Increased catalase activity in mouse cell mutants resistant to paraquat.
Paraquat is widely used as a generator of superoxide radicals in a cell. First it was shown to immediately induce premature senescence in normal human fibroblasts. To assess its defense mechanisms, we characterized three paraquat-resistant mutants from mouse FM3A cells, MPQR40-1 and MPQR40-3 isolated by a single-step selection after mutagenesis, and SPQR100-6 isolated spontaneously. All exhibited six to eight times more resistance to paraquat than the parental line. In cell-cell hybrids, their phenotypes were recessive, co-dominant, or dominant, respectively. Biochemical characterization revealed that activity and mRNA level for catalase were increased in all of the mutants. In MPQR40-3 that showed the highest degree of paraquat resistance, total SOD activity and mRNA level for Cu/Zn-SOD were also increased. These results suggest that catalase plays a major role in paraquat resistance in mouse FM3A cells.
Joguchi
Atsuhiro
A
Graduate School of Integrated Science, Yokohama City University, Maioka-cho 641-12, Totsuka-ku, 244-0813, Japan.
Fujii
Michihiko
M
Ayusawa
Dai
D
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D007305:Insecticide Resistance; D051379:Mice; D016296:Mutagenesis; D010269:Paraquat; D013482:Superoxide Dismutase / Q000378:metabolism
D017931:DNA Primers; D002374:Catalase; D013482:Superoxide Dismutase; D010269:Paraquat