MODULATION OF STRESS PROTEINS BY CD2-CELL LINE( IN A HUMAN T)

We previously showed in a human T cell line (CEM-C12 cells) that Cd2induced gene expression of stress proteins, metallothionein-IIA and he at shock protein 70 in a time- and dose-dependent manner. In the prese nt study, CEM-C12 cells were pretreated for 24 h with 1 mu M Cd2+ and then challenged with toxic concentrations of this metal. We found that maximal expression of the metallothionein-IIA and heat shock protein 70 genes was increased and this maximal level occurred at higher Cd2toxic concentrations. Actinomycin D chase experiments indicated that C d2+ pretreatment did not modify metallothionein-IIA mRNA stability. Th e modulatory effect of Cd2+ pretreatment was dose-dependent from 100 p M to 1 mu M Such pretreatment also enhanced resistance to Cd2+ toxicit y. Finally, verapamil, a calcium/potassium channel blocker displaced t he dose-response curve for Cd2+ toxicity as well as metallothionein-II A and heat shock protein 70 gene expression to higher Cd2+ concentrati ons.