title: Regulation of chondrocyte gene expression by osteogenic protein-1.
abstract: BACKGROUND
  The objective of this study was to investigate which genes are regulated by osteogenic protein-1 (OP-1) in human articular chondrocytes using Affimetrix gene array, in order to understand the role of OP-1 in cartilage homeostasis.
  
  
  METHODS
  Chondrocytes enzymatically isolated from 12 normal ankle cartilage samples were cultured in high-density monolayers and either transfected with OP-1 antisense oligonucleotide in the presence of lipofectin or treated with recombinant OP-1 (100 ng/ml) for 48 hours followed by RNA isolation. Gene expression profiles were analyzed by HG-U133A gene chips from Affimetrix. A cut-off was chosen at 1.5-fold difference from controls. Selected gene array results were verified by real-time PCR and by in vitro measures of proteoglycan synthesis and signal transduction.
  
  
  RESULTS
  OP-1 controls cartilage homeostasis on multiple levels including regulation of genes responsible for chondrocyte cytoskeleton (cyclin D, Talin1, and Cyclin M1), matrix production, and other anabolic pathways (transforming growth factor-beta (TGF-β)/ bone morphogenetic protein (BMP), insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF), genes responsible for bone formation, and so on) as well as regulation of cytokines, neuromediators, and various catabolic pathways responsible for matrix degradation and cell death. In many of these cases, OP-1 modulated the expression of not only the ligands, but also their receptors, mediators of downstream signaling, kinases responsible for an activation of the pathways, binding proteins responsible for the inhibition of the pathways, and transcription factors that induce transcriptional responses.
  
  
  CONCLUSIONS
  Gene array data strongly suggest a critical role of OP-1 in human cartilage homeostasis. OP-1 regulates numerous metabolic pathways that are not only limited to its well-documented anabolic function, but also to its anti-catabolic activity. An understanding of OP-1 function in cartilage will provide strong justification for the application of OP-1 protein as a therapeutic treatment for cartilage regeneration and repair.
authors: Department of Biochemistry, Rush University Medical Center, 1653 W, Congress Parkway, Chicago, IL 60612, USA. susanna_chubinskaya@rush.edu
authors: Susan
authors: S
authors: Chubinskaya
authors: Lori
authors: L
authors: Otten
authors: Stephan
authors: S
authors: Soeder
authors: Jeffrey A
authors: JA
authors: Borgia
authors: Thomas
authors: T
authors: Aigner
authors: David C
authors: DC
authors: Rueger
authors: Richard F
authors: RF
authors: Loeser
mesh_terms: D055419:Bone Morphogenetic Protein 7 / Q000235:genetics*; D002358:Cartilage, Articular / Q000502:physiology*; D019902:Chondrocytes / Q000502:physiology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7