An inducible system for in vitro and in vivo Fas activation using FKBP-FRB-rapamycin complex.

The inducible activation system is valuable for investigating spatiotemporal roles of molecules. A chemically inducible activation system for Fas (CD95/APO-1), which works efficiently to induce apoptosis and leads non-apoptotic pathways, has not yet been developed. Here, we engineered a rapamycin-induced dimerization system of Fas consisting of FKBP and FRB proteins. Treatment of rapamycin specifically induces cellular apoptosis. In neurons and cells with high c-FLIP expression, rapamycin-induced Fas activation triggered the activation of the non-apoptotic pathway components instead of cell death. Intracranial delivery of the system could be utilized to induce apoptosis of tumor cells upon rapamycin treatment. Our results demonstrate a novel inducible Fas activation system which operates with high efficiency and temporal precision in vitro and in vivo promising a potential therapeutic strategy.