Inducible GAL4 Systems for Gene Expression Control in Adult Drosophila
The ability to express a gene of interest in a directed place, time and magnitude is enabled by gene expression control tools. The UAS/GAL4 system is by far the most widely used tool inDrosophila with a collection of thousands of GAL4 drivers available within the community. Despite the system’s vast applications the UAS/GAL4 system does not allow for temporal control of gene expression. A major focus of many fly geneticists has been to create a new system by generating new transgenes based on entirely different transcriptional regulators. However it is much more convenient to take advantage of the existing UAS and/or GAL4 lines, many of which have already been spatially and temporally characterized through adult life (Seroude et al. Aging Cell, 2002). We have generated two new inducible GAL4-based gene expression systems: the Tet-Off GAL80 transgenes and the Lac Inducible UAS/GAL4 system.
The Tet-Off GAL80 transgenes were designed to express GAL80 under the control of a Tet-Off promoter to regulate GAL4 activity. Two versions of the transgene were generated each with a unique ubiquitous promoter that drives expression of tTA. We exhaustively examined the repressive ability of GAL80, using both UAS-grim and UAS-lacZ reporters, finding that the best repression was achieved in genotypes with four copies and both versions of the transgene. Induction was observed in tetracycline treated animals but was found to be dependent on sex, age, and the anatomical location of expression. In this study the repressive ability of GAL80 is affected by age which limits its use to regulate expression in adult animals.
The Lac Inducible UAS/GAL4 System was designed to regulate the UAS promoter by incorporating lac operator (LacO) sequences to which LacI could bind and repress UAS transcriptional activity. Two different versions of the modified LacO-UAS were built previously: pHN1 (2 operators) and pHN4 (3 operators). Here the influence of the addition of the lac operators is studied and found to negatively affect UAS transcriptional activity through age, independent of LacI.
12:30-1:30, BioSci Rm. 3110