[PDF][PDF] Activity-induced convergence of APP and BACE-1 in acidic microdomains via an endocytosis-dependent pathway

U Das, DA Scott, A Ganguly, EH Koo, Y Tang, S Roy - Neuron, 2013 - cell.com
U Das, DA Scott, A Ganguly, EH Koo, Y Tang, S Roy
Neuron, 2013cell.com
The convergence of APP (substrate) and BACE-1 (enzyme) is a rate-limiting, obligatory
event triggering the amyloidogenic pathway—a key step in Alzheimer's disease (AD)
pathology. However, as both APP/BACE-1 are highly expressed in brain, mechanisms
precluding their unabated convergence are unclear. Exploring dynamic localization of
APP/BACE-1 in cultured hippocampal neurons, we found that after synthesis via the
secretory pathway, dendritic APP/BACE-1-containing vesicles are largely segregated in …
Summary
The convergence of APP (substrate) and BACE-1 (enzyme) is a rate-limiting, obligatory event triggering the amyloidogenic pathway—a key step in Alzheimer's disease (AD) pathology. However, as both APP/BACE-1 are highly expressed in brain, mechanisms precluding their unabated convergence are unclear. Exploring dynamic localization of APP/BACE-1 in cultured hippocampal neurons, we found that after synthesis via the secretory pathway, dendritic APP/BACE-1-containing vesicles are largely segregated in physiologic states. While BACE-1 is sorted into acidic recycling endosomes, APP is conveyed in Golgi-derived vesicles. However, upon activity induction—a known trigger of the amyloidogenic pathway—APP is routed into BACE-1-positive recycling endosomes via a clathrin-dependent mechanism. A partitioning/convergence of APP/BACE-1 vesicles is also apparent in control/AD brains, respectively. Considering BACE-1 is optimally active in an acidic environment, our experiments suggest that neurons have evolved trafficking strategies that normally limit APP/BACE-1 proximity and also uncover a pathway routing APP into BACE-1-containing organelles, triggering amyloidogenesis.
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