Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing 100069, China.
J Hepatol. 2011 Jun;54(6):1205-13. doi: 10.1016/j.jhep.2010.08.028. Epub 2010 Oct 31.
BACKGROUND & AIMS: Directed migration of hepatic myofibroblasts (hMFs) contributes to the development of liver fibrosis. However, the signals regulating the motility of these cells are incompletely understood. We have recently shown that sphingosine 1-phosphate (S1P) and S1P receptors (S1PRs) are involved in mouse liver fibrogenesis. Here, we investigated the role of S1P/S1PRs signals in human liver fibrosis involving motility of human hMFs.
S1P level in the liver was examined by high-performance liquid chromatography. Expression of S1PRs was characterized, in biopsy specimens of human liver and cultured hMFs, by immunofluorescence and real-time RT-PCR or Western blot analysis. Cell migration was determined in Boyden chambers, by using the selective S1P receptor agonist or antagonist and silencing of S1PRs expression with small interfering RNA.
S1P level in the human fibrotic liver was increased through up-regulation of sphingosine kinase (SphK), irrespective of the etiology of fibrosis. S1P receptors type 1, 2, and 3 (S1P(1,2,3)) were expressed in human hMFs in vivo and in vitro. Interestingly, S1P(1,3) were strongly induced in human fibrotic samples, whereas expression of S1P(2) was massively decreased. S1P exerted a powerful migratory action on human hMFs. Furthermore, the effect of S1P was mimicked by SEW2871 (an S1P(1) agonist), and blocked by suramin (an S1P(3) antagonist) and by silencing S1P(1,3) expression. In contrast, JTE-013 (an S1P(2) antagonist) and silencing of S1P(2) expression enhanced S1P-induced migration.
SphK/S1P/S1PRs signaling axis plays an important role in human liver fibrosis and is involved in the directed migration of human hMFs into the damaged areas.
肝肌成纤维细胞（hMFs）的定向迁移有助于肝纤维化的发展。然而，调节这些细胞迁移的信号仍不完全清楚。我们最近发现，1-磷酸鞘氨醇（S1P）及其受体（S1PRs）参与了小鼠肝纤维化的发生。在此，我们研究了 S1P/S1PRs 信号在涉及 hMFs 迁移的人类肝纤维化中的作用。
采用高效液相色谱法检测肝内 S1P 水平。采用免疫荧光、实时 RT-PCR 或 Western blot 分析，在肝活检标本和培养的 hMFs 中鉴定 S1PRs 的表达。通过 Boyden 室测定细胞迁移，使用选择性 S1P 受体激动剂或拮抗剂，以及用小干扰 RNA 沉默 S1PRs 表达。
无论纤维化的病因如何，纤维化肝中 S1P 水平的增加是通过上调鞘氨醇激酶（SphK）实现的。S1P 受体 1、2 和 3（S1P(1,2,3)）在体内和体外的人 hMFs 中表达。有趣的是，S1P(1,3)在人纤维化样本中强烈诱导，而 S1P(2)的表达则大量减少。S1P 对人 hMFs 具有强大的迁移作用。此外，S1P 的作用可被 SEW2871（S1P(1)激动剂）模拟，被苏拉明（S1P(3)拮抗剂）和沉默 S1P(1,3)表达阻断，而 JTE-013（S1P(2)拮抗剂）和沉默 S1P(2)表达增强 S1P 诱导的迁移。
SphK/S1P/S1PRs 信号轴在人类肝纤维化中发挥重要作用，并参与了人 hMFs 向受损区域的定向迁移。
