Department of Medical Biochemistry and Biophysics, Umeå University, SE-90781 Umeå, Sweden.
Department of Natural Sciences, School of Science and Technology, University of Georgia, 0171 Tbilisi, Georgia.
Int J Mol Sci. 2021 Aug 9;22(16):8556. doi: 10.3390/ijms22168556.
The amyloid cascade is central for the neurodegeneration disease pathology, including Alzheimer's and Parkinson's, and remains the focus of much current research. S100A9 protein drives the amyloid-neuroinflammatory cascade in these diseases. DOPA and cyclen-based compounds were used as amyloid modifiers and inhibitors previously, and DOPA is also used as a precursor of dopamine in Parkinson's treatment. Here, by using fluorescence titration experiments we showed that five selected ligands: DOPA-D-H-DOPA, DOPA-H-H-DOPA, DOPA-D-H, DOPA-cyclen, and H-E-cyclen, bind to S100A9 with apparent K in the sub-micromolar range. Ligand docking and molecular dynamic simulation showed that all compounds bind to S100A9 in more than one binding site and with different ligand mobility and H-bonds involved in each site, which all together is consistent with the apparent binding determined in fluorescence experiments. By using amyloid kinetic analysis, monitored by thioflavin-T fluorescence, and AFM imaging, we found that S100A9 co-aggregation with these compounds does not hinder amyloid formation but leads to morphological changes in the amyloid fibrils, manifested in fibril thickening. Thicker fibrils were not observed upon fibrillation of S100A9 alone and may influence the amyloid tissue propagation and modulate S100A9 amyloid assembly as part of the amyloid-neuroinflammatory cascade in neurodegenerative diseases.
淀粉样蛋白级联反应是神经退行性疾病病理学的核心，包括阿尔茨海默病和帕金森病，并且仍然是当前许多研究的重点。S100A9 蛋白驱动这些疾病中的淀粉样蛋白-神经炎症级联反应。以前曾使用 DOPA 和环戊烷类化合物作为淀粉样蛋白修饰剂和抑制剂，并且 DOPA 也被用作帕金森病治疗中多巴胺的前体。在这里，通过使用荧光滴定实验，我们表明，五种选定的配体：DOPA-D-H-DOPA、DOPA-H-H-DOPA、DOPA-D-H、DOPA-环戊烷和 H-E-环戊烷，与 S100A9 结合的表观 K 在亚毫摩尔范围内。配体对接和分子动力学模拟表明，所有化合物都在 S100A9 上结合一个以上的结合位点，并且每个位点的配体迁移率和氢键不同，这与荧光实验中确定的表观结合一致。通过使用硫代黄素-T 荧光监测的淀粉样蛋白动力学分析和 AFM 成像，我们发现 S100A9 与这些化合物的共聚集不会阻碍淀粉样蛋白的形成，但会导致淀粉样蛋白纤维的形态发生变化，表现为纤维变厚。在单独的 S100A9 纤维化过程中未观察到更厚的纤维，并且可能会影响淀粉样蛋白组织的传播，并作为神经退行性疾病中淀粉样蛋白-神经炎症级联反应的一部分调节 S100A9 淀粉样蛋白组装。
