title: Controlled light exposure microscopy reveals dynamic telomere microterritories throughout the cell cycle.
abstract: Telomeres are complex end structures that confer functional integrity and positional stability to human chromosomes. Despite their critical importance, there is no clear view on telomere organization in cycling human cells and their dynamic behavior throughout the cell cycle. We investigated spatiotemporal organization of telomeres in living human ECV-304 cells stably expressing telomere binding proteins TRF1 and TRF2 fused to mCitrine using four dimensional microscopy. We thereby made use of controlled light exposure microscopy (CLEM), a novel technology that strongly reduces photodamage by limiting excitation in parts of the image where full exposure is not needed. We found that telomeres share small territories where they dynamically associate. These territories are preferentially positioned at the interface of chromatin domains. TRF1 and TRF2 are abundantly present in these territories but not firmly bound. At the onset of mitosis, the bulk of TRF protein dissociates from telomere regions, territories disintegrate and individual telomeres become faintly visible. The combination of stable cell lines, CLEM and cytometry proved essential in providing novel insights in compartment-based nuclear organization and may serve as a model approach for investigating telomere-driven genome-instability and studying long-term nuclear dynamics.
authors.affiliation: Department of Molecular Biotechnology, Faculty of Bio-engineering Sciences, Ghent University, Coupure links 653, Ghent 9000, Belgium. winnok.devos@Ugent.be
authors.forename: Winnok H
authors.initials: WH
authors.lastname: De Vos
authors.forename: R A
authors.initials: RA
authors.lastname: Hoebe
authors.forename: G H
authors.initials: GH
authors.lastname: Joss
authors.forename: W
authors.initials: W
authors.lastname: Haffmans
authors.forename: S
authors.initials: S
authors.lastname: Baatout
authors.forename: P
authors.initials: P
authors.lastname: Van Oostveldt
authors.forename: E M M
authors.initials: EM
authors.lastname: Manders
mesh_terms: D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D011993:Recombinant Fusion Proteins / Q000502:physiology; D016615:Telomere / Q000502:physiology*; D035321:Telomeric Repeat Binding Protein 1 / Q000502:physiology*; D035341:Telomeric Repeat Binding Protein 2 / Q000502:physiology*; D014162:Transfection
chemical_list: D011993:Recombinant Fusion Proteins; C504753:TERF2 protein, human; D035321:Telomeric Repeat Binding Protein 1; D035341:Telomeric Repeat Binding Protein 2