Abstract
Circadian clocks constitute a global regulatory system found in most eukaryotes. The center of the circadian rhythm is located in the suprachiasmatic nuclei (SCN) and informs the peripheral organs of the timing via neuronal and hormonal pathways. It is driven by complexes of the transcription factors CLOCK and BMAL1, while CRY and PER oppose CLOCK/BMAL1 activity, closing a negative feedback loop that results in an approximately 24-hour rhythm. CLOCK/BMAL1 bind the E-box in the promoter region of not only clock components, but also so-called output genes of the circadian clock. Core clocks are located all over the body and control the circadian expression of genes that regulate fat metabolism, the cell cycle, neural activity, and so on. In this symposium, we will discuss the core clock mechanism and clock gene functions from the cellular level to the level of the human body. [J Physiol Sci. 2006;56 Suppl:S15]
