α‐Amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionate attenuates glutamate‐induced caspase‐3 cleavage via regulation of glycogen synthase kinase 3β

Abstract

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.

Delayed Administration of Parecoxib, a Specific COX-2 Inhibitor, Attenuated Postischemic Neuronal Apoptosis by Phosphorylation Akt and GSK-3β

“…d Relative optical density of Cytochrome C in cytosolic and mitochondrial of ischemic core and penumbra, which showed that translocation of Cytochrome C induced by cerebral ischemia was inhibited by administration of parecoxib. kinase-3b (GSK-3b) [22][23][24]. GSK-3b is regulated by phosphorylation at Ser 9 and Tyr 216 .…”

“…As a downstream effect of Akt, glycogen synthase kinase 3b (GSK-3b) is phosphorylated or inactivated by Akt [20,21], and the phosphorylated Akt/GSK-3b provides neuroprotection against cerebral ischemic reperfusion injury in different animal models in vivo or in vitro [22][23][24][25].…”

Glycogen synthase kinase-3 (GSK3): Regulation, actions, and diseases

“…GSK3 also phosphorylates the postsynaptic protein PSD-95, which regulates AMPA receptor trafficking (Nelson et al, 2013). AMPA signaling, in turn, reduces GSK3 activity (Nishimoto et al, 2008), perhaps as a feed-back inhibitory mechanism for AMPA signaling, that also leads to reduced cell surface expression of the NMDA receptor subunit NR1 (Nishimoto et al, 2009). This interaction is consistent with the finding that GSK3 maintains the surface localization of NMDA receptors, including both the NR1 and NR2B subunits, by a mechanism that involves both Rab5 and PSD95 (Chen et al, 2007; Deng et al, 2014).…”

Resolvin D1 protects against hepatic ischemia/reperfusion injury in rats

“…Activation of Akt promotes cell survival by modulation of various downstream elements, including glycogen synthase kinase-3β (GSK-3β) and Bcl-2-associated death promoter (BAD) [12,13]. The phosphorylated Akt had been found to inhibit cell apoptosis and provide protection against hepatic I/R injury [14,15].…”