1. A light-induced small G-protein gem limits the circadian clock phase-shift magnitude by inhibiting voltage-dependent calcium channels
- Author
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30467427, 20432578, Matsuo, Masahiro, Seo, Kazuyuki, Taruno, Akiyuki, Mizoro, Yasutaka, Yamaguchi, Yoshiaki, Doi, Masao, Nakao, Rhyuta, Kori, Hiroshi, Abe, Takaya, Ohmori, Harunori, Tominaga, Keiko, Okamura, Hitoshi, 30467427, 20432578, Matsuo, Masahiro, Seo, Kazuyuki, Taruno, Akiyuki, Mizoro, Yasutaka, Yamaguchi, Yoshiaki, Doi, Masao, Nakao, Rhyuta, Kori, Hiroshi, Abe, Takaya, Ohmori, Harunori, Tominaga, Keiko, and Okamura, Hitoshi
- Abstract
Calcium signaling is pivotal to the circadian clockwork in the suprachiasmatic nucleus (SCN), particularly in rhythm entrainment to environmental light-dark cycles. Here, we show that a small G-protein Gem, an endogenous inhibitor of high-voltage-activated voltage-dependent calcium channels (VDCCs), is rapidly induced by light in SCN neurons via the calcium (Ca²⁺)-mediated CREB/CRE transcriptional pathway. Gem attenuates light-induced calcium signaling through its interaction with VDCCs. The phase-shift magnitude of locomotor activity rhythms by light, at night, increases in Gem-deficient (Gem⁻/⁻) mice. Similarly, in SCN slices from Gem⁻/⁻ mice, depolarizing stimuli induce larger phase shifts of clock gene transcription rhythms that are normalized by the application of an L-type VDCC blocker, nifedipine. Voltage-clamp recordings from SCN neurons reveal that Ca²⁺ currents through L-type channels increase in Gem⁻/⁻ mice. Our findings suggest that transcriptionally activated Gem feeds back to suppress excessive light-evoked L-type VDCC activation, adjusting the light-induced phase-shift magnitude to an appropriate level in mammals.
- Published
- 2022