Fasting activates macroautophagy in neurons of Alzheimer's disease mouse model but is insufficient to degrade amyloid-beta.
Fasting activates macroautophagy in neurons of Alzheimer's disease mouse model but is insufficient to degrade amyloid-beta.
复制标题
禁食在阿尔茨海默氏病小鼠模型的神经元中激活大噬细胞，但不足以降解淀粉样蛋白β。
DOI：
10.1038/srep12115
复制
发表时间：
2015-07-14
影响因子：
4.6
通讯作者：
Okazawa H
中科院分区：
文献类型：
--
作者：
Chen X;Kondo K;Motoki K;Homma H;Okazawa H
我们开发了一种新技术来观察体内大脑中的巨自噬，并检查禁食是否会诱导神经元中的巨自噬，以及阿尔茨海默病（AD）模型和对照小鼠之间的诱导有何不同。注射到大脑中的 EGFP-LC3 慢病毒通过双光子显微镜成功地观察到活神经元中的自噬体。延时成像显示，禁食增加了神经元中自噬体的数量、大小和信号强度。在AD模型小鼠中，自噬体的这些参数在饥饿前的基础水平较高，并且在禁食后比对照小鼠增加得更快。然而，新技术评估的外源标记 Aβ 代谢表明，激活的巨自噬不足以降解禁食后细胞外空间摄取增强而增加的细胞内 Aβ。普通免疫组织化学也显示，禁食增加了细胞内内源性 Aβ 的积累，引发细胞功能障碍，但大部分不会减少细胞外 Aβ 的积累。此外，我们意外地发现了巨自噬基础水平的昼夜节律。这些结果揭示了正常/ AD 状态下神经元自噬的新方面，并表明我们的方法在体内评估自噬功能的有用性。
We developed a new technique to observe macroautophagy in the brain in vivo, and examined whether fasting induced macroautophagy in neurons and how the induction was different between Alzheimer’s disease (AD) model and control mice. Lentivirus for EGFP-LC3 injected into the brain successfully visualized autophagosome in living neurons by two-photon microscopy. The time-lapse imaging revealed that fasting increased the number, size and signal intensity of autophagosome in neurons. In AD model mice, these parameters of autophagosome were higher at the basal levels before starvation, and increased more rapidly by fasting than in control mice. However, metabolism of exogenous labeled Aβ evaluated by the new technique suggested that the activated macroautophagy was insufficient to degrade the intracellular Aβ increased by enhanced uptake from extracellular space after fasting. Ordinary immunohistochemistry also revealed that fasting increased intracellular accumulation of endogenous Aβ, triggered cell dysfunction but did not mostly decrease extracellular Aβ accumulation. Moreover, we unexpectedly discovered a circadian rhythm of basal level of macroautophagy. These results revealed new aspects of neuronal autophagy in normal/AD states and indicated usefulness of our method for evaluating autophagy functions in vivo.