title: MicroRNA-558 regulates the expression of cyclooxygenase-2 and IL-1β-induced catabolic effects in human articular chondrocytes.
abstract: OBJECTIVE
  Cyclooxygenase-2 (COX-2) is a major prostaglandin E2 (PGE2) synthetic enzyme and is involved in the pathogenesis of chronic inflammation and pain in osteoarthritis (OA). The objective of this study was to directly address whether microRNA (miR)-558 can control the interleukin (IL)-1β-mediated induction of COX-2 and catabolic effects in human articular chondrocytes.
  
  
  METHODS
  Total RNA was extracted from the cartilage tissues of normal and OA donors or cultured human articular chondrocytes. The expression of miR-558 was quantified by TaqMan assay. To investigate the repressive effect of miR-558 on COX-2 expression, human chondrocytes and chondrogenic SW1353 cells were transfected with mature miR-558 or an antisense inhibitor (anti-miR-558). The expression of COX-2 protein was determined by Western blot analysis and the involvement of miR-558 in IL-1β-induced catabolic effects was examined by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Direct interaction between miR-558 and the putative site in the 3'-untranslated region (UTR) of COX-2 messenger RNA (mRNA) was validated by luciferase reporter assay.
  
  
  RESULTS
  Normal human articular cartilage expressed miR-558, and its expression was significantly lower in OA cartilage. Stimulation with IL-1β led to a significant reduction in miR-558 expression in normal and OA chondrocytes. IL-1β-induced activation of MAP kinase (MAPK) and nuclear factor-κB (NF-κB) decreased miR-558 expression and induced COX-2 expression in chondrocytes. The overexpression of miR-558 directly suppressed the luciferase activity of a reporter construct containing the 3'-UTR of human COX-2 mRNA and significantly inhibited IL-1β-induced upregulation of COX-2, while treatment with anti-miR-558 enhanced IL-1β-induced COX-2 expression and reporter activity in chondrocytes. Interestingly, IL-1β-induced activation of NF-κB and expression of matrix metalloproteinase (MMP)-1 and MMP-13 was significantly inhibited by miR-558 overexpression.
  
  
  CONCLUSIONS
  These findings demonstrated that cartilage homeostasis is influenced by miR-558, which directly targets COX-2 and regulates IL-1β-stimulated catabolic effects in human chondrocytes.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Kyunggi, Republic of Korea. sujin153@naver.com
authors.forename: S J
authors.initials: SJ
authors.lastname: Park
authors.forename: E J
authors.initials: EJ
authors.lastname: Cheon
authors.forename: H A
authors.initials: HA
authors.lastname: Kim
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism*; D016022:Case-Control Studies; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology*; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D020370:Osteoarthritis, Knee / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D035683:MicroRNAs; D016328:NF-kappa B; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; D020928:Mitogen-Activated Protein Kinases; D053509:Matrix Metalloproteinase 13; D020781:Matrix Metalloproteinase 1; D015232:Dinoprostone