Basal and induced sphingosine kinase 1 activity in A549 carcinoma cells:: function in cell survival and IL-1β and TNF-α induced production of inflammatory mediators
Basal and induced sphingosine kinase 1 activity in A549 carcinoma cells:: function in cell survival and IL-1β and TNF-α induced production of inflammatory mediators
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DOI：
10.1016/j.cellsig.2004.12.005
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发表时间：
2005-10-01
影响因子：
4.8
通讯作者：
Baumruker, T
中科院分区：
文献类型：
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作者：
Billich, A;Bornancin, F;Baumruker, T
鞘氨醇-1-磷酸，鞘氨醇激酶产生的脂质介质，调节多种细胞过程，从细胞生长和存活到效应功能，如促炎介质合成。使用人A549上皮性肺癌细胞作为模型系统，我们观察到在TNF-α或IL-1 β刺激后鞘氨醇激酶1型（SPHK 1）酶活性的瞬时上调。SPHK 1的这种瞬时激活被发现是奎宁诱导的考克斯-2转录和PGE（2）产生所必需的，因为不仅特异性siRNA（消除基础和诱导的SPHK 1酶活性），而且显性负性SPHK 1突变体（仅抑制诱导的SPHK 1活性）都降低了考克斯-2和PGE（2）。此外，发现TNF-α或IL-1 β诱导的选定细胞因子、趋化因子和粘附分子（IL-6、RANTES、MCP-1和VCAM-1）的转录需要SPHK 1活化。SPHK 1激活的抑制导致了马槟榔碱诱导的I κ B α磷酸化的减少，并因此由于RelA（p65）的核转位减少而降低了NF κ B活性，解释了炎性介质产生对SPHK 1激活的依赖性。通过N，N-二甲基鞘氨醇或通过使用siRNA下调其表达来抑制SPHK 1的基础活性可诱导A549细胞中的自发性凋亡，这种效应可通过干扰该细胞类型中的组成型NF κ B活性来解释。相反，显性负突变体的表达不诱导细胞凋亡。总之，这些发现表明SPHK 1活化在促炎信号传导中的作用和SPHK 1基础活性在A549肺癌细胞存活中的作用。(c)2004年爱思唯尔公司All rights reserved.
Sphingosine-1-phosphate, a lipid mediator produced by sphingosine kinases, regulates diverse cellular processes, ranging from cell growth and survival to effector functions, such as proinflammatory mediator synthesis. Using human A549 epithelial lung carcinoma cells as a model system, we observed transient upregulation of sphingosine kinase type 1 (SPHK1) enzyme activity upon stimulation with both TNF-alpha or IL-1 beta. This transient activation of SPHK1 was found to be required for cytokine-induced COX-2 transcription and PGE(2) production, since not only specific siRNA (abolishing both basal and induced SPHK1 enzyme activity), but also a dominant-negative SPHK1 mutant (suppressing induced SPHK1 activity only) both reduced COX-2 and PGE2. Furthermore, TNF-alpha- or IL-1 beta-induced transcription of selected cytokines, chemokines, and adhesion molecules (IL-6, RANTES, MCP-1, and VCAM-1) was found to require SPHK1 activation. Suppression of SPHK1 activation led to reduction of cytokine-induced I kappa B alpha phosphorylation and consequently diminished NF kappa B activity due to reduced nuclear translocation of RelA (p65), explaining the dependence of inflammatory mediator production on SPHK1 activation. Inhibition of basal SPHK1 activity by N,N-dimethylsphingosine or by downregulation of its expression using siRNA induced spontaneous apoptosis in A549 cells, an effect that can be explained through interference with constitutive NF kappa B activity in this cell type. In contrast, expression of the dominant-negative mutant did not induce apoptosis. Taken together, these findings demonstrate a role of SPHK1 activation in proinflammatory signalling and of SPHK1 basal activity in survival of A549 lung carcinoma cells. (c) 2004 Elsevier Inc. All rights reserved.