title: The thiol proteinase inhibitor E-64-d ameliorates amyloid-β-induced reduction of sAPPα secretion by reversing ceramide-induced protein kinase C down-regulation in SH-SY5Y neuroblastoma cells.
abstract: In Alzheimer's disease (AD), enhancing α-secretase processing of amyloid precursor protein (APP) is an important pathway to decrease neurotoxic amyloid β (Aβ) secretion. The α-secretase is reported to be regulated by protein kinase C (PKC) and various endogenous proteins or cell surface receptors. In this report, we first examined whether Aβ reduces α-secretase activity, and showed that Aβ peptide 1-40 (0.001 and 0.01 μM) reduced the secretion of soluble amyloid precursor protein α (sAPPα) in carbachol-stimulated SH-SY5Y neuroblastoma cells. E-64-d (3 μM), which is a potent calpain inhibitor that prevents PKC degradation, ameliorated the Aβ-induced reduction of sAPPα secretion. In addition, we observed that Aβ significantly enhanced ceramide production by activating neutral sphingomyelinase. The cell-permeable ceramide analog, C2-ceramide (1 μg/mL), also reduced sAPPα secretion, and in addition, E-64-d eliminated the observed decrease of sAPPα secretion. C2-ceramide induced down-regulation of PKC-α, -β1, and -β2 isozymes in SH-SY5Y cells. These findings suggest that ceramide may play an important role in sAPPα processing by modulating PKC activity.
authors.affiliation: Department of Human Science, Interdisciplinary Graduate School of Medicine and Engineering, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan. Electronic address: ftanabe@yamanashi.ac.jp.
authors.forename: Fuminori
authors.initials: F
authors.lastname: Tanabe
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakajima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ito
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability / Q000187:drug effects; D002518:Ceramides / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009447:Neuroblastoma / Q000201:enzymology* / Q000473:pathology; D010446:Peptide Fragments / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D013107:Sphingolipids / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism
chemical_list: C545487:APP protein, human; D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D002518:Ceramides; D007527:Isoenzymes; D010446:Peptide Fragments; D011480:Protease Inhibitors; D013107:Sphingolipids; D011493:Protein Kinase C; D013108:Sphingomyelin Phosphodiesterase; D007930:Leucine; C024974:E 64
keywords: Alzheimer’s disease; Amyloid precursor protein; Calpain; Ceramide; Protein kinase C