1
|
Zhang J, Wang L, Zhang X, Sun Q, Zhang J. Matrix attachment regions enhance transgene expression by manipulating position-dependent effects in stably transfected CHO-K1 cells. Biochem Cell Biol 2024. [PMID: 39029107 DOI: 10.1139/bcb-2023-0337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2024] Open
Abstract
We previously found that the position of matrix attachment regions (MARs) within the vector significantly affects its ability to enhance transgenic expression in the recombinant protein production. This study aims to systematically investigate the position-dependent impacts of MAR on transgene expression. We observed a significant increase in enhanced green fluorescent protein (eGFP) expression levels in stably transfected CHO-K1 cells with either MAR 1-68 or MAR X-29 when MARs located upstream of the promoter. This increase was especially evident with MAR flanked the expression cassette. Concurrently, a substantial increase was observed in the percentage of eGFP-expressing cells, with 97.8% and 96.0% in MAR-containing constructs versus 73.7% in MAR-absent constructs. Further analysis of erythropoietin (EPO) expression revealed that constructs with flanking MARs induced the highest EPO productivity. Bioinformatics analysis revealed that certain specific transcription factors are important in modulating the transcription process. In conclusion, vectors harboring both MARs around the expression cassette constitute an optimal construct for enhanced recombinant protein production in CHO-K1 cells. This insight underscores the importance of strategic MAR incorporation in vector design for optimized recombinant protein expression.
Collapse
Affiliation(s)
- Jihong Zhang
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang 453003, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang 453003, China
| | - Lin Wang
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang 453003, China
| | - Xi Zhang
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang 453003, China
| | - Qiuli Sun
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang 453003, China
| | - Junhe Zhang
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang 453003, China
- Institutes of Health Central Plains, Xinxiang Medical University, Xinxiang 453003, China
| |
Collapse
|
2
|
Wang XY, Zhang WL, Zhang X, Fu YS, Wang HM, Sun QL, Li Q, Jia YL, Zhang JH, Wang TY. Combination of MAR and intron increase transgene expression of episomal vectors in CHO cells. Biotechnol J 2023; 18:e2200643. [PMID: 37551822 DOI: 10.1002/biot.202200643] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 07/22/2023] [Accepted: 08/03/2023] [Indexed: 08/09/2023]
Abstract
Previous work has shown that the EF-1α promoter of episomal vectors maintains high-level transgene expression in stably transfected Chinese hamster ovary (CHO) cells. However, the transgene expression levels need to be further increased. Here, we first incorporated matrix attachment regions (MARs), ubiquitous chromatin opening element (UCOE), stabilizing anti repressor elements 40 (STAR 40) elements into episomal vector at different sites and orientations, and systemically assessed their effects on transgene expression in transfected CHO-K1 cells. Results showed that enhanced green fluorescent protein (eGFP) expression levels increased remarkably when MAR X-29 was inserted upstream of the promoter, followed by the insertion of MAR1 downstream of the poly A, and the orientation had no significant effect. Moreover, MAR X-29 combined with human cytomegalovirus intron (hCMVI) yielded the highest transgene expression levels (4.52-fold). Transgene expression levels were not exclusively dependent on transgene copy numbers and were not related to the mRNA expression level. In addition, vector with MAR X-29+hCMVI can induce herpes simplex virus thymidine kinase (HSV-TK) protein expression, and the HSV-TK protein showed a cell-killing effect and an obvious bystander effect on HCT116 cells. In conclusion, the combination of MAR X-29 and hCMV intron can achieve high efficiency transgene expression mediated by episomal vectors in CHO-K1 cells.
Collapse
Affiliation(s)
- Xiao-Yin Wang
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, China
| | - Wei-Li Zhang
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
- Center for Medical Genetics, Nanyang Second General Hospital, Nanyang, China
| | - Xi Zhang
- College of Pharmacy, Xinxiang Medical University, Xinxiang, China
| | - Yu-Shun Fu
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Hao-Min Wang
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Qiu-Li Sun
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, China
| | - Qin Li
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Yan-Long Jia
- College of Pharmacy, Xinxiang Medical University, Xinxiang, China
| | - Jun-He Zhang
- Institutes of Health Central Plains, Xinxiang Medical University, Xinxiang, China
| | - Tian-Yun Wang
- School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, China
| |
Collapse
|
3
|
Mulia GE, Picanço-Castro V, Stavrou EF, Athanassiadou A, Figueiredo ML. Advances in the Development and the Applications of Non-viral, Episomal Vectors for Gene Therapy. Hum Gene Ther 2021; 32:1076-1095. [PMID: 34348480 PMCID: PMC8819515 DOI: 10.1089/hum.2020.310] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Nonviral and nonintegrating episomal vectors are reemerging as a valid, alternative technology to integrating viral vectors for gene therapy, due to their more favorable safety profile, significantly lower risk for insertional mutagenesis, and a lesser potential for innate immune reactions, in addition to their low production cost. Over the past few years, attempts have been made to generate highly functional nonviral vectors that display long-term maintenance within cells and promote more sustained gene expression relative to conventional plasmids. Extensive research into the parameters that stabilize the episomal DNA within dividing and nondividing cells has shed light into the genetic and epigenetic mechanisms that govern replication and transcription of episomal DNA within a mammalian nucleus in long-term cell culture. Episomal vectors based on scaffold/matrix attachment regions (S/MARs) do not integrate into the genomic DNA and address the serious problem of plasmid loss during mitosis by providing mitotic stability to established plasmids, which results in long-term transfection and transgene expression. The inclusion, in such vectors, of an origin of replication—initiation region—from the human genome has greatly enhanced their performance in primary cell culture. A number of vectors that function as episomes have arisen, which are either devoid or depleted of harmful CpG sequences and bacterial genes, and their effectiveness, as well as that of nonintegrating viral episomes, is enhanced when combined with S/MAR elements. As a result of these advances, an “S/MAR technology” has emerged for the production of efficient episomal vectors. Significant research continues in this field and innovations, in combination with promising systems based on nanoparticles and potentially combined with physical delivery methods, will enable the generation of optimized systems with scale-up and clinical application suitability utilizing episomal vectors.
Collapse
Affiliation(s)
- Grace E Mulia
- Purdue University, Basic Medical Sciences, West Lafayette, Indiana, United States;
| | - Virginia Picanço-Castro
- University of Sao Paulo Faculty of Medicine of Ribeirao Preto, 54539, Center for Cell-based Therapy, Ribeirao Preto, São Paulo, Brazil;
| | - Eleana F Stavrou
- University of Patras, Department of General Biology, Patras, Greece;
| | - Aglaia- Athanassiadou
- University of Patras Medical School, General Biology, Asklepiou str, University Campus, Rion Patras, Greece, 26504;
| | - Marxa L Figueiredo
- Purdue University, Basic Medical Sciences, 625 Harrison St., LYNN 2177, West Lafayette, Indiana, United States, 47907;
| |
Collapse
|
4
|
Naghneh E, Pourmaleki E, Rahimpour A. Evaluation of the Effects of Human Beta-Interferon Scaffold Attachment Region (IFN-SAR) on Expression of Vascular Endothelial Growth Factor-Fc (VEGF-Fc) Fusion Protein Expression in Chinese Hamster Ovary (CHO) Cells. PHARMACEUTICAL SCIENCES 2020. [DOI: 10.34172/ps.2020.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Background: Recombinant anti-vascular endothelial growth factor (VEGF) monoclonal antibodies and Fc-fusion proteins have been widely used for the effective treatment of retinal neovascular diseases. In this regard, VEGFR-Fc fusions, which act as strong VEGF inhibitors, have been approved for the treatment of age-related macular degeneration (AMD) and diabetic macular edema (DME). Production of monoclonal antibodies and Fc-fusion proteins relies on mammalian host systems such as Chinese hamster ovary (CHO) cells. Application of genomic regulatory elements including scaffold/matrix attachment regions (SAR/MARs) can profoundly affect recombinant protein expression in CHO cells. Methods: To construct the VEGFR-Fc expression vectors, the enhanced green fluorescent protein (EGFP) gene was replaced by the VEGFR-Fc coding sequence in pEGFP-SAR-puro and pEGFP-puro vectors. Recombinant plasmids were transfected to CHO-K1 cells using TurboFect transfection reagent. VEGFR-Fc expression was evaluated in transiently transfected cells as well as stable cell pools and clones using an enzyme-linked immunosorbent assay (ELISA). Results: IFN-SAR showed no significant effect on transient expression of VEGFR-Fc during 72 h of culture. However, a 2.2-fold enhancement in VEGFR-Fc fusion protein titer was observed in IFN-SAR containing stable cell pools. Further evaluation of the VEGFR-Fc expression level in single-cell clones also indicated that clones with the highest VEGFR-Fc expression belonged to the pools transfected with IFN-SAR construct. Conclusion: Our results indicate that the incorporation of IFN-SAR in expression vector can increase the expression of VEGFR-Fc in stable cell pools as well as single-cell clones. In contrast, transient expression of the fusion protein was not affected by IFN-SAR. More studies are needed to investigate the mechanism underlying this effect, including the analysis of mRNA expression and gene copy number in stable cell pools as well as clonal cells.
Collapse
Affiliation(s)
- Ehsan Naghneh
- Department of Genetics, East Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Es'hagh Pourmaleki
- Nano-Technology and Tissue Engineering Research Center, 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
- Nano-Technology and Tissue Engineering Research Center, 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
| |
Collapse
|
5
|
Wang X, Zhang W, Jia Y, Wang M, Yi D, Wang TY. Woodchuck hepatitis post-transcriptional regulatory element improves transgene expression and stability mediated by episomal vectors in CHO-K1 cells. Acta Biochim Biophys Sin (Shanghai) 2020; 52:1285-1288. [PMID: 33196825 DOI: 10.1093/abbs/gmaa105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/02/2020] [Accepted: 08/09/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Xiaoyin Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang 453003, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| | - Weili Zhang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang 453003, China
| | - Yanlong Jia
- Pharmacy College, Xinxiang Medical University, Xinxiang 453003, China
| | - Meng Wang
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| | - Dandan Yi
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang 453003, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| | - Tian-yun Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang 453003, China
- International Joint Research Laboratory for Recombinant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang 453003, China
| |
Collapse
|
6
|
Guo X, Wang C, Wang TY. Chromatin-modifying elements for recombinant protein production in mammalian cell systems. Crit Rev Biotechnol 2020; 40:1035-1043. [PMID: 32777953 DOI: 10.1080/07388551.2020.1805401] [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] [Indexed: 02/07/2023]
Abstract
Mammalian cells are the preferred choice system for the production of complex molecules, such as recombinant therapeutic proteins. Although the technology for increasing the yield of proteins has improved rapidly, the process of selecting, identifying as well as maintaining high-yield cell clones is still troublesome, time-consuming and usually uncertain. Optimization of expression vectors is one of the most effective methods for enhancing protein expression levels. Several commonly used chromatin-modifying elements, including the matrix attachment region, ubiquitous chromatin opening elements, insulators, stabilizing anti-repressor elements can be used to increase the expression level and stability of recombinant proteins. In this review, these chromatin-modifying elements used for the expression vector optimization in mammalian cells are summarized, and future strategies for the utilization of expression cassettes are also discussed.
Collapse
Affiliation(s)
- Xiao Guo
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, China.,Perildicals Publishing House, Xinxiang Medical University, Xinxiang, China
| | - Chong Wang
- School of Biological Science and Medical Engineering, Beihang University, Beijing, China
| | - Tian-Yun Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Xinxiang, China.,Perildicals Publishing House, Xinxiang Medical University, Xinxiang, China
| |
Collapse
|
7
|
Fusion with matrix attachment regions enhances expression of recombinant protein in human HT-1080 cells. J Biosci Bioeng 2020; 130:533-538. [PMID: 32773266 DOI: 10.1016/j.jbiosc.2020.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 07/09/2020] [Accepted: 07/09/2020] [Indexed: 11/23/2022]
Abstract
Like endogenous proteins, recombinant foreign proteins produced in human cell lines also need post-translational modifications. However, high and long-term expression of a gene of interest (GOI) presents significant challenges for recombinant protein production in human cells. In this work, the effect of human matrix attachment region elements (MARs), including the β-globin MAR (gMAR), chicken lysozyme MAR (cMAR), and a combination of these two, on the stable expression of GOI was assessed in human HT-1080 cells. After transfection with vectors containing the MAR elements and eGFP, stably HT-1080 cell pools were obtained under selective pressure. eGFP protein expression was analyzed by flow cytometry, while transgene copy number and eGFP mRNA expression levels were determined with qPCR and qRT-PCR technology. We found that MARs could not enhance transfection efficiency, but gMAR could significantly increase eGFP expression in stable HT-1080 cell pools by approximately 2.69-fold. Moreover, gMAR could also increase eGFP expression stability during long-term culture. Lastly, we showed that the effect of the MARs on transgenes was related to the gene copy number. In summary, this study found that MARs could both enhance the transgene expression and stability in HT-1080 cells.
Collapse
|
8
|
Jia YL, Guo X, Ni TJ, Lu JT, Wang XY, Wang TY. Novel short synthetic matrix attachment region for enhancing transgenic expression in recombinant Chinese hamster ovary cells. J Cell Biochem 2019; 120:18478-18486. [PMID: 31168866 DOI: 10.1002/jcb.29165] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/18/2019] [Accepted: 05/23/2019] [Indexed: 01/17/2023]
Abstract
Matrix attachment regions (MARs) are DNA fragments with specific motifs that enhance transgenic expression; however, the characteristics and functions of these elements remain unclear. In this study, we designed and synthesized three short chimeric MARs, namely, SM4, SM5, and SM6, with different numbers and orders of motifs on the basis of the features and motifs of previously reported MARs, namely, SM1, SM2, and SM3, respectively. Expression vectors with six synthetic MARs flanking the down or upstream of the expression cassette for enhanced green fluorescence protein (EGFP) were constructed and introduced into Chinese hamster ovary (CHO) cells. Results indicated that the EGFP expression of the CHO cells with transfection bySM4, SM5, or SM6-containing vectors was higher than that of those containing SM1, SM2, or SM3 regardless of the MAR insertion position. The improving effect of SM5 was particularly pronounced. Transgenic expression was further enhanced with the increasing SM5 copy number. Bioinformatics analysis indicated that several arrangements of the DNA-binding motifs for CEBP, FAST, Hox, glutathione, and NMP4 may help increase transgenic expression levels and the average population of highly expressed cells. Our findings on novel synthetic MARs will help establish stable expression systems in mammalian cells.
Collapse
Affiliation(s)
- Yan-Long Jia
- School of Pharmacy, Xinxiang Medical University, Xinxiang, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Xiao Guo
- School of Pharmacy, Xinxiang Medical University, Xinxiang, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Tian-Jun Ni
- School of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan, China
| | - Jiang-Tao Lu
- School of Pharmacy, Xinxiang Medical University, Xinxiang, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, 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.,School of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan, China
| | - Tian-Yun Wang
- International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China.,School of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan, China
| |
Collapse
|
9
|
Li Q, Zhao CP, Lin Y, Song C, Wang F, Wang TY. Two human MARs effectively increase transgene expression in transfected CHO cells. J Cell Mol Med 2018; 23:1613-1616. [PMID: 30450759 PMCID: PMC6349195 DOI: 10.1111/jcmm.14018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 12/12/2022] Open
Abstract
Matrix attachment regions (MARs) can enhance the expression level of transgene in Chinese hamster ovaries (CHO) cell expression system. However, improvements in function and analyses of the mechanism remains unclear. In this study, we screened two new and more functional MAR elements from the human genome DNA. The human MAR-3 and MAR-7 element were cloned and inserted downstream of the polyA site in a eukaryotic vector. The constructs were transfected into CHO cells, and screened under G418 to produce the stably transfected cell pools. The expression levels and stability of enhanced green fluorescent protein (eGFP) were detected by flow cytometry. The transgene copy number and transgene expression at mRNA level were detected by quantitative real-time PCR. The results showed that the expression level of eGFP of cells transfected with MAR-containing vectors were all higher than those of the vectors without MARs under transient and stably transfection. The enhancing effect of MAR-7 was higher than that of MAR-3. Additionally, we found that MAR significantly increased eGFP copy numbers and eGFP gene mRNA expression level as compared with the vector without. In conclusion, MAR-3 and MAR-7 gene can promote the expression of transgene in transfected CHO cells, and its effect may be related to the increase of the number of copies.
Collapse
Affiliation(s)
- Qin Li
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chun-Peng Zhao
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yan Lin
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Chao Song
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Fang Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| | - Tian-Yun Wang
- Department of Biochemistry and Molecular Biology, Xinxiang Medical University, Henan, China.,International Joint Research Laboratory for Recombiant Pharmaceutical Protein Expression System of Henan, Xinxiang Medical University, Xinxiang, Henan, China
| |
Collapse
|
10
|
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
|