Abrogation of the CLK-2 checkpoint leads to tolerance to base-excision repair intermediates

EMBO Rep. 2006 Oct;7(10):1046-51. doi: 10.1038/sj.embor.7400782. Epub 2006 Sep 8.


Incorporation of uracil during DNA synthesis is among the most common types of endogenously generated DNA damage. Depletion of Caenorhabditis elegans dUTPase by RNA interference allowed us to study the role of DNA damage response (DDR) pathways when responding to high levels of uracil in DNA. dUTPase depletion compromised development, caused embryonic lethality and led to activation of cell-cycle arrest and apoptosis. These phenotypes manifested as a result of processing misincorporated uracil by the uracil-DNA glycosylase UNG-1. Strikingly, abrogation of the clk-2 checkpoint gene rescued lethality and developmental defects, and eliminated cell-cycle arrest and apoptosis after dUTPase depletion. These data show a genetic interaction between UNG-1 and activation of the CLK-2 DDR pathway after uracil incorporation into DNA. Our results indicate that persistent repair intermediates and/or single-stranded DNA formed during repair of misincorporated uracil are tolerated in the absence of the CLK-2 checkpoint in C. elegans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / metabolism*
  • Caenorhabditis elegans Proteins / physiology*
  • Cell Cycle / drug effects
  • DNA Adducts / adverse effects
  • DNA Damage / genetics
  • DNA Repair*
  • Embryo, Nonmammalian
  • Genes, Tumor Suppressor / physiology
  • Models, Biological
  • Mutant Proteins / metabolism
  • RNA Interference / physiology
  • RNA, Small Interfering / pharmacology
  • RNA, Small Interfering / toxicity
  • Telomere-Binding Proteins / metabolism*
  • Telomere-Binding Proteins / physiology*
  • Uracil / adverse effects
  • Uracil-DNA Glycosidase / metabolism


  • Caenorhabditis elegans Proteins
  • DNA Adducts
  • Mutant Proteins
  • RNA, Small Interfering
  • Telomere-Binding Proteins
  • clk-2 protein, C elegans
  • Uracil
  • Uracil-DNA Glycosidase