Long-term monitoring of circadian rhythms in c-fos gene expression from suprachiasmatic nucleus cultures

Curr Biol. 1997 Oct 1;7(10):758-66. doi: 10.1016/s0960-9822(06)00334-4.

Abstract

Background: The AP-1 family of transcription factors has been implicated in the control of the expression of many genes in response to environmental signals. Previous studies have provided temporal profiles for c-fos expression by taking measurements from many animals at several points in time, but these studies provide limited information about dynamic changes in expression. Here, we have devised a method of continuously measuring c-fos expression.

Results: A transgenic mouse line expressing the human c-fos promoter linked to the firefly luciferase reporter gene (fos/luc) was generated to continuously monitor c-fos gene expression. A second transgenic mouse line expressing luciferase under the control of the cytomegalovirus promoter (CMV/luc) served as a control. Luminescence originating from identifiable brain regions was imaged from fos/luc brain slice cultures. Expression of the fos/luc transgene accurately reflected transcriptional responses of the endogenous c-fos gene. Dynamic changes in fos/luc expression in suprachiasmatic nuclei (SCN) explant cultures were monitored continuously, and luminescence showed almost 24 hour rhythms lasting up to five circadian cycles. In contrast, bioluminescence monitored from CMV/luc SCN explant cultures was not rhythmic.

Conclusion: The fos/luc transgenic mouse will be useful for long-term, non-invasive monitoring of c-fos transcriptional responses to the changing cellular environment. Circadian rhythms in c-fos expression can be monitored non-invasively in real time from the SCN, clearly demonstrating that c-fos transcription is regulated by the circadian clock.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Circadian Rhythm*
  • Cytomegalovirus / genetics
  • Genes, Reporter
  • Humans
  • Luciferases / genetics
  • Luciferases / metabolism
  • Luminescent Measurements
  • Mice
  • Mice, Transgenic
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-fos / biosynthesis*
  • Proto-Oncogene Proteins c-fos / genetics
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / genetics
  • Suprachiasmatic Nucleus / metabolism*

Substances

  • Proto-Oncogene Proteins c-fos
  • Recombinant Fusion Proteins
  • Luciferases