title: Alternative lengthening of human telomeres is a conservative DNA replication process with features of break-induced replication.
abstract: Human malignancies overcome replicative senescence either by activating the reverse-transcriptase telomerase or by utilizing a homologous recombination-based mechanism, referred to as alternative lengthening of telomeres (ALT). In budding yeast, ALT exhibits features of break-induced replication (BIR), a repair pathway for one-ended DNA double-strand breaks (DSBs) that requires the non-essential subunit Pol32 of DNA polymerase delta and leads to conservative DNA replication. Here, we examined whether ALT in human cancers also exhibits features of BIR A telomeric fluorescence in situ hybridization protocol involving three consecutive staining steps revealed the presence of conservatively replicated telomeric DNA in telomerase-negative cancer cells. Furthermore, depletion of PolD3 or PolD4, two subunits of human DNA polymerase delta that are essential for BIR, reduced the frequency of conservatively replicated telomeric DNA ends and led to shorter telomeres and chromosome end-to-end fusions. Taken together, these results suggest that BIR is associated with conservative DNA replication in human cells and mediates ALT in cancer.
authors.affiliation: Laboratory of Genetics, Center of Experimental Medicine and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Fani-Marlen
authors.initials: FM
authors.lastname: Roumelioti
authors.affiliation: Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
authors.forename: Sotirios K
authors.initials: SK
authors.lastname: Sotiriou
authors.affiliation: Laboratory of Genetics, Center of Experimental Medicine and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Katsini
authors.affiliation: Laboratory of Genetics, Center of Experimental Medicine and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Chiourea
authors.affiliation: Department of Molecular Biology, University of Geneva, Geneva, Switzerland thanos.halazonetis@unige.ch sgagos@bioacademy.gr.
authors.forename: Thanos D
authors.identifier: 0000-0001-8384-5030
authors.initials: TD
authors.lastname: Halazonetis
authors.affiliation: Laboratory of Genetics, Center of Experimental Medicine and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece thanos.halazonetis@unige.ch sgagos@bioacademy.gr.
authors.forename: Sarantis
authors.initials: S
authors.lastname: Gagos
mesh_terms: D053903:DNA Breaks, Double-Stranded; D004258:DNA Polymerase III / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D059765:Homologous Recombination / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D009369:Neoplasms / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D059505:Telomere Homeostasis / Q000235:genetics; D059506:Telomere Shortening / Q000235:genetics; D015003:Yeasts / Q000235:genetics / Q000502:physiology
chemical_list: C522758:Pol32 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C435720:POLD3 protein, human; C521101:POLD4 protein, human; D019098:Telomerase; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase
keywords: PolD3; PolD4; alternative lengthening of telomeres; break‐induced replication; telomere length regulation