Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA.
Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Sci Rep. 2022 Sep 2;12(1):14985. doi: 10.1038/s41598-022-18869-3.
Evidence suggests that β-secretase (BACE1), which cleaves Amyloid Precursor Protein (APP) to form sAPPβ and amyloid-β, is elevated in Alzheimer's disease (AD) brains and biofluids and, thus, BACE1 is a therapeutic target for this devastating disease. The direct product of BACE1 cleavage of APP, sAPPβ, serves as a surrogate marker of BACE1 activity in the central nervous system. This biomarker could be utilized to better understand normal APP processing, aberrant processing in the disease setting, and modulations to processing during therapeutic intervention. In this paper, we present a method for measuring the metabolism of sAPPβ and another APP proteolytic product, sAPPα, in vivo in humans using stable isotope labeling kinetics, paired with immunoprecipitation and liquid chromatography/tandem mass spectrometry. The method presented herein is robust, reproducible, and precise, and allows for the study of these analytes by taking into account their full dynamic potential as opposed to the traditional methods of absolute concentration quantitation that only provide a static view of a dynamic system. A study of in vivo cerebrospinal fluid sAPPβ and sAPPα kinetics using these methods could reveal novel insights into pathophysiological mechanisms of AD, such as increased BACE1 processing of APP.
有证据表明，β-分泌酶（BACE1）在阿尔茨海默病（AD）大脑和生物液中升高，它能切割淀粉样前体蛋白（APP）形成 sAPPβ 和淀粉样-β，因此 BACE1 是这种破坏性疾病的治疗靶点。APP 被 BACE1 切割的直接产物 sAPPβ，是中枢神经系统中 BACE1 活性的替代标志物。该生物标志物可用于更好地了解 APP 的正常加工、疾病状态下的异常加工，以及治疗干预期间的加工调节。在本文中，我们提出了一种使用稳定同位素标记动力学、免疫沉淀和液相色谱/串联质谱联用的方法，在人类体内测量 sAPPβ 和另一种 APP 蛋白水解产物 sAPPα 的代谢。本文提出的方法具有稳健性、重现性和精确性，通过考虑到它们的全部动态潜力，而不是传统的绝对浓度定量方法，该方法可以对这些分析物进行研究，传统方法只能提供动态系统的静态视图。使用这些方法研究体内脑脊液 sAPPβ 和 sAPPα 的动力学，可以揭示 AD 病理生理学机制的新见解，例如 BACE1 对 APP 的加工增加。
