The circadian clock starts ticking at a developmentally early stage

J Biol Rhythms. 2010 Dec;25(6):442-9. doi: 10.1177/0748730410385281.


Although overt diurnal rhythms of behavior do not begin until well after birth, molecular studies suggest that the circadian clock may begin much earlier at a cellular level: mouse embryonic fibroblasts, for example, already possess robust clocks. By multiple criteria, we found no circadian clock present in mouse embryonic stem cells. Nevertheless, upon their differentiation into neurons, circadian gene expression was observed. In the first steps along the pathway from ES cells to neurons, a neural precursor cell (NPC) line already showed robust circadian oscillations. Therefore, at a cellular level, the circadian clock likely begins at the very earliest stages of mammalian development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Cell Differentiation / genetics*
  • Cell Line
  • Cell Line, Tumor
  • Circadian Clocks / genetics*
  • Embryonic Stem Cells / cytology
  • Embryonic Stem Cells / metabolism*
  • Gene Expression Regulation, Developmental*
  • Humans
  • Mice
  • Neural Stem Cells / metabolism
  • Neurons / cytology
  • Neurons / metabolism
  • Period Circadian Proteins / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Time Factors


  • Period Circadian Proteins