title: Targeted Inactivation of DNA Photolyase Genes in Medaka Fish (Oryzias latipes).
abstract: Proteins of the cryptochrome/photolyase family (CPF) exhibit sequence and structural conservation, but their functions are divergent. Photolyase is a DNA repair enzyme that catalyzes the light-dependent repair of ultraviolet (UV)-induced photoproducts, whereas cryptochrome acts as a photoreceptor or circadian clock protein. Two types of DNA photolyase exist: CPD photolyase, which repairs cyclobutane pyrimidine dimers (CPDs), and 6-4 photolyase, which repairs 6-4 pyrimidine-pyrimidone photoproducts (6-4PPs). Although the Cry-DASH protein is classified as a cryptochrome, it also has light-dependent DNA repair activity. To determine the significance of the three light-dependent repair enzymes in recovering from solar UV-induced DNA damage at the organismal level, we generated mutants in each gene in medaka using the CRISPR genome editing technique. The light-dependent repair activity of the mutants was examined in vitro in cultured cells and in vivo in skin tissue. Light-dependent repair of CPD was lost in the CPD photolyase-deficient mutant, whereas weak repair activity against 6-4PPs persisted in the 6-4 photolyase-deficient mutant. These results suggest the existence of a heretofore unknown 6-4PP repair pathway and thus improve our understanding of the mechanisms of defense against solar UV in vertebrates.
authors.affiliation: Radiation Biology and Medical Genetics, Department of Genome Biology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishikawa-Fujiwara
authors.affiliation: Radiation Biology and Medical Genetics, Department of Genome Biology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Shiraishi
authors.affiliation: Radiation Biology and Medical Genetics, Department of Genome Biology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujikawa
authors.affiliation: Radioisotope Research Center, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Mori
authors.affiliation: Department of Pathology, Hyogo College of Medicine, Nishinomiya, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Tsujimura
authors.affiliation: Radiation Biology and Medical Genetics, Department of Genome Biology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Todo
mesh_terms: D000818:Animals; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D056931:Cryptochromes / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000235:genetics*; D009154:Mutation; D009990:Oryzias / Q000235:genetics*; D011740:Pyrimidine Dimers / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D056931:Cryptochromes; D011740:Pyrimidine Dimers; C058406:pyrimidine-pyrimidone dimer; D004255:Deoxyribodipyrimidine Photo-Lyase