The American journal of pathology
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Sphingosine kinase (SphK) is involved in numerous biological processes, including cell growth, proliferation, and differentiation. However, whether SphK participates in the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) to myofibroblasts has been unknown. In a carbon tetrachloride-treated mouse model, SphK1 was expressed in BMSCs in damaged liver. ⋯ Notably, pharmacological or siRNA-mediated inhibition of SphK1 abrogated the prodifferentiating effect of TGF-β1. Moreover, using either S1PR subtype-specific antagonists or specific siRNAs, we found that the prodifferentiating effect of TGF-β1 was mediated by S1PR(1) and S1PR(3). These data suggest that SphK1 activation by TGF-β1 leads to differentiation of BMSCs to myofibroblasts mediated by S1PR(1) and S1PR(3) up-regulation, thus providing new information on the mechanisms by which TGF-β1 gives rise to fibrosis and opening new perspectives for pharmacological treatment of liver fibrosis.