N-(2-mercaptoethyl)-1,3-propanediamine (WR-1065) protects thymocytes from programmed cell death.

Gamma-irradiation, glucocorticoid hormones, and calcium ionophores stimulate a suicide process in thymocytes, known as apoptosis or programmed cell death, that involves internucleosomal DNA fragmentation by a Ca(2+)- and Mg(2+)-dependent nuclear endonuclease. In this study we report that N-(2-mercaptoethyl)-1,3-propanediamine (WR-1065) blocked DNA fragmentation and cell death in thymocytes exposed to gamma-radiation, dexamethasone, or calcium ionophore A23187. WR-1065 protected the thymocytes from radiation-induced apoptosis when incubated with cells after irradiation but not before and/or during irradiation. WR-1065 inhibited Ca(2+)- and Mg(2+)-dependent DNA fragmentation in isolated thymocyte nuclei. Our results suggest that WR-1065 protects thymocytes from apoptosis by inhibiting Ca(2+)- and Mg(2+)-dependent nuclear endonuclease action.