Neuroglobin Attenuates Beta Amyloid-Induced Apoptosis Through Inhibiting Caspases Activity by Activating PI3K/Akt Signaling Pathway

Excessive accumulation and deposition of amyloid-beta (A beta) has been considered as a pivotal event in the pathogenesis of Alzheimer's disease (AD). Neuronal apoptosis is one of the characteristics of AD, which is a possible mechanism underlying A beta-induced neuronal neurotoxicity. Neuroglobin (Ngb) is a newly discovered vertebrate heme protein that exhibits neuroprotective functions against cell death associated with hypoxic and amyloid insult. However, until now, the exact mechanism of neuroglobin's protective action has not been determined. To investigate the potential neuroprotective roles and mechanisms of Ngb, transgenic AD mice (APPswe/PSEN1dE9) and SH-SY5Y cells transfected with pAPPswe were enrolled into the study. In vivo, overexpression of Ngb via intracerebroventricular injection with pNgb attenuated memory, cognitive impairment, and plaque generations. In pAPPswe transfected SH-SY5Y cells, Ngb not only decreased the generation of A beta(42), but also attenuated mitochondrial dysfunction and apoptosis through suppressing the activation of caspase-3, caspase-9 by Akt activating phosphorylation, which were restrained by phosphatidylinositol 3-kinase inhibitor (LY294002). Our data indicate the anti-apoptotic property of Ngb may play a neuroprotective role against AD.