Differential expression of mRNAs for endopeptidases in phenotypically modulated (`dedifferentiated') human articular chondrocytes

摘要

>Human articular chondrocytes modulated away from their original phenotype by serial subcultures in monolayer differentially express mRNAs for endopeptidases. The mRNAs for the cathepsins B and L are extremely low in differentiated cells, but are soon expressed in parallel with the loss of the differentiated state. In contrast, the mRNA for collagenase-1 is strongly expressed by differentiated chondrocytes and declines rapidly following phenotypic modulation. The mRNA for stromelysin-1 and the tissue inhibitor of metalloproteinases-2 is high and does not appreciably change after modulation. Chondrocyte activation induced by alteration of its original phenotype leads to the expression of endopeptidases in a way that markedly differs from that induced by cytokines. The results are relevant to cartilage catabolism in osteoarthritis and suggest a prominent role of fibroblastic metaplasia on the part of the chondrocytes as a mechanism of expressing catabolic endopeptidases.