title: A critical role for the ubiquitin-conjugating enzyme Ubc13 in initiating homologous recombination.
abstract: The ubiquitin (Ub)-conjugating enzyme Ubc13 is implicated in Rad6/Rad18-dependent postreplication repair (PRR) in budding yeast, but its function in vertebrates is not known. We show here that disruption or siRNA depletion of UBC13 in chicken DT40 or human cells confers severe growth defects due to chromosome instability, and hypersensitivity to both UV and ionizing radiation, consistent with a conserved role for Ubc13 in PRR. Remarkably, Ubc13-deficient cells are also compromised for DNA double-strand break (DSB) repair by homologous recombination (HR). Recruitment and activation of the E3 Ub ligase function of BRCA1 and the subsequent formation of the Rad51 nucleoprotein filament at DSBs are abolished in Ubc13-deficient cells. Furthermore, generation of ssDNA/RPA complexes at DSBs is severely attenuated in the absence of Ubc13. These data reveal a critical and unexpected role for vertebrate Ubc13 in the initiation of HR at the level of DSB processing.
authors.affiliation: CREST Laboratory, Department of Radiation Genetics, Kyoto University Graduate School of Medicine, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Guang Yu
authors.initials: GY
authors.lastname: Zhao
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Sonoda
authors.forename: Louise J
authors.initials: LJ
authors.lastname: Barber
authors.forename: Hayato
authors.initials: H
authors.lastname: Oka
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Murakawa
authors.forename: Kouichi
authors.initials: K
authors.lastname: Yamada
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ikura
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Boulton
authors.forename: Shunichi
authors.initials: S
authors.lastname: Takeda
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000528:radiation effects; D002645:Chickens; D002875:Chromosomes / Q000187:drug effects / Q000528:radiation effects; D004247:DNA / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D005091:Exons / Q000235:genetics; D018390:Gene Targeting; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007259:Infrared Rays; D008957:Models, Genetic; D009153:Mutagens / Q000633:toxicity; D051135:Rad51 Recombinase / Q000378:metabolism; D011995:Recombination, Genetic / Q000187:drug effects / Q000528:radiation effects; D051716:Replication Protein A / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes / Q000172:deficiency / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D019313:BRCA1 Protein; D006657:Histones; D009153:Mutagens; D051716:Replication Protein A; D025801:Ubiquitin; D004247:DNA; C471607:UBE2N protein, human; D044763:Ubiquitin-Conjugating Enzymes; D051135:Rad51 Recombinase