Comprehensive studies on subcellular localizations and cell death inducingactivities of eight GFP-tagged apoptosis-related caspases

By using green fluorescent protein fusion, we investigated the subcellular localization of all the caspases that have been cloned from humans and impl icated in the execution of apoptosis, We divided these caspases into three groups according to subcellular localization. The first group includes casp ase-1, -3, -6, -7, and -9, which are expressed mainly in the cytoplasm with various levels of nuclear localization depending on the cell type. The sec ond group has a single member, caspase-2, which is primarily localized in t he nucleus. The nuclear localization was demonstrated to be mediated by a n uclear localization signal near the NH,terminus of the prodomain, The third group includes caspase-8 and -10, which have a cytoplasmic distribution. T hese two members have potent, rapid cell death-inducing activity and are pr one to make aggregates when overexpressed. Their prodomains formed marked f ibrous structures in the cytoplasm whose localization seemed distinct from organelles or cytoskeletons. None of the GFP-caspases examined in this stud y showed a predominant mitochondrial localization as has been reported for some caspases, (C) 2001 Academic Press.