title: Membrane-dependent Activities of Human 15-LOX-2 and Its Murine Counterpart: IMPLICATIONS FOR MURINE MODELS OF ATHEROSCLEROSIS.
abstract: The enzyme encoded by the ALOX15B gene has been linked to the development of atherosclerotic plaques in humans and in a mouse model of hypercholesterolemia. In vitro, these enzymes, which share 78% sequence identity, generate distinct products from their substrate arachidonic acid: the human enzyme, a 15-S-hydroperoxy product; and the murine enzyme, an 8-S-product. We probed the activities of these enzymes with nanodiscs as membrane mimics to determine whether they can access substrate esterified in a bilayer and characterized their activities at the membrane interface. We observed that both enzymes transform phospholipid-esterified arachidonic acid to a 15-S-product. Moreover, when expressed in transfected HEK cells, both enzymes result in significant increases in the amounts of 15-hydroxyderivatives of eicosanoids detected. In addition, we show that 15-LOX-2 is distributed at the plasma membrane when the HEK293 cells are stimulated by the addition Ca(2+) ionophore and that cellular localization is dependent upon the presence of a putative membrane insertion loop. We also report that sequence differences between the human and mouse enzymes in this loop appear to confer distinct mechanisms of enzyme-membrane interaction for the homologues.
authors.affiliation: From the Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803 and.
authors.forename: Gunes
authors.initials: G
authors.lastname: Bender
authors.affiliation: From the Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803 and.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Schexnaydre
authors.affiliation: the Department of Pharmacology, University of Colorado at Denver, Aurora, Colorado 80045.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Murphy
authors.affiliation: the Department of Pharmacology, University of Colorado at Denver, Aurora, Colorado 80045.
authors.forename: Charis
authors.initials: C
authors.lastname: Uhlson
authors.affiliation: From the Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803 and newcomer@lsu.edu.
authors.forename: Marcia E
authors.initials: ME
authors.lastname: Newcomer
mesh_terms: D000818:Animals; D001093:Arachidonate 15-Lipoxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001095:Arachidonic Acids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050197:Atherosclerosis / Q000201:enzymology / Q000235:genetics; D061207:Calcium Ionophores / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D004195:Disease Models, Animal; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D017433:Protein Structure, Secondary; D021381:Protein Transport / Q000187:drug effects
chemical_list: D001095:Arachidonic Acids; D061207:Calcium Ionophores; C458528:ALOX15B protein, human; D001093:Arachidonate 15-Lipoxygenase
keywords: arachidonic acid (AA) (ARA); eicosanoid; lipid signaling; lipoxygenase pathway; phospholipid