title: The relative efficiency of homology-directed repair has distinct effects on proper anaphase chromosome separation.
abstract: Homology-directed repair (HDR) is essential to limit mutagenesis, chromosomal instability (CIN) and tumorigenesis. We have characterized the consequences of HDR deficiency on anaphase, using markers for incomplete chromosome separation: DAPI-bridges and Ultra-fine bridges (UFBs). We show that multiple HDR factors (Rad51, Brca2 and Brca1) are critical for complete chromosome separation during anaphase, while another chromosome break repair pathway, non-homologous end joining, does not affect chromosome segregation. We then examined the consequences of mild versus severe HDR disruption, using two different dominant-negative alleles of the strand exchange factor, Rad51. We show that mild HDR disruption is viable, but causes incomplete chromosome separation, as detected by DAPI-bridges and UFBs, while severe HDR disruption additionally results in multipolar anaphases and loss of clonogenic survival. We suggest that mild HDR disruption favors the proliferation of cells that are prone to CIN due to defective chromosome separation during anaphase, whereas, severe HDR deficiency leads to multipolar divisions that are prohibitive for cell proliferation.
authors: Department of Cancer Biology, Beckman Research Institute of the City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA.
authors: Corentin
authors: C
authors: Laulier
authors: Anita
authors: A
authors: Cheng
authors: Jeremy M
authors: JM
authors: Stark
mesh_terms: D000705:Anaphase / Q000235:genetics*; D000818:Animals; D002460:Cell Line; D020090:Chromosome Segregation; D004265:DNA Helicases / Q000032:analysis; D004260:DNA Repair; D051379:Mice; D008957:Models, Genetic; D009154:Mutation; D051135:Rad51 Recombinase / Q000235:genetics
chemical_list: D051135:Rad51 Recombinase; D004265:DNA Helicases