LeBlanc A C, Goodyer C G
Department of Neurology and Neurosurgery, McGill University, and Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Mortimer B. Davis Jewish General Hospital, Montréal, Québec, Canada.
J Neurochem. 1999 May;72(5):1832-42. doi: 10.1046/j.1471-4159.1999.0721832.x.
A wide interest in amyloid precursor protein (APP) metabolism stems from the fact that increased amounts of amyloid beta peptide (Abeta), arising through proteolytic processing of APP, likely play a significant role in Alzheimer's disease. As Alzheimer's disease pathology is limited almost exclusively to the human species, we established human primary neuron cultures to address the possibility of distinctive APP processing in human CNS neurons. In the present study, we investigate the role of organelles and protein trafficking in APP metabolism. Using brefeldin A, we failed to detect APP processing into Abeta in the endoplasmic reticulum. Monensin and the lysomotropic agents, NH4Cl and chloroquine, revealed a bypass pH-dependent secretory pathway in a compartment between the endoplasmic reticulum and the medial Golgi, resulting in the secretion of full-length APP. Colchicine treatment resulting in the loss of neurites inhibited processing of APP through the secretory, but not the endosomal-lysosomal, pathway of APP metabolism. The serine protease inhibitor, leupeptin, indicates a role for lysosomes in APP, Abeta, and APP C-terminal fragment turnover. These results demonstrate that the regulation of APP metabolism in human neurons differs considerably from those reported in rodent CNS primary neuron cultures or continuously dividing cell types.
对淀粉样前体蛋白（APP）代谢的广泛关注源于这样一个事实：通过APP的蛋白水解加工产生的β淀粉样肽（Aβ）量的增加可能在阿尔茨海默病中起重要作用。由于阿尔茨海默病的病理几乎仅局限于人类，我们建立了人类原代神经元培养物，以探讨人类中枢神经系统（CNS）神经元中APP独特加工的可能性。在本研究中，我们研究了细胞器和蛋白质转运在APP代谢中的作用。使用布雷菲德菌素A，我们未能在内质网中检测到APP加工成Aβ。莫能菌素以及溶酶体促渗剂氯化铵和氯喹揭示了在内质网和高尔基体中间隔室中的一条不依赖pH的旁路分泌途径，导致全长APP的分泌。秋水仙碱处理导致神经突丧失，抑制了通过APP代谢的分泌途径而非内体-溶酶体途径对APP的加工。丝氨酸蛋白酶抑制剂亮抑酶肽表明溶酶体在APP、Aβ和APP C末端片段周转中起作用。这些结果表明，人类神经元中APP代谢的调节与啮齿动物CNS原代神经元培养物或连续分裂细胞类型中报道的调节有很大不同。
