CHANGES IN THE EXPRESSION OF DECORIN AND BIGLYCAN IN HUMAN ARTICULAR-CARTILAGE WITH AGE AND REGULATION BY TGF-BETA

In chondrocytes isolated directly from human articular cartilage, with out subsequent culture, biglycan mRNA levels decreased with the age of the donor, whereas those for decorin increased. In cultured chondrocy tes in the presence of FCS, mRNA levels for biglycan remained similar to those in uncultured counterparts, while decorin transcription becam e depressed. The differential effect on decorin and biglycan mRNA expr ession was mimicked by the addition of TGF-beta. In the absence of exo genously added growth factors (TGF-beta or FCS) biglycan mRNA levels d ecreased, while those for decorin increased. In contrast, IGF-I showed no differential modulation of the relative abundance of the two messa ges. The opposite regulation of these two proteoglycans by TGF-beta wa s also reflected at the level of protein synthesis. It would appear th at the need of articular cartilage for decorin is greatest in the adul t, whereas the need for biglycan is greatest in the juvenile.