Entrainment of disrupted circadian behavior through inhibition of casein kinase 1 (CK1) enzymes.
Circadian pacemaking requires the orderly synthesis, posttranslational modification, and degradation of clock proteins. In mammals, mutations in casein kinase 1 (CK1) epsilon or delta can alter the circadian period, but the particular functions of the WT isoforms within the pacemaker remain unclear. We selectively targeted WT CK1epsilon and CK1delta using pharmacological inhibitors (PF-4800567 and PF-670462, respectively) alongside genetic knockout and knockdown to reveal that CK1 activity is essential to molecular pacemaking. Moreover, CK1delta is the principal regulator of the clock period: pharmacological inhibition of CK1delta, but not CK1epsilon, significantly lengthened circadian rhythms in locomotor activity in vivo and molecular oscillations in the suprachiasmatic nucleus (SCN) and peripheral tissue slices in vitro. Period lengthening mediated by CK1delta inhibition was accompanied by nuclear retention of PER2 protein both in vitro and in vivo. Furthermore, phase mapping of the molecular clockwork in vitro showed that PF-670462 treatment lengthened the period in a phase-specific manner, selectively extending the duration of PER2-mediated transcriptional feedback. These findings suggested that CK1delta inhibition might be effective in increasing the amplitude and synchronization of disrupted circadian oscillators. This was tested using arrhythmic SCN slices derived from Vipr2(-/-) mice, in which PF-670462 treatment transiently restored robust circadian rhythms of PER2::Luc bioluminescence. Moreover, in mice rendered behaviorally arrhythmic by the Vipr2(-/-) mutation or by constant light, daily treatment with PF-670462 elicited robust 24-h activity cycles that persisted throughout treatment. Accordingly, selective pharmacological targeting of the endogenous circadian regulator CK1delta offers an avenue for therapeutic modulation of perturbed circadian behavior.
Meng
Qing-Jun
QJ
Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
Maywood
Elizabeth S
ES
Bechtold
David A
DA
Lu
Wei-Qun
WQ
Li
Jian
J
Gibbs
Julie E
JE
Dupré
Sandrine M
SM
Chesham
Johanna E
JE
Rajamohan
Francis
F
Knafels
John
J
Sneed
Blossom
B
Zawadzke
Laura E
LE
Ohren
Jeffrey F
JF
Walton
Kevin M
KM
Wager
Travis T
TT
Hastings
Michael H
MH
Loudon
Andrew S I
AS
D000818:Animals; D001483:Base Sequence; D048149:Casein Kinase 1 epsilon / Q000037:antagonists & inhibitors* / Q000502:physiology; D048148:Casein Kinase Idelta / Q000037:antagonists & inhibitors* / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D055785:Gene Knockdown Techniques; D066298:In Vitro Techniques; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D056950:Period Circadian Proteins / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000172:deficiency / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology
C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D034741:RNA, Small Interfering; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; C495510:Vipr2 protein, mouse; C522839:PF-670462; D048149:Casein Kinase 1 epsilon; D048148:Casein Kinase Idelta