PHYSICOCHEMICAL ANALYSIS OF GLUCOCORTICOI D RECEPTOR IN CORTICOSENSITIVE AND CORTICORESISTANT THYMOCYTES - DECREASE IN NUCLEAR TRANSFER

We have demonstrated in prior work that the density of cytoplasm recep tors was comparable in DEXA-resistant and DEXA-sensible thymocyte popu lations (1). The present study was aimed at examining whether the resi stance of thymocytes to the lytic action of glucocorticoids was linked or not to variation in the physico-chemical properties of the recepto r itself. Our results show that the cytoplasmic receptors of DEXA-resi stant thymocytes were, in terms of specificity, stability and elution profile on DEAE Sephacel columns, similar to those of DEXA-sensible ce lls. However, under condition of identical concentration of DNA and re ceptors, we revealed a decrease in the nuclear transfer of glucocortic oid receptor in the DEXA-resistant thymocytes. This deficiency may acc ount in part for the glucocorticoid resistance of these cells which ma y be related to intrathymic cell differentiation phenomenon.