Relationship between SUMO-1 modification of caspase-7 and its nuclear localization in human neuronal cells

The aim of this study was to elucidate the role of SUMO-1 modification in caspase-7 in neuronal cells. We have previously demonstrated that procaspase-2 could be a possible target for SUMO-1 modification. In the present study, we attempted to investigate whether other caspases also interact with Ubc9/SUMO-1. The specific binding of SUMO-1 with caspase-7 was observed in mammalian cells. Deletion mutant analysis revealed that a SUMO-1 modification site may be located in at least N-terminal p20 subunit of caspase-7. Furthermore, SUMO-1-modified caspase-7 appeared as a dot-like structure in nuclear localization. These findings suggest that SUMO-1 modification in caspase-7 may be linked to specific its localization in the nucleus and may therefore contribute to the cleavage of nuclear substrates during neuronal apoptosis.