Spatially discrete, light-driven protein expression.

Transgene-based inducible expression systems offer the potential to study the influence of any gene at any point during an organism's lifetime. However, the expression of individual genes is both temporally and spatially (i.e., cell/tissue)-regulated. The inducible gene expression systems devised to date do not offer fine spatial control over gene expression. We describe herein the creation and study of a light-activatable, ecdysone-inducible gene expression system. We have constructed the first example of a caged ecdysteroid, which is virtually inactive as an inducing agent in a luciferase-based gene expression system. However, upon exposure to brief illumination, the caged ecdysteroid is rapidly converted into active beta-ecdysone. Caged beta-ecdysone is cell permeable, can be intracellularly photouncaged, and, in combination with spot illumination, can be used to drive spatially discrete protein expression in a multicellular setting.