Cadmium affects the redox state of rat liver glucocorticoid receptor

It has previously been documented that cadmium displays high affinity for protein thiol groups and induces an impairment of glucocorticoid receptor (GR) cellular functions. The present study examined the possibility that cadmium exerts these effects on GR activity by disturbing the receptor's redox equillibrium. To that end, the influence of cadmium on the rat liver GR potential to form intramolecular and intermolecular disulfide bonds under nonreducing conditions and under oxidizing conditions produced by the addition of hydrogen peroxide (H2O2) to the cytosol was examined by nonreducing SDS-PAGE and immunoblotting. The results show that cadmium inhibits formation of disulfide bonds within the GR both in the absence and in the presence of H2O2. The creation of intermolecular disulfide linkages between the apo-GR and associated heat shock proteins Hsp90 and Hsp70, which was evident in the presence of H2O2, was also significantly impaired after cadmium administration. These observations are consistent with the assumption that cadmium affects the redox state of the receptor, possibly by binding to its sulfhydryl groups.