title: EP4 Receptor-Associated Protein in Macrophages Protects against Bleomycin-Induced Pulmonary Inflammation in Mice.
abstract: Excessive activation of inflammatory macrophages drives the pathogenesis of many chronic diseases. EP4 receptor-associated protein (EPRAP) has been identified as a novel, anti-inflammatory molecule in macrophages. In this study, we investigated the role of EPRAP using a murine model of bleomycin (BLM)-induced pulmonary inflammation. When compared with wild-type mice, EPRAP-deficient mice exhibited significantly higher mortality, and increased accumulation of macrophages and proinflammatory molecules in the lung 7 d post-BLM administration. Accordingly, the levels of phosphorylated p105, MEK1/2, and ERK1/2 were elevated in EPRAP-deficient alveolar macrophages following BLM administration. In contrast, macrophage-specific EPRAP overexpression decreased the production of proinflammatory cytokines and chemokines, suggesting that EPRAP in macrophages plays a key role in attenuating BLM-induced pulmonary inflammation. As EPRAP is phosphorylated after translation, we examined the role of posttranslational modifications in cellular inflammatory activation using mouse embryo fibroblasts (MEFs) expressing mutant EPRAP proteins. Expression of mutant EPRAP, in which serine-108 and serine-608 were replaced with alanine (EPRAP S108A/S608A), markedly suppressed TNF-α production in LPS-treated MEFs. Conversely, the serine phosphatase 2A (PP2A) inhibitor, cantharidic acid, increased LPS-induced TNF-α production in MEFs expressing wild-type EPRAP, but not in MEFs expressing EPRAP S108A/S608A. Immunoprecipitation analyses demonstrated that EPRAP associated with PP2A in both MEFs and alveolar macrophages from BLM-treated mice. Our data suggest that PP2A dephosphorylates EPRAP, which may be a crucial step in exertion of its anti-inflammatory properties. For these reasons, we believe the EPRAP-PP2A axis in macrophages holds the key to treating chronic inflammatory disorders.
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Sei
authors: 0000-0001-7821-0102
authors: S
authors: Higuchi
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Risako
authors: R
authors: Fujikawa
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.|Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan; and.
authors: Taichi
authors: T
authors: Ikedo
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.|Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan; and.
authors: Kosuke
authors: K
authors: Hayashi
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Mika
authors: M
authors: Yasui
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.|Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan; and.
authors: Manabu
authors: M
authors: Nagata
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.|Department of Gastroenterology and Hepatology, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Masato
authors: M
authors: Nakatsuji
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors: Masayuki
authors: M
authors: Yokode
authors: Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan; mminami@kuhp.kyoto-u.ac.jp.
authors: Manabu
authors: 0000-0003-0052-398X
authors: M
authors: Minami
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001761:Bleomycin / Q000009:adverse effects* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000276:immunology*; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000276:immunology / Q000473:pathology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000276:immunology; D005347:Fibroblasts / Q000276:immunology / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D020125:Mutation, Missense; D010766:Phosphorylation / Q000235:genetics / Q000276:immunology; D011014:Pneumonia / Q000139:chemically induced / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000276:immunology
chemical_list: D018797:Cell Cycle Proteins; C506176:Fem1a protein, mouse; D001761:Bleomycin; D048049:Extracellular Signal-Regulated MAP Kinases; D054648:Protein Phosphatase 2