ATM pathway activation limits R-loop-associated genomic instability in Werner syndrome cells

Abstract Werner syndrome (WS) is a cancer-prone disease caused by deficiency of Werner protein (WRN). WRN maintains genome integrity by promoting replication-fork stability after various forms of replication stress. Under mild replication stress, WS cells show impaired ATR-mediated CHK1 activation....

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Published in:Nucleic acids research 2019-04, Vol.47 (7), p.3485-3502
Main Authors: Marabitti, Veronica, Lillo, Giorgia, Malacaria, Eva, Palermo, Valentina, Sanchez, Massimo, Pichierri, Pietro, Franchitto, Annapaola
Format: Article
Language:English
Subjects:
Aphidicolin - pharmacology
Ataxia Telangiectasia Mutated Proteins - genetics
Checkpoint Kinase 1 - genetics
DNA Damage - drug effects
DNA Replication - genetics
Fibroblasts - drug effects
Gene Expression Regulation - drug effects
Genome Integrity, Repair and
Genomic Instability - genetics
Humans
Phosphorylation - drug effects
Signal Transduction
Werner Syndrome - genetics
Werner Syndrome - pathology
Werner Syndrome Helicase - genetics
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Summary:Abstract Werner syndrome (WS) is a cancer-prone disease caused by deficiency of Werner protein (WRN). WRN maintains genome integrity by promoting replication-fork stability after various forms of replication stress. Under mild replication stress, WS cells show impaired ATR-mediated CHK1 activation. However, it remains unclear if WS cells elicit other repair pathway. We demonstrate that loss of WRN leads to enhanced ATM phosphorylation upon prolonged exposure to aphidicolin, a specific inhibitor of DNA polymerases, resulting in CHK1 activation. Moreover, we find that loss of WRN sensitises cells to replication-transcription collisions and promotes accumulation of R-loops, which undergo XPG-dependent cleavage responsible for ATM signalling activation. Importantly, we observe that ATM pathway limits chromosomal instability in WS cells. Finally, we prove that, in WS cells, genomic instability enhanced upon chemical inhibition of ATM kinase activity is counteracted by direct or indirect suppression of R-loop formation or by XPG abrogation. Together, these findings suggest a potential role of WRN as regulator of R-loop-associated genomic instability, strengthening the notion that conflicts between replication and transcription can affect DNA replication, leading to human disease and cancer.
ISSN:0305-1048
1362-4962
1362-4962
DOI:10.1093/nar/gkz025