Abstract
Emerging evidence has suggested that glycogen synthase kinase 3 (GSK-3) is a key regulatory kinase involved in a plethora of processes in the nervous system, including neuronal development, mood stabilization, and neurodegeneration. However, the cellular mechanisms underlying the actions of GSK-3 remain to be identified. In this study, we examined the impact of GSK-3 on the N-methyl-d-aspartate (NMDA) receptor channel, a central player involved in cognitive and emotional processes. We found that application of various structurally different GSK-3 inhibitors caused a long-lasting reduction of NMDA receptor-mediated ionic and synaptic current in cortical pyramidal neurons. Cellular knockdown of GSK-3β in neuronal cultures with a small interfering RNA led to smaller NMDA receptor current and loss of its regulation by GSK-3 inhibitors. The NR2B subunit-containing NMDA receptor was the primary target of GSK-3, but the GSK-3 modulation of NMDAR current did not involve the motor protein kinesin superfamily member 17-based transport of NR2B-containing vesicles along microtubules. Combined electrophysiological, immunocytochemical, and biochemical evidence indicated that GSK-3 inhibitors induced the down-regulation of NMDAR current through increasing the Rab5-mediated and PSD-95-regulated NMDAR internalization in a clathrin/dynamin-dependent manner.
Footnotes
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This work was supported by National Institutes of Health grants (MH63128, AG21923, and NS48911) and National Alliance for Research on Schizophrenia and Depression Independent Investigator Award (to Z.Y.).
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ABBREVIATIONS: GSK-3, glycogen synthase kinase-3; AD, Alzheimer's disease; NMDA, N-methyl-d-aspartate; NR2A, N-methyl-d-aspartate receptor subunit 2A; NR2B, N-methyl-d-aspartate receptor subunit 2B; KIF17, kinesin superfamily member 17; TDZD, 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione; NMDAR, N-methyl-d-aspartate receptor; BAPTA, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid; DMSO, dimethyl sulfoxide; ANOVA, analysis of variance; DIV, days in vitro; GFP, green fluorescent protein; siRNA, small interfering RNA; EPSC, excitatory postsynaptic current; DN, dominant negative; CA, constitutively active; AP, activator protein; QX-314, 2-((2,6-dimethylphenyl)amino)-N,N,N-triethyl-2-oxoethanaminium; SB216763, 3-(2,4-dichlorophenyl)-4-(1-methyl-1H-indol-3-yl)-1H-pyrrole-2,5-dione.
- Received February 8, 2007.
- Accepted March 30, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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