TGF-BETA MODULATES THE SYNTHESIS OF PROTEOGLYCANS BY MYOCARDIAL FIBROBLASTS IN CULTURE

In this study we examined the production of proteoglycans by fibroblas ts cultured from the left ventricular myocardium of normal adult rats. Various molecular species of proteoglycan were detected, either by la beling glycosaminoglycan chains with (SO4)-S-35 or by labeling the pro teoglycan core protein with [S-35]methionine. The medium of the cell c ultures, which contained quantitatively most of the proteoglycans, app eared to consist mainly of biglycan, lesser amounts of decorin and pro teoglycans of higher molecular weight. Biglycan and decorin were ident ified not only by the characteristic mobility of the intact protein an d the core protein but also by immunolocation on Western blots, TGF-be ta upregulated the synthesis of all these proteoglycans, coincident wi th elongation of glycosaminoglycan side chains observed for biglycan a nd decorin, The apparent molecular weight of the core protein of the t wo proteoglycans remained unaffected by TGF-beta. The results of these experiments suggest that with regard to proteoglycan synthesis and it s regulation by TGF-beta, cultured fibroblasts originating from the my ocardium share to a large extent the properties of cultured fibroblast s of other organs. (C) 1995 Academic Press Limited