TEMPORARY LOSS OF GLUCOCORTICOID RECEPTOR-MEDIATED REGULATION OF GENE-EXPRESSION IN HEAT-SHOCKED CELLS

The effect of heat shock on the transcriptional activity of glucocorti coid receptor was assessed using HeLa cells stably transfected with th e chloramphenicol acetyltransferase (CAT) gene the transcription of wh ich is controlled by two glucocorticoid-responsive elements placed dir ectly upstream of a core promoter. Heat shock inactivated the high-aff inity glucocorticoid binding capacity of the cells and nullified the r ate of accumulation of CAT mRNA in the presence of hormone. Hormonal r esponsiveness was restored on return to normal temperature concomitant ly with recovery of high-affinity glucocorticoid binding capacity. Hea t inactivation of the receptor was coincident with loss of its solubil ity and apparently unrelated to receptor degradation.