Rapid induction of thymosin beta sub(4) in concanavalin A-stimulated thymocytes by translational control

The expression of thymosin beta sub(4), an ubiquitous peptide of high cellular content, was studied in concanavalin A-stimulated rat thymocytes within the first 3 h after activation of the cells. An early 6.3-fold increase of the peptide occurred after 1 h of stimulation amounting to 0.4% of the total cellular protein. The data suggest that a translational control mechanism is involved in this rapid induction. Consequently, actinomycin D did not inhibit thymosin beta sub(4) induction in contrast to cycloheximide. The peaks of maximal thymosin beta sub(4) levels and biosynthesis were followed by rapid decreases of these parameters suggesting a function of thymosin beta sub(4) in the early phase of T cell activation. (DBO)