title: MRN, CtIP, and BRCA1 mediate repair of topoisomerase II-DNA adducts.
abstract: Repair of DNA double-strand breaks (DSBs) with complex ends poses a special challenge, as additional processing is required before DNA ligation. For example, protein-DNA adducts must be removed to allow repair by either nonhomologous end joining or homology-directed repair. Here, we investigated the processing of topoisomerase II (Top2)-DNA adducts induced by treatment with the chemotherapeutic agent etoposide. Through biochemical analysis in Xenopus laevis egg extracts, we establish that the MRN (Mre11, Rad50, and Nbs1) complex, CtIP, and BRCA1 are required for both the removal of Top2-DNA adducts and the subsequent resection of Top2-adducted DSB ends. Moreover, the interaction between CtIP and BRCA1, although dispensable for resection of endonuclease-generated DSB ends, is required for resection of Top2-adducted DSBs, as well as for cellular resistance to etoposide during genomic DNA replication.
authors.affiliation: Institute for Cancer Genetics, Columbia University, New York, NY, 10032.
authors.forename: Tomas
authors.initials: T
authors.lastname: Aparicio
authors.affiliation: Institute for Cancer Genetics, Columbia University, New York, NY, 10032.
authors.forename: Richard
authors.initials: R
authors.lastname: Baer
authors.affiliation: Department of Biochemistry and Biophysics, Columbia University, New York, NY, 10032.
authors.forename: Max
authors.initials: M
authors.lastname: Gottesman
authors.affiliation: Institute for Cancer Genetics, Columbia University, New York, NY, 10032 Department of Genetics and Development, Columbia University, New York, NY, 10032 jg130@columbia.edu.
authors.forename: Jean
authors.initials: J
authors.lastname: Gautier
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018736:DNA Adducts / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology; D005260:Female; D000076228:MRE11 Homologue Protein; D046912:Multiprotein Complexes; D013997:Time Factors; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D000951:Antigens, Neoplasm; D019313:BRCA1 Protein; D002352:Carrier Proteins; D018736:DNA Adducts; D004268:DNA-Binding Proteins; C510917:Mre11 protein, Xenopus; D046912:Multiprotein Complexes; C511600:NBN protein, Xenopus; C559071:RBBP8 protein, Xenopus; C542167:Rad50 protein, Xenopus; D059005:Topoisomerase II Inhibitors; D025521:Tumor Suppressor Proteins; D029867:Xenopus Proteins; D005047:Etoposide; D000076228:MRE11 Homologue Protein; D004250:DNA Topoisomerases, Type II; D045643:DNA Repair Enzymes