Stimulation of protein synthesis in cytochalasin B-enucleate human fibroblasts by dexamethasone and insulin

Enucleation of human diploid fibroblasts with cytochalasin B (CB) was used to study the relative roles of cytoplasm and nucleus in cellular responses to dexamethasone and insulin. Cultures which contained a large fraction of enucleate cells responded to both of these hormones by an increase in protein synthesis similar to that observed in controls. Quantitative autoradiography indicated that individual enucleated cells displayed significantly increased protein synthesis in response to both insulin and dexamethasone, but not to estradiol. The results suggest that specific steroids may exert effects upon cell cytoplasm independent of nuclear involvement. It is suggested that the observed enhancement of protein synthesis by dexamethasone may be due to stimulation of membrane transport processes.