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Carl Troein

Researcher

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Circadian rhythms persist without transcription in a eukaryote

Author

  • John S. O'Neill
  • Gerben Van Ooijen
  • Laura E. Dixon
  • Carl Troein
  • Florence Corellou
  • François-Yves Bouget
  • Akhilesh B. Reddy
  • Andrew J. Millar

Summary, in English

Circadian rhythms are ubiquitous in eukaryotes, and coordinate numerous aspects of behaviour, physiology and metabolism, from sleep/wake cycles in mammals to growth and photosynthesis in plants. This daily timekeeping is thought to be driven by transcriptionaltranslational feedback loops, whereby rhythmic expression of clock- gene products regulates the expression of associated genes in approximately 24-hour cycles. The specific transcriptional components differ between phylogenetic kingdoms. The unicellular pico-eukaryotic alga Ostreococcus tauri possesses a naturally minimized clock, which includes many features that are shared with plants, such as a central negative feedback loop that involves the morning-expressed CCA1 and evening-expressed TOC1 genes. Given that recent observations in animals and plants have revealed prominent post-translational contributions to timekeeping, a reappraisal of the transcriptional contribution to oscillator function is overdue. Here we show that non-transcriptional mechanisms are sufficient to sustain circadian timekeeping in the eukaryotic lineage, although they normally function in conjunction with transcriptional components. We identify oxidation of peroxiredoxin proteins as a transcription-independent rhythmic biomarker, which is also rhythmic in mammals. Moreover we show that pharmacological modulators of the mammalian clock mechanism have the same effects on rhythms in Ostreococcus. Post-translational mechanisms, and at least one rhythmic marker, seem to be better conserved than transcriptional clock regulators. It is plausible that the oldest oscillator components are non-transcriptional in nature, as in cyanobacteria, and are conserved across kingdoms.

Publishing year

2011-01-27

Language

English

Pages

554-558

Publication/Series

Nature

Volume

469

Issue

7331

Document type

Journal article

Publisher

Nature Publishing Group

Topic

  • Genetics
  • Plant Biotechnology

Status

Published

ISBN/ISSN/Other

  • ISSN: 0028-0836