title: Caenorhabditis elegans APN-1 plays a vital role in maintaining genome stability.
abstract: We previously showed that Caenorhabditis elegans APN-1, the only metazoan apurinic/apyrimidinc (AP) endonuclease belonging to the endonuclease IV family, can functionally rescue the DNA repair defects of Saccharomyces cerevisiae mutants completely lacking AP endonuclease/3'-diesterase activities. While this complementation study provided the first evidence that APN-1 possesses the ability to act on DNA lesions that are processed by AP endonucleases/3'-diesterase activities, no former studies were conducted to examine its biological importance in vivo. Herein, we show that C. elegans knockdown for apn-1 by RNAi displayed phenotypes that are directly linked with a defect in maintaining the integrity of the genome. apn-1(RNAi) animals exhibited a 5-fold increase in the frequency of mutations at a gfp-lacZ reporter and showed sensitivities to DNA damaging agents such as methyl methane sulfonate and hydrogen peroxide that produce AP site lesions and strand breaks with blocked 3'-ends. The apn-1(RNAi) worms also displayed a delay in the division of the P1 blastomere, a defect that is consistent with the accumulation of unrepaired lesions. Longevity was only compromised, if the apn-1(RNAi) animals were challenged with the DNA damaging agents. We showed that apn-1(RNAi) knockdown suppressed formation of apoptotic corpses in the germline caused by an overburden of AP sites generated from uracil DNA glycosylase mediated removal of misincorporated uracil. Finally, we showed that depletion of APN-1 by RNAi partially rescued the lethality resulting from uracil misincorporation, suggesting that APN-1 is an important AP endonuclease for repair of misincorporated uracil.
authors.affiliation: University of Montreal, Maisonneuve-Rosemont Hospital, Research Center, 5415 de l'Assomption, Montreal, Quebec, Canada H1T 2M4.
authors.forename: Chadi
authors.initials: C
authors.lastname: Zakaria
authors.forename: Henok
authors.initials: H
authors.lastname: Kassahun
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Yang
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Labbé
authors.forename: Hilde
authors.initials: H
authors.lastname: Nilsen
authors.forename: Dindial
authors.initials: D
authors.lastname: Ramotar
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D001757:Blastomeres / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D017173:Caenorhabditis elegans / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects / Q000528:radiation effects; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D017930:Genes, Reporter; D049751:Genome, Helminth / Q000235:genetics*; D042822:Genomic Instability / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008136:Longevity / Q000187:drug effects / Q000528:radiation effects; D008741:Methyl Methanesulfonate / Q000633:toxicity; D009154:Mutation / Q000235:genetics; D034622:RNA Interference / Q000187:drug effects; D014466:Ultraviolet Rays; D014498:Uracil / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism; D020122:tert-Butylhydroperoxide / Q000633:toxicity
chemical_list: D029742:Caenorhabditis elegans Proteins; D049452:Green Fluorescent Proteins; D014498:Uracil; D020122:tert-Butylhydroperoxide; D008741:Methyl Methanesulfonate; D004706:Endodeoxyribonucleases; D001616:beta-Galactosidase; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; C504039:EXO-3 protein, C elegans; C102951:apn-1 protein, C elegans