Inhibition of dynamin-dependent endocytosis increases shedding of the amyloid precursor protein ectodomain and reduces generation of amyloid β protein
Inhibition of dynamin-dependent endocytosis increases shedding of the amyloid precursor protein ectodomain and reduces generation of amyloid β protein
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2005
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通讯作者：
Robyn M Carey;Brigitte A Balcz;I. López-Coviella;B. Slack
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作者：
Robyn M Carey;Brigitte A Balcz;I. López-Coviella;B. Slack
背景：淀粉样前体蛋白 (APP) 通过分泌途径转运至细胞表面，在细胞表面可能被 α-分泌酶在其胞外域内切割，或内化于网格蛋白包被的囊泡内。另一种蛋白水解途径发生在内吞区室中，其中 β 和 γ 分泌酶的连续作用产生 β 淀粉样蛋白 (Aβ)。在这项研究中，我们研究了内吞作用调节剂对 APP 加工的影响。结果：用 dynamin I（网格蛋白依赖性内吞作用的重要介质）的显性失活突变体转染人胚胎肾细胞，并分析 APP 蛋白水解作用。突变动力 (dyn I K44A) 的过度表达导致 APP 胞外域 (sAPPα) 脱落增加、C 端 α 分泌酶产物 C83 积累以及 Aβ 释放减少。在表达 dyn I K44A 的细胞中，细胞表面成熟 APP 的水平增加，并且通过荧光显微镜评估，表面免疫标记 APP 的内化受到抑制。 Dynamin 是蛋白激酶 C (PKC) 的底物，据推测，已知可刺激 α-分泌酶介导的 APP 裂解的 PKC 激活剂可能通过抑制动力依赖性内吞作用来发挥其作用。然而，在 α-分泌酶抑制剂 TAPI-1 存在的情况下，用佛波醇 12 肉豆蔻酸酯 13-乙酸酯处理细胞，表面生物素化 APP 的内化不受影响。结论：结果表明 APP 通过动力依赖性过程内化，并表明介导内吞作用的蛋白质活性的改变可能导致 Aβ 产生的显着变化。背景 淀粉样前体蛋白 (APP) 是一种单次跨膜蛋白，可产生小肽（称为 Aβ），在阿尔茨海默病 (AD) 患者的大脑中形成淀粉样沉积物 [1,2]。 Aβ 肽是通过 APP 的连续裂解产生的 发布：2005 年 8 月 11 日 BMC Cell Biology 2005, 6:30 doi:10.1186/1471-2121-6-30 收稿：2005 年 3 月 18 日 接受：2005 年 8 月 11 日 本文来自： http://www.biomedcentral.com/1471-2121/6/30 © 2005 Carey 等人；被许可人 BioMed Central Ltd。这是一篇根据知识共享署名许可 (http://creativecommons.org/licenses/by/2.0) 条款分发的开放获取文章，允许在任何媒体上不受限制地使用、分发和复制，前提是正确引用原始作品。
Background: The amyloid precursor protein (APP) is transported via the secretory pathway to the cell surface, where it may be cleaved within its ectodomain by α-secretase, or internalized within clathrin-coated vesicles. An alternative proteolytic pathway occurs within the endocytic compartment, where the sequential action of βand γ-secretases generates the amyloid β protein (Aβ). In this study, we investigated the effects of modulators of endocytosis on APP processing. Results: Human embryonic kidney cells were transfected with a dominant negative mutant of dynamin I, an important mediator of clathrin-dependent endocytosis, and APP proteolysis was analyzed. Overexpression of the mutant dynamin (dyn I K44A) resulted in increased shedding of the APP ectodomain (sAPPα), accumulation of the C-terminal α-secretase product C83, and a reduction in the release of Aβ. Levels of mature APP on the cell surface were increased in cells expressing dyn I K44A, and internalization of surface-immunolabeled APP, assessed by fluorescence microscopy, was inhibited. Dynamin is a substrate for protein kinase C (PKC), and it was hypothesized that activators of PKC, which are known to stimulate α-secretase-mediated cleavage of APP, might exert their effects by inhibiting dynamin-dependent endocytosis. However, the internalization of surface-biotinylated APP was unaffected by treatment of cells with phorbol 12myristate 13-acetate in the presence of the α-secretase inhibitor TAPI-1. Conclusion: The results indicate that APP is internalized by a dynamin-dependent process, and suggest that alterations in the activity of proteins that mediate endocytosis might lead to significant changes in Aβ production. Background The amyloid precursor protein (APP) is a single-pass transmembrane protein that gives rise to the small peptides (known as Aβ) that form amyloid deposits in the brains of patients with Alzheimer's disease (AD) [1,2]. Aβ peptides are generated by the successive cleavage of APP Published: 11 August 2005 BMC Cell Biology 2005, 6:30 doi:10.1186/1471-2121-6-30 Received: 18 March 2005 Accepted: 11 August 2005 This article is available from: http://www.biomedcentral.com/1471-2121/6/30 © 2005 Carey et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.