title: Interleukin-1beta enhances nucleotide-induced and alpha-secretase-dependent amyloid precursor protein processing in rat primary cortical neurons via up-regulation of the P2Y(2) receptor.
abstract: The heterologous expression and activation of the human P2Y(2) nucleotide receptor (P2Y(2)R) in human 1321N1 astrocytoma cells stimulates alpha-secretase-dependent cleavage of the amyloid precursor protein (APP), causing extracellular release of the non-amyloidogenic protein secreted amyloid precursor protein (sAPPalpha). To determine whether a similar response occurs in a neuronal cell, we analyzed whether P2Y(2)R-mediated production of sAPPalpha occurs in rat primary cortical neurons (rPCNs). In rPCNs, P2Y(2)R mRNA and receptor activity were virtually absent in quiescent cells, whereas overnight treatment with the pro-inflammatory cytokine interleukin-1beta (IL-1beta) up-regulated both P2Y(2)R mRNA expression and receptor activity by four-fold. The up-regulation of the P2Y(2)R was abrogated by pre-incubation with Bay 11-7085, an IkappaB-alpha phosphorylation inhibitor, which suggests that P2Y(2)R mRNA transcript levels are regulated through nuclear factor-kappa-B (NFkappaB) signaling. Furthermore, the P2Y(2)R agonist Uridine-5'-triphosphate (UTP) enhanced the release of sAPPalpha in rPCNs treated with IL-1beta or transfected with P2Y(2)R cDNA. UTP-induced release of sAPPalpha from rPCNs was completely inhibited by pre-treatment of the cells with the metalloproteinase inhibitor TACE inhibitor (TAPI-2) or the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, and was partially inhibited by the MAPK/extracellular signal-regulated kinase inhibitor U0126 and the protein kinase C inhibitor GF109203. These data suggest that P2Y(2)R-mediated release of sAPPalpha from cortical neurons is directly dependent on a disintegrin and metalloproteinase (ADAM) 10/17 and PI3K activity, whereas extracellular signal-regulated kinase 1/2 and PI3K activity may indirectly regulate APP processing. These results demonstrate that elevated levels of pro-inflammatory cytokines associated with neurodegenerative diseases, such as IL-1beta, can enhance non-amyloidogenic APP processing through up-regulation of the P2Y(2)R in neurons.
authors.affiliation: Interdisciplinary Neuroscience Program, University of Missouri, Columbia, Missouri, USA.
authors.forename: Qiongman
authors.initials: Q
authors.lastname: Kong
authors.forename: Troy S
authors.initials: TS
authors.lastname: Peterson
authors.forename: Olga
authors.initials: O
authors.lastname: Baker
authors.forename: Emily
authors.initials: E
authors.lastname: Stanley
authors.forename: Jean
authors.initials: J
authors.lastname: Camden
authors.forename: Cheikh I
authors.initials: CI
authors.lastname: Seye
authors.forename: Laurie
authors.initials: L
authors.lastname: Erb
authors.forename: Agnes
authors.initials: A
authors.lastname: Simonyi
authors.forename: W Gibson
authors.initials: WG
authors.lastname: Wood
authors.forename: Grace Y
authors.initials: GY
authors.lastname: Sun
authors.forename: Gary A
authors.initials: GA
authors.lastname: Weisman