[Intercellular communication-based robust circadian oscillation of the suprachiasmatic nucleus in the brain: mechanisms beyond intracellular clock machinery].
Recent advances in circadian biology strongly suggest that there are still genes involved in the generation and maintenance of biological rhythms that remain to be identified. It has been generally appreciated that circadian rhythms are generated intracellularly through transcription/translation-based autoregulatory feedback circuits of the clock genes. However, the existence of new intracellular clock machinery that cannot be explained by existing clock genes has recently been reported. This clock manifests as oxidation-reduction cycles of peroxiredoxin proteins, implying that as-yet-undiscovered clock genes may exist within cells to regulate redox cycling. Moreover, great strides have also been made in understanding the cell-cell communication-based robust circadian oscillations of the suprachiasmatic nucleus (SCN), the central pacemaker in the brain. Thousands of neurons that constitute the SCN maintain a high degree of synchrony in a way that allows the SCN neurons to create coherent signals as a whole. Inactivation of the genes involved in the cell-cell synchronization of the SCN, which include the genes encoding VIP, VPAC2, and RGS16, leads to altered circadian rhythms in behavior and physiologies. The purpose of this review is to provide an overview of recent advances in the circadian biology, with a special emphasis on the importance of cell-cell interactions within the SCN.
Department of Systems Biology, Graduate School of Pharmaceutical Sciences, Kyoto University.
Masao
M
Doi
D000818:Animals; D002450:Cell Communication / Q000502:physiology*; D002940:Circadian Rhythm / Q000235:genetics*; D005110:Extracellular Space / Q000502:physiology*; D006801:Humans; D009474:Neurons / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D012890:Sleep / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*