Expression and Localization of C-APP and N-APP in Peripheral Neurons of Rats and Crayfish After Axotomy

Abstract

Nerve injury induces a cascade of molecular-cellular events, leading to neuronal death or survival, where amyloid precursor protein (APP) and its proteolytic products play an important role. We studied the localization and expression of C-APP and N-APP in rat dorsal root ganglia (DRG) with transected sciatic nerve, axotomized crayfish stretch receptor neuron (SRN) and ventral nerve cord (VNC) ganglia with transected connectives. C-APP and N-APP localized predominantly in neurons, not in glial cells. Axotomy increased C-APP and N-APP expression in rat and crayfish neurons. The expression of APP in crustaceans confirms its conservative nature. In DRG, C-APP level was higher in neuronal nuclei than in cytoplasm in 24 hours post-axotomy. N-APP accumulation was not observed in DRG and crayfish neuronal nuclei. SRN axotomy resulted in C-APP and N-APP accumulation in 4–8 hours in perikaryon and its extensions, but only С-APP accumulated in nuclei. This indicates that not the whole APP, but its C-terminal product, AICD, enters the nucleus. Also, there was high level of C-APP in SRN nucleolus, suggesting possible AICD involvement in rRNA synthesis and ribosome formation. The APP accumulation in transected axons confirms its involvement in injury-induced axonal events.