title: PGE2 inhibits MMP expression by suppressing MKK4-JNK MAP kinase-c-JUN pathway via EP4 in human articular chondrocytes.
abstract: Prostaglandin E2 (PGE2) is one of pro-inflammatory mediators. PGE2 maintains the homeostasis of many organs including articular cartilage, and a previous report showed that continuous inhibition of PGE2 accelerates the progression of osteoarthritis (OA). While PGE2 inhibits matrix metalloprotease (MMP) expression in several types of cells, little is known on direct effects of PGE2 on MMP expression in articular chondrocytes. The objective of this study was to investigate direct effects of PGE2 on IL-1beta-induced MMP-1 and MMP-13 expression and the intracellular signaling in articular chondrocytes. PGE2 showed inhibitory effects on IL-1beta-induced MMP-1 and MMP-13 expression demonstrated by immunoblotting both in OA and normal chondrocytes, which was further confirmed by enzyme-linked immunosorbent assay and immunohistochemistry of explant cultures of articular cartilages. An EP4 agonist, ONO-AE1-329, mimicked the inhibitory effect of PGE2, while an EP4 antagonist, ONO-AE3-208, blocked the effects. PGE2 suppressed the phosphorylation of JNK and ERK MAP kinases, but only knockdown of JNK by specific siRNA mimicked the effect of PGE2. PGE2 further inhibited the phosphorylation of MKK4 without suppression of MKK7 phosphorylation, and of c-JUN to decrease expression levels of MMP-1 and MMP-13. These results demonstrate that PGE2 inhibits IL-1beta-induced MMP-1 and MMP-13 productions via EP4 by suppressing MKK4-JNK MAP kinase-c-JUN pathway.
authors.affiliation: Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo, Kyoto 606-8507, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Nishitani
authors.forename: Hiromu
authors.initials: H
authors.lastname: Ito
authors.forename: Teruko
authors.initials: T
authors.lastname: Hiramitsu
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Tsutsumi
authors.forename: Shimei
authors.initials: S
authors.lastname: Tanida
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kitaori
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshitomi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D002358:Cartilage, Articular / Q000166:cytology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism* / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D048688:MAP Kinase Kinase 7 / Q000378:metabolism*; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism*; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism*; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D018078:Receptors, Prostaglandin E / Q000378:metabolism*; D058309:Receptors, Prostaglandin E, EP4 Subtype; D015398:Signal Transduction
chemical_list: D053583:Interleukin-1beta; C545650:PTGER4 protein, human; D016755:Proto-Oncogene Proteins c-jun; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; C482559:MAP2K4 protein, human; C482569:MAP2K7 protein, human; D053509:Matrix Metalloproteinase 13; D020781:Matrix Metalloproteinase 1; D015232:Dinoprostone