Curcumin调控分子马达促进自噬体轴突转运以减轻AD自噬应激的分子机制

Accumulation of autophagosomes in distal of axon caused by axonal transport disorders induced autophagic stress in Alzheimer's disease (AD) and promoted the development of AD. Both of the anterograde and retrograde motors, kinesin and dynein are directly involved in the transport of autophagosomes. GSK-3β plays a key role in regulation of molecular motors, which is a new therapeutic target for treatment of AD. Our previous studies showed plant compounds Curcumin had neuroprotection in AD via inhibiting GSK-3β, and also found that Curcumin significantly ameliorated the accumulation of autophagosomes and enhanced the expression of dynein. Based on the recent findings, we hypothesize Curcumin ameliorates autophagic stress in AD via regulation of motor-driven axonal transport of autophagosomes by inhibiting GSK-3β. The AD cell models including N2ABP1 cells stably expressing APP695sw and the primary hippocampal neurons from AD transgenic mice, also AD transgenic mouse model will be used in this study. The effects of Curcumin on the axonal transport of autophagosomes and its neuroprotection will be firstly examined. Then, whether the effects of Curcumin are mediated by integrated regulation of anterograde and retrograde motors will be investigated. Furthermore, whether the regulation of axonal transport depends on the inhibition of GSK-3β by Curcumin will be studied. Our project will explore the molecular mechanism of neuroprotection of Curcumin from a new sight and further elucidate the multiple protective mechanisms of Curcumin on prevention and treatment of AD.

轴突转运障碍致自噬体大量堆积于轴突引发自噬应激,促进阿尔茨海默病(AD)发生发展,且顺、逆向转运分子马达Kinesin和Dynein直接参与自噬体轴突转运,而GSK-3β参与调控分子马达,是AD治疗新靶点。我们研究证实植物化合物Curcumin可抑制GSK-3β,在AD中发挥神经保护作用,同时还发现Curcumin明显减轻AD转基因鼠脑中自噬体在轴突的堆积,并增强Dynein表达。结合前期研究,我们提出:Curcumin通过抑制GSK-3β调控分子马达促进AD自噬体轴突转运以减轻AD自噬应激发挥脑保护作用。本研究利用离体及在体AD模型,先观察Curcumin对自噬体的轴突转运及神经保护作用,再分析该作用是否通过调控顺、逆向转运马达,并进一步探讨Curcumin通过此调控是否依赖于GSK-3β。本课题从一个全新的视角探讨Curcumin多重脑保护作用的分子机制,为防治神经变性疾病提供新策略。

阿尔茨海默病(AD)中，轴突运输功能障碍导致神经元轴突内自噬小体堆积，从而引发自噬应激、线粒体功能障碍和线粒体自噬损伤。本研究表明，姜黄素作为一种天然化合物，能够增强自噬，促进溶酶体与自噬小体的融合，改善自噬相关蛋白的表达，促进自噬小体的轴突运输，从而促进自噬流，并且可能是通过调节Rab7的表达来实现的。本实验提出了姜黄素改善AD自噬流的新观点，为改善AD自噬应激和治疗AD提供了新的实验依据。此外，我们还发现动力蛋白中间链DIC可以通过调节自噬小体的轴突逆行运输和溶酶体的功能来改善APP/pS1小鼠的认知障碍和Aβ沉积。同时，N2a/APP695swe细胞线粒体自噬损伤可导致受损线粒体的聚集，导致Aβ含量增加，ATP含量降低。用缬氨霉素处理3h后，PINK1/PARKIN信号通路介导的自噬作用被激活，受损的线粒体被清除，Aβ含量下降，ATP水平恢复。此外，还用气相色谱-质谱联用技术对缬霉素处理的N2a/APP695swe细胞的ATP代谢产物进行了筛选，为寻找治疗AD的代谢靶点提供了更多的证据。