Post-transcriptional elevation of mouse brain Mn-SOD protein by mercuric chloride.
Alterations in gene expression, protein content and enzyme activity of brain Mn-SOD following mercuric chloride (HgCl2) exposure were examined in ICR male mice. Subcutaneous administration of HgCl2 (1 mg Hg/kg) resulted in a significant increase (4-fold) in the brain Mn-SOD content at 6 h after injection while the total mercury concentration was about 0.11 microg/g of brain. The enhancement of Mn-SOD protein caused by HgCl2 was completely abolished by pretreatment with dexamethasone (3 mg/kg) 1 h prior to HgCl2 administration, suggesting involvement of inflammation in inorganic mercury-induced increase in the antioxidant enzyme. This increase in level of Mn-SOD content coincided with a substantial rise in the enzyme activity; however, Northern blot analysis revealed that the induction of protein level was not due to that of its gene expression. The results of the present study indicate that mouse brain Mn-SOD appears to undergo post-translational modification by the environmental toxic metal, and induction of the antioxidant enzyme could be of an initial response to the metal-induced oxidative stress.
Kumagai
Y
Y
Department of Environmental Medicine, Institute of Community Medicine, University of Tsukuba, Ibaraki, Japan. yk-em-tu@igaku.md.tsukuba.ac.jp
Mizukado
S
S
Nagafune
J
J
Shinyashiki
M
M
Homma-Takeda
S
S
Shimojo
N
N
D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000187:drug effects* / Q000201:enzymology*; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology; D008297:Male; D008627:Mercuric Chloride / Q000494:pharmacology*; D008628:Mercury / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009994:Osmolar Concentration; D011499:Protein Processing, Post-Translational; D013482:Superoxide Dismutase / Q000378:metabolism*
D005938:Glucocorticoids; D008627:Mercuric Chloride; D003907:Dexamethasone; D013482:Superoxide Dismutase; D008628:Mercury