Transcription of metallothionein isoform promoters is differentially regulated in cadmium-sensitive and -resistant CHO cells

Yu, Chi‐Wen; Chen, Hsin-Chien; Lin, Lih-Yuan

doi:10.1002/(sici)1097-4644(19980201)68:2<174::aid-jcb4>3.0.co;2-s

Cited by 15 publications

(3 citation statements)

References 33 publications

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“…Likewise, Hart et al studied repeated Cd exposures of sheep lungs but could not assess effects on MT mRNA because transcript levels remained elevated in animals receiving Cd pretreatment without any subsequent exposure. Nevertheless, MT is overexpressed in many Cd resistant cell-lines − and the MT gene has been functionally linked to the Cd sensitivity in transgenic and knockout mice. , …”

Section: Resultsmentioning

confidence: 99%

Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein

Shaw

Colbourne

Turner

et al. 2019

Environ. Sci. Technol.

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Acclimation increases tolerance to stress in individuals but is assumed to contribute fitness costs when the stressor is absent, though data supporting this widely held claim are sparse. Therefore, using clonal (i.e., genetically identical) cultures of Daphnia pulex, we isolated the contributions of acclimation to the regulation of the metal response gene, metallothionein 1 (MT1), and defined the reproductive benefits and costs of cadmium (Cd)-acclimation. Daphnia pulex were exposed for 50 parthenogenetic generations to environmentally realistic levels (1 μg Cd/L), and tolerance to Cd and other metals assessed during this period via standard toxicity tests. These tests revealed (1) increased tolerance to Cd compared to genetically identical nonacclimated cultures, (2) fitness costs in Cd-acclimated Daphnia when Cd was removed, and (3) cross-tolerance of Cd-acclimated Daphnia to zinc and silver, but not arsenic, thereby defining a functional role for metallothionein. Indeed, Cd-acclimated clones had significantly higher expression of MT1 mRNA than nonacclimated clones, when Cd exposed. Both the enhanced induction of MT1 and tolerant phenotype were rapidly lost when Cd was removed (1−2 generations), which is further evidence of acclimation costs. These findings provide evidence for the widely held view that acclimation is costly and are important for investigating evolutionary principles of genetic assimilation and the survival mechanisms of natural populations that face changing environments.

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Section: Resultsmentioning

confidence: 99%

Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein

Shaw

Colbourne

Turner

et al. 2019

Environ. Sci. Technol.

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“…The Cd R cells have the MT gene highly amplified (Morris and Huang, 1987). Due to MT gene methylation, the CHO K1 cells do not express MT mRNA (Stallings et al, 1986; Yu et al, 1998). Cells were cultured as monolayers at 37°C in McCoy's 5A medium supplemented with 10% heat‐inactivated fetal bovine serum (FBS), 0.22% sodium bicarbonate, 100 U/ml ampicillin, and 100 mg/ml streptomycin in 5% CO 2 /95% air and 100% humidity.…”

Section: Methodsmentioning

confidence: 99%

“…Cells with both MT‐I and MT‐II gene deletion have increased sensitivity to metal toxicity (Masters et al, 1994). Cells that cannot express both MT genes are very sensitive to metal damage (Yang et al, 1996; Yu et al, 1998). These findings indicate that those MTs are important in metal detoxification.…”

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confidence: 99%

Alkaline induces metallothionein gene expression and potentiates cell proliferation in Chinese hamster ovary cells

Lin¹,

Chen²,

Lee³

et al. 2005

Journal Cellular Physiology

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Metallothionein (MT) gene expression is increased in cadmium resistant Chinese hamster ovary cells (CHO Cd(R)) upon medium (regular or serum-free) change during culturing. Among the major components of the medium, NaHCO3 was found to be able to induce MT gene expression in a dose- and time-dependent manner. The same effect was observed with other alkaline solutions, such as HEPES and NaOH. Using MT promoter-luciferase reporter gene constructs, we found that the presence of metal response elements (MREs) in the promoter region is necessary for NaHCO3-induced MT gene transcription. This finding is further supported by the observation that the binding activity between the metal-responsive transcription factor 1 (MTF-1) and the MRE were increased after NaHCO3 treatment. Following NaHCO3 treatment, an increase in cell proliferation was observed in CdR cells but not in the parental CHO K1 cells that do not express MT transcripts due to MT gene methylation. Using synchronized cells, an increase in cell proliferation was observed 9 h after NaHCO3 addition. Notably, proliferation of CHO K1 cells was increased when transfected with an MT gene. The effect of MT on cell growth was affirmed by treating CHO K1 cells with 5-azacytidine (Aza) to demethylate the MT gene. Proliferation increased in Aza-treated CHO K1 cells after NaHCO3 treatment. These results demonstrate that NaHCO3 stimulates MT gene expression and causes an enhancement of cell proliferation in CHO cells.

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Consequences of trace metal variability and supplementation on Chinese hamster ovary (CHO) cell culture performance: A review of key mechanisms and considerations

Graham

Bhatia

Yoon

2019

Biotech & Bioengineering

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Trace metals are supplied to chemically-defined media (CDM) for optimal Chinese hamster ovary (CHO) cell culture performance during the production of monoclonal antibodies and other therapeutic proteins. However, lot-to-lot and vendor-to-vendor variability in raw materials consequently leads to an imbalance of trace metals that are supplied to CDM. This imbalance can yield detrimental effects rooted in several primary mechanisms and pathways including oxidative stress, apoptosis, lactate accumulation, and unfavorable glycan synthesis. Recent research endeavors involve supplying zinc, copper, and manganese to CDM in excess to further maximize culture productivity and product quality. These treatments significantly impact critical quality attributes and furthermore highlight the degree to which trace metal availability can affect CHO cell culture performance. This review highlights the role of trace metal variability, supplementation, and interplay on key cellular mechanisms responsible for overall culture performance and the production and quality of therapeutic proteins. K E Y W O R D SCHO cell culture performance, raw material variability, therapeutic proteins, trace metal deficiency, trace metal supplementation, trace metals

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Transcription of metallothionein isoform promoters is differentially regulated in cadmium-sensitive and -resistant CHO cells

Cited by 15 publications

References 33 publications

Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein

Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein

Alkaline induces metallothionein gene expression and potentiates cell proliferation in Chinese hamster ovary cells

Consequences of trace metal variability and supplementation on Chinese hamster ovary (CHO) cell culture performance: A review of key mechanisms and considerations

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