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Synoground BF, McGraw CE, Elliott KS, Leuze C, Roth JR, Harcum SW, Sandoval NR. Transient ammonia stress on Chinese hamster ovary (CHO) cells yield alterations to alanine metabolism and IgG glycosylation profiles. Biotechnol J 2021; 16:e2100098. [PMID: 34014036 DOI: 10.1002/biot.202100098] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/29/2021] [Accepted: 05/11/2021] [Indexed: 01/21/2023]
Abstract
BACKGROUND Ammonia concentrations typically increase during mammalian cell cultures, mainly due to glutamine and other amino acid consumption. An early ammonia stress indicator is a metabolic shift with respect to alanine. To determine the underlying mechanisms of this metabolic shift, a Chinese hamster ovary (CHO) cell line with two distinct ages (standard and young) was cultured in parallel fed-batch bioreactors with 0 mM or 10 mM ammonia added at 12 h. Reduced viable cell densities were observed for the stressed cells, while viability was not significantly affected. The stressed cultures had higher alanine, lactate, and glutamate accumulation. Interestingly, the ammonia concentrations were similar by Day 8.5 for all cultures. We hypothesized the ammonia was converted to alanine as a coping mechanism. Interestingly, no significant differences were observed for metabolite profiles due to cell age. Glycosylation analysis showed the ammonia stress reduced galactosylation, sialylation, and fucosylation. Transcriptome analysis of the standard-aged cultures indicated the ammonia stress had a limited impact on the transcriptome, where few of the significant changes were directly related metabolite or glycosylation reactions. These results indicate that mechanisms used to alleviate ammonia stress are most likely controlled post-transcriptionally, and this is where future research should focus.
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Affiliation(s)
| | - Claire E McGraw
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana, USA
| | - Kathryn S Elliott
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
| | - Christina Leuze
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA.,Department of Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Jada R Roth
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana, USA
| | - Sarah W Harcum
- Department of Bioengineering, Clemson University, Clemson, South Carolina, USA
| | - Nicholas R Sandoval
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana, USA
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Chitwood DG, Wang Q, Elliott K, Bullock A, Jordana D, Li Z, Wu C, Harcum SW, Saski CA. Characterization of metabolic responses, genetic variations, and microsatellite instability in ammonia-stressed CHO cells grown in fed-batch cultures. BMC Biotechnol 2021; 21:4. [PMID: 33419422 PMCID: PMC7791692 DOI: 10.1186/s12896-020-00667-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 12/11/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND As bioprocess intensification has increased over the last 30 years, yields from mammalian cell processes have increased from 10's of milligrams to over 10's of grams per liter. Most of these gains in productivity can be attributed to increasing cell densities within bioreactors. As such, strategies have been developed to minimize accumulation of metabolic wastes, such as lactate and ammonia. Unfortunately, neither cell growth nor biopharmaceutical production can occur without some waste metabolite accumulation. Inevitably, metabolic waste accumulation leads to decline and termination of the culture. While it is understood that the accumulation of these unwanted compounds imparts a suboptimal culture environment, little is known about the genotoxic properties of these compounds that may lead to global genome instability. In this study, we examined the effects of high and moderate extracellular ammonia on the physiology and genomic integrity of Chinese hamster ovary (CHO) cells. RESULTS Through whole genome sequencing, we discovered 2394 variant sites within functional genes comprised of both single nucleotide polymorphisms and insertion/deletion mutations as a result of ammonia stress with high or moderate impact on functional genes. Furthermore, several of these de novo mutations were found in genes whose functions are to maintain genome stability, such as Tp53, Tnfsf11, Brca1, as well as Nfkb1. Furthermore, we characterized microsatellite content of the cultures using the CriGri-PICR Chinese hamster genome assembly and discovered an abundance of microsatellite loci that are not replicated faithfully in the ammonia-stressed cultures. Unfaithful replication of these loci is a signature of microsatellite instability. With rigorous filtering, we found 124 candidate microsatellite loci that may be suitable for further investigation to determine whether these loci may be reliable biomarkers to predict genome instability in CHO cultures. CONCLUSION This study advances our knowledge with regards to the effects of ammonia accumulation on CHO cell culture performance by identifying ammonia-sensitive genes linked to genome stability and lays the foundation for the development of a new diagnostic tool for assessing genome stability.
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Affiliation(s)
- Dylan G Chitwood
- Department of Bioengineering, College of Engineering, Computing and Applied Sciences, Clemson University, Clemson, SC, 29634, USA
| | - Qinghua Wang
- Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, 19716, USA
| | - Kathryn Elliott
- Department of Bioengineering, College of Engineering, Computing and Applied Sciences, Clemson University, Clemson, SC, 29634, USA
| | - Aiyana Bullock
- Department of Biological Sciences, College of Agriculture, Science & Technology, Delaware State University, Dover, DE, 19901, USA
| | - Dwon Jordana
- Department of Biological Sciences, Grambling State University, Grambling, LA, 71245, USA
| | - Zhigang Li
- Department of Plant and Environmental Sciences, College of Agriculture, Forestry and Life Sciences, Clemson University, Clemson, SC, 29634, USA
| | - Cathy Wu
- Center for Bioinformatics & Computational Biology, University of Delaware, Newark, DE, 19716, USA
| | - Sarah W Harcum
- Department of Bioengineering, College of Engineering, Computing and Applied Sciences, Clemson University, Clemson, SC, 29634, USA
| | - Christopher A Saski
- Department of Plant and Environmental Sciences, College of Agriculture, Forestry and Life Sciences, Clemson University, Clemson, SC, 29634, USA.
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McDonald AG, Hayes JM, Davey GP. Metabolic flux control in glycosylation. Curr Opin Struct Biol 2016; 40:97-103. [DOI: 10.1016/j.sbi.2016.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/04/2016] [Accepted: 08/29/2016] [Indexed: 11/17/2022]
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Sha S, Agarabi C, Brorson K, Lee DY, Yoon S. N-Glycosylation Design and Control of Therapeutic Monoclonal Antibodies. Trends Biotechnol 2016; 34:835-846. [PMID: 27016033 DOI: 10.1016/j.tibtech.2016.02.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/20/2016] [Accepted: 02/24/2016] [Indexed: 12/31/2022]
Abstract
The N-linked glycan profiles on recombinant monoclonal antibody therapeutics significantly affect antibody biological functions and are largely determined by host cell genotypes and culture conditions. A key step in bioprocess development for monoclonal antibodies (mAbs) involves optimization and control of N-glycan profiles. With pressure from pricing and biosimilars looming, more efficient and effective approaches are sought in the field of glycoengineering. Metabolic studies and mathematical modeling are two such approaches that optimize bioprocesses by better understanding and predicting glycosylation. In this review, we summarize a group of strategies currently used for glycan profile modulation and control. Metabolic analysis and mathematical modeling are then explored with an emphasis on how these two techniques can be utilized to advance glycoengineering.
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Affiliation(s)
- Sha Sha
- Biomedical Engineering and Biotechnology, University of Massachusetts Lowell, Lowell, MA 01850, USA
| | - Cyrus Agarabi
- Division of Biotechnology Review and Research II, Office of Biotechnology Products, OPQ, CDER, FDA, Silver Spring, MD, USA
| | - Kurt Brorson
- Division of Biotechnology Review and Research II, Office of Biotechnology Products, OPQ, CDER, FDA, Silver Spring, MD, USA
| | - Dong-Yup Lee
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive, Singapore 117585, Singapore
| | - Seongkyu Yoon
- Biomedical Engineering and Biotechnology, University of Massachusetts Lowell, Lowell, MA 01850, USA.
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