[Molecular cloning and expression of a dexamethasone (DEX)-induced gene in mouse thymus]

During T cell development, self-reactive immature thymocytes are deleted due to negative selection in the thymus that is mediated by apoptosis. It was reported that apoptosis of immature thymocytes mediated by several stimulators such as anti-CD3 mAb, DEX, and irradiation may require the expression of a new set of genes. Using the technique of differential display, I tried to identify genes responsible for DEX-mediated death of immature thymocytes. I have identified one gene, DIG1 which was recently cloned as a G protein-coupled receptor. After DEX treatment, the expression of DIG1 is greatly induced in BALB/c mouse thymus and T cell hybridoma BD5-8. The tissue-specific expression of DIG1 and the induction of its expression during DEX-mediated cell death of thymocytes suggest that it may have a physiological role in selection of T cells.