Superoxide-mediated cytotoxicity in superoxide dismutase-deficient fetal fibroblasts.
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.
Huang
T T
TT
Department of Pediatrics, University of California at San Francisco, 94143, USA. tthuang@itsa.ucsf.edu
Yasunami
M
M
Carlson
E J
EJ
Gillespie
A M
AM
Reaume
A G
AG
Hoffman
E K
EK
Chan
P H
PH
Scott
R W
RW
Epstein
C J
CJ
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*
D013481:Superoxides; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D010269:Paraquat