First Author | Ye X | Year | 2017 |
Journal | J Neurosci | Volume | 37 |
Issue | 10 | Pages | 2639-2655 |
PubMed ID | 28159908 | Mgi Jnum | J:239680 |
Mgi Id | MGI:5829496 | Doi | 10.1523/JNEUROSCI.2851-16.2017 |
Citation | Ye X, et al. (2017) Regulation of Synaptic Amyloid-beta Generation through BACE1 Retrograde Transport in a Mouse Model of Alzheimer's Disease. J Neurosci 37(10):2639-2655 |
abstractText | Amyloid-beta (Abeta) peptides play a key role in synaptic damage and memory deficits in the early pathogenesis of Alzheimer's disease (AD). Abnormal accumulation of Abeta at nerve terminals leads to synaptic pathology and ultimately to neurodegeneration. beta-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the major neuronal beta-secretase for Abeta generation. However, the mechanisms regulating BACE1 distribution in axons and beta cleavage of APP at synapses remain largely unknown. Here, we reveal that dynein-Snapin-mediated retrograde transport regulates BACE1 trafficking in axons and APP processing at presynaptic terminals. BACE1 is predominantly accumulated within late endosomes at the synapses of AD-related mutant human APP (hAPP) transgenic (Tg) mice and patient brains. Defective retrograde transport by genetic ablation of snapin in mice recapitulates late endocytic retention of BACE1 and increased APP processing at presynaptic sites. Conversely, overexpressing Snapin facilitates BACE1 trafficking and reduces synaptic BACE1 accumulation by enhancing the removal of BACE1 from distal AD axons and presynaptic terminals. Moreover, elevated Snapin expression via stereotactic hippocampal injections of adeno-associated virus particles in mutant hAPP Tg mouse brains decreases synaptic Abeta levels and ameliorates synapse loss, thus rescuing cognitive impairments associated with hAPP mice. Altogether, our study provides new mechanistic insights into the complex regulation of BACE1 trafficking and presynaptic localization through Snapin-mediated dynein-driven retrograde axonal transport, thereby suggesting a potential approach of modulating Abeta levels and attenuating synaptic deficits in AD.SIGNIFICANCE STATEMENT beta-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) trafficking and synaptic localization significantly influence its beta secretase activity and amyloid-beta (Abeta) production. In AD brains, BACE1 is accumulated within dystrophic neurites, which is thought to augment Abeta-induced synaptotoxicity by Abeta overproduction. However, it remains largely unknown whether axonal transport regulates synaptic APP processing. Here, we demonstrate that Snapin-mediated retrograde transport plays a critical role in removing BACE1 from presynaptic terminals toward the soma, thus reducing synaptic Abeta production. Adeno-associated virus-mediated Snapin overexpression in the hippocampus of mutant hAPP mice significantly decreases synaptic Abeta levels, attenuates synapse loss, and thus rescues cognitive deficits. Our study uncovers a new pathway that controls synaptic APP processing by enhancing axonal BACE1 trafficking, thereby advancing our fundamental knowledge critical for ameliorating Abeta-linked synaptic pathology. |