Abstract
The state of cellular chromatin in response to DNA damage has been examined by monitoring the change in the linking number of circular episomes. COS cells transfected with an SV40-based vector were treated with camptothecin (CPT), a eukaryotic DNA topoisomerase I (TOP1) poison which induces TOP1-mediated DNA damage. Within minutes, a large increase in the linking number (over 10 linking number) of a small fraction (5-15%) of the episomal DNA was observed. A similar CPT-induced increase in plasmid DNA linking number was observed in Saccharomyces cerevisae expressing human DNA TOP1. In this case, the majority of the plasmid DNA can undergo rapid relaxation. The large increase in the plasmid linking number suggests major chromatin structural reorganization in response to TOP I-mediated DNA damage.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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COS Cells
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Camptothecin / pharmacology
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Cell Line
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Chloroquine / pharmacology
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Chromatin / chemistry
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Chromatin / drug effects
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Chromatin / genetics
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Chromatin / metabolism
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DNA Damage* / drug effects
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DNA Damage* / radiation effects
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DNA Topoisomerases, Type I / genetics
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DNA Topoisomerases, Type I / metabolism*
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DNA, Superhelical / chemistry
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DNA, Superhelical / genetics
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DNA, Superhelical / metabolism*
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Dose-Response Relationship, Drug
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Enzyme Inhibitors / pharmacology
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Fungal Proteins / genetics
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Fungal Proteins / physiology
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Humans
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Micrococcal Nuclease / metabolism
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Models, Genetic
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Nucleic Acid Conformation* / drug effects
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Nucleic Acid Conformation* / radiation effects
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Plasmids / chemistry*
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Plasmids / genetics
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Plasmids / metabolism
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Simian virus 40 / genetics
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Time Factors
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Topoisomerase I Inhibitors
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Transfection
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Ultraviolet Rays
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Yeasts / drug effects
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Yeasts / genetics
Substances
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Chromatin
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DNA, Superhelical
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Enzyme Inhibitors
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Fungal Proteins
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Topoisomerase I Inhibitors
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Chloroquine
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Micrococcal Nuclease
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DNA Topoisomerases, Type I
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Camptothecin