This year marks the 50th anniversary of John Olney?s seminal work that introduced the concept of excitotoxicity as a mechanism for neuronal cell death. Since that time, fundamental research on the pathophysiological activation of NMDA receptors has played a central role in our understanding of excitotoxic cellular signaling pathways, leading to the discovery of many potential therapeutic targets in the treatment of acute or chronic/progressive neurodegenerative disorders. Despites countless efforts, however, translational strategies aimed at inhibiting or regulating NMDA receptor-mediated excitotoxic injury have repeatedly failed in clinical trials, leaving only very few potential applications viable today. Nonetheless, highly innovative approaches in this important area of research could still yield tangible advances in the field of neuroprotection. We this in mind, we introduce here a previously unrecognized modulator of NMDA receptor-mediated excitotoxicity, namely, the ZnT1 (Slc30a1) zinc transporter. We present preliminary data showing that the interaction between ZnT1 and the highly zinc sensitive NMDA receptor subunit GluN2A strongly dictate the inhibitory, regulatory function of the metal on the receptor. Moreover, we reveal the development of a cell-penetrating peptide designed to specifically reduce the interaction between ZnT1 and GluN2A influences NMDA receptor-mediated synaptic responses. We tailor the proposed work by taking advantage of an endogenous neuronal mechanism of zinc-dependent excitotoxic tolerance, and utilize both in vitro and in vivo experimental approaches to achieve the proposed aims, which are: i) to investigate the role of the GluN2A-ZnT1 interaction in regulating NMDA excitotoxicity in vitro, and ii) to establish the role of ZnT1 upregulation and increased GluN2A-ZnT1 interaction in an in vivo model of ischemic preconditioning. If successful, the work proposed in this Exploratory/Development Research Grant (R21) proposal will define an novel approach to regulate NMDA receptor-mediated excitotoxic injury, with translational potential in future work.
The research proposed in this application is aimed at investigating a previously unrecognized modulator of NMDA receptor-mediated neuronal cell death, namely, the zinc transporter ZnT1 (Slc30a1). An experimental, cell-permeant peptide has been developed that can disrupt the interaction between ZnT1 and the highly zinc sensitive NMDA receptor subunit GluN2A. This peptide will serve to test the hypothesis that the GluN2A-ZnT1 interaction can strongly influence excitotoxic processes in neuronal tissue culture and in a rodent model of acute neuronal injury.
