Glutathione Peroxidase-1 Knockout Facilitates Memory Impairment Induced by beta-Amyloid (1-42) in Mice via Inhibition of PKC beta II-Mediated ERK Signaling; Application with Glutathione Peroxidase-1 Gene-Encoded Adenovirus Vector

摘要

A growing body evidence suggests that selenium (Se) deficiency is associated with an increased risk of developing Alzheimer's disease (AD). Se-dependent glutathione peroxidase-1 (GPx-1) of a major antioxidant enzyme, and the most abundant isoform of GPx in the brain. In the present study, we investigated whether GPx-1 is protective against memory impairments induced by beta-amyloid (A beta) (1-42) in mice. As the alteration of protein kinase C (PKC)-mediated ERK activation was recognized in the early stage of AD, we examined whether the GPx-1 gene modulates A beta (1-42)-induced changes in PKC and ERK levels. We observed that A beta (1-42) treatment (400 pmol, i.c.v.) significantly decreased PKC beta II expression in the hippocampus of mice. A beta (1-42)-induced neurotoxic changes [i.e., oxidative stress (i.e., reactive oxygen species, 4-hydroxy-2-noneal, and protein carbonyl), reduced PKC beta II and phospho-ERK expressions, and memory impairment under Y-maze and passive avoidance test]were more pronounced in GPx-1 knockout than in wild type mice. Importantly, exposure to a GPx-1 gene-encoded adenovirus vector (Adv-GPx-1) significantly increased GPx-1 mRNA and GPx activity in the hippocampus of GPx-1 knockout mice. Adv-GPx-1 exposure also significantly blocked the neurotoxic changes induced by A beta (1-42) in GPx-1 knockout mice. Treatment with ERK inhibitor U0126 did not significantly change Adv-GPx-1-mediated attenuation in PKC beta II expression. In contrast, treatment with PKC inhibitor chelerythrine (CHE) reversed Adv-GPx-1-mediated attenuation in ERK phosphorylation, suggesting that PKC beta II-mediated ERK signaling is important for Adv-GPx-1-mediated potentials against A beta (1-42) insult. Our results suggest that treatment with the antioxidant gene GPx-1 rescues A beta (1-42)-induced memory impairment via activating PKC beta II-mediated ERK signaling.