Endocytosis of synaptic ADAM10 in neuronal plasticity and Alzheimer’s disease
Elena Marcello, … , Fabrizio Gardoni, Monica Di Luca
Elena Marcello, … , Fabrizio Gardoni, Monica Di Luca
Published May 8, 2013
Citation Information: J Clin Invest. 2013;123(6):2523-2538. https://doi.org/10.1172/JCI65401.
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Endocytosis of synaptic ADAM10 in neuronal plasticity and Alzheimer’s disease

Abstract

A disintegrin and metalloproteinase 10 (ADAM10), a disintegrin and metalloproteinase that resides in the postsynaptic densities (PSDs) of excitatory synapses, has previously been shown to limit β-amyloid peptide (Aβ) formation in Alzheimer’s disease (AD). ADAM10 also plays a critical role in regulating functional membrane proteins at the synapse. Using human hippocampal homogenates, we found that ADAM10 removal from the plasma membrane was mediated by clathrin-dependent endocytosis. Additionally, we identified the clathrin adaptor AP2 as an interacting partner of a previously uncharacterized atypical binding motif in the ADAM10 C-terminal domain. This domain was required for ADAM10 endocytosis and modulation of its plasma membrane levels. We found that the ADAM10/AP2 association was increased in the hippocampi of AD patients compared with healthy controls. Long-term potentiation (LTP) in hippocampal neuronal cultures induced ADAM10 endocytosis through AP2 association and decreased surface ADAM10 levels and activity. Conversely, long-term depression (LTD) promoted ADAM10 synaptic membrane insertion and stimulated its activity. ADAM10 interaction with the synapse-associated protein-97 (SAP97) was necessary for LTD-induced ADAM10 trafficking and required for LTD maintenance and LTD-induced changes in spine morphogenesis. These data identify and characterize a mechanism controlling ADAM10 localization and activity at excitatory synapses that is relevant to AD pathogenesis.

Authors

Elena Marcello, Claudia Saraceno, Stefano Musardo, Hugo Vara, Alerie Guzman de la Fuente, Silvia Pelucchi, Daniele Di Marino, Barbara Borroni, Anna Tramontano, Isabel Pérez-Otaño, Alessandro Padovani, Maurizio Giustetto, Fabrizio Gardoni, Monica Di Luca

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Figure 3

ADAM10/AP2 interaction is relevant for ADAM10 endocytosis and membrane expression.

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ADAM10/AP2 interaction is relevant for ADAM10 endocytosis and membrane e...
(A) Antibody uptake assays were performed on COS7 cells transfected with either TacADAM10-RAR or the mutant TacADAM10-RAR AQA (lacking AP2-binding motif) or the deletion mutant Tac721Δ. TacADAM10-RAR internalization was also analyzed after treatment with dynamin inhibitor dynasore (TacADAM10-RAR+dynasore, 80 μM for 30 minutes before the internalization assay). Representative images of cells returned to 37°C to allow endocytosis. A decrease in the number of internalization puncta of TacADAM10-RAR AQA and of the deletion mutant Tac721Δ, of TacADAM10-RAR+dynasore is detected when compared with TacADAM10-RAR. Scale bar: 20 μm. (B) Quantification of the internalization index of experiments in A (*P < 0.05, TacADAM10-RAR AQA versus TacADAM10-RAR, Tac721Δ versus TacADAM10-RAR, TacADAM10-RAR+dynasore versus TacADAM10-RAR, n = 3 experiments, 27 cells per condition). (C) ADAM10 WT and the mutant ADAM10 AQA, lacking the AP2-binding motif, were transfected into COS7 cells and surface/total labeling was analyzed. ADAM10 WT was faintly localized at the surface despite intense intracellular labeling. In contrast, the mutant tested displayed strong surface staining. Scale bar: 20 μm. (D) Quantification of surface expression ratios in C (*P < 0.05, ADAM10 WT versus ADAM10 AQA, n = 18–20 cells per condition).