title: Hydroxytyrosol modulates the levels of microRNA-9 and its target sirtuin-1 thereby counteracting oxidative stress-induced chondrocyte death.
abstract: Nutraceutical compounds, such as hydroxytyrosol (HT), have been found to exert protective effects in osteoarthritis (OA) by affecting a variety of key molecular and cellular processes in chondrocytes. However, to our knowledge, no relationship has been reported between nutraceuticals and microRNA (miR) network in OA models. Here, we identified a miR that is implicated in HT-mediated chondroprotection following oxidative stress condition by targeting sirtuin-1 (SIRT-1).
  
  
  
  Human primary and C-28/I2 chondrocytes were pre-treated with 100 μM HT 30 min before 100 μM H2O2addition. In silico analyses were exploited to select putative candidate miRs able to target SIRT-1 mRNA. Luciferase-based gene reporter assay was employed to demonstrate the direct link between miR-9 and its putative mRNA target. Transient transfection approach was performed to examine the effects of miR-9 levels on caspase activity, cell viability and expression of OA-related genes.
  
  
  
  MiR-9 was identified and confirmed as a post-transcriptional regulator of SIRT-1. MiR-9 and SIRT-1 levels showed opposite changes in chondrocytes following H2O2and HT treatment. Moreover mir-9 silencing inhibited cell death induced by H2O2partly through down-regulation of SIRT-1, whereas miR-9 overexpression markedly reduced the protective effect of HT. The manipulation of miR-9 levels also resulted in the modulation of OA-related gene expression, including MMP-13, VEGF and RUNX-2.
  
  
  
  These results show that miR-9 is a critical mediator of the deleterious and OA-related effects of oxidative stress in chondrocytes and that modulation of miR expression may be a crucial mechanism underlying the protective action of HT.
authors.affiliation: Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy; Dipartimento di Scienze Mediche e Chirurgiche, Università di Bologna, Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: D'Adamo
authors.affiliation: Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cetrullo
authors.affiliation: Dipartimento di Scienze Mediche e Chirurgiche, Università di Bologna, Bologna, Italy; Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Guidotti
authors.affiliation: Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Bologna, Italy.
authors.forename: R M
authors.initials: RM
authors.lastname: Borzì
authors.affiliation: Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy. Electronic address: flavio.flamigni@unibo.it.
authors.forename: F
authors.initials: F
authors.lastname: Flamigni
mesh_terms: D016923:Cell Death / Q000187:drug effects*; D019902:Chondrocytes / Q000187:drug effects*; D050659:Core Binding Factor Alpha 1 Subunit / Q000187:drug effects / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D053509:Matrix Metalloproteinase 13 / Q000187:drug effects / Q000235:genetics; D035683:MicroRNAs / Q000187:drug effects* / Q000235:genetics; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D056564:Sirtuin 1 / Q000187:drug effects* / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects / Q000235:genetics
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; C541874:MIRN92 microRNA, human; D035683:MicroRNAs; D016877:Oxidants; D012333:RNA, Messenger; C493709:RUNX2 protein, human; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C005975:3,4-dihydroxyphenylethanol; D006861:Hydrogen Peroxide; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D010626:Phenylethyl Alcohol
keywords: Cartilage; Chondrocyte; Hydroxytyrosol; Oxidative stress; microRNA