Journal Article

Proximity ligation assay reveals both pre- and postsynaptic localization of the APP-processing enzymes ADAM10 and BACE1 in rat and human adult brain

Vandermeulen, Lina, Lundgren, Jolanta L., Frykman, Susanne, Winblad, Bengt, Ahmed, Saheeb, Di Luca, Monica, Marcello, Elena, Tjernberg, Lars O., Sandebring-Matton, Anna

2020

Overview

Background Synaptic degeneration and accumulation of amyloid β-peptides (Aβ) are hallmarks of the Alzheimer diseased brain. Aβ is synaptotoxic and produced by sequential cleavage of the amyloid precursor protein (APP) by the β-secretase BACE1 and by γ-secretase. If APP is instead cleaved by the α-secretase ADAM10, Aβ will not be generated. Although BACE1 is considered to be a presynaptic protein and ADAM10 has been reported to mainly localize to the postsynaptic density, we have previously shown that both ADAM10 and BACE1 are highly enriched in synaptic vesicles of rat brain and mouse primary hippocampal neurons. Results Here, using brightfield proximity ligation assay, we expanded our previous result in primary neurons and investigated the in situ synaptic localization of ADAM10 and BACE1 in rat and human adult brain using both pre- and postsynaptic markers. We found that ADAM10 and BACE1 were in close proximity with both the presynaptic marker synaptophysin and the postsynaptic marker PSD-95. The substrate APP was also detected both pre- and postsynaptically. Subcellular fractionation confirmed that ADAM10 and BACE1 are enriched to a similar degree in synaptic vesicles and as well as in the postsynaptic density. Conclusions We show that the α-secretase ADAM10 and the β-secretase BACE1 are located in both the pre- and postsynaptic compartments in intact brain sections. These findings increase our understanding of the regulation of APP processing, thereby facilitating development of more specific treatment strategies.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: ADAM10 Protein - metabolism / Aged / Aged, 80 and over / Alzheimer disease / Alzheimer's disease / Amyloid beta-protein / Amyloid beta-Protein Precursor - metabolism / Amyloid precursor protein / Amyloid Precursor Protein Secretases - metabolism / Animal Models / Animals / Aspartic Acid Endopeptidases - metabolism / Biomedical and Life Sciences / Biomedicine / Brain / Brain - metabolism / Brain research / Diseases / Enzymes / Female / Fractionation / Hippocampus / Humans / Immunoglobulins / Localization / Male / Membrane Proteins - metabolism / Nerve terminal / Neurobiology / Neurobiology of disease / Neurodegeneration / Neurons / Neurons - metabolism / Neurophysiology / Neurosciences / Peptides / Postsynaptic density / Postsynaptic density proteins / Proteins / Rats, Wistar / Research Article / Rodents / Secretase / Secretases / Synapse / Synapses - metabolism / Synaptic vesicles / Synaptophysin / Synaptophysin - metabolism / β-Site APP-cleaving enzyme 1