Common light signaling pathways controlling DNA repair and circadian clock entrainment in zebrafish

Cell Cycle. 2009 Sep 1;8(17):2794-801. doi: 10.4161/cc.8.17.9447. Epub 2009 Sep 6.


UV radiation causes a number of harmful events including growth delay, cell death and ultimately cancer. The reversal of such effects by concomitant exposure to visible light is a conserved mechanism which has been uncovered in many multi-cellular organisms. Here we show that light-dependent UV-tolerance is a cell autonomous phenomenon in zebrafish. In addition, we provide several lines of evidence indicating that light induction of 64PHR, a DNA repair enzyme, and the subsequent light-dependent DNA repair mediated by this enzyme are prerequisites for light-mediated UV tolerance. 64PHR is evolutionary related to and has a high degree of structural similarity to animal CRY, an essential circadian regulator. The zebrafish circadian clock is controlled by a cell-autonomous and light-dependent oscillator, where zCRY1a functions as an important mediator of light entrainment of the circadian clock. In this study, we show that light directly activates MAPK signaling cascades in zebrafish cells and we provide evidence that light-induced activation of these pathways controls the expression of two evolutionary-related genes, z64Phr and zCry1a, revealing that light-dependent DNA repair and the entrainment of circadian clock share common regulatory pathways.

Publication types

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

MeSH terms

  • Animals
  • Biological Clocks / physiology*
  • Cells, Cultured
  • Circadian Rhythm / physiology*
  • Cryptochromes / metabolism
  • DNA Repair*
  • Deoxyribodipyrimidine Photo-Lyase / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Eye Proteins / metabolism
  • Light Signal Transduction*
  • MAP Kinase Signaling System
  • Period Circadian Proteins / metabolism
  • Phosphorylation
  • Proto-Oncogene Proteins c-myc / metabolism
  • Time Factors
  • Ultraviolet Rays
  • Zebrafish / metabolism*
  • Zebrafish Proteins / metabolism*
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Cryptochromes
  • Eye Proteins
  • Period Circadian Proteins
  • Proto-Oncogene Proteins c-myc
  • Zebrafish Proteins
  • per2 protein, zebrafish
  • Extracellular Signal-Regulated MAP Kinases
  • p38 Mitogen-Activated Protein Kinases
  • pyrimidine(6-4)pyrimidone photolyase
  • Deoxyribodipyrimidine Photo-Lyase