title: Possible involvement of calpain-like activity in normal processing of cellular prion protein.
abstract: Time-lapse imaging analysis was previously used to show that spontaneous proteolysis of PrP(C), which is fluorescence-labeled at both NH(2)- and COOH-termini, occurred in mouse neuroblastoma neuro2a (N2a) cells susceptible to PrP(Sc). We demonstrated that, unlike other protease inhibitors, a calpain inhibitor, calpastatin, drastically inhibited endoproteolysis of PrP(C), as observed with time-lapse imaging in living cells, suggesting calpain-like activity. Calpastatin also inhibited cleavage of endogenous PrP(C), and unprocessed molecules and the double-labeled PrP(C) accumulated around the perinuclear region. The molecular weight of PrP(C) fragments generated by spontaneous proteolysis was identical to those produced when PrP(C) synthesized in vitro was exposed to exogenous calpain. These results suggest that a calpain-like activity mediates normal processing of PrP(C) in N2a cells.
authors.affiliation: Department of Neurophysiology, Tokyo Medical University, 6-1-1 Shinjuku, Tokyo 160-8402, Japan. naomi@tokyo-med.ac.jp
authors.forename: Naomi
authors.initials: N
authors.lastname: Hachiya
authors.forename: Yuko
authors.initials: Y
authors.lastname: Komata
authors.forename: Sana
authors.initials: S
authors.lastname: Harguem
authors.forename: Kana
authors.initials: K
authors.lastname: Nishijima
authors.forename: Kiyotoshi
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism / Q000494:pharmacology; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009447:Neuroblastoma / Q000201:enzymology / Q000473:pathology; D010447:Peptide Hydrolases / Q000378:metabolism; D018621:PrPC Proteins / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000502:physiology
chemical_list: D002135:Calcium-Binding Proteins; D018621:PrPC Proteins; C033668:calpastatin; D010447:Peptide Hydrolases; D002154:Calpain