TY - JOUR
T1 - Mammalian Telomeres Resemble Fragile Sites and Require TRF1 for Efficient Replication
AU - Sfeir, Agnel
AU - Kosiyatrakul, Settapong T.
AU - Hockemeyer, Dirk
AU - MacRae, Sheila L.
AU - Karlseder, Jan
AU - Schildkraut, Carl L.
AU - de Lange, Titia
N1 - Funding Information:
We thank Devon White for expert mouse husbandry and Eros Lazzerini Denchi for assistance with protocols and helpful discussion. Megan van Overbeek is thanked for assistance with TRF1 antibody, and members of the de Lange laboratory are thanked for comments on these experiments. We are grateful to Sara Buonomo for the BLM shRNA and to Brad Johnson for providing the Blm −/− , Wrn −/− , and Blm −/− Wrn −/− cell lines. We thank Scott Powers, Peter Medveczky, and Raymund Wellinger for allowing us to cite unpublished data. A.S. is supported by a postdoctoral fellowship from Susan G. Komen for the Cure. This work was supported by grants from the National Institutes of Health to T.d.L. and C.L.S. The targeting construct and the conditional TRF1 knockout strain were generated by J.K. and D.H. A.S. generated compound genotypes, isolated MEFs, and performed all other experiments with the exception of the human telomere length study (S.L.M.). All SMARD analysis was performed by A.S. with the help of S.T.K. and C.L.S. T.d.L. and A.S. designed the experiments, wrote the paper, and made the figures.
PY - 2009/7/10
Y1 - 2009/7/10
N2 - Telomeres protect chromosome ends through the interaction of telomeric repeats with shelterin, a protein complex that represses DNA damage signaling and DNA repair reactions. The telomeric repeats are maintained by telomerase, which solves the end replication problem. We report that the TTAGGG repeat arrays of mammalian telomeres pose a challenge to the DNA replication machinery, giving rise to replication-dependent defects that resemble those of aphidicolin-induced common fragile sites. Gene deletion experiments showed that efficient duplication of telomeres requires the shelterin component TRF1. Without TRF1, telomeres activate the ATR kinase in S phase and show a fragile-site phenotype in metaphase. Single-molecule analysis of replicating telomeres showed that TRF1 promotes efficient replication of TTAGGG repeats and prevents fork stalling. Two helicases implicated in the removal of G4 DNA structures, BLM and RTEL1, were required to repress the fragile-telomere phenotype. These results identify a second telomere replication problem that is solved by the shelterin component TRF1.
AB - Telomeres protect chromosome ends through the interaction of telomeric repeats with shelterin, a protein complex that represses DNA damage signaling and DNA repair reactions. The telomeric repeats are maintained by telomerase, which solves the end replication problem. We report that the TTAGGG repeat arrays of mammalian telomeres pose a challenge to the DNA replication machinery, giving rise to replication-dependent defects that resemble those of aphidicolin-induced common fragile sites. Gene deletion experiments showed that efficient duplication of telomeres requires the shelterin component TRF1. Without TRF1, telomeres activate the ATR kinase in S phase and show a fragile-site phenotype in metaphase. Single-molecule analysis of replicating telomeres showed that TRF1 promotes efficient replication of TTAGGG repeats and prevents fork stalling. Two helicases implicated in the removal of G4 DNA structures, BLM and RTEL1, were required to repress the fragile-telomere phenotype. These results identify a second telomere replication problem that is solved by the shelterin component TRF1.
KW - DNA
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U2 - 10.1016/j.cell.2009.06.021
DO - 10.1016/j.cell.2009.06.021
M3 - Article
C2 - 19596237
AN - SCOPUS:67649635974
SN - 0092-8674
VL - 138
SP - 90
EP - 103
JO - Cell
JF - Cell
IS - 1
ER -