Transformation of chick embryo fibroblasts by rous sarcoma virus does not inhibit the assembly of fibronectin into reduction-sensitive dimer and high molecular weight complex.

Chick embryo fibroblasts (CEFs) transformed by Rous sarcoma virus synthesize reduced amounts of fibronectin and also shed this protein into the medium more rapidly than do uninfected cells. We wanted to know whether or not the increased fibronectin shedding rate observed in RSV-transformed CEFs could be explained by an inability of fibronectin to form dimers and/or HMW complex. Our studies on normal and RSV-transformed fibroblasts labelled either metabolically or by lactoperoxidase-catalysed iodination indicate that RSV-induced transformation does not alter the subunit structure of either cell-bound or shed fibronectin, nor does it appear to alter the kinetics of conversion of dimeric fibronectin into HMW complex. We conclude that transformation of CEFs by Rous sarcoma virus does not prevent the assembly of fibronectin into dimeric and HMW complex forms and we offer alternative hypotheses for the more rapid shedding of fibronectin protein by these cells.