Evaluation of CD98 Expression in Normal and Osteoarthritic Human Articular Chondrocytes

Background: Recent studies have provided evidence that integrins play roles in recognition of mechanical stimuli and its translation into a cellular response. Integrin signaling may be regulated by a number of mechanisms including accessory proteins such as CD98 (4F2 antigen). Objectives: To determine CD98 expression by human articular chondrocytes and its involvement in human articular mechanotransduction. Methods: CD98 expression was assessed by immunostaining of cryostat sections of snap frozen articular cartilage and in cultured cells by western blotting. Chondrocytes enzymatically isolated from macroscopically normal and osteoarthritic (OA) articular cartilage were grown in short term, primary monolayer culture and used in a resting state or following mechanical stimulation at 0.33Hz. Results: Human articular chondrocytes express CD98 and immunoreactivity revealed a similar heterogeneous pattern of CD98 in both normal and osteoarthritic (OA) human articular cartilage. No role of CD98 was detected by electrophysiological study. Conclusion: It appears that CD98 is expressed in a similar pattern in both normal and osteoarthritic (OA) cartilage. Although we detected no role for CD98 in chondrocyte mechanotransduction, it may be involved in other biological functions in chondrocyte intracellular signalling events.