P3-371: Interleukin-1β enhances nucleotide-induced α-secretase–dependent amyloid precursor protein processing in rat primary cortical neurons via upregulation of the P2Y 2 receptor

Abstract

The P2Y2 nucleotide receptor (P2Y2R) stimulates α-secretase-dependent cleavage of the amyloid precursor protein (APP) in human 1321N1 astrocytoma cells, causing extracellular release of the neuroprotective protein sAPPα. In this study, we analyzed functional upregulation of the P2Y2R by cytokines and the P2Y2 receptor-mediated production of sAPPα in rat primary cortical neurons (rPCNs). In rPCNs, P2Y2R mRNA and receptor activity were virtually absent in unstimulated cells, whereas overnight treatment with the inflammatory cytokine interleukin 1β (IL-1β) upregulated both P2Y2R mRNA expression and receptor activity. The upregulation of P2Y2R mRNA was abrogated by pre-incubation with an IkappaBα phosphorylation inhibitor Bay 11, which suggests that P2Y2R mRNA transcript levels are regulated through NF–κB signaling. Furthermore, the P2Y2R agonist UTP enhanced the release of sAPPα in rPCNs treated with IL-1β or transfected with P2Y2R mRNA. UTP-induced release of sAPPα from rPCNs was completely inhibited by pretreatment of the cells with the metalloproteinase inhibitor TAPI-2 or the phosphatidylinositol 3-kinase (PI3K) inhibitor LY2904, and was partially inhibited by the MEK inhibitor U0126 and unaffected by the protein kinase C (PKC) inhibitor GF109203. The data indicate that P2Y2R-mediated release of sAPPα from neurons is dependent on ADAM10/17 and PI3K activity, partially dependent on ERK1/2 activity, and does not require activation of PKC. These results suggest that under inflammatory conditions, IL-1β evokes the functional upregulation of the P2Y2R in neurons to promote ADAM10/17-dependent APP processing through P2Y2R-mediated activation of PI3K. Ongoing studies with the TgCRND8 mouse model of Alzheimer's Disease and P2Y2 knockout mice are evaluating these findings in vivo.