Regulation of AMPA receptor trafficking by δ-catenin

δ-catenin is a protein that binds to the classical cadherins and to synaptic scaffolding proteins in a manner which allows the protein to serve as a link between the adherens junction and the postsynaptic complex. Here we show the regulatory role of δ-catenin on synaptic transmission. δ-catenin increased the AMPA receptor-mediated EPSC, but had no significant effect on the NMDA receptor-mediated EPSC. The effect of δ-catenin on the AMPAR EPSC was mediated by its PDZ ligand. δ-catenin regulates the surface expression of GluR2 in the dendritic spines of neurons. Immunoprecipitation revealed that δ-catenin bound to GRIP-1. In COS7 cells, co-transfection of δ-catenin, GRIP and GluR2 showed that δ-catenin regulates the membrane localization of GRIP through its PDZ ligand and increased the surface expression of GluR2. This study directly shows that δ-catenin is essential for the trafficking and positioning GluR2 in the spine and thus further links δ-catenin to neuronal plasticity.