Nobiletin protects against metabolic syndrome by enhancing circadian rhythms

OBJECTIVE Dysregulation of circadian rhythms is associated with metabolic dysfunction,yet it is unclear whether enhancing clock function by small molecules can ameliorate metabolic disorders.METHODS We used an unbiased chemical screen in fibroblasts expressing PER2::Luc to identify the Clock amplitude-Enhancing Small Mole⁃cule.In diet-induced obese mice and DB/DB mutant mice,we evaluated the effects of the Clock amplitude-Enhancing small Molecule on metabolic syndrome and locomotor activity.RESULTS We identified Nobiletin(NOB),a natural poly⁃methoxylated flavone,as a Clock amplitude-Enhancing Small Molecule by an unbiased chemical screen.In diet-induced obese mice,NOB strongly improved metabolic syndrome and enhanced locomotor activity in a Clock gene-dependent manner.Moreover,the clock is also required for the beneficial effects of NOB on metabolic disorders in DB/DB mutant mice.Notably,NOB enhanced clock protein levels and reprogramed metabolic gene expressions in the liver.Finally,we revealed retinoid acid receptor-related orphan receptors(RORα/γ)as direct targets of NOB.CONCLUSION Altogether,our results demonstrate that a pharmacological intervention that enhances circadian rhythms by small molecule may be as a novel strategy for combating metabolic disease.