Autophagy induction and autophagosome clearance in neurons: Relationship to autophagic pathology in Alzheimer's disease

被引:859
作者
Boland, Barry [1 ,2 ,3 ]
Kumar, Asok [2 ,4 ,5 ,6 ]
Lee, Sooyeon [2 ,4 ,5 ,6 ]
Platt, Frances M. [3 ]
Wegiel, Jerzy [9 ]
Yu, W. Haung [7 ,8 ]
Nixon, Ralph A. [2 ,4 ,5 ,6 ]
机构
[1] Univ Coll Dublin, Conway Inst, Lab Neurodegenerat Res, Sch Biomol & Biomed Sci, Dublin 4, Ireland
[2] Nathan S Kline Inst Psychiat Res, Ctr Dementia Res, Orangeburg, NY 10962 USA
[3] Univ Oxford, Dept Pharmacol, Oxford OX1 3QT, England
[4] NYU, Dept Psychiat, New York, NY 10016 USA
[5] NYU, Dept Cell Biol, New York, NY 10016 USA
[6] NYU, Dept Neurosci, New York, NY 10016 USA
[7] Columbia Univ, Taub Inst, New York, NY 10032 USA
[8] Columbia Univ, Dept Pathol, New York, NY 10032 USA
[9] New York State Inst Basic Res Dev Disabil, Staten Isl, NY 10314 USA
基金
英国惠康基金;
关键词
aging; Alzheimer; autophagy; culture; lysosome; neuron; neuron death; neuronal death; neuropathology; neuroprotection; neurotoxicity; storage;
D O I
10.1523/JNEUROSCI.0800-08.2008
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Macroautophagy, a major pathway for organelle and protein turnover, has been implicated in the neurodegeneration of Alzheimer's disease (AD). The basis for the profuse accumulation of autophagic vacuoles (AVs) in affected neurons of the AD brain, however, is unknown. In this study, we show that constitutive macroautophagy in primary cortical neurons is highly efficient, because newly formed autophagosomes are rapidly cleared by fusion with lysosomes, accounting for their scarcity in the healthy brain. Even after macroautophagy is strongly induced by suppressing mTOR (mammalian target of rapamycin) kinase activity with rapamycin or nutrient deprivation, active cathepsin-positive autolysosomes rather than LC3-II-positive autophagosomes predominate, implying efficient autophagosome clearance in healthy neurons. In contrast, selectively impeding late steps in macroautophagy by inhibiting cathepsin-mediated proteolysis within autolysosomes with cysteine- and aspartyl-protease inhibitors caused a marked accumulation of electron-dense double-membrane-limited AVs, containing cathepsin D and incompletely degraded LC3-II in perikarya and neurites. Similar structures accumulated in large numbers when fusion of autophagosomes with lysosomes was slowed by disrupting their transport on microtubules with vinblastine. Finally, we find that the autophagic vacuoles accumulating after protease inhibition or prolonged vinblastine treatment strongly resembled AVs that collect in dystrophic neurites in the AD brain and in an AD mouse model. We conclude that macroautophagy is constitutively active and highly efficient in healthy neurons and that the autophagic pathology observed in AD most likely arises from impaired clearance of AVs rather than strong autophagy induction alone. Therapeutic modulation of autophagy in AD may, therefore, require targeting late steps in the autophagic pathway.
引用
收藏
页码:6926 / 6937
页数:12
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