title: A biphasic U-shape effect of cellular oxidative stress on the macrophage anti-oxidant paraoxonase 2 (PON2) enzymatic activity.
abstract: Expression of macrophage paraoxonase 2 (PON2), a cellular lactonase with anti-oxidant and anti-atherogenic properties, was shown to be upregulated under high oxidative stress. The aim of the present study was to analyze the relationship between the extent of cellular oxidative stress in J774A.1 macrophage and PON2 lactonase activity under various levels of oxidation, obtained by cell incubation with either anti-oxidants or oxidants. PON2 activity exhibited a U-shape response curve. In the oxidative stress range below that of control untreated cells, PON2 activity decreased upon increasing macrophage oxidative state, whereas in the range over that of control untreated cells, PON2 activity increased. The biphasic effect of oxidative stress on macrophage PON2 activity could be related to PON2 inactivation (decreased enzymatic activity) under oxidative stress induction at its low range, whereas at high range of oxidative stress, macrophage anti-oxidant compensatory mechanism up-regulates PON2 (increased protein expression), in order to cope with oxidative burden.
authors.affiliation: Lipid Research Laboratory, Technion Faculty of Medicine, The Rappaport Family Institute for Research in the Medical Sciences and Rambam Medical Center, Haifa 31096, Israel.
authors.forename: Maayan
authors.initials: M
authors.lastname: Shiner
authors.forename: Bianca
authors.initials: B
authors.lastname: Fuhrman
authors.forename: Michael
authors.initials: M
authors.lastname: Aviram
mesh_terms: D000818:Animals; D043303:Aryldialkylphosphatase / Q000378:metabolism*; D002460:Cell Line; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress
chemical_list: D016877:Oxidants; D043303:Aryldialkylphosphatase