Subcellular localization suggests novel functions for prolyl endopeptidase in protein secretion.

摘要: For a long time, prolyl endopeptidase (PEP) was believed to inactivate neuropeptides in the extracellular space. However, reports on intracellular activity of PEP suggest additional, as yet unidentified, physiological functions for this enzyme. Here, we demonstrate using biochemical methods subcellular fractionation, immunocytochemical double-labelling procedures and localization PEP-enhanced green fluorescent protein fusion proteins that is mainly localized perinuclear space, associated with microtubulin cytoskeleton human neuroblastoma glioma cell lines. Disassembly microtubules by nocodazole treatment disrupts both fibrillar tubulin labelling. Furthermore, two-hybrid screen, identified binding partner tubulin. These findings indicate novel axonal transport and/or secretion. Indeed, metabolic labelling approach revealed inhibition antisense mRNA expression result enhanced peptide/protein secretion from U-343 cells. Because disturbances mechanisms are number ageing-associated neurodegenerative diseases, cell-permeable inhibitors may be useful application variety related clinical conditions.