A cadmium-resistant variant of the Chinese hamster (CHO) cell with increased metallothionein induction capacity

Hildebrand, C.E.; Tobey, Robert A.; Campbell, E.W.; Enger, M. Duane

doi:10.1016/0014-4827(79)90199-x

Cited by 130 publications

(52 citation statements)

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“…It has been reported that in animal and higher plant cells the toxicity of Cd2+ is lessened by the synthesis of a low molecular weight protein, metallothionein, which contains a large amount of cysteine (Hildebrand et a/., 1979;Enger et al, 1981 ;Leber & Miya, 1976;Jackson et al, 1984;Beach & Palmiter, 1981). Fogel et al (1983) also demonstrated that the resistance of yeast to Cu2+ was correlated with the synthesis of a Cu-chelatin; increased synthesis of this protein resulted from an increased copy number of the DNA at the CUP1 region.…”

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confidence: 99%

Further Studies on the Subcellular Distribution of Cd2+ in Cd-sensitive and Cd-resistant Strains of Saccharomyces cerevisiae

1985

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When a Cd-resistant strain (301 N) and a Cd-sensitive strain (101 N ) of Saccharomyces cereuisiae were incubated in medium containing Cd2+, a large proportion of the cellular Cd2+ was found in the cytosol of strain 301 N, but not in that of strain 101N. Approximately 65% of the cellular Cd2+ was released from strain 301 N after treatment with chitosan, which affects cell membrane permeability. About 807; of the cellular Cd2+ released from strain 301 N by chitosan treatment was detected in a 30000-10000 molecular weight fraction prepared by ultrafiltration. The distribution of Cd2+ into the cytosol in strain 301N was inhibited in the presence of cycloheximide. The proportion of cellular Cu2+ or Zn2+ present in the cytosol after incubation with these ions was similar for the two strains (about 40"/,).

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confidence: 99%

Further Studies on the Subcellular Distribution of Cd2+ in Cd-sensitive and Cd-resistant Strains of Saccharomyces cerevisiae

1985

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“…Gel filtration of extracts of the subcellular par- (6)(7)(8)(9). Furthermore, Waku et al (23) found that metallothionein had no inhibitory effect on the activity of the microsomal enzyme, acyltransferase, whose activity was inhibited by Cd.…”

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confidence: 99%

“…Most of the Cd thus accumulated in the organs is bound to metallothionein located in the cytosol (4,5). Recent studies have shown that the metallothionein may have a protective role against Cd poisoning (6)(7)(8)(9).…”

Section: Introductionmentioning

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The chemical form of cadmium in subcellular fractions following cadmium exposure.

Waku¹

1984

Environ Health Perspect

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Wistar rats were given drinking water containing 250 ppm Cd for 12 months. After excision of the kidney and liver, the organs were subfractionated into nuclear, mitochondrial, microsomal and cytosol fractions, and the chemical forms of Cd in the subcelulur fractions were examined. Although approximately 90%o of the total Cd was present bi the cytosol, in the form of metallothionein, 3-5% was also present in the mitochondrial fraction and 5-7% in the microsomal fraction from both organs. By Sephadex G-75 gel ifitration, after solubilizing the particulate fractions with sodium deoxycholate, approximately 89%o of Cd in the microsomal fraction and 94% in the mitochondrial fraction eluted with the same retention time as that of metallothionein in both liver and kidney, while the remainder was found in a high molecular weight protein fraction. The Cd that eluted with the high molecular protein fraction may be involved in dysfunction in subcellular organelies.For estimating the toxicity of Cd associated with the high molecular weight fraction, rat liver microsomes and CdCI2 were mixed with 1% of sodium deoxycholate and the proteinCd complex produced was isolated by eluting with Sephadex G-75. This complex had a strong toxicity toward the alcohol dehydrogenase activity (SH-enzyme), and the Ki values of the Cd-protein complexes decreased with increased amount of Cd bound to the microsomal protein fraction. The above results suggest that loosely bound Cd increased in the case of higher Cd/protein and plays a toxic role in the living cells.

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“…Since glucocorticoids induce both murine MTs coordinately (25), these results could indicate that a single cis-acting element controls the glucocorticoid inducibility of pairs of linked MT-1 and MT-2 genes (16 Several cadmium-resistant (Cdr) Chinese hamster cell lines have been derived and characterized, which provide a unique experimental system with which to study the regulation of the MT genes of rodents. These Cdr lines each differ in their extents of MT inducibility (4,5,8,11,23) and in their MT gene dosage (4). Some of these lines also carry independent chromosome translocations whose breakpoints are near the amplified MT gene domains (4,22).…”

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“…The four Cd' Chinese hamster cell lines were grown in Spinner flask culture as previously described (11 Table 3) as described previously (10,11 10,8,6, and 2 h, respectively (see Table 3). Cytoplasmic RNA was isolated from paired 2-liter cultures of uninduced and zinc-induced cells, purified with phenolchloroform, and precipitated with alcohol, and the poly(A)+ fraction was purified by chromatography on oligo(dT) cellulose, each as previously described (8).…”

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Coordinate expression of amplified metallothionein I and II genes in cadmium-resistant Chinese hamster cells.

Griffith¹

1985

Mol. Cell. Biol.

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Recombinant DNA probes complementary to Chinese hamster metallothionein (MT)-1 and MT-2 mRNAs were used to compare MT gene copy numbers, zinc-induced MT mRNA levels, and uninduced MT mRNA levels in cadmium-resistant (Cdr) Chinese hamster ovary cell lines. Quantitative hybridization analyses determined that the MT-1 and MT-2 genes are each present at approximately single-copy levels in the genome of cell line Cdr2C1O and are coordinately amplified approximately 7, 3, and 12 times over the Cdr2C1O value in the genomes of cell lines Cdr2OF4, Cdr3OF9, and Cdr200Tl, respectively. The maximum zinc-induced MT-1 mRNA concentrations in cell lines Cdr2OF4, CdF3OF9, and Cdr200Ti were equal to 1, 3, and 15 times that measured in Cdr2C1O, respectively. Similarly, the maximum zinc-induced MT-2 mRNA concentrations were equal to 1, 3, and 14 times that measured in Cdr2C1O, respectively, and in each instance they were 90 to 150 times greater than their respective concentrations in uninduced cells. Thus, relative MT gene numbers are closely correlated with both zinc-induced and uninduced MT mRNA levels in CdF2C10, Cdr3OF9, and Cdr200Tl, but not in Cdr2OF4. Each of the latter two lines possesses structurally altered chromosomes whose breakpoints are near the MT locus. Nonetheless, the ratio of the levels of MT-1 to MT-2 mRNAs was constant in each of the four cell lines, including Cdr2OF4. These results demonstrate that MT-1 and MT-2 mRNAs are induced coordinately in each Cdr cell line. Therefore, the coordination of the induction of MT-1 and MT-2 mRNA is independent of MT gene amplification, MT gene rearrangement, and the relative inducibilities of amplified MT genes. However, MT mRNA and protein levels each indicate that MT-1 and MT-2 expression is non-coordinate in uninduced cells. Thus, regulation of MT expression may involve two different mechanisms which are differentially operative in induced and uninduced cells.The genomes of mammals encode two closely related metallothioneins (MTs), MT-1 and MT-2, whose expression is induced coordinately by either metals or glucocorticoids (1,13,17). Two different mechanisms have been advanced to account for the coordinate induction of mammalian MT genes. The first has been proposed to explain human MT regulation and is based on differences in the gene dosage and relative inducibilities of the human MT-1 and MT-2 genes. In humans, the MT gene cluster is composed of several functional MT genes and nonfunctional pseudogenes which are located at a number of different chromosomal loci (12,18,19). Mutagenesis and gene transfer experiments have identified regulatory regions upstream from each human MT gene promoter. The sequences upstream from the MT-2 promoter mediate transcription induction by zinc, cadmium, and glucocorticoids (12). In contrast, the sequences upstream from the MT-1 promoter mediate transcription induction by cadmium but are much less responsive to zinc and glucocorticoids (18). Nonetheless, since there are more MT-1 than MT-2 genes, both MT species can be induced coordinately...

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A cadmium-resistant variant of the Chinese hamster (CHO) cell with increased metallothionein induction capacity

Cited by 130 publications

References 28 publications

Further Studies on the Subcellular Distribution of Cd2+ in Cd-sensitive and Cd-resistant Strains of Saccharomyces cerevisiae

Further Studies on the Subcellular Distribution of Cd2+ in Cd-sensitive and Cd-resistant Strains of Saccharomyces cerevisiae

The chemical form of cadmium in subcellular fractions following cadmium exposure.

Coordinate expression of amplified metallothionein I and II genes in cadmium-resistant Chinese hamster cells.

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