EXPRESSION OF MANGANESE SUPEROXIDE-DISMUTASE IN OVINE KIDNEY CORTEX DURING DEVELOPMENT

Manganese superoxide dismutase (MnSOD) is one of the main antioxidant enzymes in mammalian tissue. Previous studies have shown that the acti vity of MnSOD increases in the rat kidney during development. To defin e further the developmental change in MnSOD activity and better unders tand some of the steps involved in the control of MnSOD expression dur ing kidney development, we measured MnSOD messenger RNA and enzyme act ivity in the ovine kidney cortex during fetal life, in the newborn per iod, and in adults. MnSOD mRNA and enzyme activity were detected at 0. 65 gestation. Hybridization of the Northern blot with a human MnSOD cD NA probe showed evidence of two transcripts of 4.0 and 1.5 kb, respect ively. There was a significant increase with age of MnSOD activity and MnSOD mRNA (p < 0.0001). The abundance of each MnSOD transcript signi ficantly increased with age (p < 0.001). In the fetuses, both transcri pts increase in parallel; in newborns and adults the 1.5-kb increase w as significantly greater than the 4.0-kb increase. Enzyme activity and mRNA were strongly correlated (r = 0.89, p < 0.0001). These data indi cate that the expression of MnSOD is developmentally regulated in the ovine kidney cortex. This increase seems to be dependent largely on pr etranslational events.