Incorporation of sulfate and the synthesis of collagen by cultures of embryonic chondrocytes

• 1.

  1. In order to determine whether the collagen found in cartilage is synthesized by the same cells which synthesize chondroitin sulfate, ³H or ¹⁴C-labeled proline was administered to pure cultures of freshly liberated chondrocytes, and the synthesis of collagen was followed by the appearance of labeled hydroxyproline. The results indicated that the chondrocytes synthesized collagen

• 2.

  2. Double-label experiments with the chondrocytes indicated that the collagen synthesis occurred concurrently with sulfate incorporation.

• 3.

  3. The incorporation of [³⁵S]sulfate and synthesis of labeled hydroxyproline was also examined in the progeny of chondrocytes which were grown on fibrin clots for several generations. These “de-differentiated chondrocytes” did not incorporate [³⁵S]-sulfate or synthesize labeled hydroxyproline even though the rates of labeled proline incorporation were similar to those observed with freshly liberated chondrocytes.

• 4.

  4. The failure of de-differentiated chondrocytes to incorporate sulfate and to synthesize collagen suggests that the pathways for the synthesis of sulfated mucopolysaccharides and collagen may be closely interrelated.