The bud scar-based screening system for hunting human genes extending life span

We developed a high-throughput screening system that allows identification of genes prolonging life span in the budding yeast Saccharomyces cerevisiae. The method is based on isolating yeast mother cells with an extended number of cell divisions as indicated by the increased number of bud scars on their surface. Fluorescently labeled wheat germ agglutinin (WGA) was used for specific staining of bud scars. Screening of a human HepG2 cDNA expression library in yeast resulted in the isolation of several yeast transformants with a potentially prolonged life span. The budding yeast S. cerevisiae, one of the favorite models used to study aging, has been studied extensively for the better understanding of the mechanisms of human aging. Because human disease genes often have yeast counterparts, they can be studied efficiently in this organism. One interesting example is the WRN gene, the human DNA helicase, which participates in the DNA repair pathway. The mutation of the WRN gene causes Werner syndrome showing premature-aging phenotype. Budding yeast contains WRN homologue, SGS1, and its mutation results in shortening yeast life span. The knowledge gained from the studies of budding yeast will benefit studies in humans for better understanding of aging and aging-related disease.