Studies of the relationship between cell proliferation and cell death. Early gene expression during concanavelin A induced proliferation or dexamethasone-induced apoptosis of rat thymocytes

Several data in the literature suggest that an intriguing relationship exists between cell proliferation and cell death. Accordingly, we studied the early expression of different genes in the same cells, i.e. rat thymocytes, undergoing cell proliferation upon stimulation with Concanavalin A or cell death following dexamethasone treatment. We showed that an early accumulation of c-fos, c-jun and c-myc mRNA occurred in both phenomena but with different kinetics. It can be speculated that the early induction of nuclear oncogenes is necessary to allow the later induction of other genes probably regulated at the transcriptional level by the AP-1 complex and/or by Myc protein. The accumulation of the transcript for another gene, i.e. poly(ADP-ribose)polymerase, an enzyme responsible for posttranslational modifications of several nuclear proteins, could instead be related to chromatin modifications occurring in both processes.