title: Stimulation of intrachromosomal homologous recombination in mammalian cells by an inhibitor of poly(ADP-ribosylation).
abstract: We determined the effect of 3-methoxybenzamide (3-MB), a competitive inhibitor of poly(ADP-ribose) polymerase (E.C. 2.4.2.30), on intrachromosomal homologous recombination in mouse Ltk- cells. We used a cell line that contained in its genome two defective Herpes thymidine kinase (tk) genes as closely linked direct repeats. Intrachromosomal homologous recombination events were monitored by selecting for tk-positive segregants that arose during propagation of the cells and recombination rates were determined by fluctuation analysis. We found that growth of cells in the continuous presence of 2mM 3-MB increased intrachromosomal recombination between 3 and 4-fold. Growth of cells in the presence of 2mM m-anisic acid, a non-inhibitory analog of 3-MB, had no effect on intrachromosomal recombination rates. Additionally, we found that 3-MB increased both gene conversions and crossovers to similar extents, adding to the evidence that these two types of intrachromosomal rearrangements share a common pathway. These findings contrast with our previous studies [Waldman, B.C. and Waldman, A.S. (1990) Nucleic Acids Res., 18, 5981-5988] in which we determined that 3-MB inhibits illegitimate recombination and has no effect on extrachromosomal homologous recombination in mouse Ltk- cells. An hypothesis is offered that explains the influence of 3-MB on different recombination pathways in mammalian cells in terms of the role that poly(ADP-ribosylation) plays in DNA break-repair.
authors.affiliation: Walther Oncology Center, Indiana University School of Medicine, Indianapolis 46202-5151.
authors.forename: A S
authors.initials: AS
authors.lastname: Waldman
authors.forename: B C
authors.initials: BC
authors.lastname: Waldman
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology*; D015139:Blotting, Southern; D002460:Cell Line; D002875:Chromosomes / Q000378:metabolism*; D006564:Herpesviridae / Q000201:enzymology / Q000235:genetics; D051379:Mice; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011995:Recombination, Genetic / Q000187:drug effects*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid / Q000187:drug effects; D013937:Thymidine Kinase / Q000235:genetics; D014641:Vanillic Acid / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D001549:Benzamides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C056267:3-methoxybenzoic acid; D013937:Thymidine Kinase; D014641:Vanillic Acid; C025159:3-methoxybenzamide