CKIepsilon/delta-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 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 Iepsilon (CKIepsilon) or CKIdelta phosphorylation of the PER2 protein. Manipulation of CKIepsilon/delta-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 CKIepsilon/delta-dependent phosphorylation, was temperature-insensitive in living clock cells, yet sensitive to chemical perturbations. This temperature-insensitivity was preserved in the CKIepsilon/delta-dependent phosphorylation of a synthetic peptide in vitro. Thus, CKIepsilon/delta-dependent phosphorylation is likely a temperature-insensitive period-determining process in the mammalian circadian clock.
Isojima
Yasushi
Y
Comparative Systems Biology Team, Genomic Science Center, RIKEN, 1-7-22, Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Nakajima
Masato
M
Ukai
Hideki
H
Fujishima
Hiroshi
H
Yamada
Rikuhiro G
RG
Masumoto
Koh-hei
KH
Kiuchi
Reiko
R
Ishida
Mayumi
M
Ukai-Tadenuma
Maki
M
Minami
Yoichi
Y
Kito
Ryotaku
R
Nakao
Kazuki
K
Kishimoto
Wataru
W
Yoo
Seung-Hee
SH
Shimomura
Kazuhiro
K
Takao
Toshifumi
T
Takano
Atsuko
A
Kojima
Toshio
T
Nagai
Katsuya
K
Sakaki
Yoshiyuki
Y
Takahashi
Joseph S
JS
Ueda
Hiroki R
HR
D000818:Animals; D005075:Biological Evolution; D048149:Casein Kinase 1 epsilon / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D048148:Casein Kinase Idelta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002940:Circadian Rhythm / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D000458:Cyanobacteria / Q000235:genetics / Q000502:physiology; D006801:Humans; D007700:Kinetics; D051379:Mice; D008954:Models, Biological; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D014157:Transcription Factors; D048149:Casein Kinase 1 epsilon; D048148:Casein Kinase Idelta