LEVELS OF EXPRESSION OF THE GENES FOR GLUTATHIONE-REDUCTASE, GLUTATHIONE-PEROXIDASE, CATALASE AND CUZN-SUPEROXIDE DISMUTASE IN RAT LENS ANDLIVER

Oxidative mechanisms are thought to play a major role in several biolo gical phenomena, including cataract formation. In the following studie s we determined the relative levels of expression of the genes for the mRNAs for glutathione peroxidase (GPx), glutathione reductase (GR), C uZn-superoxide dismutase (CuZn-SOD) and catalase, in both the rat lens and liver. Northern blot hybridization methods were used to determine the mRNA size. The RNase protection method was used to determine leve ls of expression for these mRNAs plus levels of expression for alpha A -crystallin and gamma-crystallin mRNAs in the lens, and gamma-actin mR NAs in both the lens and the liver; using [P-32]-labeled specific cRNA probes transcribed from the various cDNA clones for the mRNAs being s tudied. The data was normalized relative to the level of expression of alpha A-crystallin and gamma-actin mRNAs in the lens, and to gamma-ac tin mRNA in the liver. We find the levels of the mRNAs in the lens fal l in the following descending order: GPx > GR > CuZn-SOD > catalase, i n the same order as has been reported for the activities of the enzyme s in the lens. In the Liver, levels of these mRNAs were as follows: GP x > CuZn-SOD > GR > catalase. In the liver, CuZn-SOD mRNA was expresse d at about four times the level found in the lens, GPx at three times, catalase at three times and GR at about the same level. The ratio of GPx mRNA to CuZn-SOD mRNA in the lens was about 2.0, while in the live r it approached 1.0; the concentration of catalase mRNA in the liver w as about three times that found in the lens.