Medical Microspectroscopy Laboratory, Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden.
Experimental Neuroinflammation Laboratory, Department of Experimental Medical Science, Lund University, 22184 Lund, Sweden.
Int J Mol Sci. 2021 Mar 26;22(7):3430. doi: 10.3390/ijms22073430.
Alzheimer's disease affects millions of lives worldwide. This terminal disease is characterized by the formation of amyloid aggregates, so-called amyloid oligomers. These oligomers are composed of β-sheet structures, which are believed to be neurotoxic. However, the actual secondary structure that contributes most to neurotoxicity remains unknown. This lack of knowledge is due to the challenging nature of characterizing the secondary structure of amyloids in cells. To overcome this and investigate the molecular changes in proteins directly in cells, we used synchrotron-based infrared microspectroscopy, a label-free and non-destructive technique available for in situ molecular imaging, to detect structural changes in proteins and lipids. Specifically, we evaluated the formation of β-sheet structures in different monogenic and bigenic cellular models of Alzheimer's disease that we generated for this study. We report on the possibility to discern different amyloid signatures directly in cells using infrared microspectroscopy and demonstrate that bigenic (amyloid-β, α-synuclein) and (amyloid-β, Tau) neuron-like cells display changes in β-sheet load. Altogether, our findings support the notion that different molecular mechanisms of amyloid aggregation, as opposed to a common mechanism, are triggered by the specific cellular environment and, therefore, that various mechanisms lead to the development of Alzheimer's disease.
阿尔茨海默病影响着全球数百万人的生命。这种终末期疾病的特征是淀粉样蛋白聚集物的形成，即所谓的淀粉样寡聚物。这些寡聚物由β-折叠结构组成，据信具有神经毒性。然而，导致神经毒性的实际二级结构仍然未知。这种知识的缺乏是由于在细胞中对淀粉样蛋白二级结构进行特征描述的挑战性。为了克服这一困难，并直接在细胞中研究蛋白质的分子变化，我们使用基于同步加速器的红外微光谱学，这是一种可用的无标记和非破坏性技术，用于原位分子成像，以检测蛋白质和脂质的结构变化。具体来说，我们评估了我们为此研究生成的不同单基因和双基因阿尔茨海默病细胞模型中β-折叠结构的形成。我们报告了使用红外微光谱术直接在细胞中辨别不同淀粉样蛋白特征的可能性，并证明双基因（淀粉样蛋白-β、α-突触核蛋白）和（淀粉样蛋白-β、Tau）神经元样细胞显示β-折叠负荷的变化。总的来说，我们的研究结果支持这样一种观点，即不同的淀粉样蛋白聚集的分子机制，而不是一种共同的机制，是由特定的细胞环境引发的，因此，各种机制导致了阿尔茨海默病的发展。
