title: Superoxide-mediated cytotoxicity in superoxide dismutase-deficient fetal fibroblasts.
abstract: To investigate the roles of CuZn superoxide dismutase (CuZnSOD) and Mn superoxide dismutase (MnSOD) in oxygen radical-mediated cytotoxicity and to distinguish the actions of these two enzymes, fetal fibroblasts were derived from mouse fetuses that are either deficient in CuZnSOD (Sod1-/+ and -/-) or MnSOD (Sod2-1+ and -/-) for in vitro studies. Whereas the phenotype of the Sod1 mutant animals did not differ from that of their normal littermates, the growth of Sod1-/- fetal fibroblasts was only 25% of that of the -/+ and +/+ cells. On the other hand, although almost all homozygous Sod2 mutant animals (-/-) died within 10 days after birth, cultivation of Sod2-/- fetal fibroblasts was possible and their growth was about 60% that of -/+ and +/+ cells. When cultured cells were subjected to treatment with paraquat to assess their ability to grow in the presence of high levels of superoxide radicals, Sod1-/- cells were 80 times more sensitive and Sod2-/- cells were 12 times more sensitive to paraquat than wild-type cells. In addition, whereas the loss of 50% CuZnSOD rendered Sod1-/+ cells almost twice more sensitive to paraquat than +/+ cells, loss of 50% MnSOD had no effect on paraquat sensitivity. Our results suggest that CuZnSOD-deficient cells are more sensitive to oxygen toxicity than are MnSOD-deficient cells, that paraquat causes free radical-induced damage in both the mitochondria and cytoplasm, and that SOD compartmentalized in the cytosol cannot compensate for the loss of SOD in the mitochondria and vice versa.
authors.affiliation: Department of Pediatrics, University of California at San Francisco, 94143, USA. tthuang@itsa.ucsf.edu
authors.forename: T T
authors.initials: TT
authors.lastname: Huang
authors.forename: M
authors.initials: M
authors.lastname: Yasunami
authors.forename: E J
authors.initials: EJ
authors.lastname: Carlson
authors.forename: A M
authors.initials: AM
authors.lastname: Gillespie
authors.forename: A G
authors.initials: AG
authors.lastname: Reaume
authors.forename: E K
authors.initials: EK
authors.lastname: Hoffman
authors.forename: P H
authors.initials: PH
authors.lastname: Chan
authors.forename: R W
authors.initials: RW
authors.lastname: Scott
authors.forename: C J
authors.initials: CJ
authors.lastname: Epstein
mesh_terms: D000818:Animals; D017209:Apoptosis; D015139:Blotting, Southern; D002374:Catalase / Q000378:metabolism; D002455:Cell Division; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts; D018390:Gene Targeting; D005979:Glutathione Peroxidase / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010269:Paraquat / Q000494:pharmacology*; D017384:Sequence Deletion; D013482:Superoxide Dismutase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013481:Superoxides / Q000633:toxicity*
chemical_list: D013481:Superoxides; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D010269:Paraquat