Differential regulation of two isoforms of the glial glutamate transporter EAAT2 by DLG1 and CaMKII - PubMed (original) (raw)

EAAT2b is internalized in response to AMPA/KA receptor-mediated CaMKII activation. A, Astrocytes were transiently transfected with EAAT2a-AP or EAAT2b-AP and cell surface expression was assessed after 30 min of treatment with vehicle or glutamate (250 μ

m

). This treatment had no significant effect on EAAT2a, but the surface localization of EAAT2b was significantly decreased by glutamate. ***p < 0.001 by two-way ANOVA (n = 14, 28, 20, 28). B, Inhibition of CaMKII with CK59 (100 μ

m

) or KN93 (10 μ

m

) also prevented EAAT2b-AP internalization in primary astrocytes. *p < 0.05 by two-way ANOVA (n = 9, 8, 10, 7, 10, 10). C, EAAT2b-AP cell-surface expression in primary astrocytes also decreases in response to kainate, but not NMDA (100 μ

m

each), indicating an AMPA/KA receptor mediates EAAT2b internalization. EAAT2a-AP expression was unaltered by treatment with the glutamate receptor agonists. ***p < 0.001 by one-way ANOVA (n = 17, 20, 4, 12, 6, 4). D, The AMPA/KA receptor antagonist NBQX (100 μ

m

) blocked the effects of glutamate on the surface expression of EAAT2b-AP-transfected astrocytes. The NMDA receptor antagonist MK-801 (10 μ

m

) had no significant effect. *p < 0.05; **p < 0.01 by two-way ANOVA (n = 9, 6, 8, 6, 9, 9). Error bars indicate SEM.