Development of Activity-Based Reporter Gene Technologyfor Imaging of Protease Activity with an Exquisite Specificity ina Single Live Cell

Imaging of protease function with an exquisite specificity in the presence of highly homologous protein within a living cell is the most challenging task. Herein, we disclose a new method called “Activity-based Reporter Gene Technology” (AbRGT). This method provides an opportunity to study the function of “active enzyme” with unprecedented specificity. As a proof-of-concept, we have applied this method to study the function of individual caspase enzyme in both intrinsic and extrinsic apoptosis signaling pathways. The versatility of this method is demonstrated by studying the function of both the initiator and effector caspases, independently. The modular fashion of this technology provides the opportunity to non-invasively image the function of cathepsin-B in a caspase-dependent cell death pathway. As a potential application, this method is used as a tool to screen compounds that are potent inhibitors of caspases and cathepsin-B enzymes. The fact that this method can be readily applied to any enzyme of in...