51
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Zhong X, Cooley C, Seth N, Juo ZS, Presman E, Resendes N, Kumar R, Allen M, Mosyak L, Stahl M, Somers W, Kriz R. Engineering novel Lec1 glycosylation mutants in CHO-DUKX cells: Molecular insights and effector modulation of N-acetylglucosaminyltransferase I. Biotechnol Bioeng 2012; 109:1723-34. [DOI: 10.1002/bit.24448] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 12/29/2022]
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52
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Efficient formation of cell spheroids using polymer nanofibers. Biotechnol Lett 2011; 34:795-803. [DOI: 10.1007/s10529-011-0836-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 12/19/2011] [Indexed: 10/14/2022]
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53
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Bort JAH, Stern B, Borth N. CHO-K1 host cells adapted to growth in glutamine-free medium by FACS-assisted evolution. Biotechnol J 2011; 5:1090-7. [PMID: 20931603 DOI: 10.1002/biot.201000095] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
During the process of recombinant cell line optimisation for production of biopharmaceuticals, multiple cellular properties like robustness against stress, the attainment of high cell concentrations and maintenance of high viability must be considered to maximize protein yield. To improve growth and viability, glutamine is supplemented as an alternative energy source for rapidly dividing cells that oxidize glucose inefficiently. However, the resulting by-product ammonia is toxic at high concentrations and has a negative impact on protein glycosylation, a major quality-determining parameter of biopharmaceuticals. In this work, the CHO-K1 cell line was adapted to a chemically defined medium and suspension growth within 3 weeks. Subsequently, the glutamine concentration was stepwise reduced from 8 to 4 and 2 mM. After each reduction, both the final cell concentration in the batch and the viability decreased. To force a rapid evolution of cells to achieve high final cell concentrations, cells were seeded at high densities (10(7) cells/mL) and surviving cells were sorted by FACS or MACS when viability declined to 10% (typically after 24 h). Sorted cells were grown in batch until viability declined to 10% and viable cells recovered again. The final sorted population was able to reach comparable or even better viable cell concentrations and showed a significantly improved viability compared to their ancestors. The 2 mM glutamine-adapted cell line was directly transferred into glutamine-free medium and was able to grow at comparable rates without requiring further adaptation. Cells compensated the lack of glutamine by increasing their consumption of glutamate and aspartate.
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Affiliation(s)
- Juan A Hernández Bort
- Department of Biotechnology, University of Natural Resources and Applied Life Sciences, Vienna, Austria
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54
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Park JH, Park HH, Park TH. Cellular engineering for the high-level production of recombinant proteins in mammalian cell systems. KOREAN J CHEM ENG 2010. [DOI: 10.1007/s11814-010-0278-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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55
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Beyer T, Lohse S, Berger S, Peipp M, Valerius T, Dechant M. Serum-free production and purification of chimeric IgA antibodies. J Immunol Methods 2009; 346:26-37. [DOI: 10.1016/j.jim.2009.05.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Revised: 04/30/2009] [Accepted: 05/01/2009] [Indexed: 12/19/2022]
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56
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Thouas GA, Thompson MC, Contreras KG, Liow KYS, Tan KBT, Hourigan K. Improved oxygen diffusion and mechanical aggregation of tumor colonies in a novel stirred mini-bioreactor. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:3586-9. [PMID: 19163484 DOI: 10.1109/iembs.2008.4649981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The feasibility of a novel stirred bioreactor, the rotating aerial disk (RAD) design, was tested in this study. The novelty lies in its method of medium recirculation by convective airflow using a non-contact planar disc, a variation on a physically defined theoretical model. Computational predictions of improved oxygenation were confirmed by increases in measured dissolved oxygen, even at Reynolds numbers (100-200) where flow is mostly laminar. EL-4 mouse lymphoma cells grown for the first time as suspension cultures in the RAD bioreactor, were mechanically re-organization into dense, circular three-dimensional colonies (diameter 3-5 mm, thickness 5-800 microm), more rapidly than we have observed previously. Cell proliferation in the RAD vessels was similar to static cultures, although lactate production from glucose was significantly lower, suggesting a shift toward aerobic glycolysis. This possible reversal of the 'Warburg effect' was accompanied by a decrease in mitochondrial activity, perhaps reflecting a more quiescent cytoplasmic state. The RAD device may be useful as scalable, three-dimensional solid tumor model under more physiological conditions then static culture.
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57
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Favre N, Camps M, Arod C, Chabert C, Rommel C, Pasquali C. Chemokine receptor CCR2 undergoes transportin1-dependent nuclear translocation. Proteomics 2008; 8:4560-76. [PMID: 18846510 DOI: 10.1002/pmic.200800211] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Chemokines (CCs) are small chemoattractant cytokines involved in a wide variety of biological and pathological processes. Released by cells in the milieu, and extracellular matrix and activating signalling cascades upon binding to specific G protein-coupled receptors (GPCRs), they trigger many cellular events. In various pathologies, CCs are directly responsible for excessive recruitment of leukocytes to inflammatory sites and recent studies using chemokine receptor (CCR) antagonists permitted these molecules to reach the market for medical use. While interaction of CCs with their receptors has been extensively documented, downstream GPCR signalling cascades triggered by CC are less well understood. Given the pivotal role of chemokine receptor 2 (CCR2) in monocyte recruitment, activation and differentiation and its implication in several autoimmune-inflammatory pathologies, we searched for potential new CCR2-interacting proteins by engineering a modified CCR2 that we used as bait. Herein, we show the direct interaction of CCR2 with transportin1 (TRN1), which we demonstrate is followed by CCR2 receptor internalization. Further characterization of this novel interaction revealed that TRN1-binding to CCR2 increased upon time in agonist treated cells and promotes its nuclear translocation in a TRN1-dependent manner. Finally, we provide evidence that following translocation, the receptor localizes at the outer edge of the nuclear envelope where it is finally released from TRN1.
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58
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Jaluria P, Chu C, Betenbaugh M, Shiloach J. Cells by design: a mini-review of targeting cell engineering using DNA microarrays. Mol Biotechnol 2008; 39:105-11. [PMID: 18327555 DOI: 10.1007/s12033-008-9048-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent studies have demonstrated the utility of DNA microarray technology in engineering cellular properties. For instance, cellular adhesion, the necessity of cells to attach to a surface in order to to proliferate, was examined by comparing two distinct HeLa cell lines. Two genes, one encoding a type II membrane glycosylating sialyltransferase (siat7e) and the other encoding a secreted glycoprotein (lama4), were found to influence adhesion. The expression of siat7e correlated with reduced adhesion, whereas expression of lama4 correlated with increased adhesion, as shown by various assays. In a separate example, a gene encoding a mitochondrial assembly protein (cox15) and a gene encoding a kinase (cdkl3), were found to influence cellular growth. Enhanced expression of either gene resulted in slightly higher specific growth rates and higher maximum cell densities for HeLa, HEK-293, and CHO cell lines. Another investigated property was the adaptation of HEK-293 cells to serum-free media. The genes egr1 and gas6, both with anti-apoptotic properties, were identified as potentially improving adaptability by impacting viability at low serum levels. In trying to control apoptosis, researchers found that by altering the expression levels of four genes faim, fadd, alg-2, and requiem, apoptotic response could be altered. In the present work, these and related studies in microorganisms (prokaryote and eukaryote) are examined in greater detail focusing on the approach of using DNA microarrays to direct cellular behavior by targeting select genes.
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Affiliation(s)
- Pratik Jaluria
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
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59
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de la Luz-Hernández K, Rojas-del Calvo L, Rabasa-Legón Y, Lage-Castellanos A, Castillo-Vitlloch A, Díaz J, Gaskell S. Metabolic and proteomic study of NS0 myeloma cell line following the adaptation to protein-free medium. J Proteomics 2008; 71:133-47. [DOI: 10.1016/j.jprot.2008.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 02/14/2008] [Accepted: 02/18/2008] [Indexed: 10/22/2022]
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60
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Jaluria P, Konstantopoulos K, Betenbaugh M, Shiloach J. Egr1 and Gas6 facilitate the adaptation of HEK-293 cells to serum-free media by conferring enhanced viability and higher growth rates. Biotechnol Bioeng 2008; 99:1443-52. [PMID: 18023050 DOI: 10.1002/bit.21707] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Animal-derived serum is an essential media supplement for mammalian cells in cell culture. For a number of reasons including cost, regulatory concerns, lot inconsistency, potential contamination with adventitious agents, and down-stream processing it is desirable to eliminate the use of serum. Existing protocols designed to adapt cells to serum-free media (SFM) are time-consuming and provide little insight into how the cells adapt. To better understand the physiological responses associated with serum withdrawal and to expedite the adaptation process, a Human Embryonic Kidney-293 (HEK-293) cell line was propagated in 10% fetal bovine serum (FBS) and was progressively adapted to SFM and analyzed at specific serum levels by oligonucleotide microarrays. Of the differentially expressed genes two, early growth response 1 (egr1) and growth arrest specific 6 (gas6), were selected for further analysis based on their level of differential expression, overall expression patterns, and proposed functionalities. HEK-293 cells, propagated in 10% FBS were transfected with egr1 or gas6 and then adapted to SFM. Results indicated that higher expression of either gene moderately enhanced the ability of both cell lines to adapt to SFM. Egr1 appeared to have a greater impact on adaptability than gas6. Results also indicated that specific protein production was unaltered when the expression of egr1 was increased. Flow cytometric analysis revealed increased expression of egr1 was associated with an increase in the percentage of cells in the G2/M phases. These results indicate that enhanced expression of egr1 or gas6 facilitate adaptation to SFM by improving growth and viability.
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Affiliation(s)
- Pratik Jaluria
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Biotechnology Unit, Building 14A, Room 173, Bethesda, Maryland 20892, USA
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61
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Liu C, Dalby B, Chen W, Kilzer JM, Chiou HC. Transient Transfection Factors for High-Level Recombinant Protein Production in Suspension Cultured Mammalian Cells. Mol Biotechnol 2008; 39:141-53. [DOI: 10.1007/s12033-008-9051-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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62
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Astley K, Al-Rubeai M. The role of Bcl-2 and its combined effect with p21CIP1 in adaptation of CHO cells to suspension and protein-free culture. Appl Microbiol Biotechnol 2008; 78:391-9. [DOI: 10.1007/s00253-007-1320-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 12/07/2007] [Accepted: 12/08/2007] [Indexed: 12/01/2022]
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63
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Sleiman RJ, Gray PP, McCall MN, Codamo J, Sunstrom NAS. Accelerated cell line development using two-color fluorescence activated cell sorting to select highly expressing antibody-producing clones. Biotechnol Bioeng 2007; 99:578-87. [PMID: 17680677 DOI: 10.1002/bit.21612] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The success of engineered monoclonal antibodies as biopharmaceuticals has generated considerable interest in strategies designed to accelerate development of antibody expressing cell lines. Stable mammalian cell lines that express therapeutic antibodies at high levels typically take 6-12 months to develop. Here we describe a novel method to accelerate selection of cells expressing recombinant proteins (e.g., antibodies) using multiparameter fluorescence activated cell sorting (FACS) in association with dual intracellular autofluorescent reporter proteins. The method is co-factor-independent and does not require complex sample preparation. Chinese hamster ovary (CHO) clones expressing high levels of recombinant antibody were selected on the basis of a two-color FACS sorting strategy using heavy and light chain-specific fluorescent reporter proteins. We were able to establish within 12 weeks of transfection cell lines with greater than a 38-fold increase in antibody production when compared to the pool from which they were isolated, following a single round of FACS. The method provides a robust strategy to accelerate selection and characterization of clones and builds a foundation for a predictive model of specific productivity based upon on two-color fluorescence.
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Affiliation(s)
- Robert J Sleiman
- ACYTE Biotech Pty Ltd., University of New South Wales, Sydney, NSW, Australia
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64
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Tsutsumi R, Fujisaki S, Shozushima M, Saito K, Sato S. Anoikis-resistant MDCK cells carrying susceptibilities to TNF-alpha and verotoxin that are suitable for influenza virus cultivation. Cytotechnology 2006; 52:71-85. [PMID: 19002866 PMCID: PMC3449419 DOI: 10.1007/s10616-006-9032-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Accepted: 10/22/2006] [Indexed: 10/23/2022] Open
Abstract
Madin-Darby canine kidney (MDCK) cells were originally anchorage-dependent epithelial cells. Here, we have isolated a novel MDCK-derived cell population, termed 6 M-4, by means of culturing MDCK cells in suspension for nearly 6 months in the presence of Streptomyces griseus metalloendopeptidase (MEP). The isolated cells showed unique proliferation characteristics, which differed from parental MDCK cells. They proliferated adherently on a polystyrene matrix, but proliferated non-adherently both in the presence of MEP and on a non-adhesive matrix coated with poly 2-methacryloyloxyethyl phosphorylcholine (MPC). The 6 M-4 cells consisted of at least two cell types. One type, termed 6 M-4-TR7, would not grow in soft agar and showed a novel phenotype in that the cells were susceptible to both TNF-alpha and verotoxin 1 (VT1). In addition, the isolated adhesion-independent cells sustained epithelial traits of parental MDCK cells. We further show that these MDCK-derivative cells are suitable for influenza virus cultivation. Hemagglutination (HA) titers of influenzaviruses A and B were increased in the suspension culture of 6 M-4-TR7 cells supplemented with the MEP in comparison to adherently growing cells in the presence of trypsin.
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Affiliation(s)
- Reiko Tsutsumi
- Department of Microbiology, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate, 020-8505 Japan
| | | | - Masanori Shozushima
- Department of Radiology, School of Dentistry, Iwate Medical University, Uchimaru, Morioka, Iwate, 020-8505 Japan
| | - Koichi Saito
- Research Institute for Environmental Sciences and Public Health of Iwate, 4 Iioka-shinden, Morioka, Iwate, 020-0852 Japan
| | - Shigehiro Sato
- Department of Microbiology, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate, 020-8505 Japan
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65
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Pak JE, Arnoux P, Zhou S, Sivarajah P, Satkunarajah M, Xing X, Rini JM. X-ray crystal structure of leukocyte type core 2 beta1,6-N-acetylglucosaminyltransferase. Evidence for a convergence of metal ion-independent glycosyltransferase mechanism. J Biol Chem 2006; 281:26693-701. [PMID: 16829524 DOI: 10.1074/jbc.m603534200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leukocyte type core 2 beta1,6-N-acetylglucosaminyltransferase (C2GnT-L) is a key enzyme in the biosynthesis of branched O-glycans. It is an inverting, metal ion-independent family 14 glycosyltransferase that catalyzes the formation of the core 2 O-glycan (Galbeta1-3[GlcNAcbeta1-6]GalNAc-O-Ser/Thr) from its donor and acceptor substrates, UDP-GlcNAc and the core 1 O-glycan (Galbeta1-3GalNAc-O-Ser/Thr), respectively. Reported here are the x-ray crystal structures of murine C2GnT-L in the absence and presence of the acceptor substrate Galbeta1-3GalNAc at 2.0 and 2.7A resolution, respectively. C2GnT-L was found to possess the GT-A fold; however, it lacks the characteristic metal ion binding DXD motif. The Galbeta1-3GalNAc complex defines the determinants of acceptor substrate binding and shows that Glu-320 corresponds to the structurally conserved catalytic base found in other inverting GT-A fold glycosyltransferases. Comparison of the C2GnT-L structure with that of other GT-A fold glycosyltransferases further suggests that Arg-378 and Lys-401 serve to electrostatically stabilize the nucleoside diphosphate leaving group, a role normally played by metal ion in GT-A structures. The use of basic amino acid side chains in this way is strikingly similar to that seen in a number of metal ion-independent GT-B fold glycosyltransferases and suggests a convergence of catalytic mechanism shared by both GT-A and GT-B fold glycosyltransferases.
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Affiliation(s)
- John E Pak
- Department of Molecular, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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66
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Liu XM, Liu H, Wu BC, Li SC, Ye LL, Wang QW, Huang PT, Chen ZL. Suspended aggregates as an immobilization mode for high-density perfusion culture of HEK 293 cells in a stirred tank bioreactor. Appl Microbiol Biotechnol 2006; 72:1144-51. [PMID: 16568312 DOI: 10.1007/s00253-006-0409-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 03/01/2006] [Accepted: 03/05/2006] [Indexed: 10/24/2022]
Abstract
Cells of the human embryonic kidney cell line (HEK 293) grown in repeated suspension and perfusion systems were characterized and described. Cell aggregates that formed immediately after the HEK 293 cells were inoculated in stirred vessels in serum-containing Dulbecco's modified Eagle's medium (D-MEM)/F-12 medium. The mean diameter of the cell aggregates reflecting the aggregate size increased with culture time, shifting from 63 to 239 mum after 1 and 8 days of culture in spinner flasks, respectively. No significant differences in cell performance were observed between HEK 293 cell populations grown as suspended aggregates and those grown as anchored monolayers. Replacing the D-MEM/F-12 with CD 293 medium caused the compact spherical cell aggregates to dissociate into single cells and small irregular aggregates without any apparent effect on cell performance. Moreover, the spherical cell aggregates could reform from individual cells and small aggregates when exposed to the serum-containing D-MEM/F-12 dominant medium. Perfusion culture of HEK 293 cells grown as suspended aggregates in a 7.5-l stirred tank bioreactor for 17 days resulted in a maximum viable cell density of 1.2 x 10(7) cells ml(-1). These results demonstrate the feasibility and proof-of-concept for using aggregates as an immobilization system in large-scale stirred bioreactors because a small-scale culture can be used as easily as the inoculum for larger bioreactors.
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Affiliation(s)
- X M Liu
- Department of Cell Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai, Beijing 100071, People's Republic of China
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67
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Jeffs SA, Goriup S, Stacey G, Yuen CT, Holmes H. Comparative analysis of HIV-1 recombinant envelope glycoproteins from different culture systems. Appl Microbiol Biotechnol 2006; 72:279-90. [PMID: 16447052 DOI: 10.1007/s00253-005-0256-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 11/04/2005] [Accepted: 11/05/2005] [Indexed: 10/25/2022]
Abstract
The productivity of stable Chinese hamster ovary cell lines secreting HIV-1 monomeric (IIIB gp120) and oligomeric (UG21 gp140) recombinant envelope glycoproteins was compared in serum-containing (S+), serum-free (S-) and protein-free (P-) culture media. UG21 gp140 expression was greatest in S+ medium, while IIIBgp120 production was lower than gp140 in all three media but highest in S-. UG21 gp140 production was highest in standard 850-cm2 roller bottle cultures in S+ media, peaking after 14 days of incubation, while expression levels in the three media were 0.5 (S+), 0.4 (S-) and 0.2 (P-) mg/l, from which 90, 80 and 12% of gp140, respectively, could be purified by immunoaffinity chromatography. Purified UG21 gp140 from S+ and S- media possessed biological functionality as evidenced by CD4 and monoclonal antibody (Mab) binding. In contrast, UG21 gp140 from P- medium appears to be misfolded and non-functional. Despite the possession of a different N-linked glycan profile, UG21 gp140 from S- media shows very similar CD4 and Mab binding characteristics to S+ UG21 gp140. The relevance of these findings to HIV vaccine development is discussed.
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Affiliation(s)
- S A Jeffs
- Division of Retrovirology, National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Herts, EN6 3QG, UK.
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68
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Abstract
The vast majority of mammalian glycosyltransferases are endoplasmic reticulum (ER) and Golgi resident type II membrane proteins. As such, producing large quantities of properly folded and active enzymes for X-ray crystallographic analysis is a challenge. Described here are the methods that we have developed to facilitate the structural characterization of these enzymes. The approach involves the production of a soluble Protein A-tagged form of the catalytic domain in a mammalian cell expression system. Production is scaled up in a perfusion-fed bioreactor with media flow rates of 3-5 liters/day. Expression levels are typically in the 1- to 4-mg/liter range and a simple and efficient purification method based on immunoglobulin G (IgG)-Sepharose affinity chromatography has been developed. Our approach to delimiting the catalytic domain and deglycosylating it when necessary is also discussed. Finally, we describe the selenomethionine labeling protocol used in our X-ray crystal structure determination of leukocyte-type Core 2 beta1,6-N-acetylglucosaminyltransferase.
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Affiliation(s)
- John E Pak
- Department of Molecular and Medical Genetics, University of Toronto, Ontario, Canada
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69
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Seth G, McIvor RS, Hu WS. 17β-Hydroxysteroid dehydrogenase type 7 (Hsd17b7) reverts cholesterol auxotrophy in NS0 cells. J Biotechnol 2006; 121:241-52. [PMID: 16126295 DOI: 10.1016/j.jbiotec.2005.07.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 06/11/2005] [Accepted: 07/04/2005] [Indexed: 11/20/2022]
Abstract
NS0 is a host cell line widely used for the production of recombinant therapeutic proteins. In this work, we investigated the cholesterol-dependent phenotype of NS0 cells. Growth response to different precursors and comparative transcript analyses pointed to deficiency of 17beta-hydroxysteroid dehydrogenase type 7 (Hsd17b7) in NS0 cells. Hsd17b7 was previously shown to encode for an enzyme involved in estrogenic steroid biosynthesis. Its recent cloning into a yeast mutant deficient in ERG27 led to its functional characterization as the 3-ketoreductase of the cholesterol biosynthesis pathway. To ascertain that its cholesterol biosynthesis is blocked at the reduction reaction catalyzed by Hsd17b7, we genetically engineered NS0 cells to over express Hsd17b7. The stable transfectants of Hsd17b7 were able to grow independent of cholesterol. The results affirm the role of Hsd17b7 in the cholesterol biosynthesis pathway in mammals. Further, the findings allow for rational engineering of this industrially important cell line to alleviate their cholesterol dependence.
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Affiliation(s)
- Gargi Seth
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455-0132, USA
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70
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Ryu JH, Kim MS, Lee GM, Choi CY, Kim BS. The enhancement of recombinant protein production by polymer nanospheres in cell suspension culture. Biomaterials 2005; 26:2173-81. [PMID: 15576193 DOI: 10.1016/j.biomaterials.2004.06.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Accepted: 06/14/2004] [Indexed: 10/26/2022]
Abstract
Recombinant Chinese hamster ovary (rCHO) cells are being increasingly used in industry for the production of recombinant therapeutic proteins. Three-dimensional suspension culture is preferred to two-dimensional monolayer culture for the efficient large-scale culture of rCHO cells and subsequent mass production of recombinant proteins. Previously, we have demonstrated that the use of plain polymer nanospheres enhances the growth of anchorage-dependent animal cells (human embryonic kidney 293 cells) in suspension culture in serum-containing medium. Vitronectin and fibronectin were adsorbed onto poly(lactic-co-glycolic acid) (PLGA) nanospheres (696 nm in average diameter) by immersing the nanospheres in fetal bovine serum. In this study, we investigated if the use of vitronectin/fibronectin-adsorbed polymer nanospheres enhances recombinant protein production in rCHO cell suspension culture in serum-free medium. Cell aggregate formation may be critical for the survival and growth of anchorage-dependent animal cells in suspension culture, and cells in single cell suspension may result in cell death. The addition of vitronectin/fibronectin-adsorbed nanospheres to rCHO cell suspension culture promoted the rate and efficiency of cell aggregate formation. The nanospheres enhanced cell growth (2.9 folds on day 10) and, importantly, recombinant antibody production (1.8 folds on day 14), compared to suspension culture without nanospheres. The viability of cells in the aggregates in the nanosphere-added culture was high for the entire culture period of 14 days. Apoptotic activity of cells was much lower in the nanosphere-added culture than in the culture without nanospheres on day 5. The nanosphere suspension culture method developed in this study may be useful for the mass production of recombinant proteins through large-scale suspension culture of anchorage-dependent animal cells.
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Affiliation(s)
- Ju Hee Ryu
- Department of Chemical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, South Korea
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71
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Abstract
Cultivated mammalian cells have become the dominant system for the production of recombinant proteins for clinical applications because of their capacity for proper protein folding, assembly and post-translational modification. Thus, the quality and efficacy of a protein can be superior when expressed in mammalian cells versus other hosts such as bacteria, plants and yeast. Recently, the productivity of mammalian cells cultivated in bioreactors has reached the gram per liter range in a number of cases, a more than 100-fold yield improvement over titers seen for similar processes in the mid-1980s. This increase in volumetric productivity has resulted mainly from improvements in media composition and process control. Opportunities still exist for improving mammalian cell systems through further advancements in production systems as well as through vector and host cell engineering.
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Affiliation(s)
- Florian M Wurm
- Laboratory of Cellular Biotechnology, Institute of Biological Engineering and Biotechnology, Faculty of Life Sciences, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland. florian@
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72
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Acker JP. Biopreservation of cells and engineered tissues. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2005; 103:157-87. [PMID: 17195463 DOI: 10.1007/b137204] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The development of effective preservation and long-term storage techniques is a critical requirement for the successful clinical and commercial application of emerging cell-based technologies. Biopreservation is the process of preserving the integrity and functionality of cells, tissues and organs held outside the native environment for extended storage times. Biopreservation can be categorized into four different areas on the basis of the techniques used to achieve biological stability and to ensure a viable state following long-term storage. These include in vitro culture, hypothermic storage, cryopreservation and desiccation. In this chapter, an overview of these four techniques is presented with an emphasis on the recent developments that have been made using these technologies for the biopreservation of cells and engineered tissues.
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Affiliation(s)
- Jason P Acker
- Department of Laboratory Medicine and Pathology, University of Alberta, 8249-114 Street, Edmonton, AB T6G 2R8, Canada.
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Schatz SM, Kerschbaumer RJ, Gerstenbauer G, Kral M, Dorner F, Scheiflinger F. Higher expression of fab antibody fragments in a CHO cell line at reduced temperature. Biotechnol Bioeng 2003; 84:433-8. [PMID: 14574700 DOI: 10.1002/bit.10793] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A chimeric Fab was expressed in Chinese hamster ovary cells under the control of the CMV promoter in a two-stage production process. Cells were first grown to 90% confluence at 37 degrees C in a proliferation phase, followed by a production phase at either 37 degrees C or 28 degrees C. Medium supplemented with serum and medium free from serum was tested in the production phase at both temperatures. Comparison of Fab expression revealed that reducing the temperature to 28 degrees C resulted in a 14-fold increase in product yield when cells were cultivated in serum-containing medium, and in a 38-fold increase in product yield when serum-free medium was applied.
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Affiliation(s)
- Simone M Schatz
- Baxter BioScience, Biomedical Research Center, Orth/Donau, Austria
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Thomas PB, Risinger KE, Klinge CM. Identification of estrogen receptor beta expression in Chinese hamster ovary (CHO) cells and comparison of estrogen-responsive gene transcription in cells adapted to serum-free media. J Steroid Biochem Mol Biol 2003; 86:41-55. [PMID: 12943744 DOI: 10.1016/s0960-0760(03)00250-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Most cultured cell lines require addition of serum to the medium to maintain their proliferative capacity. For studies examining the cellular effects of estrogens serum is charcoal-stripped to remove steroids. Nonetheless, addition of the selective estrogen receptor modulator (SERM) 4-hydroxytamoxifen (4-OHT) inhibits the basal transcriptional activity of estrogen receptors alpha or beta (ERalpha or ERbeta) in transfected cells. We tested the hypothesis that elimination of serum from the culture medium will block 4-OHT's repression of basal activity. Chinese hamster ovary (CHO-K1) cells adapted to serum-free medium exhibited estrogen responsiveness that was identical with that of the cells grown in serum-containing media. 4-OHT-suppressed basal transcription of an estrogen response element (ERE)-reporter in ERalpha-transfected cells even in the absence of serum, indicating that the 4-OHT suppressive activity is not mediated by blocking ER interaction with serum estrogens. We speculate that 4-OHT-ER recruits co-repressors to suppress basal transcription. We discovered that CHO-K1 cells express ERalpha and ERbeta mRNA. However only ERbeta protein was expressed and use of ERbeta-selective 2,3-bis(4-hydroxy-phenyl)propionitrile (DPN) and ERalpha-selective 4-propyl-1,3,5-tris(4-hydroxy-phenyl)pyrazole) (PPT) revealed that only ERbeta was transcriptionally active. In conclusion, growing CHO-K1 in serum-free medium does not impact the estrogen responsiveness and this cell line expresses functional ERbeta.
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MESH Headings
- Animals
- CHO Cells/cytology
- CHO Cells/drug effects
- CHO Cells/metabolism
- Cricetinae
- Culture Media, Serum-Free
- Estradiol/analogs & derivatives
- Estradiol/metabolism
- Estradiol/pharmacology
- Estrogen Receptor Modulators/pharmacology
- Estrogen Receptor alpha
- Estrogen Receptor beta
- Ethanol/pharmacology
- Fulvestrant
- Gene Expression Regulation/drug effects
- Genes, Reporter
- Luciferases/genetics
- Nitriles/chemistry
- Nitriles/pharmacology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, Estrogen/agonists
- Receptors, Estrogen/biosynthesis
- Receptors, Estrogen/drug effects
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Response Elements/drug effects
- Response Elements/genetics
- Tamoxifen/analogs & derivatives
- Tamoxifen/antagonists & inhibitors
- Tamoxifen/pharmacology
- Transcription, Genetic/drug effects
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Affiliation(s)
- Padmaja B Thomas
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA
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Korke R, Rink A, Seow TK, Chung MCM, Beattie CW, Hu WS. Genomic and proteomic perspectives in cell culture engineering. J Biotechnol 2002; 94:73-92. [PMID: 11792453 DOI: 10.1016/s0168-1656(01)00420-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In the last few years, the number of biologics produced by mammalian cells have been steadily increasing. The advances in cell culture engineering science have contributed significantly to this increase. A common path of product and process development has emerged in the last decade and the host cell lines frequently used have converged to only a few. Selection of cell clones, their adaptation to a desired growth environment, and improving their productivity has been key to developing a new process. However, the fundamental understanding of changes during the selection and adaptation process is still lacking. Some cells may undergo irreversible alteration at the genome level, some may exhibit changes in their gene expression pattern, while others may incur neither genetic reconstruction nor gene expression changes, but only modulation of various fluxes by changing nutrient/metabolite concentrations and enzyme activities. It is likely that the selection of cell clones and their adaptation to various culture conditions may involve alterations not only in cellular machinery directly related to the selected marker or adapted behavior, but also those which may or may not be essential for selection or adaptation. The genomic and proteomic research tools enable one to globally survey the alterations at mRNA and protein levels and to unveil their regulation. Undoubtedly, a better understanding of these cellular processes at the molecular level will lead to a better strategy for 'designing' producing cells. Herein the genomic and proteomic tools are briefly reviewed and their impact on cell culture engineering is discussed.
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Affiliation(s)
- Rashmi Korke
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN, USA
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