Light-Toggled Gene Expression in Mammalian Cells

Reported herein is the spatiotemporal regulation of the crucial phenomenon of RNA interference by exploiting photocleavable organic reagent as a caging group. Site-specific covalent attachment of the caging group to the phosphorothioate backbone of the dsRNA by a facile and mild postsynthetic method renders a noninvasive control of gene knockdown by light irradiation, blocking the RNAi and subsequently turning “on” siRNA via its photocleavage by non-toxic UV. We demonstrate that a photolabile intracellular compatible caging group formed by a nucleophilic substitution reaction between the phosphorothioate backbone of the sense or antisense strand of the dsRNA and the organic moiety can readily toggle the GFP expression in mammalian cancer cells