Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada.
Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada; Department of Medicine (Geriatric Medicine and Neurology), Dalhousie University, Halifax, NS, Canada.
Chem Biol Interact. 2024 May 25;395:111012. doi: 10.1016/j.cbi.2024.111012. Epub 2024 Apr 20.
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are associated with amyloid-β (Aβ) plaques and exhibit altered biochemical properties in human Alzheimer's disease (AD), as well as in the transgenic 5XFAD mouse model of AD amyloidosis. In the brains of the 5XFAD mouse model devoid of BChE enzyme (5XFAD/BChE-KO), incubation of tissue sections with exogenous BChE purified from human plasma (pl-BChE) leads to its association with Aβ plaques and its biochemical properties are comparable to those reported for endogenous BChE associated with plaques in both human AD and in 5XFAD mouse brain tissue. We sought to determine whether these observations in 5XFAD/BChE-KO mice also apply to human brain tissues. To do so, endogenous ChE activity in human AD brain tissue sections was quenched with 50 % aqueous acetonitrile (MeCN) leaving the tissue suitable for further studies. Quenched sections were then incubated with recombinant AChE (r-AChE) or pl-BChE and stained for each enzymes' activity. Exogenous r-AChE or pl-BChE became associated with Aβ plaques, and when bound, had properties that were comparable to the endogenous ChE enzymes associated with plaques in AD brain tissues without acetonitrile treatment. These findings in human AD brain tissue extend previous observations in the 5XFAD/BChE-KO mouse model and demonstrate that exogenously applied r-AChE and pl-BChE have high affinity for Aβ plaques in human brain tissues. This association alters the biochemical properties of these enzymes, most likely due a conformational change. If incorporation of AChE and BChE in Aβ plaques facilitates AD pathogenesis, blocking this association could lead to disease-modifying approaches to AD. This work provides a method to study the mechanism of AChE and BChE interaction with Aβ plaque pathology in post-mortem human brain tissue.
乙酰胆碱酯酶（AChE）和丁酰胆碱酯酶（BChE）与淀粉样蛋白-β（Aβ）斑块有关，并在人类阿尔茨海默病（AD）以及 AD 淀粉样变性的转基因 5XFAD 小鼠模型中表现出改变的生化特性。在缺乏 BChE 酶的 5XFAD 小鼠模型（5XFAD/BChE-KO）的大脑中，用从人血浆中纯化的外源性 BChE（pl-BChE）孵育组织切片会导致其与 Aβ 斑块结合，并且其生化特性与报道的人类 AD 和 5XFAD 小鼠脑组织中与斑块相关的内源性 BChE 相似。我们试图确定这些在 5XFAD/BChE-KO 小鼠中的观察结果是否也适用于人类脑组织。为此，用 50%的水乙腈（MeCN）淬灭人类 AD 脑组织切片中的内源性 ChE 活性，使组织适合进一步研究。然后用重组 AChE（r-AChE）或 pl-BChE 孵育淬灭的切片，并对每种酶的活性进行染色。外源性 r-AChE 或 pl-BChE 与 Aβ 斑块结合，当结合时，其性质与未经乙腈处理的 AD 脑组织中与斑块相关的内源性 ChE 酶相当。这些在人类 AD 脑组织中的发现扩展了之前在 5XFAD/BChE-KO 小鼠模型中的观察结果，并证明外源性应用的 r-AChE 和 pl-BChE 与人脑组织中的 Aβ 斑块具有高亲和力。这种结合改变了这些酶的生化特性，最有可能是由于构象变化。如果 AChE 和 BChE 掺入 Aβ 斑块中促进 AD 发病机制，那么阻断这种结合可能会导致 AD 的疾病修饰方法。这项工作提供了一种方法来研究 AChE 和 BChE 与死后人类脑组织中 Aβ 斑块病理学相互作用的机制。
