title: Prostaglandin E receptor type 4-associated protein interacts directly with NF-kappaB1 and attenuates macrophage activation.
abstract: Macrophage activation participates pivotally in the pathophysiology of chronic inflammatory diseases, including atherosclerosis. Through the receptor EP4, prostaglandin E(2) (PGE(2)) exerts an anti-inflammatory action in macrophages, suppressing stimulus-induced expression of certain proinflammatory genes, including chemokines. We recently identified a novel EP4 receptor-associated protein (EPRAP), whose function in PGE(2)-mediated anti-inflammation remains undefined. Here we demonstrate that PGE(2) pretreatment selectively inhibits lipopolysaccharide (LPS)-induced nuclear factor kappaB1 (NF-kappaB1) p105 phosphorylation and degradation in mouse bone marrow-derived macrophages through EP4-dependent mechanisms. Similarly, directed EPRAP expression in RAW264.7 cells suppresses LPS-induced p105 phosphorylation and degradation, and subsequent activation of mitogen-activated protein kinase kinase 1/2. Forced expression of EPRAP also inhibits NF-kappaB activation induced by various proinflammatory stimuli in a concentration-dependent manner. In co-transfected cells, EPRAP, which contains multiple ankyrin repeat motifs, directly interacts with NF-kappaB1 p105/p50 and forms a complex with EP4. In EP4-overexpressing cells, PGE(2) enhances the protective action of EPRAP against stimulus-induced p105 phosphorylation, whereas EPRAP silencing in RAW264.7 cells impairs the inhibitory effect of PGE(2)-EP4 signaling on LPS-induced p105 phosphorylation. Additionally, EPRAP knockdown as well as deficiency of NF-kappaB1 in macrophages attenuates the inhibitory effect of PGE(2) on LPS-induced MIP-1beta production. Thus, PGE(2)-EP4 signaling augments NF-kappaB1 p105 protein stability through EPRAP after proinflammatory stimulation, limiting macrophage activation.
authors.affiliation: Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
authors.forename: Manabu
authors.initials: M
authors.lastname: Minami
authors.forename: Koichi
authors.initials: K
authors.lastname: Shimizu
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Eduardo
authors.initials: E
authors.lastname: Folco
authors.forename: Marco-Lopez
authors.initials: ML
authors.lastname: Ilasaca
authors.forename: Mark W
authors.initials: MW
authors.lastname: Feinberg
authors.forename: Masanori
authors.initials: M
authors.lastname: Aikawa
authors.forename: Peter
authors.initials: P
authors.lastname: Libby
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D050197:Atherosclerosis / Q000235:genetics / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics; D015232:Dinoprostone / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000235:genetics / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects / Q000235:genetics; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D052002:NF-kappa B p50 Subunit / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000235:genetics; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism*; D058309:Receptors, Prostaglandin E, EP4 Subtype; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D018925:Chemokines; C444344:FEM1A protein, human; C506176:Fem1a protein, mouse; D008070:Lipopolysaccharides; D052002:NF-kappa B p50 Subunit; C545650:PTGER4 protein, human; C545651:Ptger4 protein, mouse; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; C482128:MAP2K2 protein, human; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; C482129:Map2k2 protein, mouse; D015232:Dinoprostone