[A physico-chemical analysis of glucocorticoid receptors in corticosensitive and corticoresistant thymocytes:...

We have demonstrated in prior work that the density of cytoplasm receptors was comparable in DEXA-resistant and DEXA-sensible thymocyte populations (1). The present study was aimed at examining whether the resistance of thymocytes to the lytic action of glucocorticoids was linked or not to variation in the physico-chemical properties of the receptor itself. Our results show that the cytoplasmic receptors of DEXA-resistant thymocytes were, in terms of specificity, stability and elution profile on DEAE Sephacel columns, similar to those of DEXA-sensible cells. However, under condition of identical concentrations of DNA and receptors, we revealed a decrease in the nuclear transfer of glucocorticoid receptor in the DEXA-resistant thymocytes. This deficiency may account in part for the glucocorticoid resistance of these cells which may be related to intrathymic cell differentiation phenomenon.