Porter Tenielle, Bharadwaj Prashant, Groth David, Paxman Adrian, Laws Simon M, Martins Ralph N, Verdile Giuseppe
School of Biomedical Sciences, CHIRI Biosciences Research Precinct, Faculty of Health Sciences, Curtin University, Western Australia, Australia.
Centre of Excellence for Alzheimer's Disease Research and Care, School of Medical Sciences, Edith Cowan University, Western Australia, Australia.
J Alzheimers Dis. 2016;50(3):895-905. doi: 10.3233/JAD-150790.
Latrepirdine (Dimebon) has been demonstrated to be a neuroprotective and cognition improving agent in neurodegenerative diseases that feature protein aggregation and deposition, such as Alzheimer's disease (AD). The accumulation of amyloid-β (Aβ) protein aggregates is a key event in the neurodegenerative process in AD. This study explores if latrepirdine modulation of protein aggregation contributes to its neuroprotective mechanism of action. Assessment of neuronal cell death showed that there was a significant reduction in lactate dehydrogenase release at an equimolar ratio of Aβ:latrepirdine and with lower concentrations of latrepirdine. The ability of latrepirdine to alter the formation of Aβ42 aggregates was assessed by thioflavin-T fluorescence, western immunoblotting and atomic force microscopy (AFM). Despite showing a reduction in thioflavin-T fluorescence with latrepirdine treatment, indicating a decrease in aggregation, immunoblotting and AFM showed a modest increase in both the formation and size of Aβ aggregates. The discrepancies between thioflavin-T and the other assays are consistent with previous evidence that cyclic molecules can interfere with thioflavin-T binding of amyloid protein preparations. The ability of latrepirdine to modulate Aβ aggregation appears to be independent of its neuroprotective effects, and is unlikely to be a mechanism by which latrepirdine offers protection. This study investigates the effect of latrepirdine on Aβ aggregation, and presents evidence suggesting that caution should be applied in the use of thioflavin-T fluorescence based assays as a method for screening compounds for protein aggregation altering properties.
在以蛋白质聚集和沉积为特征的神经退行性疾病（如阿尔茨海默病，AD）中，拉曲匹定（Dimebon）已被证明是一种具有神经保护和改善认知作用的药物。淀粉样β蛋白（Aβ）聚集体的积累是AD神经退行性过程中的关键事件。本研究探讨拉曲匹定对蛋白质聚集的调节作用是否有助于其神经保护作用机制。对神经元细胞死亡的评估表明，在Aβ与拉曲匹定等摩尔比以及较低浓度的拉曲匹定条件下，乳酸脱氢酶释放量显著降低。通过硫黄素-T荧光、免疫印迹和原子力显微镜（AFM）评估拉曲匹定改变Aβ42聚集体形成的能力。尽管拉曲匹定处理后硫黄素-T荧光降低，表明聚集减少，但免疫印迹和AFM显示Aβ聚集体的形成和大小均有适度增加。硫黄素-T与其他检测方法之间的差异与先前的证据一致，即环状分子可干扰淀粉样蛋白制剂与硫黄素-T的结合。拉曲匹定调节Aβ聚集的能力似乎与其神经保护作用无关，不太可能是拉曲匹定发挥保护作用的机制。本研究调查了拉曲匹定对Aβ聚集的影响，并提供证据表明，在使用基于硫黄素-T荧光的检测方法作为筛选具有改变蛋白质聚集特性化合物的方法时应谨慎。
