Reconstitution of Organismal Liver Clock Function Requires Light.

Recently Koronowski et al. (Cell, 2019) showed that reconstitution of the liver circadian clock in otherwise genetically arrhythmic mice revives the daily program of the nicotinamide adenine dinucleotide salvage pathway and glycogenesis in vivo. This liver-autonomous metabolic cycling cannot be sustained under constant darkness, revealing the importance of the daily light cycle to restore liver function.