{"doi":"10.1002/em.21672","title":"Uncoupling of RAD51 focus formation and cell survival after replication fork stalling in RAD51D null CHO cells","abstract":"<jats:title>Abstract</jats:title><jats:p>In vertebrate cells, the five RAD51 paralogs (XRCC2/3 and RAD51B/C/D) enhance the efficiency of homologous recombination repair (HRR). Stalling and breakage of DNA replication forks is a common event, especially in the large genomes of higher eukaryotes. When cells are exposed to agents that arrest DNA replication, such as hydroxyurea or aphidicolin, fork breakage can lead to chromosomal aberrations and cell killing. We assessed the contribution of the HRR protein RAD51D in resistance to killing by replication‐associated DSBs. In response to hydroxyurea, the isogenic <jats:italic>rad51d</jats:italic> null CHO mutant fails to show any indication of HRR initiation, as assessed by induction RAD51 foci, as expected. Surprisingly, these cells have normal resistance to killing by replication inhibition from either hydroxyurea or aphidicolin, but show the expected sensitivity to camptothecin, which also generates replication‐dependent DSBs. In contrast, we confirm that the V79 <jats:italic>xrcc2</jats:italic> mutant does show increased sensitivity to hydroxyurea under some conditions, which was correlated to its attenuated RAD51 focus response. In response to the PARP1 inhibitor KU58684, <jats:italic>rad51d</jats:italic> cells, like other HRR mutants, show exquisite sensitivity (&gt;1000‐fold), which is also associated with defective RAD51 focus formation. Thus, <jats:italic>rad51d</jats:italic> cells are broadly deficient in RAD51 focus formation in response to various agents, but this defect is not invariably associated with increased sensitivity. Our results indicate that RAD51 paralogs do not contribute equally to cellular resistance of inhibitors of DNAreplication, and that the RAD51 foci associated with replication inhibition may not be a reliable indicator of cellular resistance to such agents. Environ. Mol. Mutagen. 2012. © 2012 Wiley Periodicals, Inc.</jats:p>","journal":"Environmental and Molecular Mutagenesis","year":2012,"id":680543,"datarank":0.37273599746820013,"base_score":2.4849066497880004,"endowment":2.4849066497880004,"self_citation_contribution":0.37273599746820013,"citation_network_contribution":0.0,"self_endowment_contribution":0.37273599746820013,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":11,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":599665,"name":"Ingegerd Elvers","orcid":"0000-0002-6604-0369","position":1,"is_corresponding":false},{"id":1778074,"name":"John M. Hinz","orcid":null,"position":2,"is_corresponding":false},{"id":208960,"name":"Thomas Helleday","orcid":null,"position":3,"is_corresponding":false},{"id":595688,"name":"Larry H. Thompson","orcid":null,"position":4,"is_corresponding":false},{"id":1778073,"name":"Salustra S. Urbin","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Uncoupling of RAD51 focus formation and cell survival after replication fork stalling in RAD51D null CHO cells","abstract":"<jats:title>Abstract</jats:title><jats:p>In vertebrate cells, the five RAD51 paralogs (XRCC2/3 and RAD51B/C/D) enhance the efficiency of homologous recombination repair (HRR). Stalling and breakage of DNA replication forks is a common event, especially in the large genomes of higher eukaryotes. When cells are exposed to agents that arrest DNA replication, such as hydroxyurea or aphidicolin, fork breakage can lead to chromosomal aberrations and cell killing. We assessed the contribution of the HRR protein RAD51D in resistance to killing by replication‐associated DSBs. In response to hydroxyurea, the isogenic <jats:italic>rad51d</jats:italic> null CHO mutant fails to show any indication of HRR initiation, as assessed by induction RAD51 foci, as expected. Surprisingly, these cells have normal resistance to killing by replication inhibition from either hydroxyurea or aphidicolin, but show the expected sensitivity to camptothecin, which also generates replication‐dependent DSBs. In contrast, we confirm that the V79 <jats:italic>xrcc2</jats:italic> mutant does show increased sensitivity to hydroxyurea under some conditions, which was correlated to its attenuated RAD51 focus response. In response to the PARP1 inhibitor KU58684, <jats:italic>rad51d</jats:italic> cells, like other HRR mutants, show exquisite sensitivity (&gt;1000‐fold), which is also associated with defective RAD51 focus formation. Thus, <jats:italic>rad51d</jats:italic> cells are broadly deficient in RAD51 focus formation in response to various agents, but this defect is not invariably associated with increased sensitivity. Our results indicate that RAD51 paralogs do not contribute equally to cellular resistance of inhibitors of DNAreplication, and that the RAD51 foci associated with replication inhibition may not be a reliable indicator of cellular resistance to such agents. Environ. Mol. Mutagen. 2012. © 2012 Wiley Periodicals, Inc.</jats:p>","is_dataset_classified":null,"base_score":2.4849066497880004,"endowment":2.4849066497880004,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"22302683","pmcid":null,"openalex_id":"https://openalex.org/W2030531442","authors":[],"funders":[{"funder_name":"NCI NIH HHS","grant_id":"CA112566","title":null}],"total_grants":1,"fwci":1.1048,"citation_percentile":0.75490248,"influential_citations":0,"citation_trend":[{"year":2012,"count":1},{"year":2014,"count":4},{"year":2015,"count":4},{"year":2017,"count":1},{"year":2025,"count":1}],"oa_status":"closed","license":"http://onlinelibrary.wiley.com/termsAndConditions#vor","oa_locations":[{"url":"https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fem.21672","host_type":"publisher"},{"url":"https://onlinelibrary.wiley.com/doi/pdf/10.1002/em.21672","host_type":"publisher"},{"url":"https://doi.org/10.1002/em.21672","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/22302683","host_type":"repository"}],"fields_of_study":["DNA Repair Mechanisms","PARP inhibition in cancer therapy","Plant Genetic and Mutation Studies"],"mesh_terms":["Poly(ADP-ribose) Polymerase Inhibitors","Animals","Cell Survival","Cells, Cultured","DNA Replication","DNA-Binding Proteins","Enzyme Inhibitors","Cricetinae","Hydroxyurea","Kinetics","CHO Cells","Mutant Proteins","Rad51 Recombinase","DNA Breaks, Double-Stranded","Gene Knockout Techniques"],"keywords":["Aphidicolin","RAD51","Biology","DNA replication","DNA repair","Homologous recombination","Mutant","Genome instability","Genetics","DNA damage","Molecular biology","Cell biology","DNA","Gene"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-17T15:26:43.953264Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}