2012 Volume No 23 – pages 41-57
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Title: Protein kinase R plays a pivotal role in oncostatin M and interleukin-1 signalling in bovine articular cartilage chondrocytes |
Author: SJ Gilbert, EJ Blain, A Al-Sabah, Y Zhang, VC Duance, DJ Mason |
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Address: School of Biosciences, Cardiff University, Museum Avenue, Cardiff, CF10 3AX, Wales, UK |
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E-mail: gilbertsj1 at Cardiff.ac.uk |
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Key Words: Articular cartilage, chondrocytes, protein kinase R, oncostatin M, interleukin-1, matrix metalloproteinase, aggrecanase, tumour necrosis factor alpha, type II collagen. |
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Publication date: January 29th 2012 |
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Abstract: This study investigated whether treatment of articular cartilage chondrocytes with a combination of oncostatin M (OSM) and interleukin-1 (IL-1) could induce a degradative phenotype that was mediated through the protein kinase R (PKR) signalling pathway. High-density monolayer cultures of full depth, bovine chondrocytes were treated with a combination of OSM and IL-1 (OSM+IL-1) for 7 days. To inhibit the activation of PKR, a pharmacological inhibitor of PKR was added to duplicate cultures. Pro- and active matrix metalloproteinase-9 (MMP9) and MMP9 mRNA were significantly upregulated by OSM+IL-1 through a PKR dependent mechanism. ADAMTS4 and ADAMTS5 mRNA were also upregulated by OSM+IL-1. The upregulation of ADAMTS4 and ADAMTS5 were, in part, mediated through PKR. OSM+IL-1 resulted in a loss of type II collagen, which could not be rescued by PKR inhibition. OSM+IL-1 reduced the expression of COL2A1 (type II collagen), COL9A1 (type IX collagen), COL11A1 (type XI collagen), and ACAN (aggrecan) mRNAs. Expression of type II and XI collagen and aggrecan was reduced further when PKR was inhibited. OSM+IL-1 resulted in an 11-fold increase in TNFa mRNA which was, in part, mediated through the PKR pathway. This study demonstrates, for the first time, that a number of catabolic and pro-inflammatory effects known to be important in human arthritis and induced by OSM and IL-1, are mediated by the PKR signalling pathway. |
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Article download: Pages
41-57 (PDF file) |
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