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Abstract
Recent exponential advances in genome sequencing and engineering technologies have enabled an unprecedented level of interrogation into the impact of DNA variation (genotype) on cellular function (phenotype). Furthermore, these advances have also prompted realistic discussion of writing and radically re-writing complex genomes. In this Perspective, we detail the motivation for large-scale engineering, discuss the progress made from such projects in bacteria and yeast and describe how various genome-engineering technologies will contribute to this effort. Finally, we describe the features of an ideal platform and provide a roadmap to facilitate the efficient writing of large genomes.
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Affiliation(s)
- Raj Chari
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts, 02115, USA
| | - George M. Church
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Boston, Massachusetts, 02115, USA
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Blastocyst Formation Rate and Transgene Expression are Associated with Gene Insertion into Safe and Non-Safe Harbors in the Cattle Genome. Sci Rep 2017; 7:15432. [PMID: 29133827 PMCID: PMC5684190 DOI: 10.1038/s41598-017-15648-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 10/23/2017] [Indexed: 12/02/2022] Open
Abstract
Integration target site is the most important factor in successful production of transgenic animals. However, stable expression of transgene without disturbing the function of the host genome depends on promoter methylation, transgene copy number and transcriptional activity in integration regions. Recently, new genome-editing tools have made much progress, however little attention has been paid to the identification of genomic safe harbors. The aim of the present study was to evaluate the effect of insertion site, promoter and copy number of transgene on the production of embryos from cattle fibroblast cells following somatic cell nuclear transfer (SCNT). So, three donor vectors were constructed with EGFP gene under control of different promoters. Each vector was integrated into safe and non-safe harbors in the genome using phiC31 integrase. Transgenic clones with a single copy of each vector were isolated. Each clone was analyzed to find site and frequency of integration, expression level and promoter methylation before SCNT, as well as transgene expression level and blastocyst formation rate after SCNT. The data obtained demonstrated that BF5, as a safe harbor, not only showed a stable expression, but also the rate of in vitro-produced embryos from BF5-clones are similar to that of non-transfected cells.
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Luo Y, Wang Y, Liu J, Lan H, Shao M, Yu Y, Quan F, Zhang Y. Production of transgenic cattle highly expressing human serum albumin in milk by phiC31 integrase-mediated gene delivery. Transgenic Res 2015. [PMID: 26198751 DOI: 10.1007/s11248-015-9898-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transgenic cattle expressing high levels of recombinant human serum albumin (HSA) in their milk may as an alternative source for commercial production. Our objective was to produce transgenic cattle highly expressing HSA in milk by using phiC31 integrase system and somatic cell nuclear transfer (SCNT). The mammary-specific expression plasmid pIACH(-), containing the attB recognition site for phiC31 integrase, were co-transfected with integrase expression plasmid pCMVInt into bovine fetal fibroblast cells (BFFs). PhiC31 integrase-mediated integrations in genome of BFFs were screened by nested inverse PCR. After analysis of sequence of the PCR products, 46.0% (23/50) of the both attB-genome junction sites (attL and attR) were confirmed, and four pseudo attP sites were identified. The integration rates in BF3, BF11, BF19 and BF4 sites were 4.0% (2/50), 6.0% (3/50), 16.0% (8/50) and 20.0% (10/50), respectively. BF3 is located in the bovine chromosome 3 collagen alpha-3 (VI) chain isomer 2 gene, while the other three sites are located in the non-coding region. The transgenic cell lines from BF11, BF19 and BF4 sites were used as donors for SCNT. Two calves from transgenic cells BF19 were born, one died within a few hours after birth, and another calf survived healthy. PCR and Southern blot analysis revealed integration of the transgene in the genome of cloned calves. The nested reverse PCR confirmed that the integration site in cloned calves was identical to the donor cells. The western blotting assessment indicated that recombinant HSA was expressed in the milk of transgenic cattle and the expression level was about 4-8 mg/mL. The present study demonstrated that phiC31 integrase system was an efficient and safety gene delivery tool for producing HSA transgenic cattle. The production of recombinant HSA in the milk of cattle may provide a large-scale and cost-effective resource.
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Affiliation(s)
- Yan Luo
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Yongsheng Wang
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Jun Liu
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Hui Lan
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Minghao Shao
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Yuan Yu
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Fusheng Quan
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China
| | - Yong Zhang
- College of Veterinary Medicine, Northwest A&F University, Key Laboratory of Animal Biotechnology of the Ministry of Agriculture, Yangling, 712100, Shaanxi, China.
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Klymiuk N, Fezert P, Wünsch A, Kurome M, Kessler B, Wolf E. Homologous recombination contributes to the repair of zinc-finger-nuclease induced double strand breaks in pig primary cells and facilitates recombination with exogenous DNA. J Biotechnol 2014; 177:74-81. [DOI: 10.1016/j.jbiotec.2014.01.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 10/25/2022]
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