A bioluminescent probe for longitudinal monitoring of mitochondrial membrane potential

Mitochondrial membrane potential (ΔΨ_m) is a universal selective indicator of mitochondrial function and is known to play a central role in many human pathologies, such as diabetes mellitus, cancer and Alzheimer's and Parkinson's diseases. Here, we report the design, synthesis and several applications of mitochondria-activatable luciferin (MAL), a bioluminescent probe sensitive to ΔΨ_m, and partially to plasma membrane potential (ΔΨ_p), for non-invasive, longitudinal monitoring of ΔΨ_m in vitro and in vivo. We applied this new technology to evaluate the aging-related change of ΔΨ_m in mice and showed that nicotinamide riboside (NR) reverts aging-related mitochondrial depolarization, revealing another important aspect of the mechanism of action of this potent biomolecule. In addition, we demonstrated application of the MAL probe for studies of brown adipose tissue (BAT) activation and non-invasive in vivo assessment of ΔΨ_m in animal cancer models, opening exciting opportunities for understanding the underlying mechanisms and for discovery of effective treatments for many human pathologies.