Peng Y, Lee D Y W, Jiang L, Ma Z, Schachter S C, Lemere C A
Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Harvard New Research Building, Room 636F, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
Neuroscience. 2007 Dec 5;150(2):386-95. doi: 10.1016/j.neuroscience.2007.09.022. Epub 2007 Sep 14.
Alpha-secretase (alpha-secretase), cleaves the amyloid precursor protein (APP) within the amyloid-beta (Abeta) sequence, resulting in the release of a secreted fragment of APP (alphaAPPs) and precluding Abeta generation. We investigated the effects of the acetylcholinesterase inhibitor, huperzine A (Hup A), on APP processing and Abeta generation in human neuroblastoma SK-N-SH cells overexpressing wild-type human APP695. Hup A dose-dependently (0-10 microM) increased alphaAPPs release. Therefore, we evaluated two alpha-secretase candidates, a disintegrin and metalloprotease (ADAM) 10 and ADAM17 in Hup A-induced non-amyloidogenic APP metabolism. Hup A enhanced the level of ADAM10, and the inhibitor of tumor necrosis factor-alpha converting enzyme (TACE)/ADAM17 inhibited the Hup A-induced rise in alphaAPPs levels, further suggesting Hup A directed APP metabolism toward the non-amyloidogenic alpha-secretase pathway. Hup A had no effect on Abeta generation in this cell line. The steady-state levels of full-length APP and cell viability were unaffected by Hup A. Alpha-APPs release induced by Hup A treatment was significantly reduced by muscarinic acetylcholine receptor antagonists (particularly by an M1 antagonist), protein kinase C (PKC) inhibitors, GF109203X and calphostin C, and the mitogen-activated kinase kinase (MEK) inhibitors, U0126 and PD98059. Furthermore, Hup A markedly increased the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase, which was blocked by treatment with U0126 and PD98059. In addition, Hup A inhibited acetylcholinesterase activity by 20% in neuroblastoma cells. Our results indicate that the activation of muscarinic acetylcholine receptors, PKC and MAP kinase may be involved in Hup A-induced alphaAPPs secretion in neuroblastoma cells and suggest multiple pharmacological mechanisms of Hup A regarding the treatment of Alzheimer's disease (AD).
α-分泌酶可在β-淀粉样蛋白（Aβ）序列内切割淀粉样前体蛋白（APP），从而释放出APP的分泌片段（αAPPs），并阻止Aβ的产生。我们研究了乙酰胆碱酯酶抑制剂石杉碱甲（Hup A）对过表达野生型人APP695的人神经母细胞瘤SK-N-SH细胞中APP加工和Aβ产生的影响。Hup A呈剂量依赖性（0 - 10μM）增加αAPPs的释放。因此，我们评估了两种α-分泌酶候选物，即解整合素和金属蛋白酶（ADAM）10和ADAM17在Hup A诱导的非淀粉样生成性APP代谢中的作用。Hup A提高了ADAM10的水平，而肿瘤坏死因子-α转化酶（TACE）/ADAM17抑制剂抑制了Hup A诱导的αAPPs水平升高，进一步表明Hup A将APP代谢导向非淀粉样生成性α-分泌酶途径。Hup A对该细胞系中的Aβ产生没有影响。全长APP的稳态水平和细胞活力不受Hup A的影响。毒蕈碱型乙酰胆碱受体拮抗剂（特别是M1拮抗剂）、蛋白激酶C（PKC）抑制剂GF109203X和钙泊三醇C以及丝裂原活化蛋白激酶激酶（MEK）抑制剂U0126和PD98059显著降低了Hup A处理诱导的α-APPs释放。此外，Hup A显著增加了p44/p42丝裂原活化蛋白（MAP）激酶的磷酸化，而U0126和PD98059处理可阻断这种磷酸化。此外，Hup A在神经母细胞瘤细胞中抑制乙酰胆碱酯酶活性达20%。我们的结果表明，毒蕈碱型乙酰胆碱受体、PKC和MAP激酶的激活可能参与了Hup A诱导的神经母细胞瘤细胞中αAPPs的分泌，并提示了Hup A在治疗阿尔茨海默病（AD）方面的多种药理机制。
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