Department of Human Science, Interdisciplinary Graduate School of Medicine and Engineering, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
Department of Human Science, Interdisciplinary Graduate School of Medicine and Engineering, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
Biochem Biophys Res Commun. 2014 Apr 18;446(4):933-9. doi: 10.1016/j.bbrc.2014.03.038. Epub 2014 Mar 17.
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.
我们之前报道过，巯基蛋白酶抑制剂 E-64-d 通过逆转神经瘤 SH-SY5Y 细胞中神经酰胺诱导的蛋白激酶 C 下调，改善了淀粉样β（Aβ）诱导的可溶性淀粉样前体蛋白α（sAPPα）分泌减少。在本研究中，我们表明 Aβ（1-42）肽通过激活磷脂酶 D（PLD）增强二酰基甘油（DAG）的产生。随后，我们研究了 PLD 是否参与 Aβ 诱导的 sAPPα 分泌减少，并表明 2 μM 的 CAY10593（选择性抑制 PLD2）可改善 sAPPα 分泌减少，而 50 nM 的 CAY10593（选择性抑制 PLD1）则没有。此外，50 μM 的普萘洛尔（一种磷酸脂酶抑制剂）也改善了 Aβ 诱导的 sAPPα 分泌减少，这表明 DAG 可能是 Aβ 诱导的 sAPPα 分泌减少的原因。我们随后研究了 DAG 是否影响 sAPPα 分泌，并表明 DAG 类似物可减少 SH-SY5Y 细胞中 sAPPα 的分泌。此外，DAG 通过刺激中性鞘磷脂酶（N-SMase）活性增强神经酰胺的产生。我们之前证明 Aβ 可刺激 SH-SY5Y 细胞中的 N-SMase 活性。在这里，我们表明 2 μM 的 CAY10593 通过抑制 PLD2 抑制了 Aβ 诱导的 N-SMase 激活。综上所述，结果表明，通过 PLD 途径产生的 DAG 参与了 Aβ 诱导的 SH-SY5Y 细胞中 sAPPα 分泌减少。
