title: Rad18 is required for functional interactions between FANCD2, BRCA2, and Rad51 to repair DNA topoisomerase 1-poisons induced lesions and promote fork recovery.
abstract: Camptothecin (CPT) and its analogues are chemotherapeutic agents that covalently and reversibly link DNA Topoisomerase I to its nicked DNA intermediate eliciting the formation of DNA double strand breaks (DSB) during replication. The repair of these DSB involves multiple DNA damage response and repair proteins. Here we demonstrate that CPT-induced DNA damage promotes functional interactions between BRCA2, FANCD2, Rad18, and Rad51 to repair the replication-associated DSB through homologous recombination (HR). Loss of any of these proteins leads to equal disruption of HR repair, causes chromosomal aberrations and sensitizes cells to CPT. Rad18 appears to function upstream in this repair pathway as its downregulation prevents activation of FANCD2, diminishes BRCA2 and Rad51 protein levels, formation of nuclear foci of all three proteins and recovery of stalled or collapsed replication forks in response to CPT. Taken together this work further elucidates the complex interplay of DNA repair proteins in the repair of replication-associated DSB.
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, USA.
authors.forename: Kaushlendra
authors.initials: K
authors.lastname: Tripathi
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, USA.
authors.forename: Chinnadurai
authors.initials: C
authors.lastname: Mani
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Clark
authors.affiliation: Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, 36604, USA.
authors.forename: Komaraiah
authors.initials: K
authors.lastname: Palle
mesh_terms: D002166:Camptothecin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D052236:Fanconi Anemia Complementation Group D2 Protein / Q000378:metabolism*; D045325:HCT116 Cells; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D034741:RNA, Small Interfering / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism*; D014162:Transfection; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C499905:FANCD2 protein, human; D052236:Fanconi Anemia Complementation Group D2 Protein; C485954:RAD18 protein, human; D034741:RNA, Small Interfering; D044767:Ubiquitin-Protein Ligases; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D004264:DNA Topoisomerases, Type I; D002166:Camptothecin
keywords: BRCA2; DNA topoisomerase 1; FANCD2; Rad18; Rad51