title: CDK1 differentially regulates G-overhang generation at leading- and lagging-strand telomeres in telomerase-negative cells in G2 phase.
abstract: Human telomeres contain single-stranded 3' G-overhangs that function in telomere end protection and telomerase action. Previously we have demonstrated that multiple steps involving C-strand end resection, telomerase elongation and C-strand fill-in contribute to G-overhang generation in telomerase-positive cancer cells. However, how G-overhangs are generated in telomerase-negative human somatic cells is unknown. Here, we report that C-strand fill-in is present at lagging-strand telomeres in telomerase-negative human cells but not at leading-strand telomeres, suggesting that C-strand fill-in is independent of telomerase extension of G-strand. We further show that while cyclin-dependent kinase 1 (CDK1) positively regulates C-strand fill-in, CDK1 unlikely regulates G-overhang generation at leading-strand telomeres. In addition, DNA polymerase α (Polα) association with telomeres is not altered upon CDK1 inhibition, suggesting that CDK1 does not control the loading of Polα to telomeres during fill-in. In summary, our results reveal that G-overhang generation at leading- and lagging-strand telomeres are regulated by distinct mechanisms in human cells.
authors.affiliation: School of Molecular Biosciences, Washington State University, Spokane, WA, USA.
authors.forename: Xueyu
authors.initials: X
authors.lastname: Dai
authors.forename: Chenhui
authors.initials: C
authors.lastname: Huang
authors.forename: Weihang
authors.initials: W
authors.lastname: Chai
mesh_terms: D015075:2-Aminopurine / Q000031:analogs & derivatives / Q000494:pharmacology; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004256:DNA Polymerase I / Q000378:metabolism; D004261:DNA Replication; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D016195:G2 Phase; D006367:HeLa Cells; D006801:Humans; D011804:Quinolines / Q000494:pharmacology; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; C469937:N(2)-(2-aminocyclohexyl)-N(6)-(3-chlorophenyl)-9-ethyl-9H-purine-2,6-diamine; C022262:Okazaki fragments; D011804:Quinolines; C512984:RO 3306; D034501:Telomere-Binding Proteins; D013844:Thiazoles; D015075:2-Aminopurine; D004247:DNA; D016203:CDC2 Protein Kinase; D019098:Telomerase; D004256:DNA Polymerase I