title: Studying telomere replication by Q-CO-FISH: the effect of telomestatin, a potent G-quadruplex ligand.
abstract: Telomere replication is a critical process for preserving genome integrity. The telomere replication fork proceeds unidirectionally from the last subtelomeric origin towards the end of the chromosome, replicating the 5'-3' G-rich strand by lagging mechanisms and the complementary C-rich strand by leading mechanisms. It has been proposed that the G-rich nature of telomeres may favor the formation of secondary structures such as G-quadruplexes during replication and that specific mechanisms must prevent this to allow the fork to progress unimpeded. The potential of G-quadruplex formation by telomeric sequences has been clearly demonstrated in vitro but it is not known whether these structures form in vivo. We tested the effect of a potent and specific G-quadruplex ligand, telomestatin (TMS), on telomere replication using a novel quantitative approach applied to CO-FISH. We show that TMS, although it penetrates and persists within cells, does not affect telomere replication after short or long-term treatments of mouse embryonic fibroblasts. It does however affect the hybridization efficiency of FISH telomeric probes that recognize the G-rich strand. Our work illustrates the use of a novel technique to measure telomere replication efficiency and suggests that G-quadruplex ligands do not affect telomere replication in a non tumoral context.
authors.affiliation: UMR7147 Institut Curie-UPMC-CNRS, Paris, France.
authors.forename: N
authors.initials: N
authors.lastname: Arnoult
authors.forename: K
authors.initials: K
authors.lastname: Shin-Ya
authors.forename: J A
authors.initials: JA
authors.lastname: Londoño-Vallejo
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D004247:DNA / Q000235:genetics; D004261:DNA Replication; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D017404:In Situ Hybridization, Fluorescence; D008677:Metaphase / Q000502:physiology; D051379:Mice; D009693:Nucleic Acid Hybridization; D010080:Oxazoles / Q000494:pharmacology*; D019098:Telomerase / Q000187:drug effects / Q000378:metabolism; D016615:Telomere / Q000235:genetics*
chemical_list: D010080:Oxazoles; C431888:telomestatin; D004247:DNA; D019098:Telomerase