MITOCHONDRIAL RESPIRATORY-CHAIN DEFICIENCY LEADS TO OVEREXPRESSION OFANTIOXIDANT ENZYMES

U937 cell growth in the presence of either chloramphenicol or ethidium bromide rapidly leads to respiratory deficiency, The navel finding of this report is that this response is paralleled by a specific increas e in Se-dependent and independent glutathione peroxidase activities as well as of glutathione peroxidase and heme oxygenase mRNAs. Under the same experimental conditions, catalase activity and catalase mRNA do not show appreciable changes, These results can be explained by an inc reased formation of H2O2 at the early times of development of respirat ory deficiency followed by induction of antioxidant enzymes. (C) 1997 Federation of European Biochemical Societies.