Department of Anatomy, Second Military Medical University, 800 Xiangyin Road, Shanghai, 200433, PR China.
J Neuroinflammation. 2011 Feb 11;8:13. doi: 10.1186/1742-2094-8-13.
Sphingosine kinase 1 (SphK1), a key enzyme responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P) has been shown to be expressed in monocytes and monocyte-derived peripheral macrophages. This study demonstrates SphK1 immunoexpression in amoeboid microglial cells (AMC), a nascent monocyte-derived brain macrophage in the corpus callosum of developing rat brain. SphK1 immunofluorescence expression, which appeared to be weak in AMC in normal brain, was markedly induced by lipopolysaccharide (LPS) or hypoxia treatment. Western blot analysis also showed increased expression level of SphK1 in the corpus callosum rich in AMC after LPS treatment. Detection of SphK1 mRNA and its upregulation after LPS treatment was confirmed in primary culture AMC by RT-PCR. Administration of N, N-dimethylsphingosine (DMS), a specific inhibitor of SphK1, effectively reduced upregulated SphK1 immunoexpression in AMC both in vivo and in vitro. This was corroborated by western blot which showed a decrease in SphK1 protein level of callosal tissue with DMS pretreatment. Remarkably, LPS-induced upregulation of the transcription factor NFκB was suppressed by DMS. We conclude that SphK1 expression in AMC may be linked to regulation of proinflammatory cytokines via an NFκB signaling pathway.
鞘氨醇激酶 1（SphK1）是一种将鞘氨醇磷酸化为鞘氨醇-1-磷酸（S1P）的关键酶，已被证明在单核细胞和单核细胞衍生的外周巨噬细胞中表达。本研究证明了在发育中的大鼠脑胼胝体中的阿米巴样小胶质细胞（AMC）中存在 SphK1 免疫表达，AMC 是一种新出现的单核细胞衍生的脑巨噬细胞。在正常大脑中，AMC 中的 SphK1 免疫荧光表达似乎较弱，但脂多糖（LPS）或缺氧处理明显诱导了其表达。Western blot 分析还显示，LPS 处理后富含 AMC 的胼胝体中 SphK1 的表达水平增加。通过 RT-PCR 在原代培养的 AMC 中检测到 SphK1 mRNA 的表达及其在 LPS 处理后的上调。N，N-二甲基鞘氨醇（DMS），一种 SphK1 的特异性抑制剂，可有效减少体内和体外 AMC 中上调的 SphK1 免疫表达。这通过 Western blot 得到了证实，DMS 预处理可降低 DMS 预处理时的皮质组织 SphK1 蛋白水平。值得注意的是，DMS 抑制了 LPS 诱导的转录因子 NFκB 的上调。我们得出结论，AMC 中的 SphK1 表达可能与通过 NFκB 信号通路调节促炎细胞因子有关。
