Figure 7. Model describing the coordination of ribosome biogenesis by the circadian clock.

The molecular oscillator in the master circadian pacemaker localized in the SCN of the hypothalamus synchronizes peripheral clocks, including liver clock, and, in parallel, regulates feeding behavior, which itself influences peripheral oscillator. The liver circadian clock controls expression of translation initiation factors, and rRNA, and conceivably RP mRNA, through regulation of UBF1. In addition, in association with signals from nutrients, the molecular clock, via the TORC1 pathway, coordinates the rhythmic activation of signaling pathways controlling translation of RP and, in turn, ribosome biogenesis. This succession of events coordinated by the circadian clock finally leads to a subtle rhythmic change of general translation in mouse liver.