Actin nucleators safeguard replication forks by limiting nascent strand degradation.
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Authors
Nieminuszczy, J
Martin, PR
Broderick, R
Krwawicz, J
Kanellou, A
Mocanu, C
Bousgouni, V
Smith, C
Wen, K-K
Woodward, BL
Bakal, C
Shackley, F
Aguilera, A
Stewart, GS
Vyas, YM
Niedzwiedz, W
Martin, PR
Broderick, R
Krwawicz, J
Kanellou, A
Mocanu, C
Bousgouni, V
Smith, C
Wen, K-K
Woodward, BL
Bakal, C
Shackley, F
Aguilera, A
Stewart, GS
Vyas, YM
Niedzwiedz, W
Document Type
Journal Article
Date
2023-07-07
Date Accepted
2023-05-11
Abstract
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.
Citation
Nucleic Acids Research, 2023, 51 (12), pp. 6337 - 6354
Source Title
Nucleic Acids Research
Publisher
OXFORD UNIV PRESS
ISSN
0305-1048
eISSN
1362-4962
1362-4962
1362-4962
Collections
Research Team
Cancer and Genome Instab
Dynamical Cell Systems
Dynamical Cell Systems