CKIε/δ-dependent phosphorylation is a temperature-insensitive, period-determining process in the mammalian circadian clock

A striking feature of the circadian clock is its flexible yet robust response to various environmental conditions. To analyze the biochemical processes underlying this flexible-yet-robust characteristic, we examined the effects of 1,260 pharmacologically active compounds in mouse and human clock cel...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2009-09, Vol.106 (37), p.15744-15749
Main Authors: Isojima, Yasushi, Nakajima, Masato, Ukai, Hideki, Fujishima, Hiroshi, Yamada, Rikuhiro G, Masumoto, Koh-hei, Kiuchi, Reiko, Ishida, Mayumi, Ukai-Tadenuma, Maki, Minami, Yoichi, Kito, Ryotaku, Nakao, Kazuki, Kishimoto, Wataru, Yoo, Seung-Hee, Shimomura, Kazuhiro, Takao, Toshifumi, Takano, Atsuko, Kojima, Toshio, Nagai, Katsuya, Sakaki, Yoshiyuki, Takahashi, Joseph S, Ueda, Hiroki R
Format: Article
Language:English
Subjects:
Biological Sciences
Cell lines
Circadian rhythm
Clocks
Cultured cells
Gene expression regulation
NIH 3T3 cells
Phosphorylation
Proteins
Temperature dependence
Thermoregulation
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Summary:A striking feature of the circadian clock is its flexible yet robust response to various environmental conditions. To analyze the biochemical processes underlying this flexible-yet-robust characteristic, we examined the effects of 1,260 pharmacologically active compounds in mouse and human clock cell lines. Compounds that markedly (>10 s.d.) lengthened the period in both cell lines, also lengthened it in central clock tissues and peripheral clock cells. Most compounds inhibited casein kinase Iε (CKIε) or CKIδ phosphorylation of the PER2 protein. Manipulation of CKIε/δ-dependent phosphorylation by these compounds lengthened the period of the mammalian clock from circadian (24 h) to circabidian (48 h), revealing its high sensitivity to chemical perturbation. The degradation rate of PER2, which is regulated by CKIε/δ-dependent phosphorylation, was temperature-insensitive in living clock cells, yet sensitive to chemical perturbations. This temperature-insensitivity was preserved in the CKIε/δ-dependent phosphorylation of a synthetic peptide in vitro. Thus, CKIε/δ-dependent phosphorylation is likely a temperature-insensitive period-determining process in the mammalian circadian clock.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0908733106