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Methyl-beta-cyclodextrin but not retinoic acid reduces EAAT3-mediated glutamate uptake and increases GTRAP3-18
Matthew E R Butchbach1, Hong Guo, Chien-liang Glenn Lin
1Department of Neuroscience, Ohio State Biochemistry Program, The Ohio State University, 333 West 10th Avenue, Columbus, OH 43210-1239, USA.
Abstract:
The Na+-dependent glutamate transporter EAAT3 facilitates glutamate uptake into neurons as well as many other cell types. GTRAP3-18 (JWA, Arl6ip5) is a novel protein that interacts with EAAT3 and negatively modulates EAAT3-mediated glutamate uptake. Previous studies suggest that retinoic acid (RA) decreases Na+-dependent glutamate uptake and increases GTRAP3-18 protein expression. However, the RA used in those studies was complexed with methyl-beta-cyclodextrin (MebetaCD). In the present study we found that MebetaCD, but not RA, significantly reduced Na+-dependent EAAT3-mediated [3H]glutamate uptake in human embryonic kidney 293 (HEK293) cells. MebetaCD also significantly increased GTRAP3-18 protein expression in HEK293 cells as well as in rat hypothalamic neuron cultures. Intracerebroventricular administration of MebetaCD to the mouse brain resulted in a significant increase in GTRAP3-18 immunoreactivity in the hippocampus and cerebral cortex. In conclusion, we have shown that MebetaCD reduces EAAT3-mediated glutamate uptake and induces the expression of GTRAP3-18 protein.