Institut Für Allgemeine Pharmakologie Und Toxikologie, Goethe-Universität Frankfurt, Universitätsklinikum, Frankfurt am Main, Germany.
Institut Für Klinische Pharmakologie, Goethe-Universität Frankfurt, Universitätsklinikum, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
Pflugers Arch. 2024 Dec;476(12):1895-1911. doi: 10.1007/s00424-024-03027-7. Epub 2024 Oct 11.
Sphingosine-1-phosphate (S1P) is a ubiquitous lipid mediator, acting via specific G-protein-coupled receptors (GPCR) and intracellularly. Previous work has shown that deletion of S1P lyase caused a chronic elevation of cytosolic [Ca] and enhanced Ca storage in mouse embryonic fibroblasts. Here, we studied the role of sphingosine kinase (SphK)-1 in Ca signaling, using two independently generated EA.hy926 cell lines with stable knockdown of SphK1 (SphK1-KD1/2). Resting [Ca] and thapsigargin-induced [Ca] increases were reduced in both SphK1-KD1 and -KD2 cells. Agonist-induced [Ca] increases, measured in SphK1-KD1, were blunted. In the absence of extracellular Ca, thapsigargin-induced [Ca] increases declined rapidly, indicating enhanced removal of Ca from the cytosol. In agreement, plasma membrane Ca ATPase (PMCA)-1 and -4 and their auxiliary subunit, basigin, were strongly upregulated. Activation of S1P-GPCR by specific agonists or extracellular S1P did not rescue the effects of SphK1 knockdown, indicating that S1P-GPCR were not involved. Lipid measurements indicated that not only S1P but also dihydro-sphingosine, ceramides, and lactosylceramides were markedly depleted in SphK1-KD2 cells. SphK2 and S1P lyase were upregulated, suggesting enhanced flux via the sphingolipid degradation pathway. Finally, histone acetylation was enhanced in SphK1-KD2 cells, and the histone deacetylase inhibitor, vorinostat, induced upregulation of PMCA1 and basigin on mRNA and protein levels in EA.hy926 cells. These data show for the first time a transcriptional regulation of PMCA1 and basigin by S1P metabolism. It is concluded that SphK1 knockdown in EA.hy926 cells caused long-term alterations in cellular Ca homeostasis by upregulating PMCA via increased histone acetylation.
鞘氨醇-1-磷酸(S1P)是一种普遍存在的脂质介质,通过特定的 G 蛋白偶联受体(GPCR)和细胞内起作用。先前的工作表明,鞘氨醇磷酸酶(S1P 酶)的缺失导致细胞质 [Ca] 的慢性升高,并增强了小鼠胚胎成纤维细胞的 Ca 储存。在这里,我们使用两种独立生成的稳定敲低 SphK1 的 EA.hy926 细胞系(SphK1-KD1/2)研究了鞘氨醇激酶(SphK)-1 在 Ca 信号转导中的作用。在 SphK1-KD1 和 -KD2 细胞中,静息 [Ca] 和 thapsigargin 诱导的 [Ca] 增加均减少。在 SphK1-KD1 中,激动剂诱导的 [Ca] 增加减弱。在没有细胞外 Ca 的情况下,thapsigargin 诱导的 [Ca] 增加迅速下降,表明从细胞质中快速去除 Ca。一致地,质膜 Ca ATP 酶(PMCA)-1 和 -4 及其辅助亚基 basigin 强烈上调。通过特定激动剂或细胞外 S1P 激活 S1P-GPCR 不能挽救 SphK1 敲低的作用,表明 S1P-GPCR 不参与。脂质测量表明,不仅 S1P,而且二氢鞘氨醇、神经酰胺和乳糖基神经酰胺在 SphK1-KD2 细胞中明显耗竭。SphK2 和 S1P 酶被上调,表明通过鞘脂降解途径增强了通量。最后,SphK1-KD2 细胞中的组蛋白乙酰化增强,组蛋白去乙酰化酶抑制剂 vorinostat 在 EA.hy926 细胞中诱导 PMCA1 和 basigin 的 mRNA 和蛋白水平上调。这些数据首次表明 S1P 代谢对 PMCA1 和 basigin 的转录调控。结论是,EA.hy926 细胞中的 SphK1 敲低通过增加组蛋白乙酰化来上调 PMCA,从而导致细胞内 Ca 稳态的长期改变。
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