title: Cytokine-induced MMP13 Expression in Human Chondrocytes Is Dependent on Activating Transcription Factor 3 (ATF3) Regulation.
abstract: Irreversible breakdown of cartilage extracellular matrix (ECM) by the collagenase matrix metalloproteinase 13 (MMP13) represents a key event in osteoarthritis (OA) progression. Although inflammation is most commonly associated with inflammatory joint diseases, it also occurs in OA and is thus relevant to the prevalent tissue destruction. Here, inflammation generates a cFOS AP-1 early response that indirectly affects MMP13 gene expression. To ascertain a more direct effect on prolonged MMP13 production we examined the potential molecular events occurring between the rapid, transient expression of cFOS and the subsequent MMP13 induction. Importantly, we show MMP13 mRNA expression is mirrored by nascent hnRNA transcription. Employing ChIP assays, cFOS recruitment to the MMP13 promoter occurs at an early stage prior to gene transcription and that recruitment of transcriptional initiation markers also correlated with MMP13 expression. Moreover, protein synthesis inhibition following early FOS expression resulted in a significant decrease in MMP13 expression thus indicating a role for different regulatory factors modulating expression of the gene. Subsequent mRNA transcriptome analyses highlighted several genes induced soon after FOS that could contribute to MMP13 expression. Specific small interfering RNA-mediated silencing highlighted that ATF3 was as highly selective for MMP13 as cFOS. Moreover, ATF3 expression was AP-1(cFOS/cJUN)-dependent and expression levels were maintained after the early transient cFOS response. Furthermore, ATF3 bound the proximal MMP13 AP-1 motif in stimulated chondrocytes at time points that no longer supported binding of FOS Consequently, these findings support roles for both cFOS (indirect) and ATF3 (direct) in effecting MMP13 transcription in human chondrocytes.
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: Chun Ming
authors.initials: CM
authors.lastname: Chan
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Macdonald
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Litherland
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wilkinson
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Skelton
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
authors.forename: G Nicholas
authors.initials: GN
authors.lastname: Europe-Finner
authors.affiliation: From the Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne NE2 4HH, United Kingdom. Electronic address: drew.rowan@ncl.ac.uk.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rowan
mesh_terms: D051700:Activating Transcription Factor 3 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000096:biosynthesis* / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome / Q000502:physiology*
chemical_list: C490449:ATF3 protein, human; D051700:Activating Transcription Factor 3; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13
keywords: AP1 transcription factor (AP-1); arthritis; cell signaling; chondrocyte; inflammation; matrix metalloproteinase (MMP)