Research in my laboratory focuses on the properties and molecular mechanisms of synaptic plasticity at mammalian cortical glutamatergic synapses. Our primary approach is to use electrophysiological recordings from neurons in brain slices. This is combined with techniques such as viral expression of genes of interest in slices, 2 photon calcium imaging and glutamate uncaging. We are investigating the roles of phosphorylation and trafficking motifs and of proteins that interact with AMPA, NMDA and kainate receptor subunits in the functional regulation of these receptors. We use four primary approaches: 1) acute blockade of specific interactions by introducing peptides into individual neurons, 2) chronic over expression of constructs of interest using Sindbis virus in cultured slices, 3) shRNA knock down using Lenti virus in cultured slices, and 4) acute slice electrophysiology in transgenic mice. The effects of these manipulations are then assessed by investigating changes in AMPA, kainate or NMDA receptor-mediated synaptic transmission and plasticity. Current studies are focusing on PICK1. We have found that PICK1, which interacts directly with AMPA receptors at synapses and is a calcium-sensitive protein, is critical for NMDA receptor-dependent long-term potentiation (LTP) in hippocampus. Moreover, PICK1 mediates a novel activity-dependent switch in the GluR2 subunit composition of AMPA receptors during LTP, rendering them calcium-permeable. This novel mechanism provides a potential process by which the calcium-permeability of AMPA receptors is regulated during neurological disorders such as cerebral ischemia. We are also characterizing the function of novel phosphorylation sites in the regulation of NMDA and kainate receptor trafficking. Recently we have defined a number of new PKA and PKC phosphorylation sites on the kainate receptor GluR6 subunit and find that some of these regulate endocytocis. Therefore, these studies are defining novel mechanisms regulating the expression and function of glutamate receptors at synapses that are critical for the expression of forms of long-term synaptic plasticity.