title: Fen-1 facilitates homologous recombination by removing divergent sequences at DNA break ends.
abstract: Homologous recombination (HR) requires nuclease activities at multiple steps, but the contribution of individual nucleases to the processing of double-strand DNA ends at different stages of HR has not been clearly defined. We used chicken DT40 cells to investigate the role of flap endonuclease 1 (Fen-1) in HR. FEN-1-deficient cells exhibited a significant decrease in the efficiency of immunoglobulin gene conversion while being proficient in recombination between sister chromatids, suggesting that Fen-1 may play a role in HR between sequences of considerable divergence. To clarify whether sequence divergence at DNA ends is truly the reason for the observed HR defect in FEN-1(-/-) cells we inserted a unique I-SceI restriction site in the genome and tested various donor and recipient HR substrates. We found that the efficiency of HR-mediated DNA repair was indeed greatly diminished when divergent sequences were present at the DNA break site. We conclude that Fen-1 eliminates heterologous sequences at DNA damage site and facilitates DNA repair by HR.
authors.affiliation: Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hatanaka
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Sonoda
authors.forename: Helfrid
authors.initials: H
authors.lastname: Hochegger
authors.forename: Noritaka
authors.initials: N
authors.lastname: Adachi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Matsuzaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Koyama
authors.forename: Dik C
authors.initials: DC
authors.lastname: van Gent
authors.forename: Maria
authors.initials: M
authors.lastname: Jasin
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002645:Chickens; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004260:DNA Repair; D018076:DNA, Complementary / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000494:pharmacology; D045585:Flap Endonucleases / Q000378:metabolism / Q000502:physiology*; D005434:Flow Cytometry; D005720:Gamma Rays; D007700:Kinetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011995:Recombination, Genetic; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D012854:Sister Chromatid Exchange; D013997:Time Factors; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D045585:Flap Endonucleases; C037725:SCEI protein, S cerevisiae; D015252:Deoxyribonucleases, Type II Site-Specific