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Van Ly D, Low RRJ, Frölich S, Bartolec TK, Kafer GR, Pickett HA, Gaus K, Cesare AJ. Telomere Loop Dynamics in Chromosome End Protection. Mol Cell 2018; 71:510-525.e6. [PMID: 30033372 DOI: 10.1016/j.molcel.2018.06.025] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/28/2018] [Accepted: 06/15/2018] [Indexed: 01/07/2023]
Abstract
Telomeres regulate DNA damage response (DDR) and DNA repair activity at chromosome ends. How telomere macromolecular structure contributes to ATM regulation and its potential dissociation from control over non-homologous end joining (NHEJ)-dependent telomere fusion is of central importance to telomere-dependent cell aging and tumor suppression. Using super-resolution microscopy, we identify that ATM activation at mammalian telomeres with reduced TRF2 or at human telomeres during mitotic arrest occurs specifically with a structural change from telomere loops (t-loops) to linearized telomeres. Additionally, we find the TRFH domain of TRF2 regulates t-loop formation while suppressing ATM activity. Notably, we demonstrate that ATM activation and telomere linearity occur separately from telomere fusion via NHEJ and that linear DDR-positive telomeres can remain resistant to fusion, even during an extended G1 arrest, when NHEJ is most active. Collectively, these results suggest t-loops act as conformational switches that specifically regulate ATM activation independent of telomere mechanisms to inhibit NHEJ.
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Affiliation(s)
- David Van Ly
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia; School of Medicine, The University of Notre Dame Australia, Sydney, NSW 2010, Australia
| | - Ronnie Ren Jie Low
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Sonja Frölich
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Tara K Bartolec
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Georgia R Kafer
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Katharina Gaus
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia; ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW 2052, Australia
| | - Anthony J Cesare
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia.
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