title: Histone deacetylase inhibitor vorinostat (SAHA, MK0683) perturb miR-9-MCPIP1 axis to block IL-1β-induced IL-6 expression in human OA chondrocytes.
abstract: High levels of IL-6 are believed to contribute to osteoarthritis (OA) pathogenesis. The expression of IL-6 is regulated post-transcriptionally by the miR-9-MCPIP-1 axis in chondrocytes. Vorinostat (SAHA) inhibits the IL-6 expression in OA chondrocytes. We investigated whether SAHA suppresses the expression of IL-6 by perturbing the miR-9-MCPIP1 axis in OA chondrocytes under pathological conditions.
  
  
  
  OA chondrocytes were isolated by enzymatic digestion and treated with IL-1β in the absence or presence of SAHA. Genes and protein expression levels were determined by TaqMan assays and Western blotting, respectively. Secreted IL-6 was quantified by enzyme linked immunosorbent assay (ELISA). MCPIP1 promoter deletion mutants were generated by polymerase chain reaction (PCR). Promoter recruitment of transcription factors was determined by ChIP. Nuclear run-on was employed to measure the ongoing transcription. siRNA-mediated knockdown of the CEBPα expression was employed for loss of function studies.
  
  
  
  Expression of MCPIP1 was high in SAHA treated OA chondrocytes but expression of IL-6 mRNAs and secreted IL-6 were reduced by ~70%. SAHA suppressed the expression of miR-9 but enhanced the activity of the MCPIP1 promoter localized to a 156bp region which also harbors the binding site for CEBPα. Treatment with SAHA enhanced the recruitment of CEBPα to the MCPIP1 promoter. Ectopically expressed CEBPα enhanced the promoter activity and the expression of MCPIP1 while siRNA-mediated knockdown of CEBPα inhibited the expression of MCPIP1.
  
  
  
  Taken together our data indicate that SAHA-mediated suppression of the IL-6 expression is achieved through increased recruitment of CEBPα to the MCPIP1 promoter and by relieving the miR-9-mediated inhibition of MCPIP1 expression in OA chondrocytes.
authors.affiliation: a Department of Anatomy and Neurobiology , Northeast Ohio Medical University , Rootstown , OH , USA.
authors.forename: Mohammad S
authors.initials: MS
authors.lastname: Makki
authors.affiliation: a Department of Anatomy and Neurobiology , Northeast Ohio Medical University , Rootstown , OH , USA.
authors.forename: Tariq M
authors.initials: TM
authors.lastname: Haqqi
mesh_terms: D000328:Adult; D000368:Aged; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D010003:Osteoarthritis / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011401:Promoter Regions, Genetic; D012260:Ribonucleases / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D000077337:Vorinostat
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; D006877:Hydroxamic Acids; C508585:IL1B protein, human; C508600:IL6 protein, human; D053583:Interleukin-1beta; D015850:Interleukin-6; C541874:MIRN92 microRNA, human; D035683:MicroRNAs; D014157:Transcription Factors; D000077337:Vorinostat; D012260:Ribonucleases; C510646:ZC3H12A protein, human
keywords: IL-6; MCPIP1; Osteoarthritis; Vorinostat; miRNA