EXPRESSION OF FIBRONECTIN AND INTERSTITIAL COLLAGEN GENES IN SMOOTH-MUSCLE CELLS - MODULATION BY LOW-MOLECULAR-WEIGHT HEPARIN FRAGMENTS ANDSERUM

The effect of low M(r) heparin fragments (CY222) and fetal calf serum (FCS) on the level of fibronectin and fibrillar collagen mRNAs was inv estigated in smooth muscle cells (SMC) in culture. In the absence of F CS, addition of CY222 (100 mu g/10(6) cells) to postconfluent early pa ssage SMC resulted in a decrease in mRNA level of type III collagen. I n contrast, mRNA levels coding for type I collagen, fibronectin and GA PDH (used as control of cellular activity) were not modified. Addition of 5% FCS (without CY222) to the culture medium did not affect mRNA l evels of type I and type III collagens nor that of GAPDH. The level of fibronectin mRNA, however, increased in the presence of 5% FCS. In th e presence of both 5% FCS and CY222, we observed a decrease in type II I collagen mRNA and fibronectin mRNA levels (this level remained, howe ver, above the control value without FCS and the level with CY222 alon e). Our results demonstrate that low M(r) heparin fragments can modula te the steady-state levels of type III collagen and fibronectin mRNAs.