title: Circadian gene expression in individual fibroblasts: cell-autonomous and self-sustained oscillators pass time to daughter cells.
abstract: The mammalian circadian timing system is composed of a central pacemaker in the suprachiasmatic nucleus (SCN) of the brain and subsidiary oscillators in most peripheral cell types. While oscillators in SCN neurons are known to function in a self-sustained fashion, peripheral oscillators have been thought to damp rapidly when disconnected from the control exerted by the SCN. Using two reporter systems, we monitored circadian gene expression in NIH3T3 mouse fibroblasts in real time and in individual cells. In conjunction with mathematical modeling and cell co-culture experiments, these data demonstrated that in vitro cultured fibroblasts harbor self-sustained and cell-autonomous circadian clocks similar to those operative in SCN neurons. Circadian gene expression in fibroblasts continues during cell division, and our experiments unveiled unexpected interactions between the circadian clock and the cell division clock. Specifically, the circadian oscillator gates cytokinesis to defined time windows, and mitosis elicits phase shifts in circadian cycles.
authors.affiliation: Department of Molecular Biology and NCCR Frontiers in Genetics, Sciences III, University of Geneva, 30, Quai Ernest Ansermet, CH-1211 Geneva-4, Switzerland.
authors.forename: Emi
authors.initials: E
authors.lastname: Nagoshi
authors.forename: Camille
authors.initials: C
authors.lastname: Saini
authors.forename: Christoph
authors.initials: C
authors.lastname: Bauer
authors.forename: Thierry
authors.initials: T
authors.lastname: Laroche
authors.forename: Felix
authors.initials: F
authors.lastname: Naef
authors.forename: Ueli
authors.initials: U
authors.lastname: Schibler
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D002450:Cell Communication / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics*; D018920:Coculture Techniques; D048749:Cytokinesis / Q000235:genetics; D005347:Fibroblasts / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D051379:Mice; D008938:Mitosis / Q000235:genetics; D008954:Models, Biological; D041681:NIH 3T3 Cells