1. DiSFeB, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy;2. Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale “Amedeo Avogadro”, Novara, Italy
Abstract:
Zinc (Zn2+) is believed to play a relevant role in the physiology and pathophysiology of the brain. Hence, Zn2+ homeostasis is critical and involves different classes of molecules, including Zn2+ transporters. The ubiquitous Zn2+ transporter‐1 (ZNT‐1) is a transmembrane protein that pumps cytosolic Zn2+ to the extracellular space, but its function in the central nervous system is not fully understood. Here, we show that ZNT‐1 interacts with GluN2A‐containing NMDA receptors, suggesting a role for this transporter at the excitatory glutamatergic synapse. First, we found that ZNT‐1 is highly expressed at the hippocampal postsynaptic density (PSD) where NMDA receptors are enriched. Two‐hybrid screening, coimmunoprecipitation experiments and clustering assay in COS‐7 cells demonstrated that ZNT‐1 specifically binds the GluN2A subunit of the NMDA receptor. GluN2A deletion mutants and pull‐down assays indicated GluN2A(1390–1464) domain as necessary for the binding to ZNT‐1. Most importantly, ZNT‐1/GluN2A complex was proved to be dynamic, since it was regulated by induction of synaptic plasticity. Finally, modulation of ZNT‐1 expression in hippocampal neurons determined a significant change in dendritic spine morphology, PSD‐95 clusters and GluN2A surface levels, supporting the involvement of ZNT‐1 in the dynamics of excitatory PSD.
