Role of transforming growth factor-β pathway in the mechanism of wound healing by saponin from Ginseng Radix rubra

摘要

class="enumerated" style="list-style-type:decimal">The effects of saponin from Ginseng Radix rubra on extracellular matrix metabolism, the activation and synthesis of TGF-β1, and the modification of TGF-β receptor in fibroblasts were examined to elucidate the contribution of the TGF-β pathway to the mechanism of wound healing by saponin.Fibronectin synthesis was analysed by the immunoprecipitation method. Activation and synthesis of TGF-β1 were measured by ELISA. The expressions of TGF-β receptors in fibroblasts were examined at protein and mRNA levels by the cross-linking method and Northern blot analysis, respectively.The fibronectin synthesis increased 2.3- and 3.9-fold at fibroblasts treated with 1 and 10 μg ml⁻¹ of saponin, respectively, compared with that in non-treated cells. Fibronectin synthesis stimulated with 10 μg ml⁻¹ of saponin was inhibited with 69% by 5 μg ml⁻¹ of an anti-TGF-β1 antibody. mRNA of TGF-β type I receptor increased 4.8- and 4.4-fold at fibroblasts treated with 1 and 10 μg ml⁻¹ of saponin, respectively, and that of TGF-β type II receptor also increased 3.4- and 3.2-fold at fibroblasts treated with 1 and 10 μg ml⁻¹ of saponin, respectively. The significant increases of TGF-β type I and II receptors and of fibronectin synthesis were observed at the same concentrations of saponin. TGF-β1 content increased 1.74- and 1.87-fold at conditioned medium of fibroblasts treated with 100 and 250 μg ml⁻¹ of saponin, respectively, higher concentrations than those which accelerated fibronectin synthesis. Furthermore, the active TGF-β1 content was below 10% of total TGF-β1 at each concentration of saponin.These results indicate that saponin stimulates fibronectin synthesis through the changes of TGF-β receptor expressions in fibroblasts.