Abstract：
A growing number of studies link dysfunction of macroautophagy/autophagy to the pathogenesis of diseases such as Alzheimer disease (AD). Given the global importance of autophagy for homeostasis, how its dysfunction can lead to specific neurological changes is puzzling. To examine this further, we compared the global deactivation of autophagy in the adult mouse using the atg7iKO with the impact of AD-associated pathogenic changes in autophagic processing of synaptic proteins. Isolated forebrain synaptosomes, rather than total homogenates, from atg7iKO mice demonstrated accumulation of synaptic proteins, suggesting that the synapse might be a vulnerable site for protein homeostasis disruption. Moreover, the deactivation of autophagy resulted in impaired cognitive performance over time, whereas gross locomotor skills remained intact. Despite deactivation of autophagy for 6.5 weeks, changes in cognition were in the absence of cell death or synapse loss. In the symptomatic APP PSEN1 double-transgenic mouse model of AD, we found that the impairment in autophagosome maturation coupled with diminished presence of discrete synaptic proteins in autophagosomes isolated from these mice, leading to the accumulation of one of these proteins in the detergent insoluble protein fraction. This protein, SLC17A7/Vglut, also accumulated in atg7iKO mouse synaptosomes. Taken together, we conclude that synaptic autophagy plays a role in maintaining protein homeostasis, and that while decreasing autophagy interrupts normal cognitive function, the preservation of locomotion suggests that not all circuits are affected similarly. Our data suggest that the disruption of autophagic activity in AD may have relevance for the cognitive impairment in this adult-onset neurodegenerative disease. Abbreviations: 2dRAWM: 2-day radial arm water maze; AD: Alzheimer disease; Aβ: amyloid-beta; AIF1/Iba1: allograft inflammatory factor 1; APP: amyloid beta precursor protein; ATG7: autophagy related 7; AV: autophagic vacuole; CCV: cargo capture value; Ctrl: control; DLG4/PSD-95: discs large MAGUK scaffold protein 4; GFAP: glial fibrillary acidic protein; GRIN2B/NMDAR2b: glutamate ionotropic receptor NMDA type subunit 2B; LTD: long-term depression; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; m/o: months-old; PNS: post-nuclear supernatant; PSEN1/PS1: presenilin 1; SHB: sucrose homogenization buffer; SLC32A1/Vgat: solute carrier family 32 member 1; SLC17A7/Vglut1: solute carrier family 17 member 7; SNAP25: synaptosome associated protein 25; SQSTM1/p62: sequestosome 1; SYN1: synapsin I; SYP: synaptophysin ; SYT1: synaptotagmin 1; Tam: tamoxifen; VAMP2: vesicle associated membrane protein 2; VCL: vinculin; wks: weeks.
摘要：
越来越多的研究将巨自噬/自噬功能障碍与阿尔茨海默病（AD）等疾病的发病机制联系起来。鉴于自噬对体内平衡的全球重要性，它的功能障碍如何导致特定的神经系统变化令人费解。为了进一步检查这一点，我们比较了使用atg7iKO的成年小鼠自噬的整体失活与AD相关致病改变对突触蛋白自噬过程的影响.孤立的前脑突触体，而不是总匀浆，来自atg7iKO小鼠的突触蛋白的积累，这表明突触可能是蛋白质稳态破坏的脆弱位点。此外，随着时间的推移，自噬的失活导致认知能力受损，而总体运动技能保持完整。尽管自噬失活6.5周，认知的改变是在没有细胞死亡或突触丢失的情况下发生的。在有症状的APPPSEN1双转基因AD小鼠模型中，我们发现，自噬体成熟的损害与从这些小鼠分离的自噬体中离散突触蛋白的减少，导致这些蛋白质之一在洗涤剂不溶性蛋白质部分中积累。这种蛋白质,SLC17A7/Vglut,也在atg7iKO小鼠突触体中积累。一起来看,我们得出结论，突触自噬在维持蛋白质稳态中起作用，而减少自噬会干扰正常的认知功能，运动的保留表明并非所有电路都受到类似的影响。我们的数据表明，AD中自噬活性的破坏可能与这种成人发作的神经退行性疾病的认知障碍有关。缩写：2dRAWM：2天radial臂水迷宫；AD：阿尔茨海默病；Aβ：淀粉样蛋白β；AIF1/Iba1：同种异体移植炎症因子1；APP：淀粉样β前体蛋白；ATG7：自噬相关的7；AV：自噬液泡；CCV：货物捕获值；MAGINAMPT：2天臂水迷宫1；NSPAMPT：对照；
