NER and HR pathways act sequentially to promote UV-C-induced germ cell apoptosis in Caenorhabditis elegans

Cell Death Differ. 2011 May;18(5):897-906. doi: 10.1038/cdd.2010.158. Epub 2010 Dec 10.


Ultraviolet (UV) radiation-induced DNA damage evokes a complex network of molecular responses, which culminate in DNA repair, cell cycle arrest and apoptosis. Here, we provide an in-depth characterization of the molecular pathway that mediates UV-C-induced apoptosis of meiotic germ cells in the nematode Caenorhabditis elegans. We show that UV-C-induced DNA lesions are not directly pro-apoptotic. Rather, they must first be recognized and processed by the nucleotide excision repair (NER) pathway. Our data suggest that NER pathway activity transforms some of these lesions into other types of DNA damage, which in turn are recognized and acted upon by the homologous recombination (HR) pathway. HR pathway activity is in turn required for the recruitment of the C. elegans homolog of the yeast Rad9-Hus1-Rad1 (9-1-1) complex and activation of downstream checkpoint kinases. Blocking either the NER or HR pathway abrogates checkpoint pathway activation and UV-C-induced apoptosis. Our results show that, following UV-C, multiple DNA repair pathways can cooperate to signal to the apoptotic machinery to eliminate potentially hazardous cells.

Publication types

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

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Apoptosis / genetics
  • Apoptosis / radiation effects*
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / physiology
  • Caenorhabditis elegans / radiation effects*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism
  • Cell Cycle Proteins / metabolism
  • Cell Survival / radiation effects
  • DNA Repair / genetics
  • DNA Repair / radiation effects*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Endonucleases / genetics
  • Endonucleases / metabolism
  • Germ Cells / physiology
  • Germ Cells / radiation effects*
  • Pyrimidine Dimers / metabolism
  • Pyrimidine Dimers / radiation effects
  • RNA Interference
  • Recombination, Genetic / radiation effects*
  • Signal Transduction
  • Ultraviolet Rays*


  • Apoptosis Regulatory Proteins
  • Caenorhabditis elegans Proteins
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Pyrimidine Dimers
  • Endonucleases