Effects of camptothecin or TOP1 overexpression on genetic stability in Saccharomyces cerevisiae
Autor: | Sue Jinks-Robertson, Shar-yin Naomi Huang, Roketa S. Sloan, Yves Pommier |
---|---|
Jazyk: | angličtina |
Rok vydání: | 2017 |
Předmět: |
0301 basic medicine
Saccharomyces cerevisiae Proteins Saccharomyces cerevisiae Locus (genetics) Biochemistry DNA Ribosomal Article Genomic Instability 03 medical and health sciences chemistry.chemical_compound Gene Expression Regulation Fungal medicine Mutation frequency DNA Fungal Molecular Biology Ribosomal DNA biology Topoisomerase Cell Biology biology.organism_classification Molecular biology Yeast 030104 developmental biology chemistry DNA Topoisomerases Type I biology.protein Camptothecin DNA medicine.drug DNA Damage |
Popis: | Topoisomerase I (Top1) removes DNA torsional stress by nicking and resealing one strand of DNA, and is essential in higher eukaryotes. The enzyme is frequently overproduced in tumors and is the sole target of the chemotherapeutic drug camptothecin (CPT) and its clinical derivatives. CPT stabilizes the covalent Top1-DNA cleavage intermediate, which leads to toxic double-strand breaks (DSBs) when encountered by a replication fork. In the current study, we examined genetic instability associated with CPT treatment or with Top1 overexpression in the yeast Saccharomyces cerevisiae. Two types of instability were monitored: Top1-dependent deletions in haploid strains, which do not require processing into a DSB, and instability at the repetitive ribosomal DNA (rDNA) locus in diploid strains, which reflects DSB formation. Three 2-bp deletion hotspots were examined and mutations at each were elevated either when a wild-type strain was treated with CPT or when TOP1 was overexpressed, with the mutation frequency correlating with the level of TOP1 overexpression. Under both conditions, deletions at novel positions were enriched. rDNA stability was examined by measuring loss-of-heterozygosity and as was observed previously upon CPT treatment of a wild-type strain, Top1 overexpression destabilized rDNA. We conclude that too much, as well as too little of Top1 is detrimental to eukaryotic genomes, and that CPT has destabilizing effects that extend beyond those associated with DSB formation. |
Databáze: | OpenAIRE |
Externí odkaz: |