Regulation of the synthesis of extracellular matrix components in chondroblasts transformed by a temperature-sensitive mutant of Rous sarcoma virus.

Regulation of cartilage extracellular matrix synthesis has been examined in chondroblasts infected with a temperature-sensitive mutant of Rous sarcoma virus. Cells grown at the nonpermissive temperature synthesized large amounts of several chondroblast-specific polypeptides (type IV proteoglycan core protein, type II procollagen, a proteoglycan link protein(s) and a 60 kd protein) and very low levels of fibronectin. At the permissive temperature, synthesis of chondroblast-specific proteins was coordinately reduced, while fibronectin synthesis was greatly increased. These changes reflected comparable alterations in levels of translatable mRNAs encoding these proteins. This analysis also revealed the unexpected presence in the transformed cells of type I collagen mRNAs, which are not used in intact cells, indicating that a posttranscriptional control (or controls) may be acting in transformed chondroblasts.