title: Iduna is a poly(ADP-ribose) (PAR)-dependent E3 ubiquitin ligase that regulates DNA damage.
abstract: Ubiquitin mediated protein degradation is crucial for regulation of cell signaling and protein quality control. Poly(ADP-ribose) (PAR) is a cell-signaling molecule that mediates changes in protein function through binding at PAR binding sites. Here we characterize the PAR binding protein, Iduna, and show that it is a PAR-dependent ubiquitin E3 ligase. Iduna's E3 ligase activity requires PAR binding because point mutations at Y156A and R157A eliminate Iduna's PAR binding and Iduna's E3 ligase activity. Iduna's E3 ligase activity also requires an intact really interesting new gene (RING) domain because Iduna possessing point mutations at either H54A or C60A is devoid of ubiquitination activity. Tandem affinity purification reveals that Iduna binds to a number of proteins that are either PARsylated or bind PAR including PAR polymerase-1, 2 (PARP1, 2), nucleolin, DNA ligase III, KU70, KU86, XRCC1, and histones. PAR binding to Iduna activates its E3 ligase function, and PAR binding is required for Iduna ubiquitination of PARP1, XRCC1, DNA ligase III, and KU70. Iduna's PAR-dependent ubiquitination of PARP1 targets it for proteasomal degradation. Via PAR binding and ubiquitin E3 ligase activity, Iduna protects against cell death induced by the DNA damaging agent N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and rescues cells from G1 arrest and promotes cell survival after γ-irradiation. Moreover, Iduna facilitates DNA repair by reducing apurinic/apyrimidinic (AP) sites after MNNG exposure and facilitates DNA repair following γ-irradiation as assessed by the comet assay. These results define Iduna as a PAR-dependent E3 ligase that regulates cell survival and DNA repair.
authors.affiliation: Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, and Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Ho Chul
authors.initials: HC
authors.lastname: Kang
authors.forename: Yun-Il
authors.initials: YI
authors.lastname: Lee
authors.forename: Joo-Ho
authors.initials: JH
authors.lastname: Shin
authors.forename: Shaida A
authors.initials: SA
authors.lastname: Andrabi
authors.forename: Zhikai
authors.initials: Z
authors.lastname: Chi
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gagné
authors.forename: Yunjong
authors.initials: Y
authors.lastname: Lee
authors.forename: Han Seok
authors.initials: HS
authors.lastname: Ko
authors.forename: Byoung Dae
authors.initials: BD
authors.lastname: Lee
authors.forename: Guy G
authors.initials: GG
authors.lastname: Poirier
authors.forename: Valina L
authors.initials: VL
authors.lastname: Dawson
authors.forename: Ted M
authors.initials: TM
authors.lastname: Dawson
mesh_terms: D045744:Cell Line, Tumor; D019610:Cytoprotection; D004249:DNA Damage; D006801:Humans; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D025801:Ubiquitin; D011064:Poly Adenosine Diphosphate Ribose; C561932:RNF146 protein, human; D044767:Ubiquitin-Protein Ligases; D011065:Poly(ADP-ribose) Polymerases; D046988:Proteasome Endopeptidase Complex