title: 15-Lipoxygenase 1 interacts with phosphatidylethanolamine-binding protein to regulate MAPK signaling in human airway epithelial cells.
abstract: Epithelial 15-lipoxygenase 1 (15LO1) and activated ERK are increased in asthma despite modest elevations in IL-13. MAPK kinase (MEK)/ERK activation is regulated by interactions of Raf-1 with phosphatidylethanolamine-binding protein 1 (PEBP1). Epithelial 15LO1 generates intracellular 15-hydroxyeicosatetraenoic acid (15HETE) conjugated to phosphatidylethanolamine (PE) (15HETE-PE). We hypothesized that (i) 15LO1 and its product 15HETE-PE serve as signaling molecules interacting with PEBP1 to activate Raf-1/MEK/ERK and that (ii) this 15LO1-15HETE-PE-regulated ERK activation amplifies IL-4Rα downstream pathways. Our results demonstrate that high epithelial 15LO1 levels correlate with ERK phosphorylation ex vivo. In vitro, IL-13 induces 15LO1, which preferentially binds to PEBP1, causing PEBP1 to dissociate from Raf-1 and activate ERK. Exogenous 15HETE-PE similarly induces dissociation of PEBP1 from Raf-1 independently of IL-13/15LO1. siRNA knockdown of 15LO1 decreases the dissociation of Raf-1 from PEBP1, and the resulting lower ERK activation leads to lower downstream IL-4Rα-related gene expression. Identical protein-protein interactions are observed in endobronchial biopsies and fresh epithelial cells from asthmatics ex vivo. Colocalization of Raf-1 to PEBP1 is low in asthmatic tissue and cells compared with normals, whereas there is striking colocalization of 15LO1 with PEBP1 in asthma. Low 15LO1 levels in normals limit its colocalization with PEBP1. The results confirm a previously unknown signaling role for 15LO1 and its PE-conjugated eicosanoid product in human airway epithelial cells. This pathway enhances critical inflammatory pathways integral to asthma pathogenesis.
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh Asthma Institute, University of Pittsburgh Medical Center/University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
authors.forename: Jinming
authors.initials: J
authors.lastname: Zhao
authors.forename: Valerie B
authors.initials: VB
authors.lastname: O'Donnell
authors.forename: Silvana
authors.initials: S
authors.lastname: Balzar
authors.forename: Claudette M
authors.initials: CM
authors.lastname: St Croix
authors.forename: John B
authors.initials: JB
authors.lastname: Trudeau
authors.forename: Sally E
authors.initials: SE
authors.lastname: Wenzel
mesh_terms: D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D001249:Asthma / Q000201:enzymology / Q000473:pathology; D001667:Binding, Competitive / Q000187:drug effects; D001980:Bronchi / Q000473:pathology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000075906:Chemokine CCL26; D019742:Chemokines, CC / Q000378:metabolism; D003710:Demography; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology; D018793:Interleukin-13 / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D055271:Mucin 5AC / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D049488:Phosphatidylethanolamine Binding Protein / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism
chemical_list: C120429:CCL26 protein, human; D000075906:Chemokine CCL26; D019742:Chemokines, CC; D006893:Hydroxyeicosatetraenoic Acids; D018793:Interleukin-13; C524678:MUC5AC protein, human; D055271:Mucin 5AC; C511482:PEBP1 protein, human; D049488:Phosphatidylethanolamine Binding Protein; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; C515716:ALOX15 protein, human; D001093:Arachidonate 15-Lipoxygenase; D052247:Nitric Oxide Synthase Type II; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases