UV-induced mutagenesis of human p53: analysis using a double-selection method in yeast

Area of Science:

• Molecular biology
• Genetics
• Cancer research

Background:

• Comparing p53 mutation patterns in human tumors with model systems helps identify cancer etiological factors.
• A previous yeast assay allowed direct determination of mutation spectra induced by carcinogens in human p53.
• Existing methods face uncertainties when comparing mutation spectra across different target genes.

Purpose of the Study:

• To develop an improved yeast assay for efficient screening of p53 mutants.
• To enable intracellular exposure of the human p53 gene to mutagens within the yeast system.
• To facilitate the identification of environmental agents that can mutate the human p53 gene.

Main Methods:

• Modified a yeast assay by incorporating growth-based selection for transactivation-deficient p53 mutants.
• Integrated this selection with existing red/white colony color selection in yeast.
• Utilized UV light for mutagenization and sequence analysis to validate p53 mutations.

Main Results:

• The improved model system detected p53 mutations at a frequency of 10(-4) or less.
• UV light verification confirmed that most selected mutants harbored p53 mutations, not off-target genomic mutations.
• Sequence analysis of UV-induced mutations showed patterns consistent with previous studies.

Conclusions:

• The enhanced yeast assay system is effective for detecting p53 mutations induced by environmental agents.
• This system can reduce uncertainties in comparing mutation spectra from different genes or treatments.
• The assay contributes to hazard identification by assessing the mutagenic potential of environmental agents on the human p53 gene.