title: Amyloid beta enhances cytosolic phospholipase A2 level and arachidonic acid release via nitric oxide in APP-transfected PC12 cells.
abstract: Cytosolic phospholipase A2 (cPLA2) preferentially liberates arachidonic acid (AA), which is known to be elevated in Alzheimer's disease (AD). The aim of this study was to investigate the possible relationship between enhanced nitric oxide (NO) generation observed in AD and cPLA2 protein level, phosphorylation, and AA release in rat pheochromocytoma cell lines (PC12) differing in amyloid beta secretion. PC12 control cells, PC12 cells bearing the Swedish double mutation in amyloid beta precursor protein (APPsw), and PC12 cells transfected with human APP (APPwt) were used. The transfected APPwt and APPsw PC12 cells showed an about 2.8- and 4.8-fold increase of amyloid beta (Abeta) secretion comparing to control PC12 cells. An increase of NO synthase activity, cGMP and free radical levels in APPsw and APPwt PC12 cells was observed. cPLA2 protein level was higher in APPsw and APPwt PC12 cells comparing to PC12 cells. Moreover, phosphorylated cPLA2 protein level and [3H]AA release were also higher in APP-transfected PC12 cells than in the control PC12 cells. An NO donor, sodium nitroprusside, stimulated [3H]AA release from prelabeled cells. The highest NO-induced AA release was observed in control PC12 cells, the effect in the other cell lines being statistically insignificant. Inhibition of cPLA2 by AACOCF3 significantly decreased the AA release. Inhibitors of nNOS and gamma-secretase reduced AA release in APPsw and APPwt PC12 cells. The basal cytosolic [Ca2+](i) and mitochondrial Ca2+ concentration was not changed in all investigated cell lines. Stimulation with thapsigargin increased the cytosolic and mitochondrial Ca2+ level, activated NOS and stimulated AA release in APP-transfected PC12 cells. These results indicate that Abeta peptides enhance the protein level and phosphorylation of cPLA2 and AA release by the NO signaling pathway.
authors: Medical Research Center, Department of Cellular Signaling, Polish Academy of Sciences, Warszawa, Poland.
authors: Małgorzata
authors: M
authors: Chalimoniuk
authors: Anna
authors: A
authors: Stolecka
authors: Magdalena
authors: M
authors: Cakała
authors: Susane
authors: S
authors: Hauptmann
authors: Kris
authors: K
authors: Schulz
authors: Uta
authors: U
authors: Lipka
authors: Kristine
authors: K
authors: Leuner
authors: Anne
authors: A
authors: Eckert
authors: Walter E
authors: WE
authors: Muller
authors: Joanna B
authors: JB
authors: Strosznajder
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001095:Arachidonic Acids / Q000494:pharmacology; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D016716:PC12 Cells; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D001095:Arachidonic Acids; D020030:Nitric Oxide Donors; D017382:Reactive Oxygen Species; C081565:arachidonyltrifluoromethane; D009599:Nitroprusside; D016718:Arachidonic Acid; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D054510:Phospholipases A2, Cytosolic; D006152:Cyclic GMP; D002118:Calcium