The Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia.
Traffic. 2024 Mar;25(3):e12932. doi: 10.1111/tra.12932.
Alzheimer's disease is associated with increased levels of amyloid beta (Aβ) generated by sequential intracellular cleavage of amyloid precursor protein (APP) by membrane-bound secretases. However, the spatial and temporal APP cleavage events along the trafficking pathways are poorly defined. Here, we use the Retention Using Selective Hooks (RUSH) to compare in real time the anterograde trafficking and temporal cleavage events of wild-type APP (APPwt) with the pathogenic Swedish APP (APPswe) and the disease-protective Icelandic APP (APPice). The analyses revealed differences in the trafficking profiles and processing between APPwt and the APP familial mutations. While APPwt was predominantly processed by the β-secretase, BACE1, following Golgi transport to the early endosomes, the transit of APPswe through the Golgi was prolonged and associated with enhanced amyloidogenic APP processing and Aβ secretion. A 20°C block in cargo exit from the Golgi confirmed β- and γ-secretase processing of APPswe in the Golgi. Inhibition of the β-secretase, BACE1, restored APPswe anterograde trafficking profile to that of APPwt. APPice was transported rapidly through the Golgi to the early endosomes with low levels of Aβ production. This study has revealed different intracellular locations for the preferential cleavage of APPwt and APPswe and Aβ production, and the Golgi as the major processing site for APPswe, findings relevant to understand the molecular basis of Alzheimer's disease.
阿尔茨海默病与淀粉样蛋白 β（Aβ）水平升高有关，该蛋白由膜结合的分泌酶对淀粉样前体蛋白（APP）进行连续的细胞内切割产生。然而，沿着运输途径的 APP 切割事件的空间和时间仍未得到明确界定。在这里，我们使用保留使用选择性钩（RUSH）实时比较野生型 APP（APPwt）与致病性瑞典 APP（APPswe）和疾病保护型冰岛 APP（APPice）的顺行运输和时空切割事件。分析显示 APPwt 和 APP 家族突变之间的运输谱和加工存在差异。虽然 APPwt 主要通过β-分泌酶，BACE1，在高尔基体运输到早期内体后进行加工，但 APPswe 的通过高尔基体的运输延长，并与增强的淀粉样 APP 加工和 Aβ分泌相关。在 20°C 时货物从高尔基体中退出的阻断证实了 APPswe 在高尔基体中的β-和γ-分泌酶加工。β-分泌酶，BACE1 的抑制作用将 APPswe 的顺行运输谱恢复为 APPwt 的运输谱。APPice 快速通过高尔基体运输到早期内体，产生的 Aβ 水平较低。这项研究揭示了 APPwt 和 APPswe 和 Aβ产生的优先切割的不同细胞内位置，以及高尔基体是 APPswe 的主要加工部位，这些发现有助于理解阿尔茨海默病的分子基础。
