Actin nucleators safeguard replication forks by limiting nascent strand degradation

Jadwiga Nieminuszczy, Peter R. Martin, Ronan Broderick, Joanna Krwawicz, Alexandra Kanellou, Camelia Mocanu, Vicky Bousgouni, Charlotte Smith, Kuo Kuang Wen, Beth L. Woodward, Chris Bakal, Fiona Shackley, Andrcrossed D.Sign©s Aguilera, Grant S. Stewart, Yatin M. Vyas, Wojciech Niedzwiedz

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Accurate genome replication is essential for all life and a key mechanism of disease prevention, underpinned by the ability of cells to respond to replicative stress (RS) and protect replication forks. These responses rely on the formation of Replication Protein A (RPA)-single stranded (ss) DNA complexes, yet this process remains largely uncharacterized. Here, we establish that actin nucleation-promoting factors (NPFs) associate with replication forks, promote efficient DNA replication and facilitate association of RPA with ssDNA at sites of RS. Accordingly, their loss leads to deprotection of ssDNA at perturbed forks, impaired ATR activation, global replication defects and fork collapse. Supplying an excess of RPA restores RPA foci formation and fork protection, suggesting a chaperoning role for actin nucleators (ANs) (i.e. Arp2/3, DIAPH1) and NPFs (i.e, WASp, N-WASp) in regulating RPA availability upon RS. We also discover that β-actin interacts with RPA directly in vitro, and in vivo a hyper-depolymerizing β-actin mutant displays a heightened association with RPA and the same dysfunctional replication phenotypes as loss of ANs/NPFs, which contrasts with the phenotype of a hyper-polymerizing β-actin mutant. Thus, we identify components of actin polymerization pathways that are essential for preventing ectopic nucleolytic degradation of perturbed forks by modulating RPA activity.

Original languageEnglish (US)
Pages (from-to)6337-6354
Number of pages18
JournalNucleic acids research
Issue number12
StatePublished - Jul 7 2023

All Science Journal Classification (ASJC) codes

  • Genetics

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