title: Involvement of diacylglycerol produced by phospholipase D activation in Aβ-induced reduction of sAPPα secretion in SH-SY5Y neuroblastoma cells.
abstract: We previously reported that the thiol proteinase inhibitor, E-64-d, ameliorated amyloid β (Aβ)-induced reduction of soluble amyloid precursor protein α (sAPPα) secretion by reversing ceramide-induced protein kinase C down-regulation in SH-SY5Y neuroblastoma cells. In the present study, we showed that Aβ (1-42) peptide enhanced diacylglycerol (DAG) production by phospholipase D (PLD) activation in these cells. We subsequently examined whether PLD was involved in Aβ-induced reduction of sAPPα secretion and showed that 2 μM CAY10593, which selectively inhibits PLD2, ameliorated reduction of sAPPα secretion, whereas 50 nM CAY10593, which selectively inhibits PLD1, did not. Moreover, 50 µM propranolol, a phosphatidic acid phosphohydrolase inhibitor, also ameliorated Aβ-induced reduction of sAPPα secretion, suggesting that DAG may be responsible for Aβ-induced reduction of sAPPα. We subsequently examined whether DAG affects sAPPα secretion and showed that a DAG analog reduced sAPPα secretion in SH-SY5Y cells. In addition, DAG enhanced ceramide production by stimulating neutral sphingomyelinase (N-SMase) activity. We previously demonstrated that Aβ stimulates N-SMase activity in SH-SY5Y cells. Here, we showed that inhibition of PLD2 by 2 μM CAY10593 suppressed Aβ-induced N-SMase activation. Taken together, the results suggest that DAG produced through the PLD pathway is involved in Aβ-induced reduction of sAPPα secretion in SH-SY5Y cells.
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.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.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Department of Microbiology, Interdisciplinary Graduate School of Medicine and Engineering, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ito
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C011439:1,2-diacylglycerol; C545487:APP protein, human; D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D002518:Ceramides; D004075:Diglycerides; D010446:Peptide Fragments; D010739:Phospholipase D
keywords: Alzheimer disease; Amyloid β; Ceramide; Diacylglycerol; Phospholipase D; Sphingomyelinase