Li Li-Sheng, Lu Yan-Liu, Nie Jing, Xu Yun-Yan, Zhang Wei, Yang Wen-Jin, Gong Qi-Hai, Lu Yuan-Fu, Lu Yang, Shi Jing-Shan
Department of Chemistry, Basic Medical Faculty, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Pharmacology, Key Lab of Basic Pharmacology of Education Ministry, Zunyi Medical University, Zunyi, Guizhou, China.
CNS Neurosci Ther. 2017 Apr;23(4):329-340. doi: 10.1111/cns.12678. Epub 2017 Mar 5.
Axonal degeneration is a pathological symbol in the early stage of Alzheimer's disease (AD), which can be triggered by amyloid-β (Aβ) peptide deposition. Growing evidence indicates that deficit of autophagy eventually leads to the axonal degeneration. Our previous studies have shown that Dendrobium nobile Lindl alkaloid (DNLA) had protective effect on neuron impairment in vivo and in vitro; however, the underlying mechanisms is still unclear.
We exposed cultured hippocampus neurons to Aβ to investigate the effect of DNLA in vitro. Axonal degeneration was evaluated by immunofluorescence staining and MTT assay. Neurons overexpressing GFP-LC3B were used to measure the formation of autophagosome. Autophagosome-lysosome fusion, the lysosomal pH, and cathepsin activity were assessed to reflect autophagy process. Proteins of interest were analyzed by Western blot.
DNLA pretreatment significantly inhibited axonal degeneration induced by Aβ peptide in vitro. Further studies revealed DNLA treatment increased autophagic flux through promoting formation and degradation of autophagosome in hippocampus neurons. Moreover, enhancement of autophagic flux was responsible for the protective effects of DNLA on axonal degeneration.
DNLA prevents Aβ -induced axonal degeneration via activation of autophagy process and could be a novel therapeutic target.
轴突退变是阿尔茨海默病（AD）早期的病理标志，可由淀粉样β（Aβ）肽沉积引发。越来越多的证据表明自噬缺陷最终会导致轴突退变。我们之前的研究表明，金钗石斛生物碱（DNLA）在体内和体外对神经元损伤均具有保护作用；然而，其潜在机制仍不清楚。
我们将培养的海马神经元暴露于Aβ中以研究DNLA在体外的作用。通过免疫荧光染色和MTT法评估轴突退变。使用过表达绿色荧光蛋白-微管相关蛋白轻链3B（GFP-LC3B）的神经元来测量自噬体的形成。评估自噬体-溶酶体融合、溶酶体pH值和组织蛋白酶活性以反映自噬过程。通过蛋白质免疫印迹法分析相关蛋白。
DNLA预处理显著抑制了体外Aβ肽诱导的轴突退变。进一步研究表明，DNLA处理通过促进海马神经元自噬体的形成和降解增加了自噬通量。此外，自噬通量的增强是DNLA对轴突退变具有保护作用的原因。
DNLA通过激活自噬过程预防Aβ诱导的轴突退变，可能成为一个新的治疗靶点。
