, perturbation of the ATF7IP-SETDB1 complex in monoclonal antibody (mAb)-producing CHO cells led to substantial improvements in mAb production, increasing the productivity by up to 3.9-fold without affecting the product quality. Taken together, the genome-wide FACS-based CRISPR screen identified promising targets associated with histone methylation, whose perturbation enhanced the productivity by unlocking the transgene expression.
Collapse
Affiliation(s)
- Su Hyun Kim
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Jong-Ho Park
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
- Biotherapeutics Translational Research Center, KRIBB, Daejeon 34141, Republic of Korea
| | - Sungwook Shin
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Republic of Korea
| | - Seunghyeon Shin
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Dahyun Chun
- Department of R&D, ABL Bio Inc, Seongnam 13488, Republic of Korea
| | - Yeon-Gu Kim
- Biotherapeutics Translational Research Center, KRIBB, Daejeon 34141, Republic of Korea
- Department of Bioprocess Engineering, KRIBB School of Biotechnology, UST, , Daejeon 34113, Republic of Korea
| | - Jiseon Yoo
- Department of R&D, ABL Bio Inc, Seongnam 13488, Republic of Korea
| | - Weon-Kyoo You
- Department of R&D, ABL Bio Inc, Seongnam 13488, 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
| |
Collapse
|
4
|
Cordova LT, Dahodwala H, Cooley R, Lee KH. Prediction of CHO cell line stability using expression of DNA repair genes. Biotechnol J 2024; 19:e2300425. [PMID: 37970758 DOI: 10.1002/biot.202300425] [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: 08/20/2023] [Revised: 10/25/2023] [Accepted: 11/12/2023] [Indexed: 11/17/2023]
Abstract
Chinese hamster ovary (CHO) cells are essential to biopharmaceutical manufacturing and production instability, the loss of productivity over time, is a long-standing challenge in the industry. Accurate prediction of cell line stability could enable efficient screening to identify clones suitable for manufacturing saving significant time and costs. DNA repair genes may offer biomarkers to address this need. In this study, over 40 cell lines representing various host lineages from three companies/organizations were evaluated for expression of five DNA repair genes (Fam35a, Lig4, Palb2, Pari, and Xrcc6). Expression measured in cells with less than 30 population doubling levels (PDLs) was correlated to stability profiles at 60+ PDL. Principal component analysis identified markers which separate stable and unstable CHO-DG44 cell lines. Notably, two genes, Lig4 and Xrcc6, showed higher expression in unstable CHO-DG44 cell lines with copy number loss identified as the mechanism of production instability. Expression levels across all cell ages showed lower DNA repair gene expression was associated with increased cell age. Collectively, DNA repair genes provide critical insight into long-term behavior of CHO cells and their expression levels have potential to predict cell line stability in certain cases.
Collapse
Affiliation(s)
- Lauren T Cordova
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware, USA
| | - Hussain Dahodwala
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware, USA
- National Institute for Innovation in Manufacturing Biopharmaceuticals, Newark, Delaware, USA
| | - Rebecca Cooley
- Pfizer, Inc, 875 Chesterfield Pkwy W, Chesterfield, Missouri, USA
| | - Kelvin H Lee
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware, USA
- National Institute for Innovation in Manufacturing Biopharmaceuticals, Newark, Delaware, USA
| |
Collapse
|
5
|
Sinegubova MV, Orlova NA, Vorobiev II. Promoter from Chinese hamster elongation factor-1a gene and Epstein-Barr virus terminal repeats concatemer fragment maintain stable high-level expression of recombinant proteins. PeerJ 2023; 11:e16287. [PMID: 37901457 PMCID: PMC10607201 DOI: 10.7717/peerj.16287] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/22/2023] [Indexed: 10/31/2023] Open
Abstract
Background The Chinese hamster ovary (CHO) cell line is the main host for the high-titer production of therapeutic and diagnostic proteins in the biopharmaceutical industry. In most cases, plasmids for efficient protein expression in CHO cells are based on the cytomegalovirus (CMV) promoter. The autologous Chinese hamster eukaryotic translation elongation factor 1α (EEF1A1) promoter is a viable alternative to the CMV promoter in industrial applications. The EEF1A1 promoter and its surrounding DNA regions proved to be effective at maintaining high-level and stable expression of recombinant proteins in CHO cells. EEF1A1-based plasmids' large size can lead to low transfection efficiency and hamper target gene amplification. We hypothesized that an efficient EEF1A1-based expression vector with a long terminal repeat fragment from the Epstein-Barr virus (EBVTR) could be truncated without affecting promoter strength or the long-term stability of target gene expression. Methods We made a series of deletions in the downstream flanking region of the EEF1A1 gene, and then in its upstream flanking region. The resulting plasmids, which coded for the enhanced green fluorescent protein (eGFP), were tested for the level of eGFP expression in the populations of stably transfected CHO DG44 cells and the stability of eGFP expression in the long-term culture in the absence of selection agents. Results It was shown that in the presence of the EBVTR fragment, the entire downstream flanking region of the EEF1A1 gene could be excluded from the plasmid vector. Shortening of the upstream flanking region of the EEF1A1 gene to a length of 2.5 kbp also had no significant effect on the level of eGFP expression or long-term stability. The EBVTR fragment significantly increased expression stability for both the CMV and EEF1A1 promoter-based plasmids, and the expression level drop during the two-month culture was more significant for both CMV promoter-based plasmids. Conclusion Target protein expression stability for the truncated plasmid, based on the EEF1A1 gene and EBVTR fragment, is sufficient for common biopharmaceutical applications, making these plasmid vectors a viable alternative to conventional CMV promoter-based vectors.
Collapse
Affiliation(s)
- Maria V. Sinegubova
- Laboratory of Mammalian Cell Bioengineering, Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Nadezhda A. Orlova
- Laboratory of Mammalian Cell Bioengineering, Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Ivan I. Vorobiev
- Laboratory of Mammalian Cell Bioengineering, Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
6
|
Torres M, Betts Z, Scholey R, Elvin M, Place S, Hayes A, Dickson AJ. Long term culture promotes changes to growth, gene expression, and metabolism in CHO cells that are independent of production stability. Biotechnol Bioeng 2023; 120:2389-2402. [PMID: 37060548 DOI: 10.1002/bit.28399] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/28/2023] [Accepted: 04/01/2023] [Indexed: 04/16/2023]
Abstract
Phenotypic stability of Chinese hamster ovary (CHO) cells over long term culture (LTC) presents one of the most pressing challenges in the development of therapeutic protein manufacturing processess. However, our current understanding of the consequences of LTC on recombinant (r-) CHO cell lines is still limited, particularly as clonally-derived cell lines present distinct production stability phenotypes. This study evaluated changes of culture performance, global gene expression, and cell metabolism of two clonally-derived CHO cell lines with a stable or unstable phenotype during the LTC (early [EP] vs. late [LP] culture passages). Our findings indicated that LTC altered the behavior of CHO cells in culture, in terms of growth, overall gene expression, and cell metabolism. Regardless whether cells were categorized as stable or unstable in terms of r-protein production, CHO cells at LP presented an earlier decline in cell viability and loss of any observable stationary phase. These changes were parallelled by the upregulation of genes involved in cell proliferation and survival pathways (i.e., MAPK/ERK, PI3K-Akt). Stable and unstable CHO cell lines both showed increased consumption of glucose and amino acids at LP, with a parallel accumulation of greater amounts of lactate and TCA cycle intermediates. In terms of production stability, we found that decreased r-protein production in the unstable cell line directly correlated to the loss in r-gene copy number and r-mRNA expression. Our data revealed that LTC produced ubiquitious effects on CHO cell phenotypes, changes that were rooted in alterations in cell transcriptome and metabolome. Overall, we found that CHO cells adapted their cellular function to proliferation and survival during the LTC, some of these changes may well have limited effects on overall yield or specific productivity of the desired r-product, but they may be critical toward the capacity of cells to handle r-proteins with specific molecular features.
Collapse
Affiliation(s)
- Mauro Torres
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Zeynep Betts
- Department of Biology, Kocaeli University, İzmit, Turkey
| | - Rachel Scholey
- Bioinformatics Core Facility, University of Manchester, Manchester, UK
| | - Mark Elvin
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Svetlana Place
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| | - Andrew Hayes
- Genomic Technologies Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Alan J Dickson
- Manchester Institute of Biotechnology, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Department of Chemical Engineering, Biochemical and Bioprocess Engineering Group, University of Manchester, Manchester, UK
| |
Collapse
|
7
|
Feng T, Minevich G, Liu P, Qin HX, Wozniak G, Pham J, Pham K, Korgaonkar A, Kurnellas M, Defranoux NA, Long H, Mitra A, Hu F. AAV- GRN partially corrects motor deficits and ALS/FTLD-related pathology in Tmem106b-/-Grn-/- mice. iScience 2023; 26:107247. [PMID: 37519899 PMCID: PMC10371829 DOI: 10.1016/j.isci.2023.107247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/18/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023] Open
Abstract
Loss of function of progranulin (PGRN), encoded by the granulin (GRN) gene, is implicated in several neurodegenerative diseases. Several therapeutics to boost PGRN levels are currently in clinical trials. However, it is difficult to test the efficacy of PGRN-enhancing drugs in mouse models due to the mild phenotypes of Grn-/- mice. Recently, mice deficient in both PGRN and TMEM106B were shown to develop severe motor deficits and pathology. Here, we show that intracerebral ventricle injection of PGRN-expressing AAV1/9 viruses partially rescues motor deficits, neuronal loss, glial activation, and lysosomal abnormalities in Tmem106b-/-Grn-/- mice. Widespread expression of PGRN is detected in both the brain and spinal cord for both AAV subtypes. However, AAV9 but not AAV1-mediated expression of PGRN results in high levels of PGRN in the serum. Together, these data support using the Tmem106b-/-Grn-/- mouse strain as a robust mouse model to determine the efficacy of PGRN-elevating therapeutics.
Collapse
Affiliation(s)
- Tuancheng Feng
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | | | - Pengan Liu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Henry Xin Qin
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | | | - Jenny Pham
- Alector Inc, South San Francisco, CA 94080, USA
| | - Khanh Pham
- Alector Inc, South San Francisco, CA 94080, USA
| | | | | | | | - Hua Long
- Alector Inc, South San Francisco, CA 94080, USA
| | | | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| |
Collapse
|
8
|
Glinšek K, Bozovičar K, Bratkovič T. CRISPR Technologies in Chinese Hamster Ovary Cell Line Engineering. Int J Mol Sci 2023; 24:ijms24098144. [PMID: 37175850 PMCID: PMC10179654 DOI: 10.3390/ijms24098144] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 04/26/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
The Chinese hamster ovary (CHO) cell line is a well-established platform for the production of biopharmaceuticals due to its ability to express complex therapeutic proteins with human-like glycopatterns in high amounts. The advent of CRISPR technology has opened up new avenues for the engineering of CHO cell lines for improved protein production and enhanced product quality. This review summarizes recent advances in the application of CRISPR technology for CHO cell line engineering with a particular focus on glycosylation modulation, productivity enhancement, tackling adventitious agents, elimination of problematic host cell proteins, development of antibiotic-free selection systems, site-specific transgene integration, and CRISPR-mediated gene activation and repression. The review highlights the potential of CRISPR technology in CHO cell line genome editing and epigenetic engineering for the more efficient and cost-effective development of biopharmaceuticals while ensuring the safety and quality of the final product.
Collapse
Affiliation(s)
- Katja Glinšek
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Krištof Bozovičar
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Tomaž Bratkovič
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia
| |
Collapse
|
9
|
Kalkan AK, Palaz F, Sofija S, Elmousa N, Ledezma Y, Cachat E, Rios-Solis L. Improving recombinant protein production in CHO cells using the CRISPR-Cas system. Biotechnol Adv 2023; 64:108115. [PMID: 36758652 DOI: 10.1016/j.biotechadv.2023.108115] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 12/28/2022] [Accepted: 02/03/2023] [Indexed: 02/10/2023]
Abstract
Chinese hamster ovary (CHO) cells are among the most widely used mammalian cell lines in the biopharmaceutical industry. Therefore, it is not surprising that significant efforts have been made around the engineering of CHO cells using genetic engineering methods such as the CRISPR-Cas system. In this review, we summarize key recent studies that have used different CRISPR-Cas systems such as Cas9, Cas13 or dCas9 fused with effector domains to improve recombinant protein (r-protein) production in CHO cells. Here, every relevant stage of production was considered, underscoring the advantages and limitations of these systems, as well as discussing their bottlenecks and probable solutions. A special emphasis was given on how these systems could disrupt and/or regulate genes related to glycan composition, which has relevant effects over r-protein properties and in vivo activity. Furthermore, the related promising future applications of CRISPR to achieve a tunable, reversible, or highly stable editing of CHO cells are discussed. Overall, the studies covered in this review show that despite the complexity of mammalian cells, the synthetic biology community has developed many mature strategies to improve r-protein production using CHO cells. In this regard, CRISPR-Cas technology clearly provides efficient and flexible genetic manipulation and allows for the generation of more productive CHO cell lines, leading to more cost-efficient production of biopharmaceuticals, however, there is still a need for many emerging techniques in CRISPR to be reported in CHO cells; therefore, more research in these cells is needed to realize the full potential of this technology.
Collapse
Affiliation(s)
- Ali Kerem Kalkan
- Department of Bioengineering and Imperial College Centre for Synthetic Biology, Imperial College London, London, UK; Environmental Engineering Department, Gebze Technical University, Turkey
| | - Fahreddin Palaz
- Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Semeniuk Sofija
- Centre for Engineering Biology, University of Edinburgh, Edinburgh EH9 3BF, UK; Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Nada Elmousa
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh EH9 3DW, UK
| | - Yuri Ledezma
- Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh EH9 3DW, UK; Biology Department, Faculty of Pure and Natural Sciences, Universidad Mayor de San Andrés, Bolivia
| | - Elise Cachat
- Centre for Engineering Biology, University of Edinburgh, Edinburgh EH9 3BF, UK; Institute of Quantitative Biology, Biochemistry and Biotechnology, School of Biological Sciences University of Edinburgh, Edinburgh EH9 3BF, UK; UK Centre for Mammalian Synthetic Biology, University of Edinburgh, Edinburgh EH8 9YL, UK
| | - Leonardo Rios-Solis
- Centre for Engineering Biology, University of Edinburgh, Edinburgh EH9 3BF, UK; Institute for Bioengineering, School of Engineering, University of Edinburgh, Edinburgh EH9 3DW, UK; School of Natural and Environmental Sciences, Molecular Biology and Biotechnology Division, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK.
| |
Collapse
|
10
|
Chitwood DG, Wang Q, Klaubert SR, Green K, Wu CH, Harcum SW, Saski CA. Microevolutionary dynamics of eccDNA in Chinese hamster ovary cells grown in fed-batch cultures under control and lactate-stressed conditions. Sci Rep 2023; 13:1200. [PMID: 36681715 PMCID: PMC9862248 DOI: 10.1038/s41598-023-27962-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/10/2023] [Indexed: 01/22/2023] Open
Abstract
Chinese hamster ovary (CHO) cell lines are widely used to manufacture biopharmaceuticals. However, CHO cells are not an optimal expression host due to the intrinsic plasticity of the CHO genome. Genome plasticity can lead to chromosomal rearrangements, transgene exclusion, and phenotypic drift. A poorly understood genomic element of CHO cell line instability is extrachromosomal circular DNA (eccDNA) in gene expression and regulation. EccDNA can facilitate ultra-high gene expression and are found within many eukaryotes including humans, yeast, and plants. EccDNA confers genetic heterogeneity, providing selective advantages to individual cells in response to dynamic environments. In CHO cell cultures, maintaining genetic homogeneity is critical to ensuring consistent productivity and product quality. Understanding eccDNA structure, function, and microevolutionary dynamics under various culture conditions could reveal potential engineering targets for cell line optimization. In this study, eccDNA sequences were investigated at the beginning and end of two-week fed-batch cultures in an ambr®250 bioreactor under control and lactate-stressed conditions. This work characterized structure and function of eccDNA in a CHO-K1 clone. Gene annotation identified 1551 unique eccDNA genes including cancer driver genes and genes involved in protein production. Furthermore, RNA-seq data is integrated to identify transcriptionally active eccDNA genes.
Collapse
Affiliation(s)
- Dylan G Chitwood
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Qinghua Wang
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
| | - Stephanie R Klaubert
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, USA
| | - Kiana Green
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Cathy H Wu
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, USA
| | - Sarah W Harcum
- Department of Bioengineering, Clemson University, Clemson, SC, USA
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, USA
| | - Christopher A Saski
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC, USA.
| |
Collapse
|
11
|
Cabrera A, Edelstein HI, Glykofrydis F, Love KS, Palacios S, Tycko J, Zhang M, Lensch S, Shields CE, Livingston M, Weiss R, Zhao H, Haynes KA, Morsut L, Chen YY, Khalil AS, Wong WW, Collins JJ, Rosser SJ, Polizzi K, Elowitz MB, Fussenegger M, Hilton IB, Leonard JN, Bintu L, Galloway KE, Deans TL. The sound of silence: Transgene silencing in mammalian cell engineering. Cell Syst 2022; 13:950-973. [PMID: 36549273 PMCID: PMC9880859 DOI: 10.1016/j.cels.2022.11.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/22/2022] [Accepted: 11/22/2022] [Indexed: 12/24/2022]
Abstract
To elucidate principles operating in native biological systems and to develop novel biotechnologies, synthetic biology aims to build and integrate synthetic gene circuits within native transcriptional networks. The utility of synthetic gene circuits for cell engineering relies on the ability to control the expression of all constituent transgene components. Transgene silencing, defined as the loss of expression over time, persists as an obstacle for engineering primary cells and stem cells with transgenic cargos. In this review, we highlight the challenge that transgene silencing poses to the robust engineering of mammalian cells, outline potential molecular mechanisms of silencing, and present approaches for preventing transgene silencing. We conclude with a perspective identifying future research directions for improving the performance of synthetic gene circuits.
Collapse
Affiliation(s)
- Alan Cabrera
- Department of Bioengineering, Rice University, Houston, TX 77005, USA; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hailey I Edelstein
- Center for Synthetic Biology, Northwestern University, Evanston, IL 60208, USA; The Eli and Edythe Broad CIRM Center, Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Fokion Glykofrydis
- Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA 90033-9080, USA
| | - Kasey S Love
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sebastian Palacios
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Josh Tycko
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Meng Zhang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Champaign, Urbana, IL 61801, USA
| | - Sarah Lensch
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Cara E Shields
- Wallace H. Coulter Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA
| | - Mark Livingston
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA
| | - Ron Weiss
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Champaign, Urbana, IL 61801, USA
| | - Karmella A Haynes
- Wallace H. Coulter Department of Biomedical Engineering, Emory University, Atlanta, GA 30322, USA
| | - Leonardo Morsut
- Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA 90033-9080, USA
| | - Yvonne Y Chen
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA; Parker Institute for Cancer Immunotherapy Center at UCLA, Los Angeles, CA 90095, USA
| | - Ahmad S Khalil
- Biological Design Center and Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - Wilson W Wong
- Biological Design Center and Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - James J Collins
- Department of Stem Cell Biology and Regenerative Medicine, University of Southern California, Los Angeles, CA 90033-9080, USA; Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Harvard-MIT Program in Health Sciences and Technology, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA
| | - Susan J Rosser
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Karen Polizzi
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK; Imperial College Centre for Synthetic Biology, South Kensington Campus, London, UK
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
| | - Martin Fussenegger
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, Basel 4058, Switzerland; Faculty of Science, University of Basel, Mattenstrasse 26, Basel 4058, Switzerland
| | - Isaac B Hilton
- Department of Bioengineering, Rice University, Houston, TX 77005, USA
| | - Joshua N Leonard
- Center for Synthetic Biology, Northwestern University, Evanston, IL 60208, USA; The Eli and Edythe Broad CIRM Center, Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Lacramioara Bintu
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Kate E Galloway
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tara L Deans
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT 84112, USA.
| |
Collapse
|
12
|
Use of ubiquitous chromatin opening elements (UCOE) as tools to maintain transgene expression in biotechnology. Comput Struct Biotechnol J 2022; 21:275-283. [PMID: 36582439 PMCID: PMC9764128 DOI: 10.1016/j.csbj.2022.11.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
Amongst the most important outputs of the biopharmaceutical industry are recombinant proteins, many of which are produced by integrating transgenes into the genomes of mammalian cells. However, expression is highly variable and can be unstable during prolonged culture. This is often due to epigenetic mechanisms silencing the transgenes. To combat this problem, vectors have been engineered to include ubiquitous chromatin opening elements (UCOEs) that protect against silencing. Here, we recount the evidence that UCOEs can modify chromatin environments and benefit biomanufacturing.
Collapse
|
13
|
Hertel O, Neuss A, Busche T, Brandt D, Kalinowski J, Bahnemann J, Noll T. Enhancing stability of recombinant CHO cells by CRISPR/Cas9-mediated site-specific integration into regions with distinct histone modifications. Front Bioeng Biotechnol 2022; 10:1010719. [PMID: 36312557 PMCID: PMC9606416 DOI: 10.3389/fbioe.2022.1010719] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 09/30/2022] [Indexed: 11/24/2022] Open
Abstract
Chinese hamster ovary (CHO) cells are the most important platform for producing biotherapeutics. Random integration of a transgene into epigenetically instable regions of the genome results in silencing of the gene of interest and loss of productivity during upstream processing. Therefore, cost- and time-intensive long-term stability studies must be performed. Site-specific integration into safe harbors is a strategy to overcome these limitations of conventional cell line design. Recent publications predict safe harbors in CHO cells based on omics data sets or by learning from random integrations, but those predictions remain theory. In this study, we established a CRISPR/Cas9-mediated site-specific integration strategy based on ChIP-seq data to improve stability of recombinant CHO cells. Therefore, a ChIP experiment from the exponential and stationary growth phase of a fed-batch cultivation of CHO-K1 cells yielded 709 potentially stable integration sites. The reporter gene eGFP was integrated into three regions harboring specific modifications by CRISPR/Cas9. Targeted Cas9 nanopore sequencing showed site-specific integration in all 3 cell pools with a specificity between 23 and 73%. Subsequently, the cells with the three different integration sites were compared with the randomly integrated donor vector in terms of transcript level, productivity, gene copy numbers and stability. All site-specific integrations showed an increase in productivity and transcript levels of up to 7.4-fold. In a long-term cultivation over 70 generations, two of the site-specific integrations showed a stable productivity (>70%) independent of selection pressure.
Collapse
Affiliation(s)
- Oliver Hertel
- Cell Culture Technology, Faculty of Technology, Bielefeld University, Bielefeld, Germany
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
- *Correspondence: Oliver Hertel,
| | - Anne Neuss
- Biochemical Engineering (AVT.BioVT), RWTH Aachen University, Aachen, Germany
| | - Tobias Busche
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - David Brandt
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| | | | - Thomas Noll
- Cell Culture Technology, Faculty of Technology, Bielefeld University, Bielefeld, Germany
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
| |
Collapse
|
14
|
Narimatsu Y, Matsuura D, Iwakoshi-Ukena E, Furumitsu M, Ukena K. Neurosecretory Protein GL Promotes Normotopic Fat Accumulation in Male ICR Mice. Int J Mol Sci 2022; 23:ijms23126488. [PMID: 35742932 PMCID: PMC9223635 DOI: 10.3390/ijms23126488] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/08/2022] [Accepted: 06/08/2022] [Indexed: 11/16/2022] Open
Abstract
Neurosecretory protein GL (NPGL) is a small secretory protein identified in the hypothalamus of birds and mammals. We recently reported that NPGL exerts obesogenic effects in obesity-prone C57BL6/J mice. However, whether NPGL elicits adiposity in different mouse strains is poorly understood. In this study, we generated transgenic mice overexpressing Npgl using the ICR strain (Npgl Tg mice) to elucidate the obesogenic effects of NPGL in different strains. Npgl Tg mice showed increased white adipose tissue (WAT) mass. Although the mass of brown adipose tissue (BAT) was slightly altered in Npgl Tg mice, hypertrophy of lipid droplets was also observed in BAT. In contrast, fat accumulation was not induced in the liver, with the upregulation of mRNAs related to hepatic lipolysis. These results support the hypothesis that NPGL causes obesity in several strains and species. This report highlights the pivotal role of NPGL in fat accumulation in adipose tissues and contributes to the elucidation of the biological mechanisms underlying obesity and metabolic diseases in heterogeneous populations.
Collapse
|
15
|
DiAndreth B, Wauford N, Hu E, Palacios S, Weiss R. PERSIST platform provides programmable RNA regulation using CRISPR endoRNases. Nat Commun 2022; 13:2582. [PMID: 35562172 PMCID: PMC9095627 DOI: 10.1038/s41467-022-30172-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/20/2022] [Indexed: 12/26/2022] Open
Abstract
Regulated transgene expression is an integral component of gene therapies, cell therapies and biomanufacturing. However, transcription factor-based regulation, upon which most applications are based, suffers from complications such as epigenetic silencing that limit expression longevity and reliability. Constitutive transgene transcription paired with post-transcriptional gene regulation could combat silencing, but few such RNA- or protein-level platforms exist. Here we develop an RNA-regulation platform we call "PERSIST" which consists of nine CRISPR-specific endoRNases as RNA-level activators and repressors as well as modular OFF- and ON-switch regulatory motifs. We show that PERSIST-regulated transgenes exhibit strong OFF and ON responses, resist silencing for at least two months, and can be readily layered to construct cascades, logic functions, switches and other sophisticated circuit topologies. The orthogonal, modular and composable nature of this platform as well as the ease in constructing robust and predictable gene circuits promises myriad applications in gene and cell therapies.
Collapse
Affiliation(s)
- Breanna DiAndreth
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Noreen Wauford
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Eileen Hu
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Sebastian Palacios
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ron Weiss
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| |
Collapse
|
16
|
Spahn PN, Zhang X, Hu Q, Lu H, Hamaker NK, Hefzi H, Li S, Kuo CC, Huang Y, Lee JC, Davis AJ, Ly P, Lee KH, Lewis NE. Restoration of DNA repair mitigates genome instability and increases productivity of Chinese hamster ovary cells. Biotechnol Bioeng 2022; 119:963-982. [PMID: 34953085 PMCID: PMC8821244 DOI: 10.1002/bit.28016] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 11/11/2022]
Abstract
Chinese hamster ovary (CHO) cells are the primary host for manufacturing of therapeutic proteins. However, productivity loss is a major problem and is associated with genome instability, as chromosomal aberrations reduce transgene copy number and decrease protein expression. We analyzed whole-genome sequencing data from 11 CHO cell lines and found deleterious single-nucleotide variants in DNA repair genes. Comparison with primary Chinese hamster cells confirmed DNA repair to be compromised in CHO. Correction of key DNA repair genes by single-nucleotide variant reversal or expression of intact complementary DNAs successfully improved DNA repair and mitigated karyotypic instability. Moreover, overexpression of intact copies of LIG4 and XRCC6 in a CHO cell line expressing secreted alkaline phosphatase mitigated transgene copy loss and improved protein titer retention. These results show that correction of DNA repair genes yields improvements in genome stability in CHO, and provide new opportunities for cell line development for sustainable protein expression.
Collapse
Affiliation(s)
- Philipp N. Spahn
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, The Novo Nordisk Foundation Center for Biosustainability at the University of California, San Diego School of Medicine, San Diego, La Jolla, CA 92093
| | - Xiaolin Zhang
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711
| | - Qing Hu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Huiming Lu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Nathaniel K. Hamaker
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711
| | - Hooman Hefzi
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093
| | - Shangzhong Li
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093
| | - Chih-Chung Kuo
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093
| | - Yingxiang Huang
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093
| | - Jamie C. Lee
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093
| | - Anthony J. Davis
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Peter Ly
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kelvin H. Lee
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19711, These authors jointly supervised this work: Kelvin H. Lee, , 302-831-0344, Nathan E. Lewis, , 858-997-5844
| | - Nathan E. Lewis
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093, The Novo Nordisk Foundation Center for Biosustainability at the University of California, San Diego School of Medicine, San Diego, La Jolla, CA 92093, Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, These authors jointly supervised this work: Kelvin H. Lee, , 302-831-0344, Nathan E. Lewis, , 858-997-5844
| |
Collapse
|
17
|
Urusov FA, Glazkova DV, Tsyganova GM, Pozdyshev DV, Bogoslovskaya EV, Shipulin GA. The Titer of the Lentiviral Vector Encoding Chimeric TRIM5α-HRH Gene is Reduced Due to Expression of TRIM5α-HRH in Producer Cells and the Negative Effect of Ef1α Promoter. Mol Biol 2022. [DOI: 10.1134/s0026893322010083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
18
|
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: 8] [Impact Index Per Article: 4.0] [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.
Collapse
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.
| |
Collapse
|
19
|
Screening of CHO-K1 endogenous promoters for expressing recombinant proteins in mammalian cell cultures. Plasmid 2022; 119-120:102620. [DOI: 10.1016/j.plasmid.2022.102620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 12/28/2022]
|
20
|
Kim D, Yoon C, Lee GM. Small molecule epigenetic modulators for enhancing recombinant antibody production in CHO cell cultures. Biotechnol Bioeng 2021; 119:820-831. [PMID: 34961935 DOI: 10.1002/bit.28013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 11/07/2022]
Abstract
Small molecule epigenetic modulators that modify epigenetic states in cells are useful tools for regulating gene expression by inducing chromatin remodeling. To identify small molecule epigenetic modulators that enhance recombinant protein expression in CHO cells, we examined eight histone deacetylase inhibitors (iHDACs) and six DNA methyltransferase inhibitors as chemical additives in recombinant CHO (rCHO) cell cultures. Among these, a benzamide-based iHDAC, CI994, was the most effective in increasing monoclonal antibody (mAb) production. Despite suppressing cell growth, the addition of CI994 to mAb-expressing GSR cell cultures at 10 μM resulted in a 2.3-fold increase in maximum mAb concentration due to a 3.0-fold increase in specific mAb productivity (q mAb ). CI994 increased mAb mRNA levels and histone H3 acetylation in GSR cells, and ChIP-qPCR analysis revealed that CI994 significantly increased the histone H3 acetylation level at the CMV promoter driving mAb gene expression, indicating that chromatin remodeling in the promoter region results in enhanced mAb gene transcription and q mAb . Similar beneficial effects of CI994 on mAb production were observed in mAb-expressing CS13-1.00 cells. Collectively, our findings indicate that CI994 increases mAb production in rCHO cell cultures by chromatin remodeling resulting from acetylation of histones in the mAb gene promoter. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Dongil Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Chansik Yoon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Gyun Min Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| |
Collapse
|
21
|
Kudo M, Wupuer S, Fujiwara M, Saito Y, Kubota S, Inoue KI, Takada M, Seki K. Specific gene expression in unmyelinated dorsal root ganglion neurons in nonhuman primates by intra-nerve injection of AAV 6 vector. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 23:11-22. [PMID: 34552999 PMCID: PMC8426475 DOI: 10.1016/j.omtm.2021.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 07/27/2021] [Indexed: 01/14/2023]
Abstract
Adeno-associated virus 6 (AAV6) has been proposed as a potential vector candidate for specific gene expression in pain-related dorsal root ganglion (DRG) neurons, but this has not been confirmed in nonhuman primates. The aim of our study was to analyze the transduction efficiency and target specificity of this viral vector in the common marmoset by comparing it with those in the rat. When green fluorescent protein-expressing serotype-6 vector was injected into the sciatic nerve, the efficiency of gene expression in DRG neurons was comparable in both species. We found that the serotype-6 vector was largely specific to the pain-related ganglion neurons in the marmoset, as well as in the rat, whereas the serotype-9 vector resulted in contrasting effects in the two species. Neither AAV6 nor AAV9 resulted in DRG toxicity when administered via the sciatic nerve, suggesting this as a safer route of sensory nerve transduction than the currently used intrathecal or intravenous administrative routes. Furthermore, the AAV6 vector could be an optimal serotype for gene therapy for human chronic pain that has a minimal effect on other somatosensory functions of DRG neurons.
Collapse
Affiliation(s)
- Moeko Kudo
- Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
| | - Sidikejiang Wupuer
- Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
| | - Maki Fujiwara
- Systems Neuroscience Section, Department of Neuroscience, Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan
| | - Yuko Saito
- Department of Neuropathology, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo, Japan
| | - Shinji Kubota
- Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
| | - Ken-Ichi Inoue
- Systems Neuroscience Section, Department of Neuroscience, Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan
| | - Masahiko Takada
- Systems Neuroscience Section, Department of Neuroscience, Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan
| | - Kazuhiko Seki
- Department of Neurophysiology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
| |
Collapse
|
22
|
Xu P, Xu S, He C, Khetan A. Applications of small molecules in modulating productivity and product quality of recombinant proteins produced using cell cultures. Biotechnol Adv 2020; 43:107577. [PMID: 32540474 DOI: 10.1016/j.biotechadv.2020.107577] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 06/02/2020] [Accepted: 06/04/2020] [Indexed: 02/07/2023]
Abstract
Mammalian cell cultures have been used extensively for production of recombinant protein therapeutics such as monoclonal antibodies, fusion proteins and enzymes for decades. Small molecules have been investigated as media supplements to improve process productivity and reduce cost of goods. Those chemicals can lead to significant yield improvement through different mechanisms such as cell cycle modulation, cellular redox regulation, etc. In addition to productivity, small molecules have also been routinely used to regulate post-translational modifications of recombinant proteins. This review summarizes key applications of small molecules in protein productivity improvement and product quality control.
Collapse
Affiliation(s)
- Ping Xu
- Biologics Development, Global Product Development & Supply, Bristol Myers Squibb Company, New Brunswick, NJ 08903, United States of America.
| | - Sen Xu
- Biologics Development, Global Product Development & Supply, Bristol Myers Squibb Company, New Brunswick, NJ 08903, United States of America
| | - Chunyan He
- Biologics Development, Global Product Development & Supply, Bristol Myers Squibb Company, New Brunswick, NJ 08903, United States of America
| | - Anurag Khetan
- Biologics Development, Global Product Development & Supply, Bristol Myers Squibb Company, New Brunswick, NJ 08903, United States of America
| |
Collapse
|
23
|
Regulation of the MIE Locus During HCMV Latency and Reactivation. Pathogens 2020; 9:pathogens9110869. [PMID: 33113934 PMCID: PMC7690695 DOI: 10.3390/pathogens9110869] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 12/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a ubiquitous herpesviral pathogen that results in life-long infection. HCMV maintains a latent or quiescent infection in hematopoietic cells, which is broadly defined by transcriptional silencing and the absence of de novo virion production. However, upon cell differentiation coupled with immune dysfunction, the virus can reactivate, which leads to lytic replication in a variety of cell and tissue types. One of the mechanisms controlling the balance between latency and reactivation/lytic replication is the regulation of the major immediate-early (MIE) locus. This enhancer/promoter region is complex, and it is regulated by chromatinization and associated factors, as well as a variety of transcription factors. Herein, we discuss these factors and how they influence the MIE locus, which ultimately impacts the phase of HCMV infection.
Collapse
|
24
|
Chen P, Chen M, Menon A, Hussain AI, Carey E, Lee C, Horwitz J, O'Connell S, Cooper JW, Schwartz R, Gowetski DB. Development of a High Yielding Bioprocess for a Pre-fusion RSV Subunit Vaccine. J Biotechnol 2020; 325:261-270. [PMID: 33068697 DOI: 10.1016/j.jbiotec.2020.10.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/22/2020] [Accepted: 10/12/2020] [Indexed: 02/03/2023]
Abstract
Respiratory syncytial virus (RSV) is a highly contagious virus causing severe infection in infants and the elderly. Various approaches are being used to develop an effective RSV vaccine. The RSV fusion (F) subunit, particularly the cleaved trimeric pre-fusion F, is one of the most promising vaccine candidates under development. The pre-fusion conformation elicits the majority of neutralizing antibodies during natural infection. However, this pre-fusion conformation is metastable and prone to conversion to a post-fusion conformation, thus hindering the potential of this construct as a vaccine antigen. The Vaccine Research Center (VRC) at the National Institutes of Health (NIH) designed a structurally stabilized pre-fusion F glycoprotein, DS-Cav1, that showed high immunogenicity and induced a neutralizing response in animal studies. To advance this candidate to clinical manufacturing, a production process that maintained product quality (i.e. a cleaved trimer with pre-fusion conformation) and delivered high protein expression levels was required. This report describes the development of the vaccine candidate including vector design and cell culture process development to meet these challenges. Co-transfection of individual plasmids to express DS-Cav1 and furin (for DS-Cav1 cleavage and activation) demonstrated a superior protein product expression and pre-fusion conformation compared to co-expression with a double gene vector. A top clone was selected based on these measurements. Protein expression levels were further increased by seeding density optimization and a biphasic hypothermia temperature downshift. The combined efforts led to a high-yield fed-batch production of approximately 1,500 mg/L (or up to 15,000 doses per liter) at harvest. The process was scaled up and demonstrated to be reproducible at 50 L-scale for toxicity and Phase I clinical trial use. Preliminary phase I data indicate the pre-fusion antigen has a promising efficacy (Crank et al., 2019).
Collapse
Affiliation(s)
- Peifeng Chen
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA.
| | - Mingzhong Chen
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Amritha Menon
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Althaf I Hussain
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Elizabeth Carey
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Christopher Lee
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Joe Horwitz
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Sarah O'Connell
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Johnathan W Cooper
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Richard Schwartz
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| | - Daniel B Gowetski
- Vaccine Production Program, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9 West Watkins Mill Rd., Gaithersburg, MD, 20878, USA
| |
Collapse
|
25
|
Hoseinpoor R, Kazemi B, Rajabibazl M, Rahimpour A. Improving the expression of anti-IL-2Rα monoclonal antibody in the CHO cells through optimization of the expression vector and translation efficiency. J Biotechnol 2020; 324:112-120. [PMID: 33007349 DOI: 10.1016/j.jbiotec.2020.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/21/2020] [Accepted: 09/08/2020] [Indexed: 12/17/2022]
Abstract
The growing need for monoclonal antibodies (mAbs) necessitates the development of novel and efficient production approaches. Regulatory elements like ubiquitous chromatin-opening elements (UCOEs) have been employed for improvement of the mAb expression in the Chinese hamster ovary (CHO) cells. SINEUPs are a class of long non-coding RNAs, which can improve the translation of partly overlapping mRNAs. A combination of these two elements might lead to higher production of mAbs. Therefore, the current study was conducted to investigate the effects of SINEUPs and A2UCOE on the expression of an IgG1 in the CHO-K1 cells. Hence, after constructing the mAb, mAb-SINEUP, and mAb-UCOE vectors, four stable cell pools were generated through combining the above vectors. According to the expression analysis, antibody yields were higher in the mAb-SINEUP and mAb-UCOE cell pools compared to the mAb cells. In addition, the cells possessing both SINEUP and UCOE elements provided the best expression. Persistent mAb expression was observed for over 2 months in these cells, whilst the expression was decreased in the mAb pool. SINEUP and UCOE positively influenced the stable mAb expression. It can be concluded that the SINEUP and UCOE enhance the antibody stability and expression level separately and their combination improves the mAb production in the CHO cells.
Collapse
Affiliation(s)
- Reyhaneh Hoseinpoor
- Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bahram Kazemi
- Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoumeh Rajabibazl
- Department of Clinical Biochemistry, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Azam Rahimpour
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| |
Collapse
|
26
|
Derivation and Characterization of Immortalized Human Muscle Satellite Cell Clones from Muscular Dystrophy Patients and Healthy Individuals. Cells 2020; 9:cells9081780. [PMID: 32722643 PMCID: PMC7465805 DOI: 10.3390/cells9081780] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/17/2020] [Accepted: 07/22/2020] [Indexed: 12/15/2022] Open
Abstract
In Duchenne muscular dystrophy (DMD) patients, absence of dystrophin causes muscle wasting by impacting both the myofiber integrity and the properties of muscle stem cells (MuSCs). Investigation of DMD encompasses the use of MuSCs issued from human skeletal muscle. However, DMD-derived MuSC usage is restricted by the limited number of divisions that human MuSCs can undertake in vitro before losing their myogenic characteristics and by the scarcity of human material available from DMD muscle. To overcome these limitations, immortalization of MuSCs appears as a strategy. Here, we used CDK4/hTERT expression in primary MuSCs and we derived MuSC clones from a series of clinically and genetically characterized patients, including eight DMD patients with various mutations, four congenital muscular dystrophies and three age-matched control muscles. Immortalized cultures were sorted into single cells and expanded as clones into homogeneous populations. Myogenic characteristics and differentiation potential were tested for each clone. Finally, we screened various promoters to identify the preferred gene regulatory unit that should be used to ensure stable expression in the human MuSC clones. The 38 clonal immortalized myogenic cell clones provide a large collection of controls and DMD clones with various genetic defects and are available to the academic community.
Collapse
|
27
|
Effects of viral promoters, the Woodchuck hepatitis post-transcriptional regulatory element, and weakened antibiotic resistance markers on transgene expression in Chinese hamster ovary cells. Process Biochem 2020. [DOI: 10.1016/j.procbio.2020.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
28
|
Abstract
Following the success of and the high demand for recombinant protein-based therapeutics during the last 25 years, the pharmaceutical industry has invested significantly in the development of novel treatments based on biologics. Mammalian cells are the major production systems for these complex biopharmaceuticals, with Chinese hamster ovary (CHO) cell lines as the most important players. Over the years, various engineering strategies and modeling approaches have been used to improve microbial production platforms, such as bacteria and yeasts, as well as to create pre-optimized chassis host strains. However, the complexity of mammalian cells curtailed the optimization of these host cells by metabolic engineering. Most of the improvements of titer and productivity were achieved by media optimization and large-scale screening of producer clones. The advances made in recent years now open the door to again consider the potential application of systems biology approaches and metabolic engineering also to CHO. The availability of a reference genome sequence, genome-scale metabolic models and the growing number of various “omics” datasets can help overcome the complexity of CHO cells and support design strategies to boost their production performance. Modular design approaches applied to engineer industrially relevant cell lines have evolved to reduce the time and effort needed for the generation of new producer cells and to allow the achievement of desired product titers and quality. Nevertheless, important steps to enable the design of a chassis platform similar to those in use in the microbial world are still missing. In this review, we highlight the importance of mammalian cellular platforms for the production of biopharmaceuticals and compare them to microbial platforms, with an emphasis on describing novel approaches and discussing still open questions that need to be resolved to reach the objective of designing enhanced modular chassis CHO cell lines.
Collapse
|
29
|
Xu ZJ, Jia YL, Wang M, Yi DD, Zhang WL, Wang XY, Zhang JH. Effect of promoter, promoter mutation and enhancer on transgene expression mediated by episomal vectors in transfected HEK293, Chang liver and primary cells. Bioengineered 2020; 10:548-560. [PMID: 31668126 PMCID: PMC6844389 DOI: 10.1080/21655979.2019.1684863] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The episomal vector cannot integrate into the host cell chromosome, which has no potential risk in gene therapy. However, the low level of transgene expression driven by episomal vectors needs to be solved. In this study, we investigated the effects of enhancers, promoters and promoter variants on transgene expression levels driven by episomal vectors in HEK293, Chang liver and primary cells. Results showed that all eight cis-acting elements used could increase transfection efficiency and transient eGFP expression in transfected HEK293 and Chang liver cells. In stably transfected mammalian cells, the elongation factor-1 alpha (EF-1α) promoter and mutant-404 showed high and stable transgene expression. The mechanisms might be related to the type and quantity of transcription factor regulatory elements. Moreover, quantitative reverse transcription polymerase chain reaction analysis showed that mRNA expression levels were not directly proportional to protein expression levels. Furthermore, the EF-1α promoter conferred high transgene expression levels in primary cells, and the plasmid was also present in the episomal state. Taken together, these results provided valuable information for improving transgene expression with episomal vectors in mammalian cells.
Collapse
Affiliation(s)
- Zhong-Jie Xu
- Life Science and Technology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yan-Long Jia
- Pharmacy collage, Xinxiang Medical University, Xinxiang, Henan, China
| | - Meng Wang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Dan-Dan Yi
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China.,Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Wei-Li Zhang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China.,Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Xiao-Yin Wang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China.,Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Jun-He Zhang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| |
Collapse
|
30
|
Adamson CS, Nevels MM. Bright and Early: Inhibiting Human Cytomegalovirus by Targeting Major Immediate-Early Gene Expression or Protein Function. Viruses 2020; 12:v12010110. [PMID: 31963209 PMCID: PMC7019229 DOI: 10.3390/v12010110] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/11/2022] Open
Abstract
The human cytomegalovirus (HCMV), one of eight human herpesviruses, establishes lifelong latent infections in most people worldwide. Primary or reactivated HCMV infections cause severe disease in immunosuppressed patients and congenital defects in children. There is no vaccine for HCMV, and the currently approved antivirals come with major limitations. Most approved HCMV antivirals target late molecular processes in the viral replication cycle including DNA replication and packaging. “Bright and early” events in HCMV infection have not been exploited for systemic prevention or treatment of disease. Initiation of HCMV replication depends on transcription from the viral major immediate-early (IE) gene. Alternative transcripts produced from this gene give rise to the IE1 and IE2 families of viral proteins, which localize to the host cell nucleus. The IE1 and IE2 proteins are believed to control all subsequent early and late events in HCMV replication, including reactivation from latency, in part by antagonizing intrinsic and innate immune responses. Here we provide an update on the regulation of major IE gene expression and the functions of IE1 and IE2 proteins. We will relate this insight to experimental approaches that target IE gene expression or protein function via molecular gene silencing and editing or small chemical inhibitors.
Collapse
|
31
|
Dahodwala H, Lee KH. The fickle CHO: a review of the causes, implications, and potential alleviation of the CHO cell line instability problem. Curr Opin Biotechnol 2019; 60:128-137. [DOI: 10.1016/j.copbio.2019.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/04/2018] [Accepted: 01/21/2019] [Indexed: 02/08/2023]
|
32
|
Capella Roca B, Lao N, Barron N, Doolan P, Clynes M. An arginase-based system for selection of transfected CHO cells without the use of toxic chemicals. J Biol Chem 2019; 294:18756-18768. [PMID: 31666335 DOI: 10.1074/jbc.ra119.011162] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 10/29/2019] [Indexed: 11/06/2022] Open
Abstract
Polyamines have essential roles in cell proliferation, DNA replication, transcription, and translation processes, with intracellular depletion of putrescine, spermidine, and spermine resulting in cellular growth arrest and eventual death. Serum-free media for CHO-K1 cells require putrescine supplementation, because these cells lack the first enzyme of the polyamine production pathway, arginase. On the basis of this phenotype, we developed an arginase-based selection system. We transfected CHO-K1 cells with a bicistronic vector co-expressing GFP and arginase and selected cells in media devoid of l-ornithine and putrescine, resulting in mixed populations stably expressing GFP. Moreover, single clones in these selective media stably expressed GFP for a total of 42 generations. Using this polyamine starvation method, we next generated recombinant CHO-K1 cells co-expressing arginase and human erythropoietin (hEPO), which also displayed stable expression and healthy growth. The hEPO-expressing clones grew in commercial media, such as BalanCD and CHO-S serum-free media (SFM)-II, as well as in a defined serum-free, putrescine-containing medium for at least 9 passages (27 generations), with a minimal decrease in hEPO titer by the end of the culture. We observed a lack of arginase activity also in several CHO cell strains (CHO-DP12, CHO-S, and DUXB11) and other mammalian cell lines, including BHK21, suggesting broader utility of this selection system. In conclusion, we have established an easy-to-apply alternative selection system that effectively generates mammalian cell clones expressing biopharmaceutically relevant or other recombinant proteins without the need for any toxic selective agents. We propose that this system is applicable to mammalian cell lines that lack arginase activity.
Collapse
Affiliation(s)
- Berta Capella Roca
- National Institute for Cellular Biotechnology, Dublin City University, Dublin 9, Ireland; SSPC-SFI, Centre for Pharmaceuticals, Dublin City University, Dublin 9, Ireland.
| | - Nga Lao
- National Institute for Bioprocessing Research & Training, A94 X099 Dublin, Ireland
| | - Niall Barron
- National Institute for Bioprocessing Research & Training, A94 X099 Dublin, Ireland; School of Chemical & Bioprocessing Engineering, University College Dublin, Belfield, Dublin 4, D04V1W8, Ireland
| | - Padraig Doolan
- National Institute for Cellular Biotechnology, Dublin City University, Dublin 9, Ireland
| | - Martin Clynes
- National Institute for Cellular Biotechnology, Dublin City University, Dublin 9, Ireland; SSPC-SFI, Centre for Pharmaceuticals, Dublin City University, Dublin 9, Ireland
| |
Collapse
|
33
|
Zúñiga RA, Gutiérrez-González M, Collazo N, Sotelo PH, Ribeiro CH, Altamirano C, Lorenzo C, Aguillón JC, Molina MC. Development of a new promoter to avoid the silencing of genes in the production of recombinant antibodies in chinese hamster ovary cells. J Biol Eng 2019; 13:59. [PMID: 31297150 PMCID: PMC6599231 DOI: 10.1186/s13036-019-0187-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 06/11/2019] [Indexed: 11/10/2022] Open
Abstract
Background The production of recombinant proteins in mammalian cell lines is one of the most important areas in biopharmaceutical industry. Viral transcriptional promoters are widely used to express recombinant proteins in mammalian cell lines. However, these promoters are susceptible to silencing, thus limiting protein productivity. Some CpG islands can avoid the silencing of housekeeping genes; for that reason, they have been used to increase the production of recombinant genes in cells of animal origin. In this study, we evaluated the CpG island of the promoter region of the β-actin gene of Cricetulus griseous (Chinese hamster), associated to the Cytomegalovirus (CMV) promoter, to increase recombinant antibodies production in Chinese Hamster Ovary (CHO) cells. Results We focused on the non-coding region of CpG island, which we called RegCG. RegCG behaved as a promoter, whose transcriptional activity was mainly commanded by the CAAT and CArG boxes of the proximal promoter. However, the transcription started mainly at the intronic region before the proximal transcription start site. While the CMV promoter was initially more powerful than RegCG, the latter promoter was more resistant to silencing than the CMV promoter in stable cell lines, and its activity was improved when combined with the CMV promoter. Thereby, the chimeric promoter was able to maintain the expression of recombinant antibodies in stable clones for 40 days at an average level 4 times higher than the CMV promoter. Finally, the chimeric promoter showed compatibility with a genetic amplification system by induction with methotrexate in cells deficient in the dihydrofolate reductase gene. Conclusions We have generated an efficient synthetic hybrid transcription promoter through the combination of RegCG with CMV, which, in stable cell lines, shows greater activity than when both promoters are used separately. Our chimeric promoter is compatible with a genetic amplification system in CHO DG44 cells and makes possible the generation of stable cell lines with high production of recombinant antibodies. We propose that this promoter can be a good alternative for the generation of clones expressing high amount of recombinant proteins, essential for industrial applications.
Collapse
Affiliation(s)
- Roberto A Zúñiga
- 1Centro de InmunoBiotecnología, Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,2Doctorado en Química, Universidad República Oriental del Uruguay, Montevideo, Uruguay
| | - Matías Gutiérrez-González
- 1Centro de InmunoBiotecnología, Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,7Programa de Doctorado en Farmacología, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Norberto Collazo
- 6Business Development Department, Fundación Fraunhofer Chile Research, Santiago, Chile
| | - Pablo Hérnan Sotelo
- 3Departamento de Biotecnología, Facultad de Ciencias Químicas, Universidad Nacional de Asunción, San Lorenzo, Paraguay
| | - Carolina H Ribeiro
- 1Centro de InmunoBiotecnología, Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Claudia Altamirano
- 5Escuela de Ingeniería Bioquímica, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Carmen Lorenzo
- 4Facultad de Química, Universidad República Oriental del Uruguay, Montevideo, Uruguay
| | - Juan Carlos Aguillón
- 1Centro de InmunoBiotecnología, Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - María Carmen Molina
- 1Centro de InmunoBiotecnología, Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| |
Collapse
|
34
|
Wang XY, Yi DD, Wang TY, Wu YF, Chai YR, Xu DH, Zhao CP, Song C. Enhancing expression level and stability of transgene mediated by episomal vector via buffering DNA methyltransferase in transfected CHO cells. J Cell Biochem 2019; 120:15661-15670. [PMID: 31074065 DOI: 10.1002/jcb.28835] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/01/2019] [Accepted: 02/04/2019] [Indexed: 12/17/2022]
Abstract
Nonviral episomal vectors present attractive alternative vehicles for gene therapy applications. Previously, we have established a new type of nonviral episomal vector-mediated by the characteristic motifs of matrix attachment regions (MARs), which is driven by the cytomegalovirus (CMV) promoter. However, the CMV promoter is intrinsically susceptible to silencing, resulting in declined productivity during long-term culture. In this study, Chinese hamster ovary (CHO) cells and DNA methyltransferase-deficient (Dnmt3a-deficient) CHO cells were transfected with plasmid-mediated by MAR, or CHO cells were treated with the DNA methylation inhibitor 5-Aza-2'-deoxycytidine. Flow cytometry, plasmid rescue experiments, fluorescence in-situ hybridization (FISH), and bisulfite sequencing were performed to observe transgene expression, its state of existence, and the CpG methylation level of the CMV promoter. The results indicated that all DNA methylation inhibitor and methyltransferase deficient cells could increase transgene expression levels and stability in the presence or absence of selection pressure after a 60-generation culture. Plasmid rescue assay and FISH analysis showed that the vector still existed episomally after long-time culture. Moreover, a relatively lower CMV promoter methylation level was observed in Dnmt3a-deficient cell lines and CHO cells treated with 5-Aza-2'-deoxycytidine. In addition, Dnmt3a-deficient cells were superior to the DNA methylation inhibitor treatment regarding the transgene expression and long-term stability. Our study provides the first evidence that lower DNA methyltransferase can enhance expression level and stability of transgenes mediated by episomal vectors in transfected CHO cells.
Collapse
Affiliation(s)
- Xiao-Yin Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Dan-Dan Yi
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Tian-Yun Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yan-Fang Wu
- Department of Pharmacy, Medical College, Henan University of Science and Technology, Luoyang, China
| | - Yu-Rong Chai
- Department of Histology and Embryology, School of Basic Medical Sciences, University of Zhengzhou, Zhengzhou, Henan, China
| | - Dan-Hua Xu
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chun-Peng Zhao
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chao Song
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| |
Collapse
|
35
|
Pristovšek N, Nallapareddy S, Grav LM, Hefzi H, Lewis NE, Rugbjerg P, Hansen HG, Lee GM, Andersen MR, Kildegaard HF. Systematic Evaluation of Site-Specific Recombinant Gene Expression for Programmable Mammalian Cell Engineering. ACS Synth Biol 2019; 8:758-774. [PMID: 30807689 DOI: 10.1021/acssynbio.8b00453] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many branches of biology depend on stable and predictable recombinant gene expression, which has been achieved in recent years through targeted integration of the recombinant gene into defined integration sites. However, transcriptional levels of recombinant genes in characterized integration sites are controlled by multiple components of the integrated expression cassette. Lack of readily available tools has inhibited meaningful experimental investigation of the interplay between the integration site and the expression cassette components. Here we show in a systematic manner how multiple components contribute to final net expression of recombinant genes in a characterized integration site. We develop a CRISPR/Cas9-based toolbox for construction of mammalian cell lines with targeted integration of a landing pad, containing a recombinant gene under defined 5' proximal regulatory elements. Generated site-specific recombinant cell lines can be used in a streamlined recombinase-mediated cassette exchange for fast screening of different expression cassettes. Using the developed toolbox, we show that different 5' proximal regulatory elements generate distinct and robust recombinant gene expression patterns in defined integration sites of CHO cells with a wide range of transcriptional outputs. This approach facilitates the generation of user-defined and product-specific gene expression patterns for programmable mammalian cell engineering.
Collapse
Affiliation(s)
- Nuša Pristovšek
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Saranya Nallapareddy
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Lise Marie Grav
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Hooman Hefzi
- Departments of Pediatrics and Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- The Novo Nordisk Foundation Center for Biosustainability at the University of California, San Diego School of Medicine, La Jolla, California 92093, United States
| | - Nathan E. Lewis
- Departments of Pediatrics and Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- The Novo Nordisk Foundation Center for Biosustainability at the University of California, San Diego School of Medicine, La Jolla, California 92093, United States
| | - Peter Rugbjerg
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Henning Gram Hansen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| | - Gyun Min Lee
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
- Department of Biological Sciences, KAIST, 291 Daehak-ro,
Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Mikael Rørdam Andersen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 223, 2800 Kgs. Lyngby, Denmark
| | - Helene Faustrup Kildegaard
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet, Building 220, 2800 Kgs. Lyngby, Denmark
| |
Collapse
|
36
|
ER intrabody-mediated inhibition of interferon α secretion by mouse macrophages and dendritic cells. PLoS One 2019; 14:e0215062. [PMID: 30990863 PMCID: PMC6467385 DOI: 10.1371/journal.pone.0215062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/26/2019] [Indexed: 11/19/2022] Open
Abstract
Interferon α (IFNα) counteracts viral infections by activating various IFNα-stimulated genes (ISGs). These genes encode proteins that block viral transport into the host cell and inhibit viral replication, gene transcription and translation. Due to the existence of 14 different, highly homologous isoforms of mouse IFNα, an IFNα knockout mouse has not yet been established by genetic knockout strategies. An scFv intrabody for holding back IFNα isoforms in the endoplasmic reticulum (ER) and thus counteracting IFNα secretion is reported. The intrabody was constructed from the variable domains of the anti-mouse IFNα rat monoclonal antibody 4EA1 recognizing the 5 isoforms IFNα1, IFNα2, IFNα4, IFNα5, IFNα6. A soluble form of the intrabody had a KD of 39 nM to IFNα4. It could be demonstrated that the anti-IFNα intrabody inhibits clearly recombinant IFNα4 secretion by HEK293T cells. In addition, the secretion of IFNα4 was effectively inhibited in stably transfected intrabody expressing RAW 264.7 macrophages and dendritic D1 cells. Colocalization of the intrabody with IFNα4 and the ER marker calnexin in HEK293T cells indicated complex formation of intrabody and IFNα4 inside the ER. Intracellular binding of intrabody and antigen was confirmed by co-immunoprecipitation. Complexes of endogenous IFNα and intrabody could be visualized in the ER of Poly (I:C) stimulated RAW 264.7 macrophages and D1 dendritic cells. Infection of macrophages and dendritic cells with the vesicular stomatitis virus VSV-AV2 is attenuated by IFNα and IFNβ. The intrabody increased virus proliferation in RAW 264.7 macrophages and D1 dendritic cells under IFNβ-neutralizing conditions. To analyze if all IFNα isoforms are recognized by the intrabody was not in the focus of this study. Provided that binding of the intrabody to all isoforms was confirmed, the establishment of transgenic intrabody mice would be promising for studying the function of IFNα during viral infection and autoimmune diseases.
Collapse
|
37
|
A Strategy to Optimize the Generation of Stable Chromobody Cell Lines for Visualization and Quantification of Endogenous Proteins in Living Cells. Antibodies (Basel) 2019; 8:antib8010010. [PMID: 31544816 PMCID: PMC6640688 DOI: 10.3390/antib8010010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 01/04/2019] [Accepted: 01/07/2019] [Indexed: 02/07/2023] Open
Abstract
Single-domain antibodies have emerged as highly versatile nanoprobes for advanced cellular imaging. For real-time visualization of endogenous antigens, fluorescently labelled nanobodies (chromobodies, CBs) are introduced as DNA-encoded expression constructs in living cells. Commonly, CB expression is driven from strong, constitutively active promoters. However, high expression levels are sometimes accompanied by misfolding and aggregation of those intracellular nanoprobes. Moreover, stable cell lines derived from random genomic insertion of CB-encoding transgenes bear the risk of disturbed cellular processes and inhomogeneous CB signal intensities due to gene positioning effects and epigenetic silencing. In this study we propose a strategy to generate optimized CB expressing cell lines. We demonstrate that expression as ubiquitin fusion increases the fraction of intracellularly functional CBs and identified the elongation factor 1α (EF1-α) promoter as highly suited for constitutive CB expression upon long-term cell line cultivation. Finally, we applied a CRISPR/Cas9-based gene editing approach for targeted insertion of CB expression constructs into the adeno-associated virus integration site 1 (AAVS1) safe harbour locus of human cells. Our results indicate that this combinatorial approach facilitates the generation of fully functional and stable CB cell lines for quantitative live-cell imaging of endogenous antigens.
Collapse
|
38
|
Markert S, Musmann C, Hülsmann P, Joeris K. Automated and enhanced clone screening using a fully automated microtiter plate‐based system for suspension cell culture. Biotechnol Prog 2019; 35:e2760. [DOI: 10.1002/btpr.2760] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/28/2018] [Indexed: 01/30/2023]
Affiliation(s)
- Sven Markert
- Pharmaceutical Biotech Production and DevelopmentRoche Diagnostics GmbH Penzberg Germany
| | - Carsten Musmann
- Pharmaceutical Biotech Production and DevelopmentRoche Diagnostics GmbH Penzberg Germany
| | - Peter Hülsmann
- Roche Pharmaceutical Research and Early DevelopmentRoche Innovation Center Munich Germany
| | - Klaus Joeris
- Pharmaceutical Biotech Production and DevelopmentRoche Diagnostics GmbH Penzberg Germany
| |
Collapse
|
39
|
Bandyopadhyay AA, O’Brien SA, Zhao L, Fu HY, Vishwanathan N, Hu WS. Recurring genomic structural variation leads to clonal instability and loss of productivity. Biotechnol Bioeng 2019; 116:41-53. [PMID: 30144379 PMCID: PMC7058117 DOI: 10.1002/bit.26823] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/13/2018] [Accepted: 08/23/2018] [Indexed: 12/31/2022]
Abstract
Chinese hamster ovary cells, commonly used in the production of therapeutic proteins, are aneuploid. Their chromosomes bear structural abnormality and undergo changes in structure and number during cell proliferation. Some production cell lines are unstable and lose their productivity over time in the manufacturing process and during the product's life cycle. To better understand the link between genomic structural changes and productivity stability, an immunoglobulin G producing cell line was successively single-cell cloned to obtain subclones that retained or lost productivity, and their genomic features were compared. Although each subclone started with a single karyotype, the progeny quickly diversified to a population with a distribution of chromosome numbers that is not distinctive from the parent and among subclones. The comparative genomic hybridization (CGH) analysis showed that the extent of copy variation of gene coding regions among different subclones stayed at levels of a few percent. Genome regions that were prone to loss of copies, including one with a product transgene integration site, were identified in CGH. The loss of the transgene copy was accompanied by loss of transgene transcript level. Sequence analysis of the host cell and parental producing cell showed prominent structural variations within the regions prone to loss of copies. Taken together, we demonstrated the transient nature of clonal homogeneity in cell line development and the retention of a population distribution of chromosome numbers; we further demonstrated that structural variation in the transgene integration region caused cell line instability. Future cell line development may target the transgene into structurally stable regions.
Collapse
Affiliation(s)
| | | | | | | | | | - Wei-Shou Hu
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455-0132 USA
| |
Collapse
|
40
|
|
41
|
Yamano N, Omasa T. EGCG improves recombinant protein productivity in Chinese hamster ovary cell cultures via cell proliferation control. Cytotechnology 2018; 70:1697-1706. [PMID: 30069612 PMCID: PMC6269352 DOI: 10.1007/s10616-018-0243-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/24/2018] [Indexed: 10/28/2022] Open
Abstract
Chinese hamster ovary cell lines are good manufacturing practice-certified host cells and are widely used in the field of biotechnology to produce therapeutic antibodies. Recombinant protein productivity in cells is strongly associated with cell growth. To control cell proliferation, many approaches have previously been tested including: genetic engineering, chemical additives such as cell cycle inhibitors, and temperature shift of the culture. To be widely adopted in the biopharmaceutical industry, the culture methods should be simple, uniform and safe. To this end, we examined the use a natural compound to improve the production capacity. In this study, we focused on the antioxidants, catechin polyphenols, which are found in green tea, for cell proliferation control strategies. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin that induces G0/G1 cell cycle arrest, was investigated for its effect on recombinant protein production. Adding EGCG to the cell culture media resulted in slower cellular growth and longer cell longevity, which improved the specific productivity and total yield of recombinant IgG1 in batch cultures by almost 50% for an extra 2 or 3 days of culture. A lower L-glutamine consumption rate was observed in cells cultured in EGCG-containing media, which may be suggesting that there was less stress in the culture environment. Additionally, EGCG did not affect the N-glycan quality of IgG1. Our results indicated that adding EGCG only on the first day of the culture enhanced the specific productivity and total amount of recombinant protein production in batch cultures. This approach may prove to be useful for biopharmaceutical production.
Collapse
Affiliation(s)
- Noriko Yamano
- Manufacturing Technology Association of Biologics, 7-1-49, Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.
- Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Takeshi Omasa
- Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan
| |
Collapse
|
42
|
Jia Y, Guo X, Lu J, Wang X, Qiu L, Wang T. CRISPR/Cas9-mediated gene knockout for DNA methyltransferase Dnmt3a in CHO cells displays enhanced transgenic expression and long-term stability. J Cell Mol Med 2018; 22:4106-4116. [PMID: 29851281 PMCID: PMC6111867 DOI: 10.1111/jcmm.13687] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/23/2018] [Indexed: 12/14/2022] Open
Abstract
CHO cells are the preferred host for the production of complex pharmaceutical proteins in the biopharmaceutical industry, and genome engineering of CHO cells would benefit product yield and stability. Here, we demonstrated the efficacy of a Dnmt3a-deficient CHO cell line created by CRISPR/Cas9 genome editing technology through gene disruptions in Dnmt3a, which encode the proteins involved in DNA methyltransferases. The transgenes, which were driven by the 2 commonly used CMV and EF1α promoters, were evaluated for their expression level and stability. The methylation levels of CpG sites in the promoter regions and the global DNA were compared in the transfected cells. The Dnmt3a-deficent CHO cell line based on Dnmt3a KO displayed an enhanced long-term stability of transgene expression under the control of the CMV promoter in transfected cells in over 60 passages. Under the CMV promoter, the Dnmt3a-deficent cell line with a high transgene expression displayed a low methylation rate in the promoter region and global DNA. Under the EF1α promoter, the Dnmt3a-deficient and normal cell lines with low transgene expression exhibited high DNA methylation rates. These findings provide insight into cell line modification and design for improved recombinant protein production in CHO and other mammalian cells.
Collapse
Affiliation(s)
- Yan‐Long Jia
- College of PharmacyXinxiang Medical UniversityXinxiangHenanChina
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of HenanXinxiang Medical UniversityXinxiangHenanChina
| | - Xiao Guo
- College of PharmacyXinxiang Medical UniversityXinxiangHenanChina
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of HenanXinxiang Medical UniversityXinxiangHenanChina
| | - Jiang‐Tao Lu
- College of PharmacyXinxiang Medical UniversityXinxiangHenanChina
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of HenanXinxiang Medical UniversityXinxiangHenanChina
| | - Xiao‐Yin Wang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of HenanXinxiang Medical UniversityXinxiangHenanChina
- School of Basic MedicineXinxiang Medical UniversityXinxiangHenanChina
| | - Le‐Le Qiu
- School of Basic MedicineXinxiang Medical UniversityXinxiangHenanChina
| | - Tian‐Yun Wang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of HenanXinxiang Medical UniversityXinxiangHenanChina
- School of Basic MedicineXinxiang Medical UniversityXinxiangHenanChina
| |
Collapse
|
43
|
Patel NA, Anderson CR, Terkildsen SE, Davis RC, Pack LD, Bhargava S, Clarke HR. Antibody expression stability in CHO clonally derived cell lines and their subclones: Role of methylation in phenotypic and epigenetic heterogeneity. Biotechnol Prog 2018; 34:635-649. [DOI: 10.1002/btpr.2655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/24/2018] [Indexed: 11/11/2022]
Affiliation(s)
- Neha A. Patel
- Dept. of Bioprocess Development; Seattle Genetics; Bothell WA 98021
| | | | | | - Ray C. Davis
- Dept. of Bioprocess Development; Seattle Genetics; Bothell WA 98021
| | - Laura D. Pack
- Dept. of CMC Statistics; Seattle Genetics; Bothell WA 98021
| | - Swapnil Bhargava
- Dept. of Bioprocess Development; Seattle Genetics; Bothell WA 98021
| | | |
Collapse
|
44
|
Reinhart D, Damjanovic L, Kaisermayer C, Sommeregger W, Gili A, Gasselhuber B, Castan A, Mayrhofer P, Grünwald-Gruber C, Kunert R. Bioprocessing of Recombinant CHO-K1, CHO-DG44, and CHO-S: CHO Expression Hosts Favor Either mAb Production or Biomass Synthesis. Biotechnol J 2018; 14:e1700686. [PMID: 29701329 DOI: 10.1002/biot.201700686] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 03/26/2018] [Indexed: 01/02/2023]
Abstract
Chinese hamster ovary (CHO) cells comprise a variety of lineages including CHO-DXB11, CHO-K1, CHO-DG44, and CHO-S. Despite all CHO cell lines sharing a common ancestor, extensive mutagenesis, and clonal selection has resulted in substantial genetic heterogeneity among them. Data from sequencing show that different genes are missing in individual CHO cell lines and each cell line harbors a unique set of mutations with relevance to the bioprocess. However, not much literature is available about the influence of genetic differences of CHO on the performance of bioprocess operations. In this study, the host cell-specific differences among three widely used CHO cell lines (CHO-K1, CHO-S, and CHO-DG44) and recombinantly expressed the same monoclonal antibody (mAb) in an isogenic format by using bacterial artificial chromosomes (BACs) as transfer vector in all cell lines is examined. Cell-specific growth and product formation are studied in batch, fed-batch, and semi-continuous perfusion cultures. Further, two different cell culture media are used to investigate their effects. The authors find CHO cell line-specific preferences for mAb production or biomass synthesis that are determined by the host cell line. Additionally, quality attributes of the expressed mAb are influenced by the host cell line and media.
Collapse
Affiliation(s)
- David Reinhart
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 11, 1190 Vienna, Austria
| | - Lukas Damjanovic
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 11, 1190 Vienna, Austria
| | | | - Wolfgang Sommeregger
- Bilfinger Industrietechnik Salzburg GmbH, Urstein Nord 31, 5412 Puch bei Hallein, Austria
| | - Andreas Gili
- Polymun Scientific Immunbiologische Forschung GmbH, Donaustraße 99, 3400 Klosterneuburg, Austria
| | - Bernhard Gasselhuber
- Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria
| | - Andreas Castan
- GE Healthcare Life Sciences AB, Björkgatan 30, 75184 Uppsala, Sweden
| | - Patrick Mayrhofer
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 11, 1190 Vienna, Austria
| | - Clemens Grünwald-Gruber
- Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190 Vienna, Austria
| | - Renate Kunert
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 11, 1190 Vienna, Austria
| |
Collapse
|
45
|
Marx N, Grünwald-Gruber C, Bydlinski N, Dhiman H, Ngoc Nguyen L, Klanert G, Borth N. CRISPR-Based Targeted Epigenetic Editing Enables Gene Expression Modulation of the Silenced Beta-Galactoside Alpha-2,6-Sialyltransferase 1 in CHO Cells. Biotechnol J 2018; 13:e1700217. [DOI: 10.1002/biot.201700217] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/01/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Nicolas Marx
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology GmbH; Graz Austria
| | - Clemens Grünwald-Gruber
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
| | - Nina Bydlinski
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
| | - Heena Dhiman
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology GmbH; Graz Austria
| | - Ly Ngoc Nguyen
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology GmbH; Graz Austria
| | - Gerald Klanert
- Austrian Centre of Industrial Biotechnology GmbH; Graz Austria
| | - Nicole Borth
- Department of Biotechnology; BOKU University of Natural Resources and Life Sciences; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology GmbH; Graz Austria
| |
Collapse
|
46
|
Noh SM, Shin S, Lee GM. Comprehensive characterization of glutamine synthetase-mediated selection for the establishment of recombinant CHO cells producing monoclonal antibodies. Sci Rep 2018; 8:5361. [PMID: 29599455 PMCID: PMC5876325 DOI: 10.1038/s41598-018-23720-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/18/2018] [Indexed: 12/16/2022] Open
Abstract
To characterize a glutamine synthetase (GS)-based selection system, monoclonal antibody (mAb) producing recombinant CHO cell clones were generated by a single round of selection at various methionine sulfoximine (MSX) concentrations (0, 25, and 50 μM) using two different host cell lines (CHO-K1 and GS-knockout CHO). Regardless of the host cell lines used, the clones selected at 50 μM MSX had the lowest average specific growth rate and the highest average specific production rates of toxic metabolic wastes, lactate and ammonia. Unlike CHO-K1, high producing clones could be generated in the absence of MSX using GS-knockout CHO with an improved selection stringency. Regardless of the host cell lines used, the clones selected at various MSX concentrations showed no significant difference in the GS, heavy chain, and light chain gene copies (P > 0.05). Furthermore, there was no correlation between the specific mAb productivity and these three gene copies (R2 ≤ 0.012). Taken together, GS-mediated gene amplification does not occur in a single round of selection at a MSX concentration up to 50 μM. The use of the GS-knockout CHO host cell line facilitates the rapid generation of high producing clones with reduced production of lactate and ammonia in the absence of MSX.
Collapse
Affiliation(s)
- Soo Min Noh
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Seunghyeon Shin
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Gyun Min Lee
- Department of Biological Sciences, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea. .,The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark.
| |
Collapse
|
47
|
Jazayeri SH, Amiri-Yekta A, Bahrami S, Gourabi H, Sanati MH, Khorramizadeh MR. Vector and Cell Line Engineering Technologies Toward Recombinant Protein Expression in Mammalian Cell Lines. Appl Biochem Biotechnol 2018; 185:986-1003. [PMID: 29396733 DOI: 10.1007/s12010-017-2689-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/29/2017] [Indexed: 11/26/2022]
Abstract
The rapid growth of global biopharmaceutical market in the recent years has been a good indication of its significance in biotechnology industry. During a long period of time in recombinant protein production from 1980s, optimizations in both upstream and downstream processes were launched. In this regard, one of the most promising strategies is expression vector engineering technology based on incorporation of DNA opening elements found in the chromatin border regions of vectors as well as targeting gene integration. Along with these approaches, cell line engineering has revealed convenient outcomes in isolating high-producing clones. According to the fact that more than 50% of the approved therapeutic proteins is being manufactured in mammalian cell lines, in this review, we focus on several approaches and developments in vector and cell line engineering technologies in mammalian cell culture.
Collapse
Affiliation(s)
- Seyedeh Hoda Jazayeri
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Department of Genetics, Reproductive Biomedicine Research Center, ACECR, Royan Institute for Reproductive Biomedicine, P.O. Box: 14155-6343, Tehran, Iran
| | - Amir Amiri-Yekta
- Department of Genetics, Reproductive Biomedicine Research Center, ACECR, Royan Institute for Reproductive Biomedicine, P.O. Box: 14155-6343, Tehran, Iran
| | - Salahadin Bahrami
- Department of Genetics, Reproductive Biomedicine Research Center, ACECR, Royan Institute for Reproductive Biomedicine, P.O. Box: 14155-6343, Tehran, Iran
| | - Hamid Gourabi
- Department of Genetics, Reproductive Biomedicine Research Center, ACECR, Royan Institute for Reproductive Biomedicine, P.O. Box: 14155-6343, Tehran, Iran
| | - Mohammad Hossein Sanati
- Department of Genetics, Reproductive Biomedicine Research Center, ACECR, Royan Institute for Reproductive Biomedicine, P.O. Box: 14155-6343, Tehran, Iran.
- Department of Medical Genetics, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran.
| | - Mohammad Reza Khorramizadeh
- Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, P.O. Box: 1411413137, Tehran, Iran.
| |
Collapse
|
48
|
Subramanian J, Aulakh RPS, Grewal PS, Sanford M, Pynn AFJ, Yuk IH. Short- and long-term effects on mAb-producing CHO cell lines after cryopreservation. Biotechnol Prog 2018; 34:463-477. [DOI: 10.1002/btpr.2599] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 12/04/2017] [Indexed: 01/27/2023]
Affiliation(s)
- Jayashree Subramanian
- Early Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| | - Rigzen P. S. Aulakh
- Early Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| | - Parbir S. Grewal
- Early Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| | - Mark Sanford
- Early Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| | - Abigail F. J. Pynn
- Early Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| | - Inn H. Yuk
- Late Stage Cell Culture, Pharma Technical Development, Genentech, 1 DNA Way; South San Francisco CA 94080
| |
Collapse
|
49
|
Brown AJ, Gibson SJ, Hatton D, James DC. In silico design of context-responsive mammalian promoters with user-defined functionality. Nucleic Acids Res 2017; 45:10906-10919. [PMID: 28977454 PMCID: PMC5737543 DOI: 10.1093/nar/gkx768] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/22/2017] [Indexed: 12/19/2022] Open
Abstract
Comprehensive de novo-design of complex mammalian promoters is restricted by unpredictable combinatorial interactions between constituent transcription factor regulatory elements (TFREs). In this study, we show that modular binding sites that do not function cooperatively can be identified by analyzing host cell transcription factor expression profiles, and subsequently testing cognate TFRE activities in varying homotypic and heterotypic promoter architectures. TFREs that displayed position-insensitive, additive function within a specific expression context could be rationally combined together in silico to create promoters with highly predictable activities. As TFRE order and spacing did not affect the performance of these TFRE-combinations, compositions could be specifically arranged to preclude the formation of undesirable sequence features. This facilitated simple in silico-design of promoters with context-required, user-defined functionalities. To demonstrate this, we de novo-created promoters for biopharmaceutical production in CHO cells that exhibited precisely designed activity dynamics and long-term expression-stability, without causing observable retroactive effects on cellular performance. The design process described can be utilized for applications requiring context-responsive, customizable promoter function, particularly where co-expression of synthetic TFs is not suitable. Although the synthetic promoter structure utilized does not closely resemble native mammalian architectures, our findings also provide additional support for a flexible billboard model of promoter regulation.
Collapse
Affiliation(s)
- Adam J Brown
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK
| | - Suzanne J Gibson
- Biopharmaceutical Development, MedImmune, Cambridge CB21 6GH, UK
| | - Diane Hatton
- Biopharmaceutical Development, MedImmune, Cambridge CB21 6GH, UK
| | - David C James
- Department of Chemical and Biological Engineering, University of Sheffield, Mappin St., Sheffield S1 3JD, UK
| |
Collapse
|
50
|
Chen SJ, Wang W, Zhang FY, Jia YL, Wang XY, Guo X, Chen SN, Gao JH, Wang TY. A chimeric HS4 insulator-scaffold attachment region enhances transgene expression in transfected Chinese hamster ovary cells. FEBS Open Bio 2017; 7:2021-2030. [PMID: 29226088 PMCID: PMC5715248 DOI: 10.1002/2211-5463.12335] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 09/23/2017] [Accepted: 10/03/2017] [Indexed: 11/12/2022] Open
Abstract
Chinese hamster ovary (CHO) cells are one of the most commonly used expression systems for the production of recombinant proteins but low levels of transgene expression and transgene silencing are frequently encountered. Epigenetic regulatory elements such as the chicken β-globin locus control region hypersensitive site 4 (HS4) and scaffold/matrix attachment regions (S/MARs) have positive effects on transgene expression. In this study, a chimeric HS4-SAR was cloned upstream or downstream of an enhanced green fluorescent protein (eGFP) expression cassette in a eukaryotic vector, and the resulting vectors were transfected into CHO cells. eGFP was detected by flow cytometry. Real-time quantitative PCR (qPCR) was used to determine copy numbers of the stably transfected cells. And fluorescence in situ hybridization (FISH) was used to detect the status of vector in the host cell chromosome. The results showed that HS4-SAR positioned downstream of the expression cassette could enhance eGFP expression by 4.83-fold compared with the control vector. There may not be a relationship between transgene copy number and gene expression level. HS4-SAR did not appear to alter the integration of the transgene into the host cell chromosome or its position in the chromosome. We found a synthetic chimeric HS4-SAR positively increased transgene expression in CHO cells.
Collapse
Affiliation(s)
- Si-Jia Chen
- Department of Biochemistry and Molecular Biology Xinxiang Medical University Henan China
| | - Wen Wang
- Pharmacy Collage Xinxiang Medical University Henan China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine Xinxiang Medical University China
| | - Feng-Yi Zhang
- Grade 2012 The Third Clinical Medical College of Xinxiang Medical University Henan China
| | - Yan-Long Jia
- Pharmacy Collage Xinxiang Medical University Henan China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine Xinxiang Medical University China
| | - Xiao-Yin Wang
- Department of Biochemistry and Molecular Biology Xinxiang Medical University Henan China
| | - Xiao Guo
- Pharmacy Collage Xinxiang Medical University Henan China
| | - Shao-Nan Chen
- Department of Biochemistry and Molecular Biology Xinxiang Medical University Henan China
| | - Jian-Hui Gao
- Department of Biochemistry and Molecular Biology Xinxiang Medical University Henan China
| | - Tian-Yun Wang
- Department of Biochemistry and Molecular Biology Xinxiang Medical University Henan China.,Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine Xinxiang Medical University China
| |
Collapse
|