Caspase-mediated cleavage and DNase activity of the translation initiation factor 3, subunit G (eIF3g)

Abstract

Eukaryotic translation initiation factor 3 is composed of 13 subunits (eIF3a through eIF3m) and plays an essential role in translation. During apoptosis, several caspases rapidly down-regulate protein synthesis by cleaving eIF4G, -4B, -3j, and -2 alpha. In this study, we found that the activation of caspases by cisplatin in T24 cells induces the cleavage of subunit G of the eIF3 complex (eIF3g). The cleavage site (SLRD(220)G) was identified, and we found that the cleaved N-terminus was translocated to the nucleus, activating caspase-3, and that it also showed a strong DNase activity. These data demonstrate the important roles of eIF3g in the translation initiation machinery and in DNA degradation during apoptosis. (C) 2013 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.