Han, Seong-SuWen, Kuo-KuangGarcía-Rubio, María LWold, Marc SAguilera, AndrésNiedzwiedz, WojciechVyas, Yatin M2023-05-032023-05-032022-06-29http://hdl.handle.net/10668/19539Perturbation in the replication-stress response (RSR) and DNA-damage response (DDR) causes genomic instability. Genomic instability occurs in Wiskott-Aldrich syndrome (WAS), a primary immunodeficiency disorder, yet the mechanism remains largely uncharacterized. Replication protein A (RPA), a single-strand DNA (ssDNA) binding protein, has key roles in the RSR and DDR. Here we show that human WAS-protein (WASp) modulates RPA functions at perturbed replication forks (RFs). Following genotoxic insult, WASp accumulates at RFs, associates with RPA, and promotes RPA:ssDNA complexation. WASp deficiency in human lymphocytes destabilizes RPA:ssDNA-complexes, impairs accumulation of RPA, ATR, ETAA1, and TOPBP1 at genotoxin-perturbed RFs, decreases CHK1 activation, and provokes global RF dysfunction. las17 (yeast WAS-homolog)-deficient S. cerevisiae also show decreased ScRPA accumulation at perturbed RFs, impaired DNA recombination, and increased frequency of DNA double-strand break (DSB)-induced single-strand annealing (SSA). Consequently, WASp (or Las17)-deficient cells show increased frequency of DSBs upon genotoxic insult. Our study reveals an evolutionarily conserved, essential role of WASp in the DNA stress-resolution pathway, such that WASp deficiency provokes RPA dysfunction-coupled genomic instability.enAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/AnimalsAntigens, SurfaceDNA Breaks, Double-StrandedDNA RepairDNA ReplicationDNA, Single-StrandedDNA-Binding ProteinsGenomic InstabilityHumansProtein BindingReplication Protein ASaccharomyces cerevisiaeSaccharomyces cerevisiae ProteinsWiskott-Aldrich Syndrome Proteinresearch article35768435open access10.1038/s41467-022-31415-z2041-1723PMC9243104https://www.nature.com/articles/s41467-022-31415-z.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC9243104/pdf