title: Super-resolution microscopy reveals γ-secretase at both sides of the neuronal synapse.
abstract: The transmembrane protein assembly γ-secretase is a key protease in regulated intramembrane processing (RIP) of around 100 type-1 transmembrane proteins. Importantly, it has a pathological role in Alzheimer disease (AD) as it generates the neurotoxic amyloid β-peptide from the amyloid precursor protein (APP). Studies on γ-secretase location are therefore crucial both from a biological and a therapeutic perspective. Despite several years of efforts in many laboratories, it is not clear where in the neuron γ-secretase exerts it's activities. Technical challenges include the fact that the active enzyme contains four protein components and that most subcellular compartments cannot be spatially resolved by traditional light microscopy. Here, we have used a powerful combination of the two nanoscopy techniques STORM and STED microscopy to visualize the location of γ-secretase in neurons using an active-site specific probe, with a focus on the synapse. We show that γ-secretase is present in both the pre-and postsynaptic compartments. We further show that the enzyme is enriched very close to the synaptic cleft in the postsynaptic membrane, as well as to NMDA receptors, demonstrating that γ-secretase is present in the postsynaptic plasma membrane. Importantly, the expression of γ-secretase increased in the pre- and postsynaptic compartments with the size of the synapse, suggesting a correlation between γ-secretase activity and synapse maturation. Thus, our data shows the synaptic location with high precision in three dimensions and settles the long-lasting debate on the synaptic location of γ-secretase.
authors.affiliation: Department NVS, Center for Alzheimer Research, Division of Neurogeriatrics, Karolinska Institutet, 141 57, Huddinge, Sweden. sophia.schedin.weiss@ki.se.
authors.forename: Sophia
authors.initials: S
authors.lastname: Schedin-Weiss
authors.affiliation: Department NVS, Center for Alzheimer Research, Division of Neurogeriatrics, Karolinska Institutet, 141 57, Huddinge, Sweden.
authors.forename: Ina
authors.initials: I
authors.lastname: Caesar
authors.affiliation: Department NVS, Center for Alzheimer Research, Division of Neurogeriatrics, Karolinska Institutet, 141 57, Huddinge, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Winblad
authors.affiliation: Science for Life Laboratory, Royal Institute of Technology, 171 65, Solna, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Blom
authors.affiliation: Department NVS, Center for Alzheimer Research, Division of Neurogeriatrics, Karolinska Institutet, 141 57, Huddinge, Sweden.
authors.forename: Lars O
authors.initials: LO
authors.lastname: Tjernberg
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000201:enzymology*; D002478:Cells, Cultured; D003712:Dendrites / Q000201:enzymology*; D000076122:Disks Large Homolog 4 Protein; D004622:Embryo, Mammalian; D051528:Guanylate Kinases / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology; D007091:Image Processing, Computer-Assisted; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D059906:Neuroimaging; D009474:Neurons / Q000166:cytology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses / Q000378:metabolism*; D016708:Synaptophysin / Q000378:metabolism; D016875:tau Proteins / Q000378:metabolism
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; C121001:NR2B NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; D016708:Synaptophysin; D016875:tau Proteins; D051528:Guanylate Kinases; D053829:Amyloid Precursor Protein Secretases
keywords: Alzheimer disease; Hippocampal neuron; Stimulated emission depletion (STED) microscopy; Stochastic optical resolution microscopy (STORM); Super-resolution microscopy; Synapse; γ-Secretase