title: Targeting assay to study the cis functions of human telomeric proteins: evidence for inhibition of telomerase by TRF1 and for activation of telomere degradation by TRF2.
abstract: We investigated the control of telomere length by the human telomeric proteins TRF1 and TRF2. To this end, we established telomerase-positive cell lines in which the targeting of these telomeric proteins to specific telomeres could be induced. We demonstrate that their targeting leads to telomere shortening. This indicates that these proteins act in cis to repress telomere elongation. Inhibition of telomerase activity by a modified oligonucleotide did not further increase the pace of telomere erosion caused by TRF1 targeting, suggesting that telomerase itself is the target of TRF1 regulation. In contrast, TRF2 targeting and telomerase inhibition have additive effects. The possibility that TRF2 can activate a telomeric degradation pathway was directly tested in human primary cells that do not express telomerase. In these cells, overexpression of full-length TRF2 leads to an increased rate of telomere shortening.
authors.affiliation: Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665 CNRS/ENSL, Ecole Normale Supérieure de Lyon, Lyon, France.
authors.forename: Katia
authors.initials: K
authors.lastname: Ancelin
authors.forename: Michele
authors.initials: M
authors.lastname: Brunori
authors.forename: Serge
authors.initials: S
authors.lastname: Bauwens
authors.forename: Catherine-Elaine
authors.initials: CE
authors.lastname: Koering
authors.forename: Christine
authors.initials: C
authors.lastname: Brun
authors.forename: Michelle
authors.initials: M
authors.lastname: Ricoul
authors.forename: Jean-Patrick
authors.initials: JP
authors.lastname: Pommier
authors.forename: Laure
authors.initials: L
authors.lastname: Sabatier
authors.forename: Eric
authors.initials: E
authors.lastname: Gilson
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D056968:Lac Repressors; D009687:Nuclear Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*; D035321:Telomeric Repeat Binding Protein 1; D035341:Telomeric Repeat Binding Protein 2; D014162:Transfection
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D056968:Lac Repressors; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D035321:Telomeric Repeat Binding Protein 1; D035341:Telomeric Repeat Binding Protein 2; D019098:Telomerase