title: Increase in production of matrix metalloproteinase 13 by human articular chondrocytes due to stimulation with S100A4: Role of the receptor for advanced glycation end products.
abstract: OBJECTIVE
  S100 proteins have been implicated in various inflammatory conditions, including arthritis. The aims of this study were to determine whether chondrocytes produce S100A4 and whether S100A4 can stimulate the production of matrix metalloproteinase 13 (MMP-13) by articular chondrocytes via receptor for advanced glycation end products (RAGE)-mediated signaling.
  
  
  METHODS
  The expression of chondrocyte S100A4 was analyzed by immunohistochemistry using normal and osteoarthritic (OA) cartilage and by immunoblotting of chondrocyte cell lysates. RAGE signaling was examined by stimulating chondrocytes with S100A4 and monitoring for the activation of MAP kinases and NF-kappaB. Production of MMP-13 was determined in the conditioned medium. A pulldown assay using biotin-labeled S100A4 was used to demonstrate binding to RAGE.
  
  
  RESULTS
  S100A4 expression was detected in human articular chondrocytes by immunoblotting and appeared to increase in the cell lysates from OA tissue. Marked positive immunostaining for S100A4 was also noted in sections of human cartilage with changes due to OA. Stimulation of chondrocytes with S100A4 increased the phosphorylation of Pyk-2, MAP kinases, and activated NF-kappaB, followed by increased production of MMP-13 in the conditioned medium. This signaling was inhibited in cells pretreated with soluble RAGE, advanced glycation end product-bovine serum albumin, or the antioxidant Mn(III)tetrakis (4-benzoic acid) porphyrin, or by overexpression of a dominant-negative RAGE construct. A pulldown assay showed that S100A4 binds to RAGE in chondrocytes.
  
  
  CONCLUSIONS
  This is the first study to demonstrate that S100A4 binds to RAGE and stimulates a RAGE-mediated signaling cascade, leading to increased production of MMP-13. Since both S100A4 and RAGE are up-regulated in OA cartilage, this signaling pathway could contribute to cartilage degradation in OA.
authors.affiliation: Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
authors.forename: Raghunatha R
authors.initials: RR
authors.lastname: Yammani
authors.forename: Cathy S
authors.initials: CS
authors.lastname: Carlson
authors.forename: Anne R
authors.initials: AR
authors.lastname: Bresnick
authors.forename: Richard F
authors.initials: RF
authors.lastname: Loeser
mesh_terms: D002358:Cartilage, Articular / Q000201:enzymology*; D019902:Chondrocytes / Q000201:enzymology*; D017364:Collagenases / Q000235:genetics*; D017127:Glycation End Products, Advanced / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D053509:Matrix Metalloproteinase 13; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000502:physiology; D015398:Signal Transduction
chemical_list: D017127:Glycation End Products, Advanced; D011994:Recombinant Proteins; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C077591:S100A4 protein, human; D012710:Serum Albumin, Bovine; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13