Proteasome-dependent degradation of oxidized proteins in MRC-5 fibroblasts

Fibroblasts were exposed to various concentrations of hydrogen peroxide and the removal of oxidized proteins was followed by determining protein-bound carbonyls, Fibroblasts are able to increase the turnover of metabolically radiolabeled proteins after treatment with hydrogen peroxide, It was demons trated for the first time, that the increased protein turnover was accompan ied by a removal of protein-bound carbonyl groups. The proteasome-specific inhibitor lactacystin was able to inhibit the elimination of protein-bound carbonyl groups. Therefore, the key role of the proteasome in the degradati on of oxidized proteins in fibroblasts could be demonstrated, (C) 1998 Fede ration of European Biochemical Societies.