Inhibition of pro-collagen I expression by oxymatrine in hepatic stellate cells is mediated via nuclear translocation of Y-box binding protein 1

摘要

Accumulating evidence indicated that oxymatrine (OMT), an alkaloid compound from the Chinese medicinal herb Sophora flavescens, exhibits activity against hepatic fibrosis. The present study attempted to explore the underlying mechanisms of OMT-mediated inhibition of collagen production. For this, the LX-2 human hepatic stellate cell line was treated with OMT (240, 480 or 960 mg/l) for 3-5 days. The endogenic expression of pro-collagen I was decreased by OMT in a dose- and time-dependent manner, accompanied with the downregulation of Y-box binding protein 1 (YB-1), a vital transcription factor, particularly on the fourth day of incubation with a high concentration of OMT. To further explore the intracellular changes in YB-1 levels, nuclear/cytoplasmic proteins were extracted separately, and subsequent western blot analysis revealed a significant upregulation of YB-1 in the nucleus in parallel with its downregulation in the cytoplasm, indicating the nuclear translocation of YB-1 induced by OMT treatment. In another experiment, knockdown of YB-1 using small interfering RNA led to elevated mRNA levels of collagen I, thereby reversing the effects of OMT treatment. In conclusion, these present study suggested that the attenuation of pro-collagen I expression caused by OMT was, to a certain extent, mediated via nuclear translocation of YB-1.