title: Autonomous and self-sustained circadian oscillators displayed in human islet cells.
abstract: OBJECTIVE
  Following on from the emerging importance of the pancreas circadian clock on islet function and the development of type 2 diabetes in rodent models, we aimed to examine circadian gene expression in human islets. The oscillator properties were assessed in intact islets as well as in beta cells.
  
  
  METHODS
  We established a system for long-term bioluminescence recording in cultured human islets, employing lentivector gene delivery of the core clock gene Bmal1 (also known as Arntl)-luciferase reporter. Beta cells were stably labelled using a rat insulin2 promoter fluorescent construct. Single-islet/cell oscillation profiles were measured by combined bioluminescence-fluorescence time-lapse microscopy.
  
  
  RESULTS
  Human islets synchronised in vitro exhibited self-sustained circadian oscillations of Bmal1-luciferase expression at both the population and single-islet levels, with period lengths of 23.6 and 23.9 h, respectively. Endogenous BMAL1 and CRY1 transcript expression was circadian in synchronised islets over 48 h, and antiphasic to REV-ERBα (also known as NR1D1), PER1, PER2, PER3 and DBP transcript circadian profiles. HNF1A and PDX1 exhibited weak circadian oscillations, in phase with the REV-ERBα transcript. Dispersed islet cells were strongly oscillating as well, at population and single-cell levels. Importantly, beta and non-beta cells revealed oscillatory profiles that were well synchronised with each other.
  
  
  CONCLUSIONS
  We provide for the first time compelling evidence for high-amplitude cell-autonomous circadian oscillators displayed in human pancreatic islets and in dispersed human islet cells. Moreover, these clocks are synchronised between beta and non-beta cells in primary human islet cell cultures.
authors.affiliation: Division of Endocrinology, Diabetes and Nutrition, University Hospital of Geneva, Aile Jura 4-771.2, Rue Gabrielle-Perret-Gentil 4, CH-1211 Geneva, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Pulimeno
authors.forename: T
authors.initials: T
authors.lastname: Mannic
authors.forename: D
authors.initials: D
authors.lastname: Sage
authors.forename: L
authors.initials: L
authors.lastname: Giovannoni
authors.forename: P
authors.initials: P
authors.lastname: Salmon
authors.forename: S
authors.initials: S
authors.lastname: Lemeille
authors.forename: M
authors.initials: M
authors.lastname: Giry-Laterriere
authors.forename: M
authors.initials: M
authors.lastname: Unser
authors.forename: D
authors.initials: D
authors.lastname: Bosco
authors.forename: C
authors.initials: C
authors.lastname: Bauer
authors.forename: J
authors.initials: J
authors.lastname: Morf
authors.forename: P
authors.initials: P
authors.lastname: Halban
authors.forename: J
authors.initials: J
authors.lastname: Philippe
authors.forename: C
authors.initials: C
authors.lastname: Dibner
mesh_terms: D056930:ARNTL Transcription Factors / Q000378:metabolism*; D000818:Animals; D057906:Circadian Clocks / Q000235:genetics / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D051381:Rats; D013696:Temperature
chemical_list: D056930:ARNTL Transcription Factors; C538960:BMAL1 protein, human