Increase of inhibitor-2 of
protein phosphatase-2A [Formula: see text] is associated with
protein phosphatase-2A (PP2A) inhibition and tau hyperphosphorylation in
Alzheimer's disease (AD). Down-regulating [Formula: see text] attenuated amyloidogenesis and improved the cognitive functions in transgenic mice expressing
amyloid precursor
protein (tg2576). Here, we found that silencing [Formula: see text] by hippocampal infusion of [Formula: see text] down-regulated [Formula: see text] (~45%) with reduction of tau phosphorylation/accumulation, improvement of
memory deficits, and dendritic plasticity in 12-month-old human tau transgenic mice. Silencing [Formula: see text] not only restored PP2A activity but also inhibited
glycogen synthase kinase-3β (GSK-3β) with a significant activation of
protein kinase A (PKA) and Akt. In HEK293/tau and N2a/tau cells, silencing [Formula: see text] by [Formula: see text] also significantly reduced tau hyperphosphorylation with restoration of PP2A activity and inhibition of GSK-3β, demonstrated by the decreased GSK-3β total
protein and
mRNA levels, and the increased inhibitory phosphorylation of GSK-3β at serine-9. Furthermore, activation of PKA but not Akt mediated the inhibition of GSK-3β by [Formula: see text] silencing. We conclude that targeting [Formula: see text] can improve tau pathologies and
memory deficits in human tau transgenic mice, and activation of PKA contributes to GSK-3β inhibition induced by silencing [Formula: see text]in vitro, suggesting that [Formula: see text] is a promising multiple target of AD.