Collagen is the most abundant structural protein in mammals and is expressed in various tissues. In recent years, sphingosine 1-phosphate receptors (S1PRs) have been proven to play an important role in the regulation of collagen expression. Our previous studies reported that S1PRs are involved in TGF-β1-induced collagen expression via up-regulating S1PR1/3 in mouse bone marrow-derived mesenchymal stem cells (BMSCs), and result in experimental mouse liver fibrogenesis. But it remains unclear whether this process happens in human bone marrow-derived mesenchymal stem cells (hMSCs). In this study, we provide evidences that S1PR1/3, but not S1PR2, negatively regulate the expression of collagen in hMSCs using cellular and molecular approaches in vitro. We find that treatment of hMSCs with TGF-β1 up-regulated collagen expression in a dose- and time-dependent manner. Meanwhile, TGF-β1 inhibited the expression of S1PR1/3, but not S1PR2, in hMSCs in a time-dependent manner. Furthermore, either selective knock-down of S1PR1 or silencing S1PR3 induced collagen α1(I) and collagen α1(III) expression in hMSCs. In contrast, inhibition of S1PR2 by siRNA had no effects on the expression of collagen. Altogether, all these findings demonstrated that collagen expression was negatively regulated by S1PR1 and S1PR3 in hMSCs. This study highlights the differences between hMSCs and mouse BMSCs, provides a new regulation mechanism for collagen expression, and points out the risk of utilizing hMSCs in clinical applications. J. Cell. Biochem. 115: 359–367, 2014. © 2013 Wiley Periodicals, Inc.
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