title: P2Y2 nucleotide receptors enhance alpha-secretase-dependent amyloid precursor protein processing.
abstract: The amyloid precursor protein (APP) is proteolytically processed by beta- and gamma-secretases to release amyloid beta, the main component in senile plaques found in the brains of patients with Alzheimer disease. Alternatively, APP can be cleaved within the amyloid beta domain by alpha-secretase releasing the non-amyloidogenic product sAPP alpha, which has been shown to have neuroprotective properties. Several G protein-coupled receptors are known to activate alpha-secretase-dependent processing of APP; however, the role of G protein-coupled nucleotide receptors in APP processing has not been investigated. Here it is demonstrated that activation of the G protein-coupled P2Y2 receptor (P2Y2R) subtype expressed in human 1321N1 astrocytoma cells enhanced the release of sAPP alpha in a time- and dose-dependent manner. P2Y2 R-mediated sAPP alpha release was dependent on extracellular calcium but was not affected by 1,2-bis(2-aminophenoxy)ethane-N,N,N,-trimethylammonium salt, an intracellular calcium chelator, indicating that P2Y2R-stimulated intracellular calcium mobilization was not involved. Inhibition of protein kinase C (PKC) with GF109203 or by PKC down-regulation with phorbol ester pre-treatment had no effect on UTP-stimulated sAPP alpha release, indicating a PKC-independent mechanism. U0126, an inhibitor of the mitogen-activated protein kinase pathway, partially inhibited sAPPalpha release by UTP, whereas inhibitors of Src-dependent epidermal growth factor receptor transactivation by P2Y2Rs had no effect. The metalloprotease inhibitors phenanthroline and TAPI-2 and the furin inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethylketone also diminished UTP-induced sAPP alpha release. Furthermore, small interfering RNA silencing of an endogenous adamalysin, ADAM10 or ADAM17/TACE, partially suppressed P2Y2R-activated sAPP alpha release, whereas treatment of cells with both ADAM10 and ADAM17/TACE small interfering RNAs completely abolished UTP-activated sAPP alpha release. These results may contribute to an understanding of the non-amyloidogenic processing of APP.
authors.affiliation: Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7310, USA.
authors.forename: Jean M
authors.initials: JM
authors.lastname: Camden
authors.forename: Ann M
authors.initials: AM
authors.lastname: Schrader
authors.forename: Ryan E
authors.initials: RE
authors.lastname: Camden
authors.forename: Fernando A
authors.initials: FA
authors.lastname: González
authors.forename: Laurie
authors.initials: L
authors.lastname: Erb
authors.forename: Cheikh I
authors.initials: CI
authors.lastname: Seye
authors.forename: Gary A
authors.initials: GA
authors.lastname: Weisman
mesh_terms: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D053829:Amyloid Precursor Protein Secretases; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000737:chemistry*; D016282:Aspartic Acid Endopeptidases; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D045744:Cell Line, Tumor; D002490:Central Nervous System / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D045683:Furin / Q000737:chemistry; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D008301:Maleimides / Q000494:pharmacology; D008666:Metalloendopeptidases / Q000737:chemistry; D009570:Nitriles / Q000494:pharmacology; D010703:Phorbol Esters / Q000737:chemistry; D011493:Protein Kinase C / Q000737:chemistry; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism / Q000502:physiology*; D058473:Receptors, Purinergic P2Y2; D013755:Tetradecanoylphorbol Acetate; D013997:Time Factors; D014162:Transfection; D014544:Uridine Triphosphate / Q000737:chemistry
chemical_list: C111573:1-oxodecyl-arginyl-valyl-lysyl-arginine chloromethyl ketone; D000590:Amino Acid Chloromethyl Ketones; D016564:Amyloid beta-Protein Precursor; D002070:Butadienes; D002614:Chelating Agents; D007211:Indoles; D008301:Maleimides; D009570:Nitriles; C546385:P2RY2 protein, human; D010703:Phorbol Esters; D034741:RNA, Small Interfering; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; C113580:U 0126; D004533:Egtazic Acid; D011493:Protein Kinase C; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D045683:Furin; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D014544:Uridine Triphosphate