title: Secretory phospholipase A2 type III enhances alpha-secretase-dependent amyloid precursor protein processing through alterations in membrane fluidity.
abstract: In the non-amyloidogenic pathway, amyloid precursor protein (APP) is cleaved by alpha-secretases to produce alpha-secretase-cleaved soluble APP (sAPP(alpha)) with neuroprotective and neurotrophic properties; therefore, enhancing the non-amyloidogenic pathway has been suggested as a potential pharmacological approach for the treatment of Alzheimer's disease. Here, we demonstrate the effects of type III secretory phospholipase A(2) (sPLA(2)-III) on sAPP(alpha) secretion. Exposing differentiated neuronal cells (SH-SY5Y cells and primary rat neurons) to sPLA(2)-III for 24 h increased sAPP(alpha) secretion and decreased levels of Abeta(1-42) in SH-SY5Y cells, and these changes were accompanied by increased membrane fluidity. We further tested whether sPLA(2)-III-enhanced sAPP(alpha) release is due in part to the production of its hydrolyzed products, including arachidonic acid (AA), palmitic acid (PA), and lysophosphatidylcholine (LPC). Addition of AA but neither PA nor LPC mimicked sPLA(2)-III-induced increases in sAPP(alpha) secretion and membrane fluidity. Treatment with sPLA(2)-III and AA increased accumulation of APP at the cell surface but did not alter total expressions of APP, alpha-secretases, and beta-site APP cleaving enzyme. Taken together, these results support the hypothesis that sPLA(2)-III enhances sAPP(alpha) secretion through its action to increase membrane fluidity and recruitment of APP at the cell surface.
authors.affiliation: Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Yang
authors.forename: Wenwen
authors.initials: W
authors.lastname: Sheng
authors.forename: Yan
authors.initials: Y
authors.lastname: He
authors.forename: Jiankun
authors.initials: J
authors.lastname: Cui
authors.forename: Mark A
authors.initials: MA
authors.lastname: Haidekker
authors.forename: Grace Y
authors.initials: GY
authors.lastname: Sun
authors.forename: James C-M
authors.initials: JC
authors.lastname: Lee
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D054520:Group III Phospholipases A2 / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D006868:Hydrolysis; D008244:Lysophosphatidylcholines / Q000378:metabolism / Q000494:pharmacology; D008560:Membrane Fluidity / Q000187:drug effects*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019308:Palmitic Acid / Q000378:metabolism / Q000494:pharmacology; D051381:Rats
chemical_list: D016564:Amyloid beta-Protein Precursor; D008244:Lysophosphatidylcholines; D016718:Arachidonic Acid; D019308:Palmitic Acid; D054520:Group III Phospholipases A2; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509281:Bace1 protein, rat