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Mutational specificity in a shuttle vector replicating in chromium(VI)-treated mammalian cells
1Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Environmental and Molecular Mutagenesis
|July 9, 1999
Summary
Chromium(VI) exposure induces mutations in mammalian cells, primarily at GC base pairs, via oxidative DNA damage. This mechanism mirrors hydrogen peroxide
Area of Science:
- Molecular Biology
- Toxicology
- Genetics
Background:
- Chromium(VI) is a known mutagenic agent.
- Previous in vitro studies suggested reactive oxygen intermediates mediate chromium mutagenesis.
- The precise mechanism in mammalian cells required further investigation.
Purpose of the Study:
- To elucidate the mechanism of chromium(VI) mutagenesis in cultured mammalian cells.
- To characterize the mutation specificity induced by chromium(VI) exposure.
- To compare chromium-induced mutation spectra with those induced by oxidative stress.
Main Methods:
- Cultured mammalian cells containing the pZ189 shuttle vector were treated with chromium(VI).
- Mutations within the supF gene were analyzed.
- Mutation spectra were compared between chromium(VI)-treated and control groups, as well as with hydrogen peroxide-treated groups.
Main Results:
- Chromium(VI) induced mutations in a dose-dependent manner.
- The majority of mutations were base substitutions, predominantly at GC base pairs.
- A specific mutation hotspot at position 43 was observed in chromium(VI)-treated cells.
- Mutation spectra showed similarities to those induced by hydrogen peroxide.
Conclusions:
- Chromium(VI) induces mutations in mammalian cells through the generation of oxidative DNA damage.
- The findings support the hypothesis that reactive oxygen species are key mediators of chromium mutagenesis.
- The study provides insights into the genotoxic mechanisms of chromium exposure.
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