Application of the gene search system to screen for longevity genes in Drosophila

We have developed a strategy using Drosophila as a model system to identify genes that are crucial for extension of longevity. A collection of transgenic lines with a P-element based gene search (GS) vector containing UAS (Upstream Activating Sequence) was screened for longevity in combination with an hsp70 promoter-driven GAL4 transgene. Misexpression of the vector-flanking sequence was induced throughout the adult stage to assess its effects on the aging process rather than development. We showed that the longevity was greatly affected by GS inserts, and it was positively correlated with paraquat resistance. Of 646 GS inserts, we selected 23 inserts with relatively longer longevity for further molecular analysis. All of the misexpressed sequences matched either known genes or ESTs (Expressed Sequence Tags). Among 13 genes whose functions are already known or suggested, six were related to stress resistance or redox balance (DmGST2, hsp26, nla, and Drosophila homologs of mammalian TRX, GILT and POSH), suggesting the importance of stress resistance for the extension of longevity. This is the first demonstration that a systematic gain-of-function screen could efficiently detect longevity genes.