DIFFERENTIAL REGULATION OF SUPEROXIDE-DISMUTASE IN COPPER-DEFICIENT RAT ORGANS

The effects of dietary copper deprivation on the activities, immunorea ctive protein concentrations, and mRNA abundance of copper/zinc- and m anganese-superoxide dismutase (Cu/Zn- and Mn-SOD) were examined in liv er, heart, and brain of weanling rats fed a Cu-deficient diet for 4 we eks. Hepatic Cu/Zn-SOD activity, enzyme content, and mRNA abundance we re significantly reduced, and, conversely, the activity, protein, and mRNA levels of Mn-SOD were significantly elevated in Cu-deficient rats . In Cu-deficient heart, the activity and protein content for Cu/Zn-SO D were reduced, whereas those for Mn-SOD were increased; the levels of mRNAs for these two enzymes was unaffected. Dietary Cu deficiency was without effect on the activities, enzyme contents, and mRNA abundance of brain Cu/Zn- and Mn-SOD. These results indicate that SODs from liv er, heart, and brain exhibit differential sensitivities to dietary Cu deprivation, and that different mechanisms (transcriptional, posttrans criptional, or posttranslational) may be involved in their regulation.