title: RBP-Jκ-dependent Notch signaling is required for murine articular cartilage and joint maintenance.
abstract: OBJECTIVE
  Osteoarthritis (OA) is a degenerative disease resulting in severe joint cartilage destruction and disability. While the mechanisms underlying the development and progression of OA are poorly understood, gene mutations have been identified within cartilage-related signaling molecules, implicating impaired cell signaling in OA and joint disease. The Notch pathway has recently been identified as a crucial regulator of growth plate cartilage development, and components are expressed in joint tissue. This study was undertaken to investigate a novel role for Notch signaling in joint cartilage development, maintenance, and the pathogenesis of joint disease in a mouse model.
  
  
  METHODS
  We performed the first mouse gene study in which the core Notch signaling component, RBP-Jκ, was tissue specifically deleted within joints. The Prx1Cre transgene removed Rbpjk loxP-flanked alleles in mesenchymal joint precursor cells, while the Col2Cre(ERT2) transgene specifically deleted Rbpjk in postnatal chondrocytes. Murine articular chondrocyte cultures were also used to examine Notch regulation of gene expression.
  
  
  RESULTS
  Loss of Notch signaling in mesenchymal joint precursor cells did not affect embryonic joint development in mice, but rather, resulted in an early, progressive OA-like pathology. Additionally, partial loss of Notch signaling in murine postnatal cartilage resulted in progressive joint cartilage degeneration and an age-related OA-like pathology. Inhibition of Notch signaling altered the expression of the extracellular matrix (ECM)-related factors type II collagen (COL2A1), proteoglycan 4, COL10A1, matrix metalloproteinase 13, and ADAMTS.
  
  
  CONCLUSIONS
  Our findings indicate that the RBP-Jκ-dependent Notch pathway is a novel pathway involved in joint maintenance and articular cartilage homeostasis, a critical regulator of articular cartilage ECM-related molecules, and a potentially important therapeutic target for OA-like joint disease.
authors.affiliation: University of Rochester and University of Rochester Medical Center, Rochester, New York.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Mirando
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Liu
authors.forename: Tyler
authors.initials: T
authors.lastname: Moore
authors.forename: Alexandra
authors.initials: A
authors.lastname: Lang
authors.forename: Anat
authors.initials: A
authors.lastname: Kohn
authors.forename: Alana M
authors.initials: AM
authors.lastname: Osinski
authors.forename: Regis J
authors.initials: RJ
authors.lastname: O'Keefe
authors.forename: Robert A
authors.initials: RA
authors.lastname: Mooney
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Zuscik
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hilton
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000502:physiology*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000502:physiology; D000090602:Collagen Type I, alpha 1 Chain; D024043:Collagen Type II / Q000235:genetics / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000502:physiology*; D007596:Joints / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D023421:Models, Animal; D010003:Osteoarthritis / Q000503:physiopathology; D051880:Receptors, Notch / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C447413:Col2a1 protein, mouse; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D024043:Collagen Type II; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D051880:Receptors, Notch