Sphingosine-1-phosphate (S1P), a bioactive lipid mediator, is generated from sphingosine by sphingosine kinases (SPHKs) 1 and 2 and is metabolized to ∆2-hexadecenal (∆2-HDE) and ethanolamine phosphate by S1P lyase (S1PL) in mammalian cells. We have recently demonstrated the activation of nuclear SPHK2 and the generation of S1P in the nucleus of lung epithelial cells exposed to Pseudomonas aeruginosa. Here, we have investigated the nuclear localization of S1PL and the role of ∆2-HDE generated from S1P in the nucleus as a modulator of histone deacetylase (HDAC) activity and histone acetylation. Electron micrographs of the nuclear fractions isolated from MLE-12 cells showed nuclei free of ER contamination, and S1PL activity was detected in nuclear fractions isolated from primary lung bronchial epithelial cells and alveolar epithelial MLE-12 cells. Pseudomonas aeruginosa-mediated nuclear ∆2-HDE generation, and H3/H4 histone acetylation was attenuated by S1PL inhibitors in MLE-12 cells and human bronchial epithelial cells. In vitro, the addition of exogenous ∆2-HDE (100–10,000 nM) to lung epithelial cell nuclear preparations inhibited HDAC1/2 activity, and increased acetylation of Histone H3 and H4, whereas similar concentrations of S1P did not show a significant change. In addition, incubation of ∆2-HDE with rHDAC1 generated five different amino acid adducts as detected by LC-MS/MS; the predominant adduct being ∆2-HDE with lysine residues of HDAC1. Together, these data show an important role for the nuclear S1PL-derived ∆2-HDE in the modification of HDAC activity, histone acetylation, and chromatin remodeling in lung epithelial cells.

1-磷酸鞘氨醇 (S1P) 是一种生物活性脂质介质，由鞘氨醇激酶 (SPHK) 1 和 2 从鞘氨醇生成，并通过 S1P 裂合酶 (S1PL) 代谢为 Δ2-十六碳烯醛 (Δ2-HDE) 和磷酸乙醇胺在哺乳动物细胞中。我们最近证明了暴露于铜绿假单胞菌的肺上皮细胞核中 SPHK2 的激活和 S1P 的生成。在这里，我们研究了 S1PL 的核定位以及 S1P 在细胞核中产生的Δ 2-HDE 作为组蛋白脱乙酰酶 (HDAC) 活性和组蛋白乙酰化调节剂的作用。从 MLE-12 细胞分离的核级分的电子显微照片显示，细胞核没有 ER 污染，并且在从原代肺支气管上皮细胞和肺泡上皮 MLE-12 细胞分离的核级分中检测到 S1PL 活性。在 MLE-12 细胞和人支气管上皮细胞中，S1PL 抑制剂可减弱铜绿假单胞菌介导的核 Δ2-HDE 生成和 H3/H4 组蛋白乙酰化。在体外，向肺上皮细胞核制剂中添加外源 Δ2-HDE (100–10,000 nM) 可抑制 HDAC1/2 活性，并增加组蛋白 H3 和 H4 的乙酰化，而相似浓度的 S1P 并未显示出显着变化。此外，LC-MS/MS 检测到，Δ2-HDE 与 rHDAC1 一起孵育产生了五种不同的氨基酸加合物；主要的加合物是 Δ2-HDE 与 HDAC1 的赖氨酸残基。总之，这些数据表明核 S1PL 衍生的 Δ2-HDE 在肺上皮细胞 HDAC 活性、组蛋白乙酰化和染色质重塑的修饰中发挥重要作用。