Abstract
Telomerase counteracts telomere shortening and cellular senescence in germ, stem, and cancer cells by adding repetitive DNA sequences to the ends of chromosomes. Telomeres are susceptible to damage by reactive oxygen species (ROS), but the consequences of oxidation of telomeres on telomere length and the mechanisms that protect from ROS-mediated telomere damage are not well understood. In particular, 8-oxoguanine nucleotides at 3′ ends of telomeric substrates inhibit telomerase in vitro, whereas, at internal positions, they suppress G-quadruplex formation and were therefore proposed to promote telomerase activity. Here, we disrupt the peroxiredoxin 1 (PRDX1) and 7,8-dihydro-8-oxoguanine triphosphatase (MTH1) genes in cancer cells and demonstrate that PRDX1 and MTH1 cooperate to prevent accumulation of oxidized guanine in the genome. Concomitant disruption of PRDX1 and MTH1 leads to ROS concentration-dependent continuous shortening of telomeres, which is due to efficient inhibition of telomere extension by telomerase. Our results identify antioxidant systems that are required to protect telomeres from oxidation and are necessary to allow telomere maintenance by telomerase conferring immortality to cancer cells.
Funder
Swiss National Science Foundation
National Center of Competence in Research RNA and Disease Network
Swiss Cancer League
École Polytechnique Fédérale de Lausanne
Publisher
Cold Spring Harbor Laboratory
Subject
Developmental Biology,Genetics
Cited by
53 articles.
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