Increased MIG-6 mRNA transcripts in osteoarthritic cartilage.

The biochemical mechanism for initiation of cartilage destruction in osteoarthritis (OA) is unknown but may involve as yet unidentified cartilage genes. The first evidence that MIG-6, a protein involved in signal transduction, is expressed in articular cartilage came from our recent in vitro microarray experiments using the Affymetrix canine GeneChip. Quantitative RT-PCR (q RT-PCR) confirmed a fourfold increase in MIG-6 mRNA in cartilage in response to mechanical impact in vitro. Our goal is to determine if MIG-6, which responds to mechanical impact, could have a role in the initiation of OA. We determined that mRNA transcript levels of MIG-6 were fourfold higher in degenerated cartilage from dogs with hip osteoarthritis than in disease-free cartilage from unaffected dogs and twofold higher than in the cartilage surrounding the lesion. This is the first report associating MIG-6 with OA. Additional studies will determine what role MIG-6 has in the origin of cartilage degeneration.