title: Thromboxane receptor activation mediates isoprostane-induced increases in amyloid pathology in Tg2576 mice.
abstract: Alzheimer's disease (AD) amyloid plaques are composed of amyloid-beta (Abeta) peptides produced from proteolytic cleavage of amyloid precursor protein (APP). Isoprostanes, markers of in vivo oxidative stress, are elevated in AD patients and in the Tg2576 mouse model of AD-like Abeta brain pathology. To determine whether isoprostanes increase Abeta production, we delivered isoprostane iPF(2alpha)-III into the brains of Tg2576 mice. Although treated mice showed increased brain Abeta levels and plaque-like deposits, this was blocked by a thromboxane (TP) receptor antagonist, suggesting that TP receptor activation mediates the effects of iPF(2alpha)-III on Abeta. This hypothesis was supported by cell culture studies that showed that TP receptor activation increased Abeta and secreted APP ectodomains. This increase was a result of increased APP mRNA stability leading to elevated APP mRNA and protein levels. The increased APP provides more substrate for alpha and beta secretase proteolytic cleavages, thereby increasing Abeta generation and amyloid plaque deposition. To test the effectiveness of targeting the TP receptor for AD therapy, Tg2576 mice underwent long-term treatment with S18886, an orally available TP receptor antagonist. S18886 treatment reduced amyloid plaques, insoluble Abeta, and APP levels, thereby implicating TP receptor signaling as a novel target for AD therapy.
authors.affiliation: Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Diana W
authors.initials: DW
authors.lastname: Shineman
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Susan N
authors.initials: SN
authors.lastname: Leight
authors.forename: Domenico
authors.initials: D
authors.lastname: Pratico
authors.forename: Virginia M-Y
authors.initials: VM
authors.lastname: Lee
mesh_terms: D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D028421:Isoprostanes / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D009281:Naphthalenes / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology; D011863:Radioimmunoassay / Q000379:methods; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D028421:Isoprostanes; D009281:Naphthalenes; D010446:Peptide Fragments; D011422:Propionates; D017482:Receptors, Thromboxane; C438786:isoprostane F2alpha III; C501362:terutroban