title: ADAM10 and BACE1 are localized to synaptic vesicles.
abstract: Synaptic degeneration and accumulation of the neurotoxic amyloid β-peptide (Aβ) in the brain are hallmarks of Alzheimer disease. Aβ is produced by sequential cleavage of the amyloid precursor protein (APP), by the β-secretase β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. However, Aβ generation is precluded if APP is cleaved by the α-secretase ADAM10 instead of BACE1. We have previously shown that Aβ can be produced locally at the synapse. To study the synaptic localization of the APP processing enzymes we used western blotting to demonstrate that, compared to total brain homogenate, ADAM10 and BACE1 were greatly enriched in synaptic vesicles isolated from rat brain using controlled-pore glass chromatography, whereas Presenilin1 was the only enriched component of the γ-secretase complex. Moreover, we detected ADAM10 activity in synaptic vesicles and enrichment of the intermediate APP-C-terminal fragments (APP-CTFs). We confirmed the western blotting findings using in situ proximity ligation assay to demonstrate close proximity of ADAM10 and BACE1 with the synaptic vesicle marker synaptophysin in intact mouse primary hippocampal neurons. In contrast, only sparse co-localization of active γ-secretase and synaptophysin was detected. These results indicate that the first step of APP processing occurs in synaptic vesicles whereas the final step is more likely to take place elsewhere.
authors: Karolinska Institutet, Department of Neurobiology, Care Science and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Huddinge, Sweden.
authors: Jolanta L
authors: http://orcid.org/0000-0003-2440-4686
authors: JL
authors: Lundgren
authors: European Neuroscience Institute, Göttingen, Germany.
authors: Saheeb
authors: S
authors: Ahmed
authors: Karolinska Institutet, Department of Neurobiology, Care Science and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Huddinge, Sweden.
authors: Sophia
authors: S
authors: Schedin-Weiss
authors: Lund University, Department of Experimental Medical Science, Experimental Dementia Research Unit, Lund, Sweden.
authors: Gunnar K
authors: GK
authors: Gouras
authors: Karolinska Institutet, Department of Neurobiology, Care Science and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Huddinge, Sweden.
authors: Bengt
authors: B
authors: Winblad
authors: Karolinska Institutet, Department of Neurobiology, Care Science and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Huddinge, Sweden.
authors: Lars O
authors: LO
authors: Tjernberg
authors: Karolinska Institutet, Department of Neurobiology, Care Science and Society, Division of Neurogeriatrics, Center for Alzheimer Research, Huddinge, Sweden.
authors: Susanne
authors: S
authors: Frykman
mesh_terms: D051722:ADAM Proteins / Q000032:analysis*; D000072197:ADAM10 Protein; D053829:Amyloid Precursor Protein Secretases / Q000032:analysis*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000032:analysis*; D002478:Cells, Cultured; D006624:Hippocampus / Q000737:chemistry / Q000166:cytology; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D013572:Synaptic Vesicles / Q000737:chemistry*
chemical_list: D008565:Membrane Proteins; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse; D051722:ADAM Proteins; D000072197:ADAM10 Protein; C491234:Adam10 protein, mouse
keywords: APP processing; Alzheimer Disease; nerve terminals; secretases; synapse; trafficking