Dual origins of the intracellular circadian calcium rhythm in the suprachiasmatic nucleus.
In mammals, the master circadian clock is located in the suprachiasmatic nucleus (SCN), where most neurons show circadian rhythms of intracellular Ca2+levels. However, the origin of these Ca2+rhythms remains largely unknown. In this study, we successfully monitored the intracellular circadian Ca2+rhythms together with the circadian PER2 and firing rhythms in a single SCN slice ex vivo, which enabled us to explore the origins. The phase relation between the circadian PER2 and Ca2+rhythms, but not between the circadian PER2 and firing rhythms, was significantly altered in Cry1/Cry2 double knockout mice, which display a loss of intercellular synchronization in the SCN. In addition, in Cry1/Cry2 double knockout mice, circadian Ca2+rhythms were abolished in the dorsolateral SCN, but were maintained in the majority of the ventromedial SCN. These findings indicate that intracellular circadian Ca2+rhythms are composed of an exogenous and endogenous component involving PER2 expression.
Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, 060-8638, Japan.|Department of Chronomedicine, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, 060-8638, Japan.|Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan.
Ryosuke
R
Enoki
Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, 060-8638, Japan.
Daisuke
D
Ono
Mathematical and Physical Ethology Laboratory, Research Institute for Electrical Science, Hokkaido University, N20 W10, Kita-ku, Sapporo, Japan.
Shigeru
S
Kuroda
Department of Chronomedicine, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, 060-8638, Japan.
Sato
S
Honma
Department of Chronomedicine, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo, 060-8638, Japan.
Ken-Ichi
KI
Honma
D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002940:Circadian Rhythm; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000502:physiology*
D015415:Biomarkers; D056931:Cryptochromes; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D002118:Calcium