Translesion polymerase eta both facilitates DNA replication and promotes increased human genetic variation at common fragile sites
| Autor: | Ruth B De-Paula, Advaitha Madireddy, Shyam Twayana, William C. Drosopoulos, Settapong T. Kosiyatrakul, Albino Bacolla, John A. Tainer, Eric E. Bouhassira, Angelica Barreto-Galvez, Carl L. Schildkraut |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
DNA Replication
DNA Repair DNA polymerase Population SNP DNA-Directed DNA Polymerase replication fork pause Genomic Instability Cell Line chemistry.chemical_compound Proliferating Cell Nuclear Antigen Chromosome instability non-B DNA Humans education Gene Polymerase DNA Polymerase III Genetics education.field_of_study Multidisciplinary biology Chromosome Fragile Sites Chromosome Fragility Chromosomal fragile site DNA replication Genetic Variation DNA Cell Biology Biological Sciences chemistry biology.protein polymerase eta common fragile sites DNA Damage |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.2106477118 |
| Popis: | Significance Common fragile sites (CFSs) are normal loci that are genetically unstable under normal and oncogenic replication stress. Pol eta has been proposed to play a key role in CFS replication. Here, we show that in the absence of Pol eta, replication at five specific CFS loci is perturbed, with fork pausing observed at several sites. Sequence analysis showed that certain pause sites are associated with the presence of non-B DNA motifs, while others are not. Importantly, pause sites are located within regions of increased genetic variation in healthy human populations that could be attributed to Pol eta activity. Our data unveil a role for Pol eta in overcoming replication stress, reducing DNA breakage, and promoting genetic variation at CFSs. Common fragile sites (CFSs) are difficult-to-replicate genomic regions that form gaps and breaks on metaphase chromosomes under replication stress. They are hotspots for chromosomal instability in cancer. Repetitive sequences located at CFS loci are inefficiently copied by replicative DNA polymerase (Pol) delta. However, translesion synthesis Pol eta has been shown to efficiently polymerize CFS-associated repetitive sequences in vitro and facilitate CFS stability by a mechanism that is not fully understood. Here, by locus-specific, single-molecule replication analysis, we identified a crucial role for Pol eta (encoded by the gene POLH) in the in vivo replication of CFSs, even without exogenous stress. We find that Pol eta deficiency induces replication pausing, increases initiation events, and alters the direction of replication-fork progression at CFS-FRA16D in both lymphoblasts and fibroblasts. Furthermore, certain replication pause sites at CFS-FRA16D were associated with the presence of non-B DNA-forming motifs, implying that non-B DNA structures could increase replication hindrance in the absence of Pol eta. Further, in Pol eta-deficient fibroblasts, there was an increase in fork pausing at fibroblast-specific CFSs. Importantly, while not all pause sites were associated with non-B DNA structures, they were embedded within regions of increased genetic variation in the healthy human population, with mutational spectra consistent with Pol eta activity. From these findings, we propose that Pol eta replicating through CFSs may result in genetic variations found in the human population at these sites. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|