Open AccessA Super-Resolved View of the Alzheimer’s Disease-Related Amyloidogenic Pathway in Hippocampal Neurons
Author(s) -
Yang Yu,
Yang Gao,
Bengt Winblad,
Lars O. Tjernberg,
Sophia SchedinWeiss
Publication year - 2021
Publication title -
journal of alzheimer's disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.677
H-Index - 139
eISSN - 1875-8908
pISSN - 1387-2877
DOI - 10.3233/jad-215008
Subject(s) - endosome , sted microscopy , soma , colocalization , amyloid precursor protein , hippocampal formation , microbiology and biotechnology , synapse , presenilin , chemistry , amyloid precursor protein secretase , neurite , cleavage (geology) , confocal microscopy , vesicle , postsynaptic potential , biophysics , neuroscience , alzheimer's disease , biology , biochemistry , superresolution , pathology , in vitro , artificial intelligence , membrane , image (mathematics) , receptor , fracture (geology) , computer science , intracellular , paleontology , medicine , disease
Background: Processing of the amyloid-β protein precursor (AβPP) is neurophysiologically important due to the resulting fragments that regulate synapse biology, as well as potentially harmful due to generation of the 42 amino acid long amyloid β-peptide (Aβ42), which is a key player in Alzheimer’s disease. Objective: Our aim was to clarify the subcellular locations of the fragments involved in the amyloidogenic pathway in primary neurons with a focus on Aβ42 and its immediate substrate AβPP C-terminal fragment (APP-CTF). To overcome the difficulties of resolving these compartments due to their small size, we used super-resolution microscopy. Methods: Mouse primary hippocampal neurons were immunolabelled and imaged by stimulated emission depletion (STED) microscopy, including three-dimensional three-channel imaging, and quantitative image analyses. Results: The first (β-secretase) and second (γ-secretase) cleavages of AβPP were localized to functionally and distally distinct compartments. The β-secretase cleavage was observed in early endosomes in soma, where we were able to show that the liberated N- and C-terminal fragments were sorted into distinct vesicles budding from the early endosomes. Lack of colocalization of Aβ42 and APP-CTF in soma suggested that γ-secretase cleavage occurs in neurites. Indeed, APP-CTF was, in line with Aβ42 in our previous study, enriched in the presynapse but absent from the postsynapse. In contrast, full-length AβPP was not detected in either the pre- or the postsynaptic side of the synapse. Furthermore, we observed that endogenously produced and endocytosed Aβ42 were localized in different compartments. Conclusion: These findings provide critical super-resolved insight into amyloidogenic AβPP processing in primary neurons.