Differential regulation of the expression of transforming growth factor‐β mRNAs by growth factors and retinoic acid in chicken embryo chondrocytes, myocytes, and fibroblasts

Transforming growth factor‐beta (TGF‐β) autoregulates its expression in several mammalian cell types. We now report that addition of TGF‐βs 1, 2, and 3 to primary chicken embryo cells differentially affects expression of the messenger RNAs for the different TGF‐β isoforms depending on the cell type. In cultured sternal chondrocytes, addition of TGF‐βs 1, 2, or 3 results in an increase in the steady‐state levels of the messenger RNAs for TGF‐βs 2 and 3, but does not change expression of TGF‐β4 mRNA. In contrast, in cultured cardiac myocytes, addition of TGF‐βs 1, 2, or 3 results in an increase in expression of TGF‐βs 3 and 4 mRNAs, but does not change expression of TGF‐β2 mRNA. Moreover, expression of TGF‐βs 2, 3, and 4 mRNAs is not affected by addition of any of the TGF‐βs to fibroblasts. Addition of platelet‐derived growth factor (PDGF), epidermal growth factor (EGF), or interleukin‐1 (IL‐1) to these chicken cells also has differential effects on expression of the different TGF‐β mRNAs depending on the cell type. Retinoic acid also has contrasting effects on chondrocytes and myocytes either increasing or decreasing, respectively, expression of TGF‐βs 2 and 3 mRNAs and TGF‐β2 protein. Our results indicate a complex pattern of regulation of the different TGF‐β genes by themselves as well as by PDGF, EGF, IL‐1, dexamethasone, TPA, and retinoic acid in chicken embryo cells.