Association of the rat liver glucocorticoid receptor with Hsp90 and Hsp70 upon whole body hyperthermic stress

The influence of whole body hyperthermic stress (41 degrees C, 15 min) on a ssociation of the glucocorticoid receptor (GR) with heat shock proteins Hsp 90 and Hsp70 was followed in rat liver cytosol during a 24h period after th e stress. Total cytosolic concentration of the GR, Hsp90 and Hsp70 and the amounts of Hsp90 and Hsp70 co-immunopurified with the GR were determined by a quantitative Western blotting using appropriate monoclonal antibodies. A significant decrease in the cytosolic GR level in response to the stress w as noticed. The ratio of the amount of the GR to Hsp90 recruited by the GR was found to be unaltered by hyperthermia, in spite of the stress-induced i ncrease in the total Hsp90 concentration in the cytosol. Hsp70 was also fou nd in association with the GR and its 2.5-fold induction by the stress was accompanied by about 3-fold increase in its relative amount that co-immunop urified with the GR. The results suggest that heat stress influences the in teraction of the GR with Hsp70 through the mechanisms controlling the untra nsformed rat liver GR heterocomplexes assembly process. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.