What is telomere sister chromatid?
Telomeres are a hotspot for sister chromatid exchange (T-SCE). Any biological consequence of this form of instability remained obscure until quantitative modeling revealed a link between elevated T-SCE rates and accelerated cellular replicative senescence.
Can telomeres fuse?
Chromosome-end fusions were also observed in telomerase-positive human cell lines ( 23 ). Most involve critically short telomeres, suggesting that telomeres fuse after eroding past a minimum length required for protection. In contrast to these studies, wild-type length telomeres can engage end fusions.
Do telomeres prevent chromosome fusion?
Telomeres prevent chromosome ends from activating DNA damage checkpoints and DSB repair pathways, and thereby prevent the degradation and fusion of chromosome ends.
What are telomere fusions?
Telomere–subtelomere fusion, junctions containing telomeric DNA presumably from one chromosome fused with another chromosome end with subtelomeric deletions. Complex fusion, fusion junctions containing nontelomeric DNA from interstitial chromosomal regions.
What is the purpose of sister chromatid exchange?
Sister chromatid exchanges (SCEs) are formed by the rupture, exchange, and repair between DNA molecules in homologous regions in the chromatids of duplicating chromosomes.
What is SCE disease?
SCE is elevated in pathologies including Bloom syndrome, having recombination rates ~10-100 times above normal, depending on cell type. Frequent SCEs may also be related to formation of tumors. Sister chromatid exchange has also been observed more frequently in B51(+) Behçet’s disease.
What happens if telomerase is mutated?
Mutations in the template region of a telomerase RNA gene can lead to the corresponding sequence alterations appearing in newly synthesized telomeric repeats.
What is the role of telomere in a chromosome?
Telomeres do indeed play an essential role in stabilizing the ends of chromosomes, but they do not contain active genes. Instead, telomeres contain an array of highly repeated DNA sequences and specific binding proteins that form a unique structure at the end of the chromosome.
How do telomeres protect chromosomes?
They protect the ends of our chromosomes by forming a cap, much like the plastic tip on shoelaces. If the telomeres were not there, our chromosomes may end up sticking to other chromosomes.
What is telomere damage?
Telomeres are specialized nucleoprotein structures, which protect chromosome ends and have been implicated in the ageing process. Telomere shortening has been shown to contribute to a persistent DNA damage response (DDR) during replicative senescence, the irreversible loss of division potential of somatic cells.
Why is telomere lost?
THE MECHANISM OF TELOMERE SHORTENING DURING CELL DIVISION This telomere shortening results from a combination of a failure to completely replicate the ends of linear DNA molecules, termed the “end replication problem,” and the processing of DNA that occurs on the ends of linear chromosomes.