Looping-out mechanism for resolution of replicative stress at telomeres.
EMBO Rep
; 18(8): 1412-1428, 2017 08.
Article
en En
| MEDLINE
| ID: mdl-28615293
ABSTRACT
Repetitive DNA is prone to replication fork stalling, which can lead to genome instability. Here, we find that replication fork stalling at telomeres leads to the formation of t-circle-tails, a new extrachromosomal structure that consists of circular telomeric DNA with a single-stranded tail. Structurally, the t-circle-tail resembles cyclized leading or lagging replication intermediates that are excised from the genome by topoisomerase II-mediated cleavage. We also show that the DNA damage repair machinery NHEJ is required for the formation of t-circle-tails and for the resolution of stalled replication forks, suggesting that NHEJ, which is normally constitutively suppressed at telomeres, is activated in the context of replication stress. Inhibition of NHEJ or knockout of DNA-PKcs impairs telomere replication, leading to multiple-telomere sites (MTS) and telomere shortening. Collectively, our results support a "looping-out" mechanism, in which the stalled replication fork is cut out and cyclized to form t-circle-tails, and broken DNA is religated. The telomere loss induced by replication stress may serve as a new factor that drives replicative senescence and cell aging.
Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Telómero
/
Replicación del ADN
/
Acortamiento del Telómero
Límite:
Humans
Idioma:
En
Revista:
EMBO Rep
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2017
Tipo del documento:
Article
País de afiliación:
China