ANTIOXIDANT ENZYME GENE-TRANSCRIPTION IN COPPER-DEFICIENT RAT-LIVER

Antioxidant enzymes, Cu/Zn- and Mn-superoxide dismutase, catalase, and glutathione peroxidase, constitute an important defense mechanism aga inst cytotoxicity of reactive oxygen species. Copper is essential for the activity of Cu/Zn-superoxide dismutase. Oxidative stress, therefor e, is expected in organs of rats fed copper-deficient diet due to redu ced Cu/Zn-superoxide dismutase activity. Our previous studies have sho wn that the expression of antioxidant enzymes was altered in copper-de ficient rat liver. The present report was undertaken to study further the transcription of these enzymes in liver nuclei of rats made copper -deficient for 4 weeks. While copper deficiency decreased the copper i n liver by about 80%, it did not alter the copper content in liver nuc lei. In spite of a 100% elevation in nuclear iron concentration, Liver nuclei from copper-deficient rats showed normal appearance. The trans criptional rates for Cu/Zn-superoxide dismutase, glutathione peroxidas e, and glyceraldehyde-3-phosphate dehydrogenase were not altered by di etary copper deprivation. In contrast, transcriptional rates for Mn-su peroxide dismutase and beta-actin were increased but that for catalase was reduced in the nuclei isolated from the copper-deficient rat live r. These results suggest that oxidative stress, resulting from copper deficiency, differentially modulates the gene transcription for the an tioxidant enzymes in rat liver.