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Slack J, Nguyen C, Ibe-Enwo A. A Lac Repressor-Inducible Baculovirus Expression Vector for Controlling Adeno-Associated Virus Capsid Ratios. Viruses 2023; 16:51. [PMID: 38257750 PMCID: PMC10820722 DOI: 10.3390/v16010051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 12/19/2023] [Accepted: 12/23/2023] [Indexed: 01/24/2024] Open
Abstract
The baculovirus expression vector (BEV) system is an efficient, cost-effective, and scalable method to produce recombinant adeno-associated virus (rAAV) gene therapy vectors. Most BEV designs emulate the wild-type AAV transcriptome and translate the AAV capsid proteins, VP1, VP2, and VP3, from a single mRNA transcript with three overlapping open reading frames (ORFs). Non-canonical translation initiation codons for VP1 and VP2 reduce their abundances relative to VP3. Changing capsid ratios to improve rAAV vector efficacy requires a theoretical modification of the translational context. We have developed a Lac repressor-inducible system to empirically regulate the expression of VP1 and VP2 proteins relative to VP3 in the context of the BEV. We demonstrate the use of this system to tune the abundance, titer, and potency of a neurospecific rAAV9 serotype derivative. VP1:VP2:VP3 ratios of 1:1:8 gave optimal potency for this rAAV. It was discovered that the ratios of capsid proteins expressed were different than the ratios that ultimately were in purified capsids. Overexpressed VP1 did not become incorporated into capsids, while overexpressed VP2 did. Overabundance of VP2 correlated with reduced rAAV titers. This work demonstrates a novel technology for controlling the production of rAAV in the BEV system and shows a new perspective on the biology of rAAV capsid assembly.
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Affiliation(s)
- Jeffrey Slack
- Voyager Therapeutics, 64 Sidney St., Cambridge, MA 02139, USA;
| | | | - Amanda Ibe-Enwo
- Voyager Therapeutics, 64 Sidney St., Cambridge, MA 02139, USA;
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2
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Tan S, Dong H, Sun S, Guo H. [Construction of foot-and-mouth disease virus like particles-induced expression vectors and screening of BHK-21 cell pools]. Sheng Wu Gong Cheng Xue Bao 2023; 39:4849-4860. [PMID: 38147986 DOI: 10.13345/j.cjb.230114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Transient expression is the major method to express foot-and-mouth disease virus (FMDV) capsid proteins in mammalian cells. To achieve stable expression of FMDV capsid proteins and efficient assembly of virus like particles (VLPs) in cells, the plasmids of piggyBac (PB) transposon-constitutive expression and PB transposon-tetracycline (Tet) inducible expression vectors were constructed. The function of the plasmids was tested by fluorescent proteins. By adding antibiotics, the constitutive cell pools (C-WT, C-L127P) expressing P12A3C (WT/L127P) genes and the inducible cell pools (I-WT, I-L127P) expressing P12A3C (WT/L127P) genes were generated. The genes of green fluorescent protein, 3C protease and reverse tetracycline transactivator (rtTA) were integrated into chromosome, which was confirmed by fluorescence observation and PCR testing. The cell pool I-L127P has a stronger production capacity of capsid proteins and VLPs, which was confirmed by Western blotting and enzyme linked immunosorbent assay (ELISA), respectively. In conclusion, inducing the chromosomal expression of FMDV capsid proteins was firstly reported, which may facilitate the technical process of mammalian production of FMDV VLPs vaccine and the construction of mammalian inducible expression systems for other proteins.
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Affiliation(s)
- Shuzhen Tan
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, Gansu, China
| | - Hu Dong
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, Gansu, China
| | - Shiqi Sun
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, Gansu, China
| | - Huichen Guo
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, Gansu, China
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou 730070, Gansu, China
- Yunnan Provincial Key Laboratory of Tropical and Subtropical Animal Viral Diseases, Yunnan Academy of Animal Husbandry and Veterinary Sciences, Kunming 650224, Yunnan, China
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3
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Ma Y, Guo N, Li X, Jiang Z, Zhang D, Guo L, Wang Y. Development of an Efficient Recombinant Protein Expression System in Clostridium saccharoperbutylacetonicum Based on the Bacteriophage T7 System. ACS Synth Biol 2023; 12:3092-3105. [PMID: 37712503 DOI: 10.1021/acssynbio.3c00439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Recombinant proteins have broad applications. However, there is a lack of a recombinant protein expression system specifically for large-scale production in anaerobic hosts. Here, we developed a powerful and stringently inducible protein expression system based on the bacteriophage T7 system in the strictly anaerobic solvent-producing Clostridium saccharoperbutylacetonicum. With the integration of a codon optimized T7 RNA polymerase into the chromosome, a single plasmid carrying a T7 promoter could efficiently drive high-level expression of the target gene in an orthogonal manner, which was tightly regulated by a lactose-inducible system. Furthermore, by deleting beta-galactosidase genes involved in lactose metabolism, the transcriptional strength was further improved. In the ultimately optimized strain TM-07, the transcriptional strength of the T7 promoter showed 9.5-fold increase compared to the endogenous strong promoter Pthl. The heterologous NADP+-dependent 3-hydroxybutyryl-CoA dehydrogenase (Hbd1) from C. kluyveri was expressed in TM-07, and the yield of the recombinant protein reached 30.4-42.4% of the total cellular protein, surpassing the strong protein expression systems in other Gram-positive bacteria. The relative activity of Hbd1 in the crude enzyme was 198.0 U/mg, which was 8.3-fold higher than the natural activity in C. kluyveri. The relative activity of the purified enzyme reached 467.4 U/mg. To the best of our knowledge, this study represents the first application of the T7 expression system in Clostridium species, and this optimized expression system holds great potential for large-scale endotoxin-free recombinant protein production under strictly anaerobic conditions. This development paves the way for significant advancements in biotechnology and opens up new avenues for industrial applications.
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Affiliation(s)
- Yuechao Ma
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
| | - Na Guo
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
| | - Xiao Li
- Department of Crop, Soil and Environmental Sciences, Auburn University, Auburn, Alabama 36849, United States
| | - Zhihua Jiang
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - Dunhua Zhang
- Aquatic Animal Health Research Unit, Agricultural Research Service, USDA, Auburn, Alabama 36832, United States
| | - Liang Guo
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yi Wang
- Department of Biosystems Engineering, Auburn University, Auburn, Alabama 36849, United States
- Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
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Maltais JS, Lord-Dufour S, Morasse A, Stuible M, Loignon M, Durocher Y. Repressing expression of difficult-to-express recombinant proteins during the selection process increases productivity of CHO stable pools. Biotechnol Bioeng 2023; 120:2840-2852. [PMID: 37232536 DOI: 10.1002/bit.28435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/04/2023] [Accepted: 05/09/2023] [Indexed: 05/27/2023]
Abstract
More than half of licensed therapeutic recombinant proteins (r-proteins) are manufactured using constitutively-expressing, stably-transfected Chinese hamster ovary (CHO) clones. While constitutive CHO expression systems have proven their efficacy for the manufacturing of monoclonal antibodies, many next-generation therapeutics such as cytokines and bispecific antibodies as well as biological targets such as ectodomains of transmembrane receptors remain intrinsically challenging to produce. Herein, we exploited a cumate-inducible CHO platform allowing reduced expression of various classes of r-proteins during selection of stable pools. Following stable pool generation, fed-batch productions showed that pools generated without cumate (OFF-pools) were significantly more productive than pools selected in the presence of cumate (ON-pools) for 8 out of the 10 r-proteins tested, including cytokines, G-protein coupled receptors (GPCRs), the HVEM membrane receptor ectodomain, the multifunctional protein High Mobility Group protein B1 (HMGB1), as well as monoclonal and bispecific T-cell engager antibodies. We showed that OFF-pools contain a significantly larger proportion of cells producing high levels of r-proteins and that these cells tend to proliferate faster when expression is turned off, suggesting that r-protein overexpression imposes a metabolic burden on the cells. Cell viability was lower and pool recovery was delayed during selection of ON-pools (mimicking constitutive expression), suggesting that high producers were likely lost or overgrown by faster-growing, low-producing cells. We also observed a correlation between the expression levels of the GPCRs with Binding immunoglobulin Protein, an endoplasmic reticulum (ER) stress marker. Taken together, these data suggest that using an inducible system to minimize r-protein expression during stable CHO pool selection reduces cellular stresses, including ER stress and metabolic burden, leading to pools with greater frequency of high-expressing cells, resulting in improved volumetric productivity.
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Affiliation(s)
- Jean-Sébastien Maltais
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Simon Lord-Dufour
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Audrey Morasse
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Matthew Stuible
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Martin Loignon
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
| | - Yves Durocher
- Mammalian Cell Expression, Human Health Therapeutics Research Centre, National Research Council Canada, Montréal, Québec, Canada
- Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
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Kretz J, Israel V, McIntosh M. Design-Build-Test of Synthetic Promoters for Inducible Gene Regulation in Alphaproteobacteria. ACS Synth Biol 2023; 12:2663-2675. [PMID: 37561940 DOI: 10.1021/acssynbio.3c00251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Inducible gene expression is useful for biotechnological applications and for studying gene regulation and function in bacteria. Many inducible systems that perform in model organisms such as the Gammaproteobacterium Escherichia coli do not perform well in other bacteria that are of biotechnological interest. Typical problems include weak or leaky expression. Here, we describe an invention named ACIT (Alphaproteobacteria chromosomally integrating transcription-control cassette) that is carried on a suicide plasmid to enable insertion into the chromosome of the host. ACIT consists of multiple DNA fragments specifically arranged in a cassette that allows tight transcription control over any gene or gene cluster of interest following homologous recombination. At the heart of the invention is the ability to modify or exchange parts, e.g., promoters, to suit particular bacteria and growth conditions, allowing for customized gene expression control. Furthermore, ACIT provides a basis for a design-build-test approach for controlling gene expression in less studied bacteria. We describe examples of its control over pigment and exopolysaccharide production, growth, cell form, and social behavior in various Alphaproteobacteria.
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Affiliation(s)
- Jonas Kretz
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
| | - Vera Israel
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
| | - Matthew McIntosh
- Institute of Microbiology and Molecular Biology, IFZ, Justus-Liebig-Universität, 35292 Giessen, Germany
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Jalšić L, Lytvyn V, Elahi SM, Hrapovic S, Nassoury N, Chahal PS, Gaillet B, Gilbert R. Inducible HEK293 AAV packaging cell lines expressing Rep proteins. Mol Ther Methods Clin Dev 2023; 30:259-275. [PMID: 37560197 PMCID: PMC10407821 DOI: 10.1016/j.omtm.2023.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 07/11/2023] [Indexed: 08/11/2023]
Abstract
Packaging or producer cell lines for scalable recombinant adeno-associated virus (rAAV) production have been notoriously difficult to create due in part to the cytostatic nature of the Rep proteins required for AAV production. The most difficult challenge being creating AAV packaging cell lines using HEK293 parental cells, currently the best mammalian platform for rAAV production due to the constitutive expression of E1A in HEK293 cells, a key REP transcription activator. Using suspension and serum-free media adapted HEK293SF carrying a gene expression regulation system induced by addition of cumate and coumermycin, we were able to create REP-expressing AAV packaging cells. This was achieved by carefully choosing two of the AAV Rep proteins (Rep 40 and 68), using two inducible promoters with different expression levels and integrating into the cells through lentiviral vector transduction. Three of our best clones produced rAAV titers comparable to titers obtained by standard triple plasmid transfection of their parental cells. These clones were stable for up to 7 weeks under continuous cultures condition. rAAV production from one clone was also validated at scale of 1 L in a wave bioreactor using serum-free suspension culture.
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Affiliation(s)
- Lovro Jalšić
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Viktoria Lytvyn
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Seyyed Mehdy Elahi
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Sabahudin Hrapovic
- Advanced Biomaterials and Chemical Synthesis Team, Aquatic and Crop Resource Development Research Centre, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Nasha Nassoury
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Parminder Singh Chahal
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Bruno Gaillet
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
| | - Rénald Gilbert
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
- Department of Bioengineering, McGill University, Montréal, QC H3A 0E9 Canada
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Horch R, Rasp D, Dietz A, Ebbert R, Steinmann J, Schaible UE, Mamat U, Bertram R. tet-Dependent Gene Expression in Stenotrophomonas maltophilia. Microbiol Spectr 2023; 11:e0157623. [PMID: 37378537 PMCID: PMC10434252 DOI: 10.1128/spectrum.01576-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 06/20/2023] [Indexed: 06/29/2023] Open
Abstract
Stenotrophomonas maltophilia is increasingly recognized as an important nosocomial pathogen among the Gram-negative bacteria. Intrinsic resistance to different classes of antibiotics makes treatment of infections challenging. A deeper understanding of S. maltophilia physiology and virulence requires molecular genetic tools. Here, we describe the implementation of tetracycline-dependent gene regulation (tet regulation) in this bacterium. The exploited tet regulatory sequence of transposon Tn10 contained the tetR gene and three intertwined promoters, one of which was required for regulated expression of a target gene or operon. The episomal tet architecture was tested with a gfp variant as a quantifiable reporter. Fluorescence intensity was directly correlated with the concentration of the inducer anhydrotetracycline (ATc) applied and the duration of induction. Also, the expression of the rmlBACD operon of S. maltophilia K279a was subjected to tet control. These genes code for the synthesis of dTDP-l-rhamnose, an activated nucleotide sugar precursor of lipopolysaccharide (LPS) formation. A ΔrmlBACD mutant was complemented with a plasmid carrying this operon downstream of the tet sequence. In the presence of ATc, the LPS pattern was similar to that of wild-type S. maltophilia, whereas without the inducer, fewer and apparently shorter O-antigen chains were detected. This underscores the functionality and usefulness of the tet system for gene regulation and, prospectively, the validation of targets for new anti-S. maltophilia drugs. IMPORTANCE Stenotrophomonas maltophilia is an emerging pathogen in hospital settings and poses a threat to immunocompromised patients. Due to a high level of resistance to different types of antibiotics, treatment options are limited. We here adapted a tool for inducible expression of genes of interest, known as the tet system, to S. maltophilia. Genes relevant to producing surface carbohydrate structures (lipopolysaccharide [LPS]) were placed under the control of the tet system. In the presence of an inducer, the LPS pattern was similar to that of wild-type S. maltophilia, whereas in the "off" state of the system (without inducer), fewer and apparently shorter versions of LPS were detected. The tet system is functional in S. maltophilia and may be helpful to reveal gene-function relationships to gain a deeper understanding of the bacterium's physiology and virulence.
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Affiliation(s)
- Rebecca Horch
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Diana Rasp
- Study Program in Human Medicine, Paracelsus Medical University, Nuremberg, Germany
| | - Annika Dietz
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Ronald Ebbert
- Technische Hochschule Nürnberg Georg Simon Ohm, Faculty of Applied Chemistry, Nuremberg, Germany
| | - Joerg Steinmann
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
| | - Ulrich E. Schaible
- Department of Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, Leibniz Research Alliance INFECTIONS, Borstel, Germany
| | - Uwe Mamat
- Department of Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, Leibniz Research Alliance INFECTIONS, Borstel, Germany
| | - Ralph Bertram
- Institute of Clinical Hygiene, Medical Microbiology and Infectiology, Klinikum Nürnberg, Paracelsus Medical University, Nuremberg, Germany
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Di D, Huang Q, Ly H, Liang Y. Evaluating the Biological Role of Lassa Viral Z Protein-Mediated RIG-I Inhibition Using a Replication-Competent Trisegmented Pichinde Virus System in an Inducible RIG-IN Expression Cell Line. J Virol 2022; 96:e0075422. [PMID: 35913216 PMCID: PMC9400496 DOI: 10.1128/jvi.00754-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 07/14/2022] [Indexed: 02/03/2023] Open
Abstract
Lassa virus (LASV) is a mammarenavirus that can cause lethal Lassa fever disease with no FDA-approved vaccine and limited treatment options. Fatal LASV infections are associated with innate immune suppression. We have previously shown that the small matrix Z protein of LASV, but not of a nonpathogenic arenavirus Pichinde virus (PICV), can inhibit the cellular RIG-I-like receptors (RLRs), but its biological significance has not been evaluated in an infectious virus due to the multiple essential functions of the Z protein required for the viral life cycle. In this study, we developed a stable HeLa cell line (HeLa-iRIGN) that could be rapidly and robustly induced by doxycycline (Dox) treatment to express RIG-I N-terminal effector, with concomitant production of type I interferons (IFN-Is). We also generated recombinant tri-segmented PICVs, rP18tri-LZ, and rP18tri-PZ, which encode LASV Z and PICV Z, respectively, as an extra mScarlet fusion protein that is nonessential for the viral life cycle. Upon infection, rP18tri-LZ consistently expressed viral genes at a higher level than rP18tri-PZ. rP18tri-LZ also showed a higher level of a viral infection than rP18tri-PZ did in HeLa-iRIGN cells, especially upon Dox induction. The heterologous Z gene did not alter viral growth in Vero and A549 cells by growth curve analysis, while LASV Z strongly increased and prolonged viral gene expression, especially in IFN-competent A549 cells. Our study provides important insights into the biological role of LASV Z-mediated RIG-I inhibition and implicates LASV Z as a potential virulence factor. IMPORTANCE Lassa virus (LASV) can cause lethal hemorrhagic fever disease in humans but other arenaviruses, such as Pichinde virus (PICV), do not cause obvious disease. We have previously shown that the Z protein of LASV but not of PICV can inhibit RIG-I, a cytosolic innate immune receptor. In this study, we developed a stable HeLa cell line that can be induced to express the RIG-I N-terminal effector domain, which allows for timely control of RIG-I activation. We also generated recombinant PICVs encoding LASV Z or PICV Z as an extra gene that is nonessential for the viral life cycle. Compared to PICV Z, LASV Z could increase viral gene expression and viral infection in an infectious arenavirus system, especially when RIG-I signaling is activated. Our study presented a convenient cell system to characterize RIG-I signaling and its antagonists and revealed LASV Z as a possible virulence factor and a potential antiviral target.
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Affiliation(s)
- Da Di
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, USA
| | - Qinfeng Huang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, USA
| | - Hinh Ly
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, USA
| | - Yuying Liang
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota, USA
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Zandalinas SI, Song L, Nechushtai R, Mendoza-Cozatl DG, Mittler R. The Cluster Transfer Function of AtNEET Supports the Ferredoxin-Thioredoxin Network of Plant Cells. Antioxidants (Basel) 2022; 11:1533. [PMID: 36009251 DOI: 10.3390/antiox11081533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/29/2022] [Accepted: 08/05/2022] [Indexed: 11/16/2022] Open
Abstract
NEET proteins are conserved 2Fe-2S proteins that regulate the levels of iron and reactive oxygen species in plant and mammalian cells. Previous studies of seedlings with constitutive expression of AtNEET, or its dominant-negative variant H89C (impaired in 2Fe-2S cluster transfer), revealed that disrupting AtNEET function causes oxidative stress, chloroplast iron overload, activation of iron-deficiency responses, and cell death. Because disrupting AtNEET function is deleterious to plants, we developed an inducible expression system to study AtNEET function in mature plants using a time-course proteomics approach. Here, we report that the suppression of AtNEET cluster transfer function results in drastic changes in the expression of different members of the ferredoxin (Fd), Fd-thioredoxin (TRX) reductase (FTR), and TRX network of Arabidopsis, as well as in cytosolic cluster assembly proteins. In addition, the expression of Yellow Stripe-Like 6 (YSL6), involved in iron export from chloroplasts was elevated. Taken together, our findings reveal new roles for AtNEET in supporting the Fd-TFR-TRX network of plants, iron mobilization from the chloroplast, and cytosolic 2Fe-2S cluster assembly. In addition, we show that the AtNEET function is linked to the expression of glutathione peroxidases (GPXs), which play a key role in the regulation of ferroptosis and redox balance in different organisms.
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Meng W, Qiao K, Zhang W, Liu F, Gao X, Hu X, Zhu J. Development and Application of a New Arabinose-Inducible Vector in High-Attachment Strain Stenotrophomonas AGS-1 from Aerobic Granular Sludge. ACS Synth Biol 2022; 11:69-76. [PMID: 34989221 DOI: 10.1021/acssynbio.1c00446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To explore the molecular structure of attachment genes, we constructed and characterized a new arabinose-inducible vector for the high-attachment strain Stenotrophomonas AGS-1 isolated from aerobic granular sludge (AGS). mCherry was used as a simple observation biomarker, and the araC-PBAD-inducible promoter was chosen to artificially regulate the expression of target genes. The system achieved little leaky basal expression and high maximal induced expression. The araC-PBAD-based inducible expression was modulated over a wide range of 0.0005 to 0.2% l-arabinose. Notably, a "lag expression" phenomenon was observed in which mCherry was expressed after bacterial growth in LB medium. Using the system and the strategy of fusion expression of target genes (rmlA and AsCas12a) plus mCherry, the recombinant AGS-1 strain achieved the effective induction of rmlA and AsCas12a-mCherry gene expression in the range of 0.0005 to 0.1% l-arabinose. These results demonstrate that the new arabinose-inducible vector could be used as an important molecular tool in the gene function and genome-editing research of strain AGS-1.
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Affiliation(s)
- Wei Meng
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
| | - Kai Qiao
- School of Environment, Beijing Normal University, Beijing 100875, China
- State Key Laboratory of Water Simulation, Beijing 100875, China
| | - Wei Zhang
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
| | - Fan Liu
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xu Gao
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xuan Hu
- School of Environment, Beijing Normal University, Beijing 100875, China
- State Key Laboratory of Water Simulation, Beijing 100875, China
| | - Jianrong Zhu
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
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Sathesh-Prabu C, Ryu YS, Lee SK. Levulinic Acid-Inducible and Tunable Gene Expression System for Methylorubrum extorquens. Front Bioeng Biotechnol 2022; 9:797020. [PMID: 34976985 PMCID: PMC8714952 DOI: 10.3389/fbioe.2021.797020] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/17/2021] [Indexed: 11/13/2022] Open
Abstract
Methylorubrum extorquens AM1 is an efficient platform strain possessing biotechnological potential in formate- and methanol-based single carbon (C1) bioeconomy. Constitutive expression or costly chemical-inducible expression systems are not always desirable. Here, several glucose-, xylose-, and levulinic acid (LA)-inducible promoter systems were assessed for the induction of green fluorescent protein (GFP) as a reporter protein. Among them, the LA-inducible gene expression system (HpdR/P hpdH ) showed a strong expression of GFP (51-fold) compared to the control. The system was induced even at a low concentration of LA (0.1 mM). The fluorescence intensity increased with increasing concentrations of LA up to 20 mM. The system was tunable and tightly controlled with meager basal expression. The maximum GFP yield obtained using the system was 42 mg/g biomass, representing 10% of the total protein content. The efficiency of the proposed system was nearly equivalent (90%-100%) to that of the widely used strong promoters such as P mxaF and P L/O4 . The HpdR/P hpdH system worked equally efficiently in five different strains of M. extorquens. LA is a low-cost, renewable, and sustainable platform chemical that can be used to generate a wide range of products. Hence, the reported system in potent strains of M. extorquens is highly beneficial in the C1-biorefinery industry to produce value-added products and bulk chemicals.
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Affiliation(s)
- Chandran Sathesh-Prabu
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Young Shin Ryu
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Sung Kuk Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea.,Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
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12
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Lam CKC, Truong K. Design of a synthesis-friendly hypoxia-responsive promoter for cell-based therapeutics. Eng Life Sci 2021; 21:848-856. [PMID: 34899121 PMCID: PMC8638314 DOI: 10.1002/elsc.202100045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/11/2021] [Accepted: 10/16/2021] [Indexed: 11/24/2022] Open
Abstract
Towards the goal of making 'smart' cell therapies, one that recognizes disease conditions (e.g. hypoxia) and then produces mitigating biologics, it is important to develop suitable promoters. Currently, hypoxia responsive promoters are composed of strongly repeated sequences containing hypoxia response elements upstream of a minimal core promoter. Unfortunately, such repeated sequences have inherent genomic instability that may compromise the long-term consistency of cell-based therapeutics. Thus, we designed a synthesis-friendly hypoxia-inducible promoter (named SFHp) that has GC content between 25% and 75% and no repeats greater than 9 base pairs. In HEK293 cells stably integrated with genes regulated by synthetic SFHp, we demonstrated inducible reporter expression with fluorescent proteins, cell morphology rewiring with our previously engineered RhoA protein and intercellular cell signalling with secreted cytokines. These experiments exemplify the potential usage of SFHp in cell-based therapeutics with integrated genetic circuits that inducibly respond to the disease microenvironment.
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Affiliation(s)
| | - Kevin Truong
- Institute of Biomedical EngineeringUniversity of TorontoTorontoONCanada
- Edward S. RogersSr. Department of Electrical and Computer EngineeringUniversity of TorontoTorontoONCanada
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13
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Berg MD, Isaacson JR, Cozma E, Genereaux J, Lajoie P, Villén J, Brandl CJ. Regulating Expression of Mistranslating tRNAs by Readthrough RNA Polymerase II Transcription. ACS Synth Biol 2021; 10:3177-3189. [PMID: 34726901 PMCID: PMC8765249 DOI: 10.1021/acssynbio.1c00461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
Transfer RNA (tRNA)
variants that alter the genetic code increase
protein diversity and have many applications in synthetic biology.
Since the tRNA variants can cause a loss of proteostasis, regulating
their expression is necessary to achieve high levels of novel protein.
Mechanisms to positively regulate transcription with exogenous activator
proteins like those often used to regulate RNA polymerase II (RNAP
II)-transcribed genes are not applicable to tRNAs as their expression
by RNA polymerase III requires elements internal to the tRNA. Here,
we show that tRNA expression is repressed by overlapping transcription
from an adjacent RNAP II promoter. Regulating the expression of the
RNAP II promoter allows inverse regulation of the tRNA. Placing either
Gal4- or TetR–VP16-activated promoters downstream of a mistranslating
tRNASer variant that misincorporates serine at proline
codons in Saccharomyces cerevisiae allows
mistranslation at a level not otherwise possible because of the toxicity
of the unregulated tRNA. Using this inducible tRNA system, we explore
the proteotoxic effects of mistranslation on yeast cells. High levels
of mistranslation cause cells to arrest in the G1 phase. These cells
are impermeable to propidium iodide, yet growth is not restored upon
repressing tRNA expression. High levels of mistranslation increase
cell size and alter cell morphology. This regulatable tRNA expression
system can be applied to study how native tRNAs and tRNA variants
affect the proteome and other biological processes. Variations of
this inducible tRNA system should be applicable to other eukaryotic
cell types.
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Affiliation(s)
- Matthew D. Berg
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Joshua R. Isaacson
- Department of Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Ecaterina Cozma
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Julie Genereaux
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Patrick Lajoie
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Judit Villén
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Christopher J. Brandl
- Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada
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Jiang YH, Liu YF, Wang K, Zhou JY, Guo F, Zhao QW, Mao XM. Fine-Tuning Cas9 Activity with a Cognate Inhibitor AcrIIA4 to Improve Genome Editing in Streptomyces. ACS Synth Biol 2021; 10:2833-2841. [PMID: 34734710 DOI: 10.1021/acssynbio.1c00141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Efficient enabling technology is required for synthetic biology in Streptomyces due to its natural product reservoir. Though the CRISPR-Cas9 system is powerful for genome editing in this genus, the proposed Cas9 toxicity has limited its application. Here on the basis of previous inducible Cas9 expression at the transcriptional and translational levels coupled with atpD overexpression, a Cas9 cognate inhibitor AcrIIA4 was further introduced to fine-tune the Cas9 activity. In both laboratory and industrial Streptomyces species, we showed that, compared to the constitutively expressed Cas9, incorporating AcrIIA4 increased the conjugation efficiency from 700- to 7000-fold before induction, while a comparable 65%-90% editing efficiency was obtained even on multiple loci for simultaneous deletion after Cas9 expression was induced, along with no significant off-targets. Thus, AcrIIA4 could be a modulator to control Cas9 activity to significantly improve genome editing, and this new toolkit would be widely adaptable and fasten genetic engineering in Streptomyces.
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Affiliation(s)
- Yu-Hang Jiang
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolic Engineering, Hangzhou 310058, China
| | - Yi-Fan Liu
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolic Engineering, Hangzhou 310058, China
| | - Kai Wang
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolic Engineering, Hangzhou 310058, China
| | - Jing-Yi Zhou
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolic Engineering, Hangzhou 310058, China
| | - Fengzhu Guo
- Zhejiang Silver-Elephant Bio-engineering Co., Ltd. No 18 Shifeng Road E., Fuxi Sub-district, Tiantai 317200, Zhejiang Province China
| | - Qing-Wei Zhao
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
| | - Xu-Ming Mao
- Research Center for Clinical Pharmacy, The First Affiliated Hospital & Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolic Engineering, Hangzhou 310058, China
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15
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Okombo J, Kanai M, Deni I, Fidock DA. Genomic and Genetic Approaches to Studying Antimalarial Drug Resistance and Plasmodium Biology. Trends Parasitol 2021; 37:476-492. [PMID: 33715941 PMCID: PMC8162148 DOI: 10.1016/j.pt.2021.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 12/14/2022]
Abstract
Recent progress in genomics and molecular genetics has empowered novel approaches to study gene functions in disease-causing pathogens. In the human malaria parasite Plasmodium falciparum, the application of genome-based analyses, site-directed genome editing, and genetic systems that allow for temporal and quantitative regulation of gene and protein expression have been invaluable in defining the genetic basis of antimalarial resistance and elucidating candidate targets to accelerate drug discovery efforts. Using examples from recent studies, we review applications of some of these approaches in advancing our understanding of Plasmodium biology and illustrate their contributions and limitations in characterizing parasite genomic loci associated with antimalarial drug responses.
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Affiliation(s)
- John Okombo
- Department of Microbiology & Immunology, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Mariko Kanai
- Department of Microbiology & Immunology, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - Ioanna Deni
- Department of Microbiology & Immunology, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - David A Fidock
- Department of Microbiology & Immunology, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA; Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA.
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16
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Kelly CL, Taylor GM, Šatkutė A, Dekker L, Heap JT. Transcriptional Terminators Allow Leak-Free Chromosomal Integration of Genetic Constructs in Cyanobacteria. Microorganisms 2019; 7:microorganisms7080263. [PMID: 31426276 PMCID: PMC6723963 DOI: 10.3390/microorganisms7080263] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/09/2019] [Accepted: 08/12/2019] [Indexed: 01/10/2023] Open
Abstract
Cyanobacteria are promising candidates for sustainable bioproduction of chemicals from sunlight and carbon dioxide. However, the genetics and metabolism of cyanobacteria are less well understood than those of model heterotrophic organisms, and the suite of well-characterised cyanobacterial genetic tools and parts is less mature and complete. Transcriptional terminators use specific RNA structures to halt transcription and are routinely used in both natural and recombinant contexts to achieve independent control of gene expression and to ‘insulate’ genes and operons from one another. Insulating gene expression can be particularly important when heterologous or synthetic genetic constructs are inserted at genomic locations where transcriptional read-through from chromosomal promoters occurs, resulting in poor control of expression of the introduced genes. To date, few terminators have been described and characterised in cyanobacteria. In this work, nineteen heterologous, synthetic or putative native Rho-independent (intrinsic) terminators were tested in the model freshwater cyanobacterium, Synechocystis sp. PCC 6803, from which eleven strong terminators were identified. A subset of these strong terminators was then used to successfully insulate a chromosomally–integrated, rhamnose-inducible rhaBAD expression system from hypothesised ‘read-through’ from a neighbouring chromosomal promoter, resulting in greatly improved inducible control. The addition of validated strong terminators to the cyanobacterial toolkit will allow improved independent control of introduced genes.
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Affiliation(s)
- Ciarán L Kelly
- Imperial College Centre for Synthetic Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - George M Taylor
- Imperial College Centre for Synthetic Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Aistė Šatkutė
- Imperial College Centre for Synthetic Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Linda Dekker
- Imperial College Centre for Synthetic Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - John T Heap
- Imperial College Centre for Synthetic Biology, Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
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17
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Lin X, Guo C, Li L, Li T, Lin S. Non-Conventional Metal Ion Cofactor Requirement of Dinoflagellate Alkaline Phosphatase and Translational Regulation by Phosphorus Limitation. Microorganisms 2019; 7:E232. [PMID: 31374942 DOI: 10.3390/microorganisms7080232] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/15/2019] [Accepted: 07/30/2019] [Indexed: 12/30/2022] Open
Abstract
Alkaline phosphatase (AP) enables marine phytoplankton to utilize dissolved organic phosphorus (DOP) when dissolved inorganic phosphate (DIP) is depleted in the ocean. Dinoflagellate AP (Dino-AP) represents a newly classified atypical type of AP, PhoAaty. Despite While being a conventional AP, PhoAEC is known to recruit Zn2+ and Mg2+ in the active center, and the cofactors required by PhoAaty have been contended and remain unclear. In this study, we investigated the metal ion requirement of AP in five dinoflagellate species. After AP activity was eliminated by using EDTA to chelate metal ions, the enzymatic activity could be recovered by the supplementation of Ca2+, Mg2+ and Mn2+ in all cases but not by that of Zn2+. Furthermore, the same analysis conducted on the purified recombinant ACAAP (AP of Amphidinium carterae) verified that the enzyme could be activated by Ca2+, Mg2+, and Mn2+ but not Zn2+. We further developed an antiserum against ACAAP, and a western blot analysis using this antibody showed a remarkable up-regulation of ACAAP under a phosphate limitation, consistent with elevated AP activity. The unconventional metal cofactor requirement of Dino-AP may be an adaptation to trace metal limitations in the ocean, which warrants further research to understand the niche differentiation between dinoflagellates and other phytoplankton that use Zn–Mg AP in utilizing DOP.
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18
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Abstract
Members of the genus Clostridium represent a diverse assemblage of species exhibiting both medical and industrial importance. Deriving both a greater understanding of their biology, while at the same time enhancing their exploitable properties, requires effective genome editing tools. Here, we demonstrate the first implementation in the genus of theophylline-dependent, synthetic riboswitches exhibiting a full set of dynamic ranges, also suitable for applications where tight control of gene expression is required. Their utility was highlighted by generating a novel riboswitch-based editing tool-RiboCas-that overcomes the main obstacles associated with CRISPR/Cas9 systems, including low transformation efficiencies and excessive Cas9 toxicity. The universal nature of the tool was established by obtaining chromosomal modifications in C. pasteurianum, C. difficile, and C. sporogenes, as well as by carrying out the first reported example of CRISPR-targeted gene disruption in C. botulinum. The high efficiency (100% mutant generation) and ease of application of RiboCas make it suitable for use in a diverse range of microorganisms.
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Affiliation(s)
- Inés C. Cañadas
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K
| | - Daphne Groothuis
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K
| | - Maria Zygouropoulou
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K
| | - Raquel Rodrigues
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K
| | - Nigel P. Minton
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD, U.K
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham NG7 2RD, U.K
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19
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Hintze J, Ye Z, Narimatsu Y, Madsen TD, Joshi HJ, Goth CK, Linstedt A, Bachert C, Mandel U, Bennett EP, Vakhrushev SY, Schjoldager KT. Probing the contribution of individual polypeptide GalNAc-transferase isoforms to the O-glycoproteome by inducible expression in isogenic cell lines. J Biol Chem 2018; 293:19064-19077. [PMID: 30327431 PMCID: PMC6295722 DOI: 10.1074/jbc.ra118.004516] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/04/2018] [Indexed: 12/25/2022] Open
Abstract
The GalNAc-type O-glycoproteome is orchestrated by a large family of polypeptide GalNAc-transferase isoenzymes (GalNAc-Ts) with partially overlapping contributions to the O-glycoproteome besides distinct nonredundant functions. Increasing evidence indicates that individual GalNAc-Ts co-regulate and fine-tune specific protein functions in health and disease, and deficiencies in individual GALNT genes underlie congenital diseases with distinct phenotypes. Studies of GalNAc-T specificities have mainly been performed with in vitro enzyme assays using short peptide substrates, but recently quantitative differential O-glycoproteomics of isogenic cells with and without GALNT genes has enabled a more unbiased exploration of the nonredundant contributions of individual GalNAc-Ts. Both approaches suggest that fairly small subsets of O-glycosites are nonredundantly regulated by specific GalNAc-Ts, but how these isoenzymes orchestrate regulation among competing redundant substrates is unclear. To explore this, here we developed isogenic cell model systems with Tet-On inducible expression of two GalNAc-T genes, GALNT2 and GALNT11, in a knockout background in HEK293 cells. Using quantitative O-glycoproteomics with tandem-mass-tag (TMT) labeling, we found that isoform-specific glycosites are glycosylated in a dose-dependent manner and that induction of GalNAc-T2 or -T11 produces discrete glycosylation effects without affecting the major part of the O-glycoproteome. These results support previous findings indicating that individual GalNAc-T isoenzymes can serve in fine-tuned regulation of distinct protein functions.
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Affiliation(s)
- John Hintze
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Zilu Ye
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Yoshiki Narimatsu
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Thomas Daugbjerg Madsen
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Hiren J Joshi
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Christoffer K Goth
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Adam Linstedt
- the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Collin Bachert
- the Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Ulla Mandel
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Eric P Bennett
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Sergey Y Vakhrushev
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
| | - Katrine T Schjoldager
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark and
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20
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Mellahi K, Cambay F, Brochu D, Gilbert M, Perrier M, Ansorge S, Durocher Y, Henry O. Process development for an inducible rituximab-expressing Chinese hamster ovary cell line. Biotechnol Prog 2018; 35:e2742. [PMID: 30414355 DOI: 10.1002/btpr.2742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/25/2018] [Accepted: 10/31/2018] [Indexed: 12/12/2022]
Abstract
Inducible mammalian expression systems are becoming increasingly available and are not only useful for the production of cytotoxic/cytostatic products, but also confer the unique ability to uncouple the growth and production phases. In this work, we have specifically investigated how the cell culture state at the time of induction influences the cumate-inducible expression of recombinant rituximab by a GS-CHO cell line. To this end, cells grown in batch and fed-batch cultures were induced at increasing cell densities (1 to 10 × 10 6 cells/mL). In batch, the cell specific productivity and the product yield were found to reduce with increasing cell density at induction. A dynamic feeding strategy using a concentrated nutrient solution applied prior and postinduction allowed to significantly increase the integral of viable cells and led to a 3-fold increase in the volumetric productivity (1.2 g/L). The highest product yields were achieved for intermediate cell densities at induction, as cultures induced during the late exponential phase (10 × 10 6 cells/mL) were associated with a shortened production phase. The final glycosylation patterns remained however similar, irrespective of the cell density at induction. The kinetics of growth and production in a 2 L bioreactor were largely comparable to shake flasks for a similar cell density at induction. The degree of galactosylation was found to decrease over time, but the final glycan distribution at harvest was consistent to that of the shake flasks cultures. Taken together, our results provide useful insights for the rational development of fed-batch cell culture processes involving inducible CHO cells. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2742, 2019.
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Affiliation(s)
- Kahina Mellahi
- Dept. of Chemical Engineering, École Polytechnique de Montréal, Montréal, QC, H3C 3A7
| | - Florian Cambay
- Dept. of Chemical Engineering, École Polytechnique de Montréal, Montréal, QC, H3C 3A7
| | - Denis Brochu
- Human Health Therapeutics Research Center, National Research Council Canada, Ottawa, ON
| | - Michel Gilbert
- Human Health Therapeutics Research Center, National Research Council Canada, Ottawa, ON
| | - Michel Perrier
- Dept. of Chemical Engineering, École Polytechnique de Montréal, Montréal, QC, H3C 3A7
| | - Sven Ansorge
- Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC
| | - Yves Durocher
- Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC
| | - Olivier Henry
- Dept. of Chemical Engineering, École Polytechnique de Montréal, Montréal, QC, H3C 3A7
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21
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Li S, Han X, Lyu N, Xie Q, Deng H, Mu L, Pan T, Huang X, Wang X, Shi Y, Zhao M. Mechanism and prognostic value of indoleamine 2,3-dioxygenase 1 expressed in hepatocellular carcinoma. Cancer Sci 2018; 109:3726-3736. [PMID: 30264546 PMCID: PMC6272112 DOI: 10.1111/cas.13811] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 09/23/2018] [Accepted: 09/25/2018] [Indexed: 12/13/2022] Open
Abstract
Indoleamine 2,3‐dioxygenase 1 (IDO1) is a tryptophan‐metabolizing enzyme that is widely distributed in normal or malignant tissues and contributes to immunologic tolerance and immune escape. However, in hepatocellular carcinoma (HCC), the characteristics and mechanism of IDO1 expression have not been well defined. In this study, IDO1 expression in tumor cells (T‐IDO1) was frequently detected (109/112) by immunohistochemistry in formalin‐fixed paraffin‐embedded specimens from HCC patients, and the expression patterns were mostly focal (102/109). Expression of T‐IDO1 was significantly associated with the infiltration of CD8+ T cells (P = .043), as well as younger age (<50 years old, P = .02). It was also found that IDO1 had diffuse expression in inflammatory cells in all specimens, which were defined as antigen‐presenting cells. Significant correlations among IDO1,IFNG, and CD8A transcriptional levels were observed in freshly resected HCC specimens; moreover, no constitutive IDO1 expression was detected in HCC cell lines until stimulated by interferon‐γ through the JAK2‐STAT1 signaling pathway, but not type I interferon. Survival analyses showed that increased T‐IDO1 and CD8+ T cell infiltration were significantly associated with superior overall survival (OS) (T‐IDO1, P = .003; CD8+ T cells, P = .004), and T‐IDO1 expression is an independent prognosis factor in both OS and disease‐free survival (OS, P = .007; disease‐free survival, P = .044). These findings indicated that T‐IDO1 expression in HCC is common and is dominantly driven by the host antitumor immune response, which is a favorable prognostic factor in HCC.
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Affiliation(s)
- Shaolong Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Minimally Invasive Interventional Division, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xue Han
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Minimally Invasive Interventional Division, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Ning Lyu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Minimally Invasive Interventional Division, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Qiankun Xie
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,VIP Region, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Haijing Deng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Minimally Invasive Interventional Division, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Luwen Mu
- Department of Vascular Interventional Radiology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Tao Pan
- Department of Vascular Interventional Radiology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xin Huang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Department of Hepatobilliary Oncology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xia Wang
- Department of Pathology, Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yuanyuan Shi
- Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Guangzhou, China
| | - Ming Zhao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Minimally Invasive Interventional Division, Sun Yat-sen University Cancer Center, Guangzhou, China
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22
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Li Y, Jin K, Zhang L, Ding Z, Gu Z, Shi G. Development of an Inducible Secretory Expression System in Bacillus licheniformis Based on an Engineered Xylose Operon. J Agric Food Chem 2018; 66:9456-9464. [PMID: 30129762 DOI: 10.1021/acs.jafc.8b02857] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The xylose operon can be an efficient biological component for regulatory expression uses in Bacillus licheniformis. However, its characteristic susceptibility to carbon catabolite repression (CCR) makes its application inconvenient. In this study, plasmids harboring the wild-type operons from three Bacillus species were constructed and introduced into B. licheniformis. These plasmids ensured secretory expression of maltogenic α-amylase (BLMA) in B. licheniformis under strict regulation. The glucose-mediated CCR was then alleviated by engineering the xylose operon of the expression system. Evidence showed that mutations in the highly conserved nucleotides of the identified catabolite responsive element (cre) consensus sequence prevented association of the regulator CcpA with DNA, thus resulting in an increase in BLMA activity of up to 12-fold. Furthermore, features of this engineered system for inducible expression were investigated. Induction in mid-log phase using 10 g/L xylose at 37 °C was found to be beneficial for promoting the accumulation of recombinant product, and the maximum yield of BlmMA reached 715.4 U/mL. This study contributes to the industrial application of the generally recognized as safe (GRAS) workhorse B. licheniformis.
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Affiliation(s)
- Youran Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Ke Jin
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Liang Zhang
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Zhongyang Ding
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Zhenghua Gu
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
| | - Guiyang Shi
- Key Laboratory of Industrial Biotechnology, Ministry of Education , Jiangnan University , Wuxi 214122 , P. R. China
- National Engineering Laboratory for Cereal Fermentation Technology , Jiangnan University , 1800 Lihu Avenue , Wuxi , Jiangsu Province 214122 , P. R. China
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23
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Abstract
Converging evidence suggest that levels of alpha-synuclein (aSyn) expression play a critical role in Parkinson's disease (PD). Several mutations of the SNCA gene, encoding for aSyn have been associated to either the familial or the sporadic forms of PD. Nonetheless, the mechanism underlying wild-type aSyn-mediated neurotoxicity in neuronal cells as well as its specific driving role in PD pathogenesis has yet to be fully clarified. In this view, the development of proper in vitro cellular systems is a crucial step. In this study, we present a novel human Tet-on human neural stem cell (hNSC) line, in which aSyn timing and level of expression can be tightly experimentally tuned. Induction of aSyn in self-renewing hNSCs leads to progressive formation of aSyn aggregates and impairs their proliferation and cell survival. Furthermore, aSyn induction during the neuronal differentiation process results in reduced neuronal differentiation and increased number of astrocytes and undifferentiated cells in culture. Finally, acute aSyn induction in hNSC-derived dopaminergic neuronal cultures results in cell toxicity. This novel conditional in vitro cell model system may be a valuable tool for dissecting of aSyn pathogenic effects in hNSCs and neurons and in developing new potential therapeutic strategies.
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Affiliation(s)
- Jacopo Zasso
- Centre for Integrative Biology-CIBIO, Università degli Studi di Trento , Trento, Italy
| | - Mastad Ahmed
- Centre for Integrative Biology-CIBIO, Università degli Studi di Trento , Trento, Italy
| | - Alessandro Cutarelli
- Centre for Integrative Biology-CIBIO, Università degli Studi di Trento , Trento, Italy
| | - Luciano Conti
- Centre for Integrative Biology-CIBIO, Università degli Studi di Trento , Trento, Italy
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24
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Avagliano Trezza R, van den Burg J, van den Oever N, Distel B. A versatile plasmid system for reconstitution and analysis of mammalian ubiquitination cascades in yeast. ACTA ACUST UNITED AC 2017; 5:150-157. [PMID: 29487861 PMCID: PMC5826702 DOI: 10.15698/mic2018.03.620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Ubiquitination is a posttranslational protein modification that regulates most aspects of cellular life. The sheer number of ubiquitination enzymes that are present in a mammalian cell, over 700 in total, has thus far hampered the analysis of distinct protein ubiquitination cascades in a cellular context. To overcome this complexity we have developed a versatile vector system that allows the reconstitution of specific ubiquitination cascades in the model eukaryote Saccharomyces cerevisae (baker’s yeast). The vector system consists of 32 modular yeast shuttle plasmids allowing inducible or constitutive expression of up to four proteins of interest in a single cell. To demonstrate the validity of the system, we show that co-expression in yeast of the mammalian HECT type E3 ubiquitin ligase E6AP (E6-Associated Protein) and a model substrate faithfully recapitulates E6AP-dependent substrate ubiquitination and degradation. In addition, we show that the endogenous sumoylation pathway of S. cerevisiae can specifically sumoylate mouse PML (Promyelocytic leukemia protein). In conclusion, the yeast vector system described in this paper provides a versatile tool to study complex post-translational modifications in a cellular setting.
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Affiliation(s)
- Rossella Avagliano Trezza
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Janny van den Burg
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nico van den Oever
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Ben Distel
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
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25
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Dembek M, Willing SE, Hong HA, Hosseini S, Salgado PS, Cutting SM. Inducible Expression of spo0A as a Universal Tool for Studying Sporulation in Clostridium difficile. Front Microbiol 2017; 8:1793. [PMID: 28983286 PMCID: PMC5613124 DOI: 10.3389/fmicb.2017.01793] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/05/2017] [Indexed: 01/01/2023] Open
Abstract
Clostridium difficile remains a leading nosocomial pathogen, putting considerable strain on the healthcare system. The ability to form endospores, highly resistant to environmental insults, is key to its persistence and transmission. However, important differences exist between the sporulation pathways of C. difficile and the model Gram-positive organism Bacillus subtilis. Amongst the challenges in studying sporulation in C. difficile is the relatively poor levels of sporulation and high heterogeneity in the sporulation process. To overcome these limitations we placed Ptet regulatory elements upstream of the master regulator of sporulation, spo0A, generating a new strain that can be artificially induced to sporulate by addition of anhydrotetracycline (ATc). We demonstrate that this strain is asporogenous in the absence of ATc, and that ATc can be used to drive faster and more efficient sporulation. Induction of Spo0A is titratable and this can be used in the study of the spo0A regulon both in vitro and in vivo, as demonstrated using a mouse model of C. difficile infection (CDI). Insights into differences between the sporulation pathways in B. subtilis and C. difficile gained by study of the inducible strain are discussed, further highlighting the universal interest of this tool. The Ptet-spo0A strain provides a useful background in which to generate mutations in genes involved in sporulation, therefore providing an exciting new tool to unravel key aspects of sporulation in C. difficile.
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Affiliation(s)
- Marcin Dembek
- Institute for Cell and Molecular Biosciences, Newcastle UniversityNewcastle upon Tyne, United Kingdom
| | - Stephanie E Willing
- School of Biological Sciences, Royal Holloway, University of LondonLondon, United Kingdom
| | - Huynh A Hong
- School of Biological Sciences, Royal Holloway, University of LondonLondon, United Kingdom
| | - Siamand Hosseini
- School of Biological Sciences, Royal Holloway, University of LondonLondon, United Kingdom
| | - Paula S Salgado
- Institute for Cell and Molecular Biosciences, Newcastle UniversityNewcastle upon Tyne, United Kingdom
| | - Simon M Cutting
- School of Biological Sciences, Royal Holloway, University of LondonLondon, United Kingdom
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26
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Song C, Do QB, Antic SD, Knöpfel T. Transgenic Strategies for Sparse but Strong Expression of Genetically Encoded Voltage and Calcium Indicators. Int J Mol Sci 2017; 18:ijms18071461. [PMID: 28686207 PMCID: PMC5535952 DOI: 10.3390/ijms18071461] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 07/03/2017] [Accepted: 07/04/2017] [Indexed: 01/09/2023] Open
Abstract
Rapidly progressing development of optogenetic tools, particularly genetically encoded optical indicators, enables monitoring activities of neuronal circuits of identified cell populations in longitudinal in vivo studies. Recently developed advanced transgenic approaches achieve high levels of indicator expression. However, targeting non-sparse cell populations leads to dense expression patterns such that optical signals from neuronal processes cannot be allocated to individual neurons. This issue is particularly pertinent for the use of genetically encoded voltage indicators whose membrane-delimited signals arise largely from the neuropil where dendritic and axonal membranes of many cells intermingle. Here we address this need for sparse but strong expression of genetically encoded optical indicators using a titratable recombination-activated transgene transcription to achieve a Golgi staining-type indicator expression pattern in vivo. Using different transgenic strategies, we also illustrate that co-expression of genetically encoded voltage and calcium indicators can be achieved in vivo for studying neuronal circuit input–output relationships.
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Affiliation(s)
- Chenchen Song
- Laboratory for Neuronal Circuit Dynamics, Imperial College London, London W12 0NN, UK.
| | - Quyen B Do
- Laboratory for Neuronal Circuit Dynamics, Imperial College London, London W12 0NN, UK.
| | - Srdjan D Antic
- Institute for Systems Genomics, Stem Cell Institute, UConn Health, Farmington, CT 06030-3401, USA.
| | - Thomas Knöpfel
- Laboratory for Neuronal Circuit Dynamics, Imperial College London, London W12 0NN, UK.
- Centre for Neurotechnology, Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, UK.
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27
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Xu QQ, Xu P, Zhou JW, Pan TS, Tuo R, Ai K, Yang DQ. [Cloning and expression analysis of two pro-inflammatory cytokines, IL-1β and its receptor, IL-1R2, in the Asian swamp eel Monopterus albus]. Mol Biol (Mosk) 2017; 50:760-774. [PMID: 27830678 DOI: 10.7868/s0026898416030125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/31/2015] [Indexed: 11/23/2022]
Abstract
Interleukin-1β (IL-1β) is the prototypic pro-inflammatory cytokine, whose functions are mediated through interaction with its receptors (IL-1R1 and IL-1R2). Herein, we cloned the full-length cDNA and genomic DNA of IL-1β and IL-1R2 in the Asian swamp eel (Monopterus albus). The eel IL-1β cDNA encodes a putative polypeptide of 246 amino acids. The protein sequence includes a typical IL-1 family signature, but lacked an interleukin-converting enzyme cleavage site. The genomic DNA of eel IL-1β was 2520 bp and comprised five exons and four introns. The eel IL-1R2 cDNA encoded a putative propeptide of 423 amino acid residues, comprising a signal peptide, a transmembrane region and two Ig-like domains in the extracellular region. Similar to other vertebrates, the genomic DNA of the eel IL-1R2 has nine exons and eight introns. Real-time PCR analysis indicated that IL-1β and IL-1R2 were constitutively expressed in all tissues, especially in the liver and immune-related organs. After infection with Aeromonas hydrophila, the transcript levels of IL-1β and IL-1R2 were induced in the head kidney and spleen, reaching their highest levels at 6 h post injection. In vitro, IL-1β and IL-1R2 mRNA levels were also upregulated rapidly at 1h post infection with A. hydrophila. Furthermore, acanthocephalan Pallisentis (Neosentis) celatus could induce the expression of both genes in the head kidney and intestine. In infected intestines, the transcript levels of IL-1β and IL-1R2 were increased by 21.4-fold and 20.8-fold, respectively, relative to the control. The present study indicated that IL-1β and IL-1R2 play an important role in inflammation and host defense, especially in the antiacanthocephalan response.
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Affiliation(s)
- Q Q Xu
- Engineering Research Center of Ecology and Agricultural, Use of Wetland, Ministry of Education, Yangtze University, Jingzhou, Hubei Province, 434020 China.,School of Animal Science, Yangtze University, Jingzhou, Hubei Province, 434020 China
| | - P Xu
- School of Animal Science, Yangtze University, Jingzhou, Hubei Province, 434020 China
| | - J W Zhou
- School of Animal Science, Yangtze University, Jingzhou, Hubei Province, 434020 China
| | - T S Pan
- Fisheries Institute, Anhui Academy of Agricultural Sciences, Hefei, Anhui Province, 230031 China
| | - R Tuo
- School of Animal Science, Yangtze University, Jingzhou, Hubei Province, 434020 China
| | - K Ai
- School of Animal Science, Yangtze University, Jingzhou, Hubei Province, 434020 China
| | - D Q Yang
- Engineering Research Center of Ecology and Agricultural, Use of Wetland, Ministry of Education, Yangtze University, Jingzhou, Hubei Province, 434020 China.,Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, 430070 China.,
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28
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Hong C, Chen Y, Li L, Chen S, Wei X. Identification of a Key Gene Involved in Branched-Chain Short Fatty Acids Formation in Natto by Transcriptional Analysis and Enzymatic Characterization in Bacillus subtilis. J Agric Food Chem 2017; 65:1592-1597. [PMID: 28165735 DOI: 10.1021/acs.jafc.6b05518] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Natto as a fermented soybean product has many health benefits for human due to its rich nutritional and functional components. However, the unpleasant odor of natto, caused by the formation of branched-chain short fatty acids (BCFAs), prohibits the wide acceptance of natto products. This work is to identify the key gene of BCFAs formation and develop the guidance to reduce natto odor. Transcriptional analysis of BCFAs synthesis pathway genes was conducted in two Bacillus subtilis strains with obvious different BCFAs synthesis abilities. The transcriptional levels of bcd, bkdAA, and ptb in B. subtilis H-9 were 2.7-fold, 0.7-fold, and 8.9-fold higher than that of B. subtilis H-4, respectively. Therefore, the ptb gene with the highest transcriptional change was considered as the key gene in BCFAs synthesis. The ptb encoded enzyme Ptb was further characterized by inducible expression in Escherichia coli. The recombinant Ptb protein (about 32 kDa) was verified by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis analysis. The catalysis functions of Ptb were confirmed on substrates of isovaleryl-CoA and isobutyryl-CoA, and the higher catalysis efficiency of Ptb on isovaleryl-CoA explained the higher level of isovaleric acid in natto. The optimal activities of Ptb were observed at 50 °C and pH 8.0, and the enzymatic activity was inhibited by Ca2+, Zn2+, Ba2+, Mn2+, Cu2+, SDS, and EDTA. Collectively, this study reports a key gene responsible for BCFAs formation in natto fermentation and provides potential strategies to solve the odor problem.
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Affiliation(s)
- Chenlu Hong
- Key Laboratory of Environment Correlative Dietology (Ministry of Education), College of Food Science and Technology and ‡State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan 430070, P. R. China
| | - Yangyang Chen
- Key Laboratory of Environment Correlative Dietology (Ministry of Education), College of Food Science and Technology and ‡State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan 430070, P. R. China
| | - Lu Li
- Key Laboratory of Environment Correlative Dietology (Ministry of Education), College of Food Science and Technology and ‡State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan 430070, P. R. China
| | - Shouwen Chen
- Key Laboratory of Environment Correlative Dietology (Ministry of Education), College of Food Science and Technology and ‡State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan 430070, P. R. China
| | - Xuetuan Wei
- Key Laboratory of Environment Correlative Dietology (Ministry of Education), College of Food Science and Technology and ‡State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan 430070, P. R. China
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29
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Lam C, Santell L, Wilson B, Yim M, Louie S, Tang D, Shaw D, Chan P, Lazarus RA, Snedecor B, Misaghi S. Taming hyperactive hDNase I: Stable inducible expression of a hyperactive salt- and actin-resistant variant of human deoxyribonuclease I in CHO cells. Biotechnol Prog 2017; 33:523-533. [PMID: 28127892 DOI: 10.1002/btpr.2439] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/22/2016] [Indexed: 12/17/2022]
Abstract
While the most common causes of clonal instability are DNA copy number loss and silencing, toxicity of the expressed protein(s) may also induce clonal instability. Human DNase I (hDNase I) is used therapeutically for the treatment of cystic fibrosis (CF) and may have potential benefit for use in systemic lupus erythematosus (SLE). hDNase I is an endonuclease that catalyzes degradation of extracellular DNA and is inhibited by both salt and G-actin. Engineered versions of hDNase I, bearing multiple point mutations, which renders them Hyperactive, Salt- and Actin-Resistant (HSAR-hDNase I) have been developed previously. However, constitutive expression of HSAR-hDNase I enzymes has been very challenging and, despite considerable efforts and screening thousands of clones, no stable clone capable of constitutive expression had been obtained. Here, we developed a regulated expression system for stable expression of an HSAR-hDNase I in Chinese Hamster Ovary (CHO) cells. The HSAR-hDNase I clones were stable and, upon induction, expressed enzymatically functional protein. Our findings suggest that degradation of host's DNA mediated by HSAR-hDNase I during cell division is the likely cause of clonal instability observed in cells constitutively expressing this protein. Purified HSAR-hDNase I was both hyperactive and resistant to inhibition by salt and G-actin, resulting in an enzyme having ca. 10-fold greater specific activity and the potential to be a superior therapeutic agent to wild type (WT) hDNase I. Furthermore, the ability to regulate hDNase I expression has enabled process development improvements that achieve higher cell growth and product titers while maintaining product quality. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 32:523-533, 2017.
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Affiliation(s)
- Cynthia Lam
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - Lydia Santell
- Early Discovery Biochemistry, Genentech, Inc, South San Francisco, CA, 94080
| | - Blair Wilson
- Biochemical and Cellular Pharmacology Dept., Genentech, Inc, South San Francisco, CA, 94080
| | - Mandy Yim
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - Salina Louie
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - Danming Tang
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - David Shaw
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - Pamela Chan
- Biochemical and Cellular Pharmacology Dept., Genentech, Inc, South San Francisco, CA, 94080
| | - Robert A Lazarus
- Early Discovery Biochemistry, Genentech, Inc, South San Francisco, CA, 94080
| | - Brad Snedecor
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
| | - Shahram Misaghi
- Early Stage Cell Culture, Genentech, Inc, South San Francisco, CA, 94080
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30
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Papaevangelou E, Whitley GS, Johnstone AP, Robinson SP, Howe FA. Investigating the role of tumour cell derived iNOS on tumour growth and vasculature in vivo using a tetracycline regulated expression system. Int J Cancer 2016; 138:2678-87. [PMID: 26756734 DOI: 10.1002/ijc.29997] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 12/16/2015] [Indexed: 11/10/2022]
Abstract
Nitric oxide (NO) is a free radical signalling molecule involved in various physiological and pathological processes, including cancer. Both tumouricidal and tumour promoting effects have been attributed to NO, making its role in cancer biology controversial and unclear. To investigate the specific role of tumour-derived NO in vascular development, C6 glioma cells were genetically modified to include a doxycycline regulated gene expression system that controls the expression of an antisense RNA to inducible nitric oxide synthase (iNOS) to manipulate endogenous iNOS expression. Xenografts of these cells were propagated in the presence or absence of doxycycline. Susceptibility magnetic resonance imaging (MRI), initially with a carbogen (95% O2/5% CO2) breathing challenge and subsequently an intravascular blood pool contrast agent, was used to assess haemodynamic vasculature (ΔR2*) and fractional blood volume (fBV), and correlated with histopathological assessment of tumour vascular density, maturation and function. Inhibition of NO production in C6 gliomas led to significant growth delay and inhibition of vessel maturation. Parametric fBV maps were used to identify vascularised regions from which the carbogen-induced ΔR2* was measured and found to be positively correlated with vessel maturation, quantified ex vivo using fluorescence microscopy for endothelial and perivascular cell staining. These data suggest that tumour-derived iNOS is an important mediator of tumour growth and vessel maturation, hence a promising target for anti-vascular cancer therapies. The combination of ΔR2* response to carbogen and fBV MRI can provide a marker of tumour vessel maturation that could be applied to non-invasively monitor treatment response to iNOS inhibitors.
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Affiliation(s)
- Efthymia Papaevangelou
- Cardiovascular and Cell Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom
| | - Guy S Whitley
- Cardiovascular and Cell Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom
| | - Alan P Johnstone
- Cardiovascular and Cell Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom
| | - Simon P Robinson
- Division of Radiotherapy and Imaging, The Institute of Cancer Research, Belmont, Sutton, Surrey, SM2 5NG, United Kingdom
| | - Franklyn A Howe
- Cardiovascular and Cell Sciences Research Institute, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom
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31
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Matsumoto M, Hashimoto Y, Saitoh Y, Kumano T, Kobayashi M. Development of nitrilase promoter-derived inducible vectors for Streptomyces. Biosci Biotechnol Biochem 2016; 80:1230-7. [PMID: 26923287 DOI: 10.1080/09168451.2016.1148577] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
An inducible expression vector, pSH19, which harbors regulatory expression system PnitA-NitR, for streptomycetes was constructed previously. Here, we have modified pSH19 to obtain shuttle vectors for Streptomyces-E. coli by introducing the replication origin of a plasmid for E. coli (ColE1) and an antibiotic-resistant gene. Six inducible shuttle vectors, pESH19cF, pESH19cR, pESH19kF, pESH19kR, pESH19aF, and pESH19aR, for Streptomyces-E. coli, were successfully developed. The stability of these vectors was examined in five different E. coli strains and Streptomyces lividans TK24. The stability test showed that the pSH19-derived shuttle vectors were stable in E. coli Stbl2 and S. lividans TK24. Heterologous expression experiments involving each of the catechol 2,3-dioxygenase, nitrilase, and N-substituted formamide deformylase genes as a reporter gene showed that pESH19cF, pESH19kF, and pESH19aF possess inducible expression ability in S. lividans TK24. Thus, these vectors were found to be useful expression tools for experiments on both Gram-negative and Gram-positive bacterial genes.
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Affiliation(s)
- Masako Matsumoto
- a Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences , The University of Tsukuba , Tsukuba , Japan
| | - Yoshiteru Hashimoto
- a Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences , The University of Tsukuba , Tsukuba , Japan
| | - Yuki Saitoh
- a Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences , The University of Tsukuba , Tsukuba , Japan
| | - Takuto Kumano
- a Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences , The University of Tsukuba , Tsukuba , Japan
| | - Michihiko Kobayashi
- a Institute of Applied Biochemistry, and Graduate School of Life and Environmental Sciences , The University of Tsukuba , Tsukuba , Japan
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Economou C, Tsakiridis A, Wymeersch FJ, Gordon-Keylock S, Dewhurst RE, Fisher D, Medvinsky A, Smith AJH, Wilson V. Intrinsic factors and the embryonic environment influence the formation of extragonadal teratomas during gestation. BMC Dev Biol 2015; 15:35. [PMID: 26453549 PMCID: PMC4599726 DOI: 10.1186/s12861-015-0084-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 09/18/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND Pluripotent cells are present in early embryos until the levels of the pluripotency regulator Oct4 drop at the beginning of somitogenesis. Elevating Oct4 levels in explanted post-pluripotent cells in vitro restores their pluripotency. Cultured pluripotent cells can participate in normal development when introduced into host embryos up to the end of gastrulation. In contrast, pluripotent cells efficiently seed malignant teratocarcinomas in adult animals. In humans, extragonadal teratomas and teratocarcinomas are most frequently found in the sacrococcygeal region of neonates, suggesting that these tumours originate from cells in the posterior of the embryo that either reactivate or fail to switch off their pluripotent status. However, experimental models for the persistence or reactivation of pluripotency during embryonic development are lacking. METHODS We manually injected embryonic stem cells into conceptuses at E9.5 to test whether the presence of pluripotent cells at this stage correlates with teratocarcinoma formation. We then examined the effects of reactivating embryonic Oct4 expression ubiquitously or in combination with Nanog within the primitive streak (PS)/tail bud (TB) using a transgenic mouse line and embryo chimeras carrying a PS/TB-specific heterologous gene expression cassette respectively. RESULTS Here, we show that pluripotent cells seed teratomas in post-gastrulation embryos. However, at these stages, induced ubiquitous expression of Oct4 does not lead to restoration of pluripotency (indicated by Nanog expression) and tumour formation in utero, but instead causes a severe phenotype in the extending anteroposterior axis. Use of a more restricted T(Bra) promoter transgenic system enabling inducible ectopic expression of Oct4 and Nanog specifically in the posteriorly-located primitive streak (PS) and tail bud (TB) led to similar axial malformations to those induced by Oct4 alone. These cells underwent induction of pluripotency marker expression in Epiblast Stem Cell (EpiSC) explants derived from somitogenesis-stage embryos, but no teratocarcinoma formation was observed in vivo. CONCLUSIONS Our findings show that although pluripotent cells with teratocarcinogenic potential can be produced in vitro by the overexpression of pluripotency regulators in explanted somitogenesis-stage somatic cells, the in vivo induction of these genes does not yield tumours. This suggests a restrictive regulatory role of the embryonic microenvironment in the induction of pluripotency.
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Affiliation(s)
- Constantinos Economou
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Anestis Tsakiridis
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Filip J Wymeersch
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Sabrina Gordon-Keylock
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Robert E Dewhurst
- Drug Discovery Unit, Telethon Kids Institute, PO Box 855, West Perth, WA, 6872, Australia
| | - Dawn Fisher
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Alexander Medvinsky
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Andrew J H Smith
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK
| | - Valerie Wilson
- MRC Centre for Regenerative Medicine, School of Biological Sciences, SCRM Building, The University of Edinburgh, Edinburgh bioQuarter, 5 Little France Drive, Edinburgh, EH16 4UU, UK.
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Misaghi S, Chang J, Snedecor B. It's time to regulate: coping with product-induced nongenetic clonal instability in CHO cell lines via regulated protein expression. Biotechnol Prog 2014; 30:1432-40. [PMID: 25104235 DOI: 10.1002/btpr.1970] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/13/2014] [Indexed: 12/20/2022]
Abstract
Clonal instability and titer loss during Chinese hamster ovary (CHO) cell line development (CLD) has several underlying causes, the most prominent of which are DNA copy number loss and DNA silencing. However, in some cases, clonal instability is due to the toxicity of the therapeutic protein(s) that clones express. Unlike DNA copy number loss, which may occur in some clones or DNA silencing that is prevalent in certain regions of the genome, the hallmark of product induced clonal instability is its manifestation in all the selected clones. To circumvent such product induced clonal instability, we have developed a vector construct that utilizes a regulated protein expression system in which the constitutive expression of the target protein(s) is prevented unless doxycycline is added to the culture. We have then successfully used this system to express, at high titers, an antibody for which constitutive expression results in clonal instability perhaps due to intracellular accumulation of the antibody. Our data shows that unlike the constitutively expressed or continuously induced clones, uninduced clones do not display instability. Furthermore, maintaining the uninduced clones in culture for months or subjecting them to freeze-thaws did not have any effects on their titers. All together, our findings suggest that a regulated expression system could be suitable for production of difficult proteins that trigger instability.
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Affiliation(s)
- Shahram Misaghi
- Dept. of Early Stage Cell Culture, Genentech, Inc, 1 DNA way, South San, Francisco, CA, 94080
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Cho IK, Moran SP, Paudyal R, Piotrowska-Nitsche K, Cheng PH, Zhang X, Mao H, Chan AW. Longitudinal monitoring of stem cell grafts in vivo using magnetic resonance imaging with inducible maga as a genetic reporter. Am J Cancer Res 2014; 4:972-89. [PMID: 25161700 PMCID: PMC4143941 DOI: 10.7150/thno.9436] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 06/29/2014] [Indexed: 01/06/2023] Open
Abstract
PURPOSE The ability to longitudinally monitor cell grafts and assess their condition is critical for the clinical translation of stem cell therapy in regenerative medicine. Developing an inducible genetic magnetic resonance imaging (MRI) reporter will enable non-invasive and longitudinal monitoring of stem cell grafts in vivo. METHODS MagA, a bacterial gene involved in the formation of iron oxide nanocrystals, was genetically modified for in vivo monitoring of cell grafts by MRI. Inducible expression of MagA was regulated by a Tet-On (Tet) switch. A mouse embryonic stem cell-line carrying Tet-MagA (mESC-MagA) was established by lentivirus transduction. The impact of expressing MagA in mESCs was evaluated via proliferation assay, cytotoxicity assay, teratoma formation, MRI, and inductively coupled plasma atomic emission spectroscopy (ICP-OES). Mice were grafted with mESCs with and without MagA (mESC-MagA and mESC-WT). The condition of cell grafts with induced "ON" and non-induced "OFF" expression of MagA was longitudinally monitored in vivo using a 7T MRI scanner. After imaging, whole brain samples were harvested for histological assessment. RESULTS Expression of MagA in mESCs resulted in significant changes in the transverse relaxation rate (R2 or 1/T2) and susceptibility weighted MRI contrast. The pluripotency of mESCs carrying MagA was not affected in vitro or in vivo. Intracranial mESC-MagA grafts generated sufficient T2 and susceptibility weighted contrast at 7T. The mESC-MagA grafts can be monitored by MRI longitudinally upon induced expression of MagA by administering doxycycline (Dox) via diet. CONCLUSION Our results demonstrate MagA could be used to monitor cell grafts noninvasively, longitudinally, and repetitively, enabling the assessment of cell graft conditions in vivo.
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Yakimov AP, Seregina TA, Kholodnyak AA, Kreneva RA, Mironov AS, Perumov DA, Timkovskii AL. Possible Function of the ribT Gene of Bacillus subtilis: Theoretical Prediction, Cloning, and Expression. Acta Naturae 2014; 6:106-9. [PMID: 25349719 PMCID: PMC4207565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The complete decipherment of the functions and interactions of the elements of the riboflavin biosynthesis operon (rib operon) of Bacillus subtilis are necessary for the development of superproducers of this important vitamin. The function of its terminal ribT gene has not been established to date. In this work, a search for homologs of the hypothetical amino acid sequence of the gene product through databases, as well as an analysis of the homolgs, was performed; the distribution of secondary structure elements was theoretically predicted; and the tertiary structure of the RibT protein was proposed. The ribT gene nucleotide sequence was amplified and cloned into the standard high-copy expression vector pET15b and then expressed after induction with IPTG in E. coli BL21 (DE3) strain cells containing the inducible phage T7 RNA polymerase gene. The ribT gene expression was confirmed by SDS-PAGE. The protein product of the expression was purified by affinity chromatography. Therefore, the real possibility of RibT protein production in quantities sufficient for further investigation of its structure and functional activity was demonstrated.
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Affiliation(s)
- A. P. Yakimov
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Orlova Roshcha, Gatchina, Leningrad Region, Russia, 188300
- St. Petersburg State Polytechnical University, Polytechnicheskaya Str., 29, St. Petersburg, Russia, 195251
| | - T. A. Seregina
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1st Dorozhnyi Proezd, 1, Moscow, Russia, 117545
| | - A. A. Kholodnyak
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1st Dorozhnyi Proezd, 1, Moscow, Russia, 117545
| | - R. A. Kreneva
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Orlova Roshcha, Gatchina, Leningrad Region, Russia, 188300
| | - A. S. Mironov
- State Research Institute of Genetics and Selection of Industrial Microorganisms, 1st Dorozhnyi Proezd, 1, Moscow, Russia, 117545
| | - D. A. Perumov
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Orlova Roshcha, Gatchina, Leningrad Region, Russia, 188300
| | - A. L. Timkovskii
- B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Center “Kurchatov Institute”, Orlova Roshcha, Gatchina, Leningrad Region, Russia, 188300
- St. Petersburg State Polytechnical University, Polytechnicheskaya Str., 29, St. Petersburg, Russia, 195251
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Bian Z, Yu Y, Yang T, Quan C, Sun W, Fu S. Effect of tumor suppressor gene cyclin-dependent kinase inhibitor 2A wild-type and A148T mutant on the cell cycle of human ovarian cancer cells. Oncol Lett 2014; 7:1229-1232. [PMID: 24944698 PMCID: PMC3961237 DOI: 10.3892/ol.2014.1867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 01/15/2014] [Indexed: 01/23/2023] Open
Abstract
Single-base substitution may affect the function of genes. This study identified a single-base substitution of G for A in codon 148 of cyclin-dependent kinase inhibitor 2A (CDKN2A/p16) by sequencing human ovarian cancer cell line UACC-1598. As a tumor suppressor gene, the expression of CDKN2A/p16 should be strictly controlled. In order to control CDKN2A/p16 gene expression, an inducible pTUNE vector system was selected. Using recombinant DNA technology, a CDKN2A/p16-A148T and CDKN2A/p16-wild-type gene expression system was successfully constructed to investigate whether this single-base substitution affects the function of CDKN2A/p16. For the wild-type and the mutant, expression of CDKN2A/p16-green fluorescent protein fusion protein increased markedly following isopropyl-β-D-thiogalactoside induction, and was accompanied by significant G1 arrest in the transfected human ovarian cancer SKOV3 cell line. The inducible vectors used in this study, CDKN2A/p16-wild-type and CDKN2A/p16-A148T open reading frame, may be useful for further investigation into whether this somatic mutation could alter the function of CDKN2A/p16 as a tumor suppressor gene. In summary, CDKN2A/p16-A148T was identified in ovarian cancer cells, and this single-base substitution did not affect the ability of CDKN2A/p16 to arrest the cell cycle.
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Affiliation(s)
- Zehua Bian
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
| | - Yang Yu
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
| | - Terigele Yang
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
| | - Chao Quan
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
| | - Wenjing Sun
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China ; Key Laboratory of Medical Genetics (Harbin Medical University), Heilongjiang Higher Education Institutions, Harbin, Heilongjiang 150081, P.R. China
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Ha TK, Jeon MK, Yu DY, Lee GM. Effect of Bcl-x(L) overexpression on lactate metabolism in chinese hamster ovary cells producing antibody. Biotechnol Prog 2013; 29:1594-8. [PMID: 24039207 DOI: 10.1002/btpr.1805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 08/23/2013] [Indexed: 11/08/2022]
Abstract
Previously, overexpression of anti-apoptotic proteins, such as E1B-19K and Aven, was reported to alter lactate metabolism of CHO cells in culture. To investigate the effect of Bcl-xL , a well-known anti-apoptotic protein, on lactate metabolism of recombinant CHO (rCHO) cells, two antibody-producing rCHO cell lines with regulated Bcl-xL overexpression (CS13*-0.02-off-Bcl-xL and CS13*-1.00-off-Bcl-xL ) were established using the Tet-off system. When cells were cultivated without Bcl-xL overexpression, the specific lactate production rate (qLac ) of CS13*-0.02-off-Bcl-xL and CS13*-1.00-off-Bcl-xL were 7.32 ± 0.37 and 6.78 ± 0.56 pmol/cell/day, respectively. Bcl-xL overexpression, in the absence of doxycycline, did not affect the qLac of either cell line, though it enhanced the viability during cultures. Furthermore, activities of the enzymes related to glucose and lactate metabolism, such as hexokinase, glucose-6-phosphate dehydrogenase, lactate dehydrogenases, and alanine aminotransferase, were not affected by Bcl-xL overexpression either. Taken together, Bcl-xL overexpression showed no significant effect on the lactate metabolism of rCHO cells.
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Affiliation(s)
- Tae Kwang Ha
- Dept. of Biological Sciences, Graduate School of Nanoscience and Technology (WCU), KAIST, 373-1 Kusong-Dong, Yusong-gu, Daejon, 305-701, Korea
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Doherty JE, Woodard LE, Bear AS, Foster AE, Wilson MH. An adaptable system for improving transposon-based gene expression in vivo via transient transgene repression. FASEB J 2013; 27:3753-62. [PMID: 23752206 DOI: 10.1096/fj.13-232090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transposons permit permanent cellular genome engineering in vivo. However, transgene expression falls rapidly postdelivery due to a variety of mechanisms, including immune responses. We hypothesized that delaying initial transgene expression would improve long-term transgene expression by using an engineered piggyBac transposon system that can regulate expression. We found that a 2-part nonviral Tet-KRAB inducible expression system repressed expression of a luciferase reporter in vitro. However, we also observed nonspecific promoter-independent repression. Thus, to achieve temporary transgene repression after gene delivery in vivo, we utilized a nonintegrating version of the repressor plasmid while the gene of interest was delivered in an integrating piggyBac transposon vector. When we delivered the luciferase transposon and repressor to immunocompetent mice by hydrodynamic injection, initial luciferase expression was repressed by 2 orders of magnitude. When luciferase expression was followed long term in vivo, we found that expression was increased >200-fold compared to mice that received only the luciferase transposon and piggyBac transposase. We found that repression of early transgene expression could prevent the priming of luciferase-specific T cells in vivo. Therefore, transient transgene repression postgene delivery is an effective strategy for inhibiting the antitransgene immune response and improving long-term expression in vivo without using immunosuppression.
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Affiliation(s)
- Joseph E Doherty
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030, USA
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Niu YF, Yang ZK, Zhang MH, Zhu CC, Yang WD, Liu JS, Li HY. Transformation of diatom Phaeodactylum tricornutum by electroporation and establishment of inducible selection marker. Biotechniques 2012; 52:000113881. [PMID: 26307256 DOI: 10.2144/000113881] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 05/18/2012] [Indexed: 11/23/2022] Open
Abstract
Diatoms are important primary producers in the marine ecosystem. Currently it is difficult to genetically transform diatoms due to the technical limitations of existing methods. The promoter/terminator of the nitrate reductase gene of the model diatom Phaeodactylum tricornutum was cloned and used to drive chloramphenicol acetyltransferase (CAT) reporter gene expression. The construct was transferred by electroporation into P. tricornutum grown in medium lacking silicon. CAT expression was induced in transformed diatoms in the presence of nitrate, enabling growth in selective medium, and was repressed when ammonium was the only nitrogen source. Expression of CAT transcript and protein were demonstrated by RT-PCR and Western blot analysis, respectively. Our study is the first to report a successful genetic transformation of diatom by electroporation in an economical and efficient manner and provides a tightly regulated inducible gene expression system for diatom.
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Affiliation(s)
- Ying-Fang Niu
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Zhi-Kai Yang
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Meng-Han Zhang
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Cong-Cong Zhu
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Wei-Dong Yang
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Jie-Sheng Liu
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
| | - Hong-Ye Li
- Key Laboratory of Eutrophication and Control of HAB of Guangdong Higher Education Institute, Jinan University, Guangzhou, China
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Affiliation(s)
- Igor V Korobko
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
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Kenny PA, Enver T, Ashworth A. Retroviral vectors for establishing tetracycline-regulated gene expression in an otherwise recalcitrant cell line. BMC Mol Biol 2002; 3:13. [PMID: 12392602 PMCID: PMC126263 DOI: 10.1186/1471-2199-3-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2002] [Accepted: 09/03/2002] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tetracycline-regulated systems have been used to control the expression of heterologous genes in such diverse organisms as yeast, plants, flies and mice. Adaptation of this prokaryotic regulatory system avoids many of the problems inherent in other inducible systems. There have, however, been many reports of difficulties in establishing functioning stable cell lines due to the cytotoxic effects of expressing high levels of the tetracycline transactivator, tTA, from a strong viral promoter. RESULTS Here we report the successful incorporation of tetracycline-mediated gene expression in a mouse mammary epithelial cell line, HC11, in which conventional approaches failed. We generated retroviruses in which tTA expression was controlled by one of three promoters: a synthetic tetracycline responsive promoter (TRE), the elongation factor 1-alpha promoter (EF1alpha) or the phosphoglycerate kinase-1 promoter (PGK), and compared the resulting cell lines to one generated using a cytomegalovirus immediate early gene promoter (CMV). In contrast to cells produced using the CMV and PGK promoters, those produced using the EF1alpha and TRE promoters expressed high levels of beta-galactosidase in a tetracycline-dependent manner. CONCLUSIONS These novel retroviral vectors performed better than the commercially available system and may have a more general utility in similarly recalcitrant cell lines.
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Affiliation(s)
- Paraic A Kenny
- Section of Gene Function and Regulation, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, United Kingdom
- Current address: Life Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 USA
| | - Tariq Enver
- Section of Gene Function and Regulation, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, United Kingdom
| | - Alan Ashworth
- The Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, United Kingdom
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Abstract
Proteins with expanded polyglutamine (polyQ) tracts have been linked to neurodegenerative diseases. One common characteristic of expanded-polyQ expression is the formation of intracellular aggregates (IAs). IAs purified from polyQ-expressing cells were dissociated and studied by protein blot assay and mass spectrometry to determine the identity, condition, and relative level of several proteins sequestered within aggregates. Most of the sequestered proteins comigrated with bands from control extracts, indicating that the sequestered proteins were intact and not irreversibly bound to the polyQ polymer. Among the proteins found sequestered at relatively high levels in purified IAs were ubiquitin, the cell cycle-regulating proteins p53 and mdm-2, HSP70, the global transcriptional regulator Tata-binding protein/TFIID, cytoskeleton proteins actin and 68-kD neurofilament, and proteins of the nuclear pore complex. These data reveal that IAs are highly complex structures with a multiplicity of contributing proteins.
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Affiliation(s)
- S T Suhr
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Johns DC, Marx R, Mains RE, O'Rourke B, Marbán E. Inducible genetic suppression of neuronal excitability. J Neurosci 1999; 19:1691-7. [PMID: 10024355 PMCID: PMC6782162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
Graded, reversible suppression of neuronal excitability represents a logical goal of therapy for epilepsy and intractable pain. To achieve such suppression, we have developed the means to transfer "electrical silencing" genes into neurons with sensitive control of transgene expression. An ecdysone-inducible promoter drives the expression of inwardly rectifying potassium channels in polycistronic adenoviral vectors. Infection of superior cervical ganglion neurons did not affect normal electrical activity but suppressed excitability after the induction of gene expression. These experiments demonstrate the feasibility of controlled ion channel expression after somatic gene transfer into neurons and serve as the prototype for a novel generalizable approach to modulate excitability.
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Affiliation(s)
- D C Johns
- Section of Molecular and Cellular Cardiology, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Hermans E, Challiss RA, Nahorski SR. Effects of varying the expression level of recombinant human mGlu1alpha receptors on the pharmacological properties of agonists and antagonists. Br J Pharmacol 1999; 126:873-82. [PMID: 10193767 PMCID: PMC1571208 DOI: 10.1038/sj.bjp.0702359] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. Different expression levels of the human type 1alpha metabotropic glutamate (mGlu1alpha) receptor were obtained in transfected Chinese hamster ovary cells using an isopropyl beta-D-thiogalactopyranoside (IPTG) inducible system. Expression of mGlu1alpha receptors could not be detected using immunoblotting or immunocytochemical approaches in non-induced cells, however, controlled expression could be induced following IPTG addition in a time- and concentration-dependent manner. 2. In induced cells (100 microM IPTG, 20 h) the agonists L-quisqualate or 1-aminocyclopentane-1S,3R-dicarboxylic acid stimulated large increases in [3H]-inositol (poly)phosphate (in the presence of Li+) and inositol, 1,4,5-trisphosphate levels. 3. Induction with 1-100 microM IPTG allowed the receptor density to be increased incrementally and this not only resulted in an increase in the maximum response to L-quisqualate, 1-aminocyclopentane-1S,3R-dicarboxylic acid and (S)-3,5-dihydroxy-phenylglycine, but also in an increase in the respective potencies of each agent to activate phosphoinositide hydrolysis. 4. The intrinsic activity of the partial agonist 1-aminocyclopentane-1S,3R-dicarboxylic acid dramatically increased with increasing receptor expression. 5. The activities of the competitive mGlu1alpha receptor antagonists (S)-alpha-methyl-4-carboxyphenylglycine and (S)-4-carboxy-3-hydroxyphenylglycine for inhibition of the effects of L-quisqualate or (S)-3,5-dihydroxyphenylglycine were found to be independent of the receptor expression level. 6. When the mGlu1alpha receptor was expressed at very high levels, no evidence for receptor constitutive activity could be detected, and none of the antagonists tested revealed either any intrinsic activity or negative efficacy. 7. These data demonstrate that both the potency and efficacy of mGlu1alpha receptor agonists are influenced by expression level, whilst mGlu1alpha receptor antagonist activities are independent of expression level.
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Affiliation(s)
- E Hermans
- Department of Cell Physiology and Pharmacology, University of Leicester, England, UK
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Abstract
In this report, we have analyzed the potential role and mechanisms of integrin signaling through FAK in cell cycle regulation by using tetracycline-regulated expression of exogenous FAK and mutants. We have found that overexpression of wild-type FAK accelerated G1 to S phase transition. Conversely, overexpression of a dominant-negative FAK mutant DeltaC14 inhibited cell cycle progression at G1 phase and this inhibition required the Y397 in DeltaC14. Biochemical analyses indicated that FAK mutant DeltaC14 was mislocalized and functioned as a dominant-negative mutant by competing with endogenous FAK in focal contacts for binding signaling molecules such as Src and Fyn, resulting in a decreases of Erk activation in cell adhesion. Consistent with this, we also observed inhibition of BrdU incorporation and Erk activation by FAK Y397F mutant and FRNK, but not FRNKDeltaC14, in transient transfection assays using primary human foreskin fibroblasts. Finally, we also found that DeltaC14 blocked cyclin D1 upregulation and induced p21 expression, while wild-type FAK increased cyclin D1 expression and decreased p21 expression. Taken together, these results have identified FAK and its associated signaling pathways as a mediator of the cell cycle regulation by integrins.
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Affiliation(s)
- J H Zhao
- Cancer Biology Laboratories, Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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Levy LM, Warr O, Attwell D. Stoichiometry of the glial glutamate transporter GLT-1 expressed inducibly in a Chinese hamster ovary cell line selected for low endogenous Na+-dependent glutamate uptake. J Neurosci 1998; 18:9620-8. [PMID: 9822723 PMCID: PMC6793325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Glutamate transport across the plasma membrane of neurons and glia is powered by the transmembrane electrochemical gradients for sodium, potassium, and pH, but there is controversy over the number of Na+ cotransported with glutamate. The stoichiometry of glutamate transporters is important because it determines a lower limit to the extracellular glutamate concentration, [glu]o, in both normal and pathological conditions. We used whole-cell clamping to study the stoichiometry of the glial transporter GLT-1, the most abundant glutamate transporter in the brain, expressed under control of the Tet-On system in a Chinese hamster ovary (CHO) cell line selected for low endogenous glutamate transport. After the induction of GLT-1 expression with doxycycline, glutamate evoked a Na+-dependent inward current with the voltage dependence and pharmacology of GLT-1 and acidified the cell cytoplasm. Raising [K+]o around cells clamped with electrodes containing sodium and glutamate evoked an outward reversed uptake current. These responses were reduced by the specific GLT-1 blocker dihydrokainate (DHK). DHK evoked an outward current with NO3-, but not with Cl-, as the main intracellular anion, suggesting that the anion conductance of the transporter is active even without external glutamate but generates little current in the absence of highly permeable anions like NO3-. Measuring the reversal potential of the transporter current in various ionic conditions suggested that the transport of one glutamate anion is coupled to the cotransport of three Na+ and one H+ and to the countertransport of one K+. This suggests that in ischemia, when [K+]o rises to 60 mM, the reversal of glutamate transporters will raise [glu]o to >50 microM.
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Affiliation(s)
- L M Levy
- Department of Anatomy, University of Oslo, Blindern, N-0317 Oslo, Norway
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