COX-2 metabolic products the prostaglandin I2 and F2α mediate the effects of TNF-α and Zn2+ in stimulating the phosphorylation of Tau

摘要

Although the roles of cyclooxygenase-2 (COX-2) and prostaglandins (PGs) in regulating amyloid precursor protein (APP) cleavage and β-amyloid protein (Aβ) production have been the subjects of numerous investigations, their effects on tau phosphorylation have been largely overlooked. Using human Tau^P301S transgenic (Tg) mice as in vivo model, our results demonstrated that PGI2 and PGF2α mediated the effects of tumor necrosis factor α (TNF-α) and Zinc ions (Zn²⁺) on upregulating the phosphorylation of tau via the PI3-K/AKT, ERK1/2 and JNK/c-Jun signaling pathways. Specifically, we initially found that high level of Zn²⁺ upregulates the expression of COX-2 via stimulating the activity of TNF-α in a zinc transporter 3 (ZnT3)-dependent mechanism. COX-2 upregulation then stimulates the phosphorylation of tau at both Ser 202 and Ser 400/Thr 403/Ser 404 via PGI2 and F2α treatment either in i.c.v.-injected mice or in n2a cells. Using n2a cells as in vitro model, we further revealed critical roles for the PI3-K/AKT, ERK1/2 and JNK/c-Jun pathways in mediating the effects of PGI2 and F2α in the phosphorylation of tau. Finally, NS398 treatment delayed the onset of cognitive decline in Tau^P301S Tg mice according to the nest construction or limb clasping test.