title: Involvement of the Notch pathway in the regulation of matrix metalloproteinase 13 and the dedifferentiation of articular chondrocytes in murine cartilage.
abstract: OBJECTIVE
  To demonstrate the activation of the Notch signaling pathway during changes in the phenotype of chondrocytes in vitro, and to assess the influence of Notch on the production of chondrocyte markers.
  
  
  METHODS
  Serial monolayer primary cultures of murine articular chondrocytes (MACs), as a model of chondrocyte dedifferentiation, were prepared. MACs were cultured with or without a Notch inhibitor and transfected with different Notch-expressing vectors. The Notch pathway and chondrocyte marker profiles were assessed by quantitative reverse transcription-polymerase chain reaction, immunoblotting, and immunocytochemistry.
  
  
  RESULTS
  Successive passages of MACs resulted in a loss of type II collagen and aggrecan (chondrocyte differentiation markers), an increase in type I collagen (dedifferentiation marker), an increase in Notch ligands, and augmented target gene activity. The Notch inhibitor decreased the type II collagen protein content but had no effect on Col2a1 messenger RNA, while transfection with the constitutive active forms of the Notch1 receptor led to a decrease in type II collagen in transfected cells. In assays to investigate the mechanism of type II collagen breakdown, matrix metalloproteinase 13 (MMP-13) synthesis was regulated in a Notch-dependent manner, whereas MMP-2 synthesis was unchanged.
  
  
  CONCLUSIONS
  The Notch signaling pathway is associated with decreased type II collagen production during the dedifferentiation of MACs in vitro. This may be correlated with the increase in MMP-13 production linked to activation of Notch.
authors.affiliation: CNRS, UMR 7079, Paris Universitas Université Pierre-et-Marie-Curie Paris 6, Paris, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Blaise
authors.forename: Mouna
authors.initials: M
authors.lastname: Mahjoub
authors.forename: Colette
authors.initials: C
authors.lastname: Salvat
authors.forename: Ullah
authors.initials: U
authors.lastname: Barbe
authors.forename: Christel
authors.initials: C
authors.lastname: Brou
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Corvol
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Savouret
authors.forename: François
authors.initials: F
authors.lastname: Rannou
authors.forename: Francis
authors.initials: F
authors.lastname: Berenbaum
authors.forename: Pedro
authors.initials: P
authors.lastname: Bausero
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002358:Cartilage, Articular / Q000166:cytology; D054337:Cell Dedifferentiation / Q000235:genetics*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D053509:Matrix Metalloproteinase 13 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D051881:Receptor, Notch1 / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction
chemical_list: D015415:Biomarkers; C447413:Col2a1 protein, mouse; D024043:Collagen Type II; C497762:Notch1 protein, mouse; D012333:RNA, Messenger; D051881:Receptor, Notch1; D053509:Matrix Metalloproteinase 13