Failure of the interaction between presenilin 1 and the substrate of γ‐secretase to produce Aβ in insect cells
Failure of the interaction between presenilin 1 and the substrate of γ‐secretase to produce Aβ in insect cells
复制标题
早老素 1 与 γ-分泌酶底物之间的相互作用未能在昆虫细胞中产生 Aβ
作者：
D. Pitsi;P. Kienlen;J. Octave
β-淀粉样肽（Aβ）聚集体是阿尔茨海默病（AD）中观察到的老年斑淀粉样蛋白核心的主要成分。Aβ是通过β-和γ-分泌酶活性对其前体淀粉样前体蛋白（APP）进行淀粉样加工而产生的。虽然β-分泌酶最近被鉴定并命名为BACE，但γ-分泌酶的身份仍不清楚。对基因敲除小鼠的研究表明，早老素1（PS1）的突变是遗传性AD的首要原因，对γ分泌酶活性是必需的。然而，PS1的蛋白水解活性仍然是一个有争议的问题。在这里，我们使用转染的Sf 9昆虫细胞，一种缺乏内源性β-和/或γ-分泌酶活性的细胞模型，来表征BACE和PS1在人APP淀粉样蛋白形成过程中的作用。我们发现，在Sf 9细胞中，BACE执行预期的APP β-分泌酶切割，产生C99。我们还表明，C99是γ分泌酶的底物，与人PS1紧密结合。尽管存在这种相互作用，Sf 9细胞仍然不产生Aβ。这强烈反对PS1在APP加工中的直接蛋白水解活性，并指出PS1在将其底物运输/呈递给γ分泌酶中的暗示。
Aggregates of β‐amyloid peptide (Aβ) are the major component of the amyloid core of the senile plaques observed in Alzheimer's disease (AD). Aβ results from the amyloidogenic processing of its precursor, the amyloid precursor protein (APP), by β‐ and γ‐secretase activities. If β‐secretase has recently been identified and termed BACE, the identity of γ‐secretase is still obscure. Studies with knock‐out mice showed that presenilin 1 (PS1), of which mutations are known to be the first cause of inherited AD, is mandatory for the γ‐secretase activity. However, the proteolytic activity of PS1 remains a matter of debate. Here we used transfected Sf9 insect cells, a cellular model lacking endogenous β‐ and/or γ‐secretase activities, to characterize the role of BACE and PS1 in the amyloidogenic processing of human APP. We show that, in Sf9 cells, BACE performs the expected β‐secretase cleavage of APP, generating C99. We also show that C99, which is a substrate of γ‐secretase, tightly binds to the human PS1. Despite this interaction, Sf9 cells still do not produce Aβ. This strongly argues against a direct proteolytic activity of PS1 in APP processing, and points toward an implication of PS1 in trafficking/presenting its substrate to the γ‐secretase.
影响因子：
4.8
作者：
Murphy, MP;Uljon, SN;Golde, TE
通讯作者：
Golde, TE