alpha-Amino-3-hydroxy-5-methyl-4-isoxazole propionate attenuates glutamate-induced caspase-3 cleavage via regulation of glycogen synthase kinase 3beta.
Preconditioning of sublethal ischemia exhibits neuroprotection against subsequent ischemia-induced neuronal death. It has been indicated that glutamate, an excitatory amino acid, is involved in the pathogenesis of ischemia-induced neuronal death or neurodegeneration. To elucidate whether prestimulation of glutamate receptor could counter ischemia-induced neuronal death or neurodegeneration, we examined the effect of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), an ionotropic subtype of glutamate receptor, on excess glutamate-induced excitotoxicity using primary cortical neuronal cultures. We found that AMPA exerted a neuroprotective effect in a time- and concentration-dependent manner. A blocker of phosphatidylinositol-3 kinase (PI3K), LY294002 (10 microM), significantly attenuated AMPA-induced protection. In addition, Ser473 of Akt/PKB, a downstream target of PI3K, was phosphorylated by AMPA administration (10 microM). Glycogen synthase kinase 3beta (GSK3beta), which has been reported to be inactivated by Akt, was phosphorylated at Ser9 by AMPA. Ser9-phosphorylated GSK3beta or inactivated form would be a key molecule for neuroprotection, insofar as lithium chloride (100 microM) and SB216763 (10 microM), inhibitors of GSK3beta, also induced phosphorylation of GSK3beta at Ser9 and exerted neuroprotection, respectively. Glutamate (100 microM) increased cleaved caspase-3, an apoptosis-related cysteine protease, and caspase-3 inhibitor (Ac-DEVD-CHO; 1 microM) blocked glutamate-induced excitotoxicity in our culture. AMPA (10 microM, 24 hr) and SB216763 (10 microM) prominently decreased glutamate-induced caspase-3 cleavage. These findings suggest that AMPA activates PI3K-Akt and subsequently inhibits GSK3beta and that inactivated GSK3beta attenuates glutamate-induced caspase-3 cleavage and neurotoxicity.
Department of Neuroscience for Drug Discovery, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
Takaaki
T
Nishimoto
Takeshi
T
Kihara
Akinori
A
Akaike
Tetsuhiro
T
Niidome
Hachiro
H
Sugimoto
D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D002545:Brain Ischemia / Q000378:metabolism / Q000503:physiopathology; D053148:Caspase 3 / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism* / Q000633:toxicity; D038362:Glycogen Synthase Kinase 3 / Q000187:drug effects* / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D009410:Nerve Degeneration / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D018091:Receptors, AMPA / Q000187:drug effects* / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology*
D053148:Caspase 3; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018698:Glutamic Acid; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D018696:Neuroprotective Agents; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D018091:Receptors, AMPA; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C000605508:Gsk3b protein, rat