MOLECULAR PATHOLOGICAL STUDIE OF ALZHEIMER'S DISEASE : ROLE OF β-AMYLOID AND PRESENILINS

阿尔茨海默病的分子病理学研究：β-淀粉样蛋白和早老蛋白的作用

• 批准号: 10480214
• 负责人: IWATSUBO Takeshi
• 金额: $ 6.98万
• 依托单位: UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B).
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-10480214/
• 关键词: Alzheimer's disease; presenilin; amyloid β peptide; γ-secretase

Deposition of amyloid β peptides (Aβ) as senile plaques (SP) is an invariant feature of Alzheimer's disease (AD) brains. Aβ is a 40-42 amino acid peptide that is proteolytically produced from βAPP through sequential cleavages by β- and γ-secretases. The role of presenilin (PS) as a catalytic subunit of γ-secretase is recently highlighted. We and others have shown that mutations in PS (i.e., PS1 and PS2) genes linked to familial AD (FAD) increase production and secretion of Aβ42, that initially and predominantly deposits in the brains of patients with all types of AD.In the present study, we showed that modifications at the C terminus of PS abolish stabilization of PS fragments as well as overproduction of Aβ42 on FAD mutant basis, suggesting that stable fragment forms of PS is the pathologically active species. We further searched for PS subdomains that is critical to its stabilization and function, and identified another motif which we designated "PALP". PALP motif is located at the proximal site of the C terminus of PS (corresponding to residues 414-417 based on human PS2) and is highly conserved, and mutations in drosophila PS and spe-4 in C.elegans that replace the 1st Pro of PALP with Leu lead to Notch phenotype caused by loss-of-function of PS, although the mechanism whereby these mutations deteriorate PS function remained unknown. We found that human PS harboring Pro to Leu mutation at the 1st residue of PALP fails to promote Aβ42 overproduction on FAD mutant basis as well as Notch processing through failure in stabilization and high-molecular-weight complex formation of PS, as observed with modifications at PS C terminus. Hence, search for cofactors that serve as stabilizing or regulatory subunit (s) of PS/γ-secretase, as well as understanding of the mechanism of γ-cleavage, should be the next goal in PS research.

淀粉样β肽（Aβ）以老年斑（SP）的形式沉积是阿尔茨海默病（AD）脑内的一个不变特征。Aβ是一种40-42个氨基酸的肽，由βAPP通过β-和γ-分泌酶的连续切割蛋白水解产生。早老素（PS）作为γ-分泌酶的催化亚基的作用最近受到重视。我们和其他人已经表明，PS中的突变（即，与家族性AD（FAD）相关的PS1和PS2基因增加了Aβ42的产生和分泌，Aβ42最初主要沉积在所有类型AD患者的脑中。在本研究中，我们发现PS C末端的修饰消除了PS片段的稳定性以及FAD突变体基础上Aβ42的过度产生，表明PS的稳定片段形式是病理活性物质。我们进一步寻找PS亚结构域，这是至关重要的稳定和功能，并确定了另一个基序，我们指定为“PALP”。PALP基序位于PS的C末端的近端位点（对应于基于人PS2的残基414-417）并且是高度保守的，并且果蝇PS和秀丽隐杆线虫中的spe-4中的用Leu替换PALP的第一Pro的突变导致由PS功能丧失引起的Notch表型，尽管这些突变使PS功能恶化的机制仍然未知。我们发现，在PALP的第一个残基处携带Pro至Leu突变的人PS不能促进基于FAD突变体的Aβ42过量产生，并且通过PS的稳定性和高分子量复合物形成的失败而不能促进Notch加工，如在PS C末端的修饰所观察到的。因此，寻找PS/γ-分泌酶的稳定或调节亚基，以及了解γ-切割的机制，应该是PS研究的下一个目标。

项目成果

Tomita T,Takikawa R,Koyama A,Morohashi Y,Takasugi N,Saido TC,Maruyama K,Iwatsubo T: "C terminus of presenilin is required for overproduction of amyloidogenic Aβ42 through stabilization and endoproteolysis of presenilin."J Neurosci. 19. 10627-10634 (1999)

Tomita T、Takikawa R、Koyama A、Morohashi Y、Takasugi N、Saido TC、Maruyama K、Iwatsubo T：“通过早老素的稳定和内蛋白水解，淀粉样蛋白形成 Aβ42 的过量产生需要早老素的 C 末端。”J Neurosci 19. 10627。 -10634 (1999)

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Naruse S 等人：“PS1 缺陷对近邻中 memlorane 蛋白运输的影响”神经元。

Hosoda R et al: "Quantification of modified forms of amyloid β peptides in Alzheimer's disease and Down's syndrome brains." Journal of Neuropathology and Experimental Neurology. 57. 1089-1095 (1998)

Hosoda R 等人：“阿尔茨海默病和唐氏综合症大脑中淀粉样蛋白 β 肽的修饰形式。”《神经病理学和实验神经学杂志》57. 1089-1095 (1998)。

岩坪 威: "プレセニリン 新臨床医のための分子医学 アルツハイマー病研究の最前線"羊土社. 56-66 (1999)

Takeshi Iwatsubo：“早老素：新临床医生的分子医学，阿尔茨海默病研究的前沿”Yodosha 56-66 (1999)。

Takeuchi A,Irizarry MC,Duff K,Saido TC,Hsiao Ashe K,Hasegawa M,Mann DMA,Hyman BT,Iwatsubo T: "Age-related amyloid β deposition in transgenic mice overexpressing both presenilin l and amyloid β precursor protein Swedish mutant is not associated with global

Takeuchi A、Irizarry MC、Duff K、Saido TC、Hsiao Ashe K、Hasekawa M、Mann DMA、Hyman BT、Iwatsubo T：“过度表达早老素 l 和淀粉样β前体蛋白瑞典突变体的转基因小鼠中与年龄相关的β淀粉样蛋白沉积是与全局无关