title: Leukotriene B4 receptor type 2 (BLT2) enhances skin barrier function by regulating tight junction proteins.
abstract: GPCRs are involved in numerous physiologic functions and are important drug targets. Although the epithelial barrier is important for protection from invading pathogens, the correlation between GPCRs and epithelial barrier function remains unknown. Leukotriene B4 (LTB4) receptor type 2 (BLT2), mainly expressed in epithelial cells, is a GPCR for 12(S)-hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) and LTB4. In our study, BLT2 localized at the lateral membrane in BLT2-overexpressing Madin-Darby canine kidney (MDCK) II cells and in the small intestine of BLT2-transgenic mice. BLT2-deficient mice exhibited higher transepidermal water loss and were more sensitive to epicutaneous sensitization. MDCK-BLT2 cells recovered transepithelial electrical resistance (TER) after a calcium switch faster than did MDCK-Mock cells, and 12-HHT stimulation accelerated TER recovery only in MDCK-BLT2 cells. Quantitative PCR and immunoblot analyses revealed that the 12-HHT/BLT2 axis up-regulated claudin-4 (CLDN4) expression in MDCK-BLT2 cells and human primary keratinocytes, and CLDN4 knockdown abolished 12-HHT-dependent TER recovery. Acceleration of TER recovery and induction of CLDN4 expression by 12-HHT stimulation were abolished by inhibition of Gαi protein or p38 MAPK. These results show that 12-HHT/BLT2 enhances epithelial barrier function by increasing CLDN4 expression via the Gαi protein-p38 MAPK pathway.
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Ishii
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China ksaeki@juntendo.ac.jp yokomizo-tky@umin.ac.jp.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Saeki
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Sasaki
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Koga
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Chikara
authors.initials: C
authors.lastname: Meno
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Okuno
authors.affiliation: *Department of Medical Biochemistry, Research Institute for Diseases of the Chest, and Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan; and Department of Endocrinology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China ksaeki@juntendo.ac.jp yokomizo-tky@umin.ac.jp.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yokomizo
mesh_terms: D000818:Animals; D062506:Claudin-4 / Q000096:biosynthesis / Q000235:genetics; D004285:Dogs; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D018345:Mice, Knockout; D018102:Receptors, Leukotriene B4 / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000166:cytology / Q000378:metabolism*; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D062506:Claudin-4; C568158:Cldn4 protein, mouse; D005231:Fatty Acids, Unsaturated; C412867:Ltb4r2 protein, mouse; D018102:Receptors, Leukotriene B4; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; D048051:p38 Mitogen-Activated Protein Kinases
keywords: G protein; GPCR; claudin-4; p38 MAPK