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Effect of circadian clock mutations on DNA damage response in mammalian cells

Shobhan Gaddameedhi1, Joyce T Reardon, Rui Ye

  • 1Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA.

Cell Cycle (Georgetown, Tex.)
|August 25, 2012
PubMed

Insights

The circadian clock does not appear to regulate DNA repair pathways in mouse cells. Cellular mechanisms may override any organism-level clock control of DNA damage responses.

Area of Science:

  • Molecular Biology
  • Chronobiology
  • Genetics

Background:

  • The circadian clock regulates daily rhythms in mammalian physiology and biochemical functions.
  • DNA repair mechanisms are crucial for maintaining genomic integrity.
  • The interplay between circadian rhythms and DNA damage response (DDR) is not fully understood.

Purpose of the Study:

  • To investigate the influence of the circadian clock on major DNA damage response pathways.
  • To determine if mutations in core circadian clock genes affect cellular responses to DNA damaging agents.

Main Methods:

  • Utilized mouse cell lines with mutations in key circadian clock genes (Bmal1, CLOCK, Cry 1/2, Per 1/2).
  • Assessed cellular responses to various DNA damaging agents, including UV radiation, ionizing radiation, and mitomycin C.
  • Compared the DNA damage response of mutant cell lines to wild-type cells.

Main Results:

  • Mutant cell lines lacking functional circadian clock components showed no significant difference in their response to UV, ionizing radiation, or mitomycin C compared to wild-type cells.
  • The DNA damage response pathways investigated were not observably affected by the absence of a functional circadian clock in these cellular models.

Conclusions:

  • The circadian clock may not directly control most DNA damage response reactions at the cellular level in vitro.
  • Homeostatic control mechanisms within cells might supersede circadian clock influence on DNA repair in tissue culture.
  • Extrapolation of circadian clock effects on DNA damage response from cell culture to whole organisms requires caution.

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