High Sensitivity and Low-Cost Flavin luciferase (FLUX)-based Reporter Gene for Mammalian Cell Expression

Luciferase-based gene reporters generating bioluminescence signals are important tools for biomedical research. Amongst the luciferases, flavin-dependent enzymes use the most common, and thus most economical chemicals. However, their applications in mammalian cells are limited due to their low signals compared to other systems. Here, we constructed Flavin Luciferase for Mammalian Cell Expression (FLUX) by engineering luciferase from Vibrio campbellii (the most thermostable bacterial luciferase reported to date) and optimizing its expression and reporter assays in mammalian cells. We found that the FLUX reporter gene can be overexpressed in various cell lines and showed outstanding signal-to-background in HepG2 cells, significantly higher than that of firefly luciferase (Fluc). The combined use of FLUX/Fluc as target/control vectors gave the most stable signals, better than the standard set of Fluc(target)/Rluc(control). We demonstrated that FLUX can be used for testing inhibitors of the NF-kappa-B signaling pathway, validating FLUX applications for various assays in the future.