Transforming growth factor-β (TGF-β)-receptor gene expression in cultured rat hepatocytes

The expression of TGF-β receptor types I, II and III in freshly-isolated and monolayer cultured rat hepatocytes was studied at the RNA and protein level applying semiquantitative RT-PCR and immunocytochemistry (APAAP-, and fluorescence-staining, respectively). Transcripts of receptor types I, II and III were detected in cultured cells, the level of mRNA for the type I and type II receptors were present at each time point of culture and showed no change of expression during cultivation. The transcript of TGF-β type III receptor (betaglycan) was very sparse in freshly-isolated cells but showed a 5–6-fold increase up to 72 h of culture. Southern blotting and enzymatic cleavage of the PCR-amplificates proved the specificity of the PCR products. Immunochemical staining of cultured PC (48 h) with polyclonal anti-type I, -type II and -type III TGF-β receptor antibodies demonstrated the presence of the receptors with almost similar staining intensities. In freshly isolated PC staining for type III receptor was weakly. The results indicate a differential expression of TGF-β signaling receptors (I and II) and betaglycan co-receptor (III), respectively, in cultured PC.