Feedback repression is required for mammalian circadian clock function

Nat Genet. 2006 Mar;38(3):312-9. doi: 10.1038/ng1745. Epub 2006 Feb 12.

Abstract

Direct evidence for the requirement of transcriptional feedback repression in circadian clock function has been elusive. Here, we developed a molecular genetic screen in mammalian cells to identify mutants of the circadian transcriptional activators CLOCK and BMAL1, which were uncoupled from CRYPTOCHROME (CRY)-mediated transcriptional repression. Notably, mutations in the PER-ARNT-SIM domain of CLOCK and the C terminus of BMAL1 resulted in synergistic insensitivity through reduced physical interactions with CRY. Coexpression of these mutant proteins in cultured fibroblasts caused arrhythmic phenotypes in population and single-cell assays. These data demonstrate that CRY-mediated repression of the CLOCK/BMAL1 complex activity is required for maintenance of circadian rhythmicity and provide formal proof that transcriptional feedback is required for mammalian clock function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • ARNTL Transcription Factors
  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • CLOCK Proteins
  • Cell Line
  • Circadian Rhythm / physiology*
  • Feedback
  • Gene Expression Regulation*
  • Genes, Reporter
  • Humans
  • Luciferases / analysis
  • Luciferases / genetics
  • Luminescence
  • Mice
  • Plasmids
  • Time
  • Trans-Activators / genetics*

Substances

  • ARNTL Transcription Factors
  • ARNTL protein, human
  • Arntl protein, mouse
  • Basic Helix-Loop-Helix Transcription Factors
  • Trans-Activators
  • Luciferases
  • CLOCK Proteins
  • CLOCK protein, human
  • Clock protein, mouse