Document Detail

Rapid down-regulation of mammalian period genes during behavioral resetting of the circadian clock.
MedLine Citation:
PMID:  10611364     Owner:  NLM     Status:  MEDLINE    
The pervasive role of circadian clocks in regulating physiology and behavior is widely recognized. Their adaptive value is their ability to be entrained by environmental cues such that the internal circadian phase is a reliable predictor of solar time. In mammals, both light and nonphotic behavioral cues can entrain the principal oscillator of the hypothalamic suprachiasmatic nuclei (SCN). However, although light can advance or delay the clock during circadian night, behavioral events trigger phase advances during the subjective day, when the clock is insensitive to light. The recent identification of Period (Per) genes in mammals, homologues of dperiod, which encodes a core element of the circadian clockwork in Drosophila, now provides the opportunity to explain circadian timing and entrainment at a molecular level. In mice, expression of mPer1 and mPer2 in the SCN is rhythmic and acutely up-regulated by light. Moreover, the temporal relations between mRNA and protein cycles are consistent with a clock based on a transcriptional/translational feedback loop. Here we describe circadian oscillations of Per1 and Per2 in the SCN of the Syrian hamster, showing that PER1 protein and mRNA cycles again behave in a manner consistent with a negative-feedback oscillator. Furthermore, we demonstrate that nonphotic resetting has the opposite effect to light: acutely down-regulating these genes. Their sensitivity to nonphotic resetting cues supports their proposed role as core elements of the circadian oscillator. Moreover, this study provides an explanation at the molecular level for the contrasting but convergent effects of photic and nonphotic cues on the clock.
E S Maywood; N Mrosovsky; M D Field; M H Hastings
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  96     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1999 Dec 
Date Detail:
Created Date:  2000-01-27     Completed Date:  2000-01-27     Revised Date:  2013-04-17    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  15211-6     Citation Subset:  IM    
Department of Anatomy, Downing Street, University of Cambridge, Cambridge, United Kingdom CB2 3DY.
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MeSH Terms
Arousal / physiology
Biological Clocks / genetics*
Cell Cycle Proteins
Circadian Rhythm / genetics*
In Situ Hybridization
Motor Activity / physiology
Nuclear Proteins / biosynthesis*,  genetics
Period Circadian Proteins
RNA, Messenger / isolation & purification
Suprachiasmatic Nucleus / metabolism*
Transcription Factors
Reg. No./Substance:
0/Cell Cycle Proteins; 0/Nuclear Proteins; 0/Per1 protein, mouse; 0/Per2 protein, mouse; 0/Period Circadian Proteins; 0/RNA, Messenger; 0/Transcription Factors

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