Implication of CYP for new bioluminescence system by luciferin analogue TokeOni

Abstract

Bioluminescence imaging has become an essential part of life science research and has routinely used to detect target cells in various tissues and to monitor disease processes. By introducing genes of luminescent enzymes, luciferases, into the target sites, it is possible to detect light emission from there. Although the firefly bioluminescent system is the most widely used, the yellow-green light is not able to penetrate deeper through living organisms and has significant limitations for its use in bioluminescence imaging. To overcome the problem, we have developed three longer wavelength luciferin analogues, "AkaLumine", "TokeOni" and "SeMpai" based on the substrate of the firefly bioluminescence system, which are extremely transmissive to living organisms. Unexpectedly, without introduction of a luciferase gene, we observed the luminescence from the liver of mice in vivo when AkaLumine and TokeOni were administered. To elucidate the enzyme that produces this luminescence, we administered inhibitors of cytochrome P450s (CYPs), which greatly reduced luminescence. This suggested that CYPs are involved in this luminescence system. When luminescence was observed in mice with liver disease, the amount of luminescence in the drug-induced liver injury model was less than half that of the control group, while that in the non-alcoholic fatty liver disease model was about twice that of the control group. This may have practical applications as a diagnostic method for liver disease. In order to study the luminescence in other organisms, these analogues were added to the extracts of pill bugs and blow flies, and the luminescence was observed. This suggests that the new luminescent system is conserved in a wide range of animals.