The culture of chick embryo chondrocytes and the control of their differentiated functions in vitro. Transformation by rous sarcoma virus induces a switch in the collagen type synthesis and enhances fibronectin expression.

Epithelial-like chondrocytes obtained from chick embryo were transformed with Rous sarcoma virus. Cellular transformation was monitored looking at the morphology change, the cell growth, and the expression of plasminogen activator. Analysis on polyacrylamide gel of intracellular and secreted proteins showed: 1) a disappearance of the specific products of differentiated chondrocytes; 2) a switch in the collagen synthesis from the type II, the chondrocyte-specific type, to the type I, characteristic of fibroblasts and other cells of mesenchymal origin; 3) an enhancement of fibronectin synthesis. Analysis of the proteins from chondrocytes infected with Rous-associated virus 1, a virus unable to induce cell transformation in vitro, indicated that the altered expression of the differentiated proteins in Rous sarcoma virus-infected chondrocytes depended upon the action of src gene product.