Faculty Collaboration Database

Shell neurons of the master circadian clock coordinate the phase of tissue clocks throughout the brain and body. BMC Biol 2015 Jun 23;13:43

Date

06/24/2015

Pubmed ID

26099272

Pubmed Central ID

PMC4489020

DOI

10.1186/s12915-015-0157-x

Scopus ID

2-s2.0-85019259133 (requires institutional sign-in at Scopus site)   42 Citations

Abstract

BACKGROUND: Daily rhythms in mammals are programmed by a master clock in the suprachiasmatic nucleus (SCN). The SCN contains two main compartments (shell and core), but the role of each region in system-level coordination remains ill defined. Herein, we use a functional assay to investigate how downstream tissues interpret region-specific outputs by using in vivo exposure to long day photoperiods to temporally dissociate the SCN. We then analyze resulting changes in the rhythms of clocks located throughout the brain and body to examine whether they maintain phase synchrony with the SCN shell or core.

RESULTS: Nearly all of the 17 tissues examined in the brain and body maintain phase synchrony with the SCN shell, but not the SCN core, which indicates that downstream oscillators are set by cues controlled specifically by the SCN shell. Interestingly, we also found that SCN dissociation diminished the amplitude of rhythms in core clock gene and protein expression in brain tissues by 50-75 %, which suggests that light-driven changes in the functional organization of the SCN markedly influence the strength of rhythms in downstream tissues.

CONCLUSIONS: Overall, our results reveal that body clocks receive time-of-day cues specifically from the SCN shell, which may be an adaptive design principle that serves to maintain system-level phase relationships in a changing environment. Further, we demonstrate that lighting conditions alter the amplitude of the molecular clock in downstream tissues, which uncovers a new form of plasticity that may contribute to seasonal changes in physiology and behavior.

Author List

Evans JA, Suen TC, Callif BL, Mitchell AS, Castanon-Cervantes O, Baker KM, Kloehn I, Baba K, Teubner BJ, Ehlen JC, Paul KN, Bartness TJ, Tosini G, Leise T, Davidson AJ

Author

Jennifer A. Evans PhD Assistant Professor in the Biomedical Sciences department at Marquette University

MESH terms used to index this publication - Major topics in bold

Animals
Brain
Circadian Clocks
Circadian Rhythm
Light
Male
Mice, Inbred C57BL
Neurons
Photoperiod
Suprachiasmatic Nucleus