Genetically encoded bioluminescent voltage indicator for multi-purpose use in wide range of bioimaging.
Inagaki S., Tsutsui H., Suzuki K., Agetsuma M., Arai Y., Jinno Y., Bai G., Daniels MJ., Okamura Y., Matsuda T., Nagai T.
We report development of the first genetically encoded bioluminescent indicator for membrane voltage called LOTUS-V. Since it is bioluminescent, imaging LOTUS-V does not require external light illumination. This allows bidirectional optogenetic control of cellular activity triggered by Channelrhodopsin2 and Halorhodopsin during voltage imaging. The other advantage of LOTUS-V is the robustness of a signal-to-background ratio (SBR) wherever it expressed, even in the specimens where autofluorescence from environment severely interferes fluorescence imaging. Through imaging of moving cardiomyocyte aggregates, we demonstrated the advantages of LOTUS-V in long-term imaging are attributable to the absence of phototoxicity, and photobleaching in bioluminescent imaging, combined with the ratiometric aspect of LOTUS-V design. Collectively LOTUS-V extends the scope of excitable cell control and simultaneous voltage phenotyping, which should enable applications in bioscience, medicine and pharmacology previously not possible.