Feeding differentially regulates clocks and rhythmicity of peripheral tissues through the liver-clock

The mammalian circadian system consists of a central clock in the brain that synchronizes clocks in peripheral tissues. While the hierarchy between the central and peripheral clocks is well established, peripheral clocks are largely viewed as a group and little is known regarding their specificity and functional organization. We employed feeding paradigms in conjunction with liver-specific clock-deficient murine model to map disparities and potential interactions between peripheral clocks. We found that peripheral clocks largely differ in their response to feeding-time. In view of its prominent role in nutrient processing, we hypothesized that the liver-clock instigate the response of peripheral clocks to feeding. Although the liver-clock did not affect the rhythmicity of clocks in other peripheral tissues, it strongly modulated their transcriptional rhythmicity upon daytime feeding. Overall, our findings suggest a role for the liver-clock in buffering feeding-related signals that affect rhythmicity of other peripheral tissues upon nutrient challenge, irrespective of their clocks. Mice of either Alb-Cre+ (control) or Bmal1 fl/fl Alb-Cre+ (aka BLKO), where fed either Ad Libitum (AL) or only during the light-phase (Daytime-feeding, DF)