Summary
Astrocytic GLT-1 is the main glutamate transporter involved in glutamate buffering in the brain, pivotal for glutamate removal at excitatory synapses to terminate neurotransmission and for preventing excitotoxicity. We show here that the surface expression and function of GLT-1 can be rapidly modulated through the interaction of its N-terminus with the nonadrenergic imidazoline-1 receptor protein, Nischarin. The phox domain of Nischarin is critical for interaction and internalization of surface GLT-1. Using live super-resolution imaging, we found that glutamate accelerated Nischarin-GLT-1 internalization into endosomal structures. The surface GLT-1 level increased in Nischarin knockout astrocytes, and this correlated with a significant increase in transporter uptake current. Furthermore, Nischarin knockout in astrocytes is neuroprotective against glutamate excitotoxicity. These data provide new molecular insights into regulation of GLT-1 surface level and function and suggest novel drug targets for the treatment of neurological disorders.
Highlights
The phox domain of Nischarin interacts with the N-terminal tail of the main astrocyte glutamate transporter, GLT-1.
Nischarin promotes internalization of GLT-1 to endosomes.
Glutamate modulates GLT-1 surface levels via regulation of the Nischarin-GLT-1 interaction.
Genetic loss of Nischarin significantly increases GLT-1 surface expression, resulting in increased glutamate transport currents and enhanced neuroprotection.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
↵* Current Affiliations: Swati Gupta - Nash Family Department of Neuroscience and Friedman Brain Institute, The Icahn School of Medicine at Mount Sinai, New York, NY 10029, James Drew - Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK, Hélène Marie - Université Côte d’Azur, CNRS UMR 7275, IPMC, Valbonne, France