metallothionein and cupric-chloride

Topics: Acclimatization; Animals; Arachidonic Acid; Biomarkers; Bufonidae; Chromatography, High Pressure Liquid; Copper; Dose-Response Relationship, Drug; Embryo, Nonmammalian; Lipid Metabolism; Metallothionein; Phospholipids; Protein Binding; Time Factors; Water Pollutants, Chemical

We applied a battery of biomarkers in the earthworm Eisenia andrei to assess the pollutant-induced stress syndrome. Earthworms were exposed to sublethal concentrations of copper (1-10 microM) and benzo[a]pyrene (0.01-10 microM) as models of inorganic and organic pollutants for 1, 3 and 7 days. Four potential biomarkers of stress were measured: lysosomal membrane stability of coelomocytes, lysosomal accumulation of lipofuscin in chloragogenous tissue and of neutral lipids in coelomatic cells, plasma membrane Ca2+-ATPase activity in the intestinal epithelium; metallothionein content was also evaluated as a biomarker of exposure. Significant changes were observed in the parameters measured in earthworms exposed to both contaminants. Certain biomarkers, such as lysosomal membrane stability and Ca2+-ATPase activity, that showed a decreasing trend with increasing pollutant concentration and time of exposure, proved to be particularly suitable to describe the evolution of a stress syndrome from its early phase to the development of pathological conditions. On the other hand, contaminant-induced changes in lysosomal lipofuscin and neutral lipid accumulation showed a bell-shaped trend, indicating that these biomarkers are able to follow the development of pollutant-induced stress syndrome as far as an equilibrium in the cell functions is maintained; therefore, they are particularly useful to describe mild stress conditions.

Topics: Animals; Benzo(a)pyrene; Biomarkers; Calcium-Transporting ATPases; Cell Membrane; Copper; Digestive System; Dose-Response Relationship, Drug; Environmental Monitoring; Intestinal Mucosa; Intracellular Membranes; Lipofuscin; Lysosomes; Metallothionein; Oligochaeta; Oxidative Stress; Soil Pollutants; Toxicity Tests

Adult female frogs Rana ridibunda were exposed to 50 and 100 ppm of Cu (as CuCl2) dissolved in water for 5, 15 and 30 days. We measured the Cu content in the liver, kidneys, ventral skin, and large intestine. Hepatic metallothionein (MT) was also measured and we identified by elution the type of proteins bound to copper. Gross morphological characteristics of the frogs were not affected by Cu accumulation. Cu uptake took place first across the skin, then accumulated first in the large intestine, and then in the liver which was continuously accumulating Cu at all exposure concentrations and times. The highest concentration of the metal was recorded in the kidneys at 30 days and 100 ppm exposure. It appears that the kidneys act as the secondary route of Cu detoxification, probably after a Cu overload of liver. The concentration of hepatic MT increased with the increase of Cu concentration in liver at the 5th and 15th day of exposure but we observed a decrease by the end of the experiment. Cu was observed in the MT-fraction, and in the high-molecular weight protein fraction.

Topics: Animals; Copper; Female; Inactivation, Metabolic; Intestinal Mucosa; Intestines; Kidney; Liver; Metallothionein; Organ Size; Rana ridibunda; Skin

To clarify the relationships between DNA damage and Cu-MT and between DNA damage and Cu in kidneys of rats injected with Au, we examined the histochemical localization of DNA damage, metallothionein (MT), and the accumulated Cu in the kidneys of rats injected with Au, Cu, or Cu-MT. The immunoreactivity of MT was observed predominantly in the outer stripe of the outer medulla and the inner cortex of the Au-injected rat, and the signals of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) were observed in the cortex. Cu detected by Timm's method was mainly distributed in the cortex of the Au-injected rat. These results indicated that DNA damage could be caused by free Cu in the cortex but not by the Cu bound to MT in the outer stripe of the outer medulla. This consideration was supported by the data from rats injected with Cu and Cu-MT. Furthermore, we determined the Cu contents in three fractions (cytosol, organelle, and precipitate-containing nuclei) of the kidneys. Interestingly, most of the Cu content in the kidney of the rat injected with Au or Cu-MT was detected in the cytosol, whereas most of the Cu content in the kidney of the rat injected with Cu was detected in the nuclei-containing precipitate. These findings suggest that the DNA damage in the kidneys of rats injected with Au may be associated with Cu-binding proteins but not with Cu-MT.

Topics: Animals; Chlorides; Chromatography, Gel; Copper; DNA Damage; Gold Compounds; Immunohistochemistry; In Situ Nick-End Labeling; Injections, Intraperitoneal; Kidney; Male; Metallothionein; Microscopy, Confocal; Rats; Rats, Sprague-Dawley

Redox properties of metallothioneins (MTs) and Cu in the cytosol from Long-Evans Cinnamon (LEC) rat livers 13 weeks after birth were investigated. MTs from LEC rat livers contain 8 g atoms of Cu and 1 g atom of Zn per mole of protein (Cu(I)8-MTs). Titration of Cu(I)8-MTs with CuCl2 indicates that Cu(I)8-MTs were able to reduce further 2-g atoms of cupric ions per mole MTs as bound form. Hg2+-induced hydroxyl radical generation from Cu(I)8-MTs was demonstrated by ESR using the spin trap, 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The intensity of DMPO-OH signal from Cu-loaded MTs was increased with the increasing number of Cu in MTs. The used cytosol fraction contained 1.37 mM total Cu and 5 mM DTNB titrable-SH groups has a potential to reduce 2 mM CuCl2. No ESR signal due to Cu2+ was also detected with LEC rat liver cytosol, whereas strong Cu2+ signal appeared by the addition of HgCl2. The rate constants for the reaction of Cu(I)8-MTs with superoxide and hydroxyl radicals were estimated to be 2 x 10(6) and > or = 10(12) M(-1)s(-1), respectively, from competition kinetics. Cu2+-catalyzed oxidation of DNA was strongly inhibited both in the presence of Cu-unsaturated MTs and GSH. The results suggest that Cu(I)8-MTs from LEC rat livers just before hepatitis still act as antioxidants.

Topics: Animals; Antioxidants; Binding, Competitive; Cadmium Chloride; Copper; Cyclic N-Oxides; Cytosol; DNA; Dose-Response Relationship, Drug; Electron Spin Resonance Spectroscopy; Glutathione; Hepatolenticular Degeneration; Hydroxyl Radical; Liver; Male; Mercuric Chloride; Metallothionein; Oxidation-Reduction; Rats; Rats, Inbred LEC; Reactive Oxygen Species; Superoxide Dismutase

Copper cells were originally identified in Drosophila midgut epithelium by their striking orange fluorescence in copper-fed larvae. Here, we examined copper cell fluorescence in light of the previous observations that (1) a similar fluorescent signal in yeast is produced by a complex between copper and metallothionein, and (2) metallothionein is expressed constitutively in the copper cell region and inducibly in other regions of the Drosophila midgut. Pulse-feeding experiments with 1 mM CuCl2 revealed that fluorescence appeared rapidly in copper cells (<5 min) and slowly in other cells of the midgut (days), suggesting a constitutive cofactor in the former and an inducible cofactor in the latter. Fluorescence was also detected in Drosophila S2 tissue culture cells after induction of metallothionein synthesis by addition of CuCl2 to the growth medium. Thus, fluorescence coincided spatially and temporally with the expression of metallothionein. Fluorescence was also linked to the acid-secreting activity of copper cells. Fluorescence was not observed when acid secretion was inhibited by a mutation in the alpha spectrin gene and acidification was blocked in copper-fed wild-type larvae. However, acidification was restored after a 1-day chase period in which the fluorescent signal became sequestered within a vesicular compartment. We therefore conclude that copper cell fluorescence is most probably attributable to a cytoplasmic copper-metallothionein complex, suggesting an unanticipated role for metallothionein in acid-secreting cells.

Topics: Animals; Cells, Cultured; Copper; Drosophila; Drosophila Proteins; Fluorescence; Gastric Mucosa; Hydrogen-Ion Concentration; Kinetics; Larva; Metallothionein; Microscopy, Fluorescence; Mutation; Spectrin

Metallothioneins (MTs) are the major low molecular weight, zinc-binding proteins in mammalian cells. It has been hypothesized that they play a role in the function of zinc-dependent signal transduction proteins and transcription factors. We investigated the capacity of zinc and other metal ions and conditions to increase both Zn-associated MT levels and the receptiveness of cells to transcriptional activation mediated by the zinc-dependent glucocorticoid receptor (GR). We studied, in a GR-responsive mouse mammary-tumor cell line, the ability of dexamethasone (DEX) to stimulate transcription of a chloramphenicol acetyltransferase (CAT) gene controlled by a mouse mammary-tumor virus promoter. In cells pretreated with 20 to 100 microM ZnCl(2), DEX-induced CAT activity correlated with zinc-induced MT levels. However, 0.05 to 0.5 microM CdCl(2) had no effect on CAT activity, despite an increase in Cd-associated MT. Copper-associated MT was detected in cells treated with 20 microM CuCl(2,) but there was no change in the level of Zn-MT, nor was CAT activity altered in cells exposed to 5 to 20 microM CuCl(2). These results may reflect a functional difference between zinc-associated MT, and MT associated with other metals. Significantly more CAT activity was observed in both heat-shocked cells and in cells exposed to 40 or 50 nM HgCl(2). Although absolute amounts of MT were unchanged by these two treatments, a higher percentage of total cellular zinc was associated with the MT protein fractions after treatment. Changes in GR levels could not account for variations in CAT activity. These data indicate that hormonal signalling can be altered by exposure to metal salts and heat shock, and the effect is correlated with the level of Zn-MT.

Topics: Animals; Cadmium Chloride; Cell Fractionation; Cell Nucleus; Chlorides; Copper; Dexamethasone; Gene Expression Regulation; Genes, Reporter; Glucocorticoids; Hot Temperature; Mercuric Chloride; Metallothionein; Mice; Promoter Regions, Genetic; Receptors, Glucocorticoid; Transcription, Genetic; Tumor Cells, Cultured; Zinc; Zinc Compounds

Lysyl oxidase, a copper-dependent metalloenzyme, plays a central role in crosslinking of collagen and elastin in the extracellular matrix. Notably, lung lysyl oxidase activity is markedly stimulated in rats exposed to cadmium vapors. To further understand the mechanism of cadmium toxicity, the mRNA expression, synthesis, post-translational processing, and catalytic activity of lysyl oxidase were examined in cadmium-resistant (CdR) cells and the cadmium-sensitive Swiss mouse 3T3 cells from which they were derived. These CdR cells synthesized and accumulated markedly elevated levels of metallothionein, a known marker for cadmium resistance, whereas the expression of lysyl oxidase was reduced considerably. In comparison to the parental, cadmium-sensitive cells, the suppression of enzyme production in the CdR cells was seen at the mRNA level, at the levels of intracellular proprotein production and mature enzyme secreted into the medium, and in terms of total enzyme activity in the culture. The presence of cupric chloride in the culture medium during the incubation of the CdR cells for 16 h significantly enhanced lysyl oxidase activity accumulating in the medium, suggesting that lysyl oxidase deficiency in CdR cells may be related to abnormal copper metabolism.

Topics: 3T3 Cells; Animals; Cadmium; Cells, Cultured; Copper; Down-Regulation; Drug Resistance; Gene Expression Regulation, Enzymologic; Metallothionein; Mice; Protein Precursors; Protein Processing, Post-Translational; Protein-Lysine 6-Oxidase; RNA, Messenger

Topics: Analysis of Variance; Animals; Aspartate Aminotransferases; Cadmium; Cadmium Poisoning; Copper; Injections, Subcutaneous; Liver; Liver Function Tests; Male; Metallothionein; Mice; Mice, Inbred ICR; Random Allocation; Specific Pathogen-Free Organisms; Testis; Thiobarbituric Acid Reactive Substances; Zinc

Iron and copper ions mediate generation of reactive oxygen radicals from O2 and H2O2 by the Fenton reaction: these radicals are capable of damaging DNA. We studied (a) the ability of these metals to induce double-strand breaks in DNA in vitro in the presence of H2O2 and ascorbic acid as donors of reactive oxygen, and (b) the ability of the metal-binding protein metallothionein (MT) to protect DNA from damage. Strand cleavage was measured by loss of fluorescence after binding to ethidium bromide and by increased mobility of DNA in agarose. The results show that Cu(II), Fe(II) and Fe(III) all can induce damage to calf thymus DNA under our experimental conditions. Cu(II)-induced DNA damage was dose-dependent and the degree of damage was proportional to the concentration of H2O2. On the other hand, DNA fragmentation was significant only in the presence of high concentrations of Fe(II) or Fe(III). Addition of Zn-MT to the reaction mixture prior to addition of Cu(II) inhibited fragmentation of DNA in a dose-dependent manner but had little effect on iron induced damage. Other proteins (histone or albumin) were not effective in protecting DNA from Cu-induced damage, as compared to Zn-MT. The formation of Cu(I) from Cu(II) in the presence of hydrogen peroxide and ascorbate was also inhibited by addition of Zn-MT. Thus, MT may protect DNA from damage by free radicals by sequestering copper and preventing its participation in redox reactions.

Topics: Animals; Ascorbic Acid; Copper; DNA Damage; Dose-Response Relationship, Drug; Drug Synergism; Electrophoresis, Agar Gel; Ethidium; Ferric Compounds; Ferrous Compounds; Free Radicals; Hydrogen Peroxide; In Vitro Techniques; Metallothionein; Oxidation-Reduction; Reactive Oxygen Species; Zinc

The LEC rat is a mutant strain displaying hereditary hepatitis, and shows abnormal accumulation of copper (Cu) similar to that occurring in Wilson's disease. We prepared a multicellular spheroid composed of LEC rat liver cells to investigate the mechanism for abnormal accumulation of Cu. These multicellular spheroids were prepared by detaching the monolayer on the collagen-conjugated thermo-responsive polymer coated culture dish at a temperature below the critical solution temperature and culturing on the non-adhesive substratum. Long-term cultured spheroids of LEC rat liver cells as well as SD rat liver cells were attempted. Non-parenchymal cells obtained by collagenase perfusion from the LEC liver were fewer than those from the SD liver. Cells from the LEC rat, over 11 weeks of age, did not form a cell sheet; however, a mixture of parenchymal cells from LEC rats over aged 11 weeks and non-parenchymal cells from SD rats of any age yielded intact spheroids. We examined the toxicity, the accumulation and distribution of Cu in spheroids. The accumulation of Cu in LEC spheroids was higher than that in SD spheroids. Results suggest that spheroids consisting of LEC liver cells are useful as an alternative model to in vivo tests to investigate the mechanism for abnormal accumulation of Cu in liver.

Topics: Animals; Copper; Hepatolenticular Degeneration; Kinetics; Liver; Male; Metallothionein; Rats; Rats, Mutant Strains; Rats, Sprague-Dawley; Spheroids, Cellular; Zinc

The concentration of biliary Cu was 0.12 +/- 0.01 microgram/ml in male LEC rats aged 14 weeks and 0.43 +/- 0.09 micrograms/ml in Fischer rats of the same age. When copper chloride (170 micrograms/kg b.w. as Cu) was infused intravenously (i.v.), the concentration of biliary Cu increased to only 0.21 +/- 0.06 microgram/ml 30 min after the infusion in LEC rats. In contrast, Fischer rats showed a concentration about 10 times higher (4.02 +/- 2.2 micrograms/ml) than that before the infusion. In Fischer rats pretreated with cadmium chloride, the biliary Cu concentration was 1.04 + 0.43 micrograms/ml 30 min after infusion of copper. Horseradish peroxidase (E.C.1.11.1.7) infused iv along with copper chloride was excreted into bile at a low level in LEC rats compared to Fischer rats. Our results suggest that the gross accumulation of hepatic Cu in the new, mutant LEC rats is due to a low excretion of Cu into bile and that the hepatobiliary dysfunction is related to spontaneous hepatitis.

Topics: Animals; Bile; Cadmium; Cadmium Chloride; Chlorides; Copper; Hepatitis, Animal; Horseradish Peroxidase; Injections, Intravenous; Liver; Male; Metallothionein; Rats; Rats, Inbred Strains

Cultured skin fibroblasts from patients with Menkes disease and Wilson disease were analyzed as to their sensitivities to copper and cadmium by means of a colony-forming ability and cell growth study. All the Menkes strains exhibited about 3-fold higher levels of resistance to cadmium, whereas the cytotoxicity of copper did not differ among the Menkes, Wilson and normal fibroblast strains. The resistance to cadmium of Menkes skin fibroblasts may provide a diagnostic marker of Menkes disease and useful or valuable model for the understanding of detoxification system against heavy metals.

Topics: Brain Diseases, Metabolic; Cadmium; Cadmium Chloride; Cell Division; Colony-Forming Units Assay; Copper; Drug Resistance; Fibroblasts; Hepatolenticular Degeneration; Humans; Menkes Kinky Hair Syndrome; Metallothionein; Osmolar Concentration; Skin

The copper complex of 3-ethoxy-2-oxobutyraldehyde bis(thiosemicarbazone) or CuKTS is reduced and dissociated upon reaction with Ehrlich cells. Titration of the cells with the complex leads to the specific binding of copper to metallothionein with 1 to 1 displacement of its complement of zinc. Under conditions of complete titration of metallothionein, 1.25-2.5 nmol CuKTS/10(7) cells, cellular DNA synthesis is rapidly inhibited but no long term effects on cell proliferation are observed. The kinetics of redistribution of Cu and Zn in Ehrlich cells in culture and in animals were studied after pulse reaction of CuKTS with cells. After exposure of cells to the noncytotoxic concentration of 2.5 nmol of CuKTS/10(7) cells, nonmetallothionein bound copper is lost rapidly from the cells, after which copper in metallothionein decays. New zinc metallothionein is made as soon as exposed cells are placed in culture. New synthesis stops when the level of zinc in metallothionein reaches control levels. A second pulse treatment of cells with CuKTS to displace zinc from metallothionein again stimulates new synthesis of the protein to restore its normal concentration. The kinetics of metal metabolism in Ehrlich cells exposed to 5.5 nmol of CuKTS/10(7) cells, which inhibits cell proliferation, are qualitatively similar except there is a pronounced lag before new zinc metallothionein is synthesized. The Ehrlich ascites tumor in mice responds to CuKTS similarly to cells in culture. It is also shown that cultured Ehrlich cells do not make extra zinc metallothionein in the presence of high levels of ZnCl2, and fail to accumulate copper in the presence of large concentrations of CuCl2.

Topics: Animals; Antineoplastic Agents; Carcinoma, Ehrlich Tumor; Cell Division; Cells, Cultured; Chlorides; Copper; Female; Kinetics; Metallothionein; Mice; Mice, Inbred ICR; Organometallic Compounds; Thiosemicarbazones; Time Factors; Zinc; Zinc Compounds

Topics: Animals; Apoproteins; Cadmium; Cadmium Chloride; Cell Nucleus; Chlorides; Copper; Lead; Liver; Male; Metallothionein; Metals; Mice; RNA; Zinc; Zinc Compounds

Copper chloride injection of rats resulted in a 4.5- to 9-fold increase in translatable metallothionein messenger RNA in the liver. Metallothionein in the translation products was identified on the basis of high cysteine and serine incorporation and absence of leucine incorporation as well as comigration with authentic zinc-induced rat-liver metallothionein on SDS-polyacrylamide gels.

Topics: Animals; Copper; Cysteine; Electrophoresis, Polyacrylamide Gel; Leucine; Liver; Male; Metalloproteins; Metallothionein; Protein Biosynthesis; Rats; Rats, Inbred Strains; RNA, Messenger; Serine; Sulfates; Zinc; Zinc Sulfate