Regulation of AMPA receptor trafficking by delta-catenin.

delta-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 delta-catenin on synaptic transmission. delta-catenin increased the AMPA receptor-mediated EPSC, but had no significant effect on the NMDA receptor-mediated EPSC. The effect of delta-catenin on the AMPAR EPSC was mediated by its PDZ ligand. delta-catenin regulates the surface expression of GluR2 in the dendritic spines of neurons. Immunoprecipitation revealed that delta-catenin bound to GRIP-1. In COS7 cells, co-transfection of delta-catenin, GRIP and GluR2 showed that delta-catenin regulates the membrane localization of GRIP through its PDZ ligand and increased the surface expression of GluR2. This study directly shows that delta-catenin is essential for the trafficking and positioning GluR2 in the spine and thus further links delta-catenin to neuronal plasticity.