title: A role for nuclear translocation of tripeptidyl-peptidase II in reactive oxygen species-dependent DNA damage responses.
abstract: Responses to DNA damage are influenced by cellular metabolism through the continuous production of reactive oxygen species (ROS), of which most are by-products of mitochondrial respiration. ROS have a strong influence on signaling pathways during responses to DNA damage, by relatively unclear mechanisms. Previous reports have shown conflicting data on a possible role for tripeptidyl-peptidase II (TPPII), a large cytosolic peptidase, within the DNA damage response. Here we show that TPPII translocated into the nucleus in a p160-ROCK-dependent fashion in response to gamma-irradiation, and that nuclear expression of TPPII was present in most gamma-irradiated transformed cell lines. We used a panel of nine cell lines of diverse tissue origin, including four lymphoma cell lines (T, B and Hodgkins lymphoma), a melanoma, a sarcoma, a colon and two breast carcinomas, where seven out of nine cell lines showed nuclear TPPII expression after gamma-irradiation. Further, this required cellular production of ROS; treatment with either N-acetyl-Cysteine (anti-oxidant) or Rotenone (inhibitor of mitochondrial respiration) inhibited nuclear accumulation of TPPII. The local density of cells was important for nuclear accumulation of TPPII at early time-points following gamma-irradiation (at 1-4h), indicating a bystander effect. Further, we showed that the peptide-based inhibitor Z-Gly-Leu-Ala-OH, but not its analogue Z-Gly-(D)-Leu-Ala-OH, excluded TPPII from the nucleus. This correlated with reduced nuclear expression of p53 as well as caspase-3 and -9 activation in gamma-irradiated lymphoma cells. Our data suggest a role for TPPII in ROS-dependent DNA damage responses, through alteration of its localization from the cytosol into the nucleus.
authors.affiliation: Center for Molecular Medicine (CMM), Department of Medicine, Karolinska Institutet, Karolinska University Hospital, 171 76 Stockholm, Sweden.
authors.forename: Giulio
authors.initials: G
authors.lastname: Preta
authors.forename: Rainier
authors.initials: R
authors.lastname: de Klark
authors.forename: Rickard
authors.initials: R
authors.lastname: Glas
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000528:radiation effects; D000626:Aminopeptidases; D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology*; D004249:DNA Damage; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D005720:Gamma Rays; D006801:Humans; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C048001:tripeptidyl-peptidase 2; D012697:Serine Endopeptidases