• Masahiro Matsuo, Kazuyuki Seo, Naoki Mizuguchi, Fumiyoshi Yamazaki, Shoichi Urabe, Naoto Yamada, Masao Doi, Keiko Tominaga, and Hitoshi Okamura.
• Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan; Department of Psychiatry, Shiga University of Medical Science, Shiga 520-2192, Japan.
• Neuroscience. 2021 May 1; 461: 1-10.

AbstractBy the effort to identify candidate signaling molecules important for the formation of robust circadian rhythms in the suprachiasmatic nucleus (SCN), the mammalian circadian center, here we characterize the role of α2δ proteins, synaptic molecules initially identified as an auxiliary subunit of the voltage dependent calcium channel, in circadian rhythm formation. In situ hybridization study demonstrated that type 3 α2δ gene (α2δ3) was strongly expressed in the SCN. Mice without this isoform (Cacna2d3-/-) did not maintain proper circadian locomotor activity rhythms under a constant light (LL) condition, whereas under a constant dark (DD) condition, these mice showed a similar period length and similar light-responsiveness as compared to wild type mice. Reflecting this behavioral phenotype, Cacna2d3-/- mice showed a severely impaired Per1 expression rhythm in the SCN under LL, but not under DD. Cultured SCN slices from Per1-luc transgenic Cacna2d3-/- mice revealed reduced synchrony of Per1-luc gene expression rhythms among SCN neurons. These findings suggest that α2δ3 is essential for synchronized cellular oscillations in the SCN and thereby contributes to enhancing the sustainability of circadian rhythms in behavior.Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.

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