title: Analysis of isoform specific ERK signaling on the effects of interleukin-1β on COX-2 expression and PGE2 production in human chondrocytes.
abstract: The MAPK/ERK pathway is involved in IL-1β-induced cyclooxygenase (COX-2) expression and prostaglandin E2 (PGE2) production; two factors that play important roles in OA pathogenesis. In the present study, we find that IL-1β induced COX-2 expression and PGE2 production in human chondrocytes via a process that required the activation of the MAPK/ERK pathway. To evaluate the respective roles and relationship of ERK1 and ERK2 on IL-1β induced COX-2 expression and PGE2 production, small interfering RNA was used to knockdown ERK1, ERK2 or both in human chondrocytes. COX-2 expression and PGE2 production were significantly suppressed to a similar degree by the silencing of ERK1 or ERK2 alone. Moreover, the combined knockdown displayed a synergistic effect. Simultaneously, Western blotting indicated that the knockdown of ERK1 or ERK2 down regulated phospho-ERK1 and ERK1 or phospho-ERK2 and ERK2 levels, respectively. No significant compensatory mechanism through the upregulation of the other phospho-ERK and ERK isoform was observed. The combined silencing suppressed both phospho-ERK1/2 and ERK1/2. In conclusion, each ERK isoform similarly influenced IL-1β-mediated COX-2 expression and PGE2 production in human chondrocytes, and ERK1 and ERK2 displayed synergistic effects. Although, inhibition of both ERK1 and ERK2 would be a more effective, each ERK isoform may sufficiently regulate these effects in human chondrocytes. ERK1 or ERK2 may be potential therapeutic target for the inflammatory process of OA.
authors.affiliation: Department of Orthopaedics, The No. 6 Affiliated Hospital of Shanghai Jiaotong University School of Medicine, 600 Yishan Road, Shanghai, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.forename: Fengfeng
authors.initials: F
authors.lastname: Li
authors.forename: Cunyi
authors.initials: C
authors.lastname: Fan
authors.forename: Chunyang
authors.initials: C
authors.lastname: Wang
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Ruan
mesh_terms: D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000201:enzymology*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D015232:Dinoprostone / Q000096:biosynthesis*; D055785:Gene Knockdown Techniques; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism* / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D010003:Osteoarthritis / Q000201:enzymology*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction
chemical_list: D053583:Interleukin-1beta; D007527:Isoenzymes; D034741:RNA, Small Interfering; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D015232:Dinoprostone