V. Conclusion

The circadian clock prepares the biological processes of the body for daily environmental changes. The data described above demonstrate that interconnected transcriptional and biochemical feedback loops ensure the synchronization of gene expression at the cellular level and the synchronization of anabolic and catabolic processes at the levels of the tissue and whole organism. In peripheral organs, clock synchronization is strongly regulated by daily feeding rhythms. Among the large number of signaling pathways regulating clock, the transcription factor Rev-erb α and the metabolite NAD+ are presented as robust links between nutrition and clock. Indeed, the capacity of both to control the core molecular clock and metabolic pathways specific to each tissue appears to be crucial in maintaining the crosstalk between circadian oscillations and metabolic pathways. The different lectures also highlighted that desynchronization of circadian oscillations and metabolism induced by current human lifestyles, with extended activities or feeding habits outside the conventional light-dark cycle, induce metabolic alterations. Via several types of integration and feedback mechanisms, oscillations induced by light, temperature, or feeding-induced metabolism maintain the delicate balance between energy intake and expenditure necessary for whole-body homeostasis.

Acknowledgments: Illustrations were made with Servier Medical Art.

“The Islet and Metabolism Keep Time”
I. The circadian system
II. Circadian regulation of the transcriptional network
III. Circadian rhythms and metabolism
IV. Clock and the islet
V. Conclusion