title: Inhibition of cytosolic Phospholipase A2 prevents prion peptide-induced neuronal damage and co-localisation with Beta III Tubulin.
abstract: BACKGROUND
  Activation of phospholipase A2 (PLA2) and the subsequent metabolism of arachidonic acid (AA) to prostaglandins have been shown to play an important role in neuronal death in neurodegenerative disease. Here we report the effects of the prion peptide fragment HuPrP106-126 on the PLA2 cascade in primary cortical neurons and translocation of cPLA2 to neurites.
  
  
  RESULTS
  Exposure of primary cortical neurons to HuPrP106-126 increased the levels of phosphorylated cPLA2 and caused phosphorylated cPLA2 to relocate from the cell body to the cellular neurite in a PrP-dependent manner, a previously unreported observation. HuPrP106-126 also induced significant AA release, an indicator of cPLA2 activation; this preceded synapse damage and subsequent cellular death. The novel translocation of p-cPLA2 postulated the potential for exposure to HuPrP106-126 to result in a re-arrangement of the cellular cytoskeleton. However p-cPLA2 did not colocalise significantly with F-actin, intermediate filaments, or microtubule-associated proteins. Conversely, p-cPLA2 did significantly colocalise with the cytoskeletal protein beta III tubulin. Pre-treatment with the PLA2 inhibitor, palmitoyl trifluoromethyl ketone (PACOCF3) reduced cPLA2 activation, AA release and damage to the neuronal synapse. Furthermore, PACOCF3 reduced expression of p-cPLA2 in neurites and inhibited colocalisation with beta III tubulin, resulting in protection against PrP-induced cell death.
  
  
  CONCLUSIONS
  Collectively, these findings suggest that cPLA2 plays a vital role in the action of HuPrP106-126 and that the colocalisation of p-cPLA2 with beta III tubulin could be central to the progress of neurodegeneration caused by prion peptides. Further work is needed to define exactly how PLA2 inhibitors protect neurons from peptide-induced toxicity and how this relates to intracellular structural changes occurring in neurodegeneration.
authors.affiliation: Department of Pathology and Infectious Diseases, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire AL9 7TA, UK. v.last@medsch.ucl.ac.uk
authors.forename: Victoria
authors.initials: V
authors.lastname: Last
authors.forename: Alun
authors.initials: A
authors.lastname: Williams
authors.forename: Dirk
authors.initials: D
authors.lastname: Werling
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007659:Ketones / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000187:drug effects*; D010446:Peptide Fragments / Q000633:toxicity*; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism*; D011328:Prions / Q000633:toxicity*; D021381:Protein Transport / Q000187:drug effects; D016708:Synaptophysin / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007659:Ketones; D010446:Peptide Fragments; D011328:Prions; D016708:Synaptophysin; D014404:Tubulin; C109341:palmitoyl trifluoromethyl ketone; C082632:prion protein (106-126); D014316:Tritium; D016718:Arachidonic Acid; D015759:Ionomycin; C020922:4-O-methyl-12-O-tetradecanoylphorbol 13-acetate; D054510:Phospholipases A2, Cytosolic; D013755:Tetradecanoylphorbol Acetate