Variable TGF-beta receptor expression regulates TGF-beta responses of articular chondrocytes.

: TGF-beta inhibits the proteoglycan synthesis of freshly isolated articular chondrocytes while TGF-beta stimulates the proteoglycan synthesis of articular chondrocytes cultured for 14 days. To investigate if this differential effect was the result of differences in TGF-beta receptor expression this parameter was studied by affinity labeling in combination with SDS-PAGE. Using this method we demonstrated a difference in size of the TGF-beta type II receptor between freshly isolated and cultured chondrocytes. This difference might explain the differential effect of TGF-beta on the proteoglycan synthesis of chondrocytes cultured for 1 or 14 days.