The Terminal Telomeric DNA Sequence Determines the Mechanism of Dysfunctional Telomere Fusion
Overview
Affiliations
Mammalian telomeres consist of tandem DNA repeats that bind protective protein factors collectively termed shelterins. Telomere disruption typically results in genome instability induced by telomere fusions. The mechanism of telomere fusion varies depending on the means of telomere disruption. Here, we investigate telomere fusions caused by overexpression of mutant telomerases that add mutated telomeric repeats, thereby compromising shelterin binding to telomeric termini. While all mutant telomeric sequences tested induced heterodicentric chromosome fusions in ATM-competent cells, only those mutant repeat sequences with significant self complementarity induced ATM-independent sister chromatid and isodicentric chromosome fusions. Thus, once a telomere becomes dysfunctional, the terminal telomeric sequence itself determines the fate of that telomere. These results suggest that annealing of self-complementary DNA sequence engages an alternative telomere fusion pathway in human cells, and provide one explanation for the conspicuous lack of self complementarity in the majority of known naturally occurring eukaryotic telomeric sequences.
A persistent variant telomere sequence in a human pedigree.
Hinchie A, Sanford S, Loughridge K, Sutton R, Parikh A, Gil Silva A Nat Commun. 2024; 15(1):4681.
PMID: 38824190 PMC: 11144197. DOI: 10.1038/s41467-024-49072-9.
The ALT pathway generates telomere fusions that can be detected in the blood of cancer patients.
Muyas F, Rodriguez M, Cascao R, Afonso A, Sauer C, Faria C Nat Commun. 2024; 15(1):82.
PMID: 38167290 PMC: 10762111. DOI: 10.1038/s41467-023-44287-8.
Al-Zain A, Nester M, Ahmed I, Symington L Nat Commun. 2023; 14(1):7020.
PMID: 37919272 PMC: 10622511. DOI: 10.1038/s41467-023-42640-5.
Dynamics of TRF1 organizing a single human telomere.
Li X, Wang M, Zheng W, Huang W, Wang Z, Jin K Nucleic Acids Res. 2020; 49(2):760-775.
PMID: 33347580 PMC: 7826288. DOI: 10.1093/nar/gkaa1222.
How RNAi machinery enters the world of telomerase.
Laudadio I, Carissimi C, Fulci V Cell Cycle. 2019; 18(10):1056-1067.
PMID: 31014212 PMC: 6592256. DOI: 10.1080/15384101.2019.1609834.