Optimization of Light-Inducible Gal4/UAS Gene Expression System in Mammalian Cells.

Light-inducible gene expression systems represent powerful methods for studying the functional roles of dynamic gene expression. Here, we developed an optimized light-inducible Gal4/UAS gene expression system for mammalian cells. We designed photoactivatable (PA)-Gal4 transcriptional activators based on the concept of split transcription factors, in which light-dependent interactions between Cry2-CIB1 PA-protein interaction modules can reconstitute a split Gal4 DNA-binding domain and p65 transcription activation domain. We developed a set of PA-Gal4 transcriptional activators (PA-Gal4cc), which differ in terms of induced gene expression levels following pulsed or prolonged light exposure, and which have different activation/deactivation kinetics. These systems offer optogenetic tools for the precise manipulation of gene expression at fine spatiotemporal resolution in mammalian cells.