Department of Immunology, Nanjing Medical University, Nanjing, 101 Longmian Avenue, Jiangsu, 211166, China.
Department of Pharmacology, Nanjing Medical University, Nanjing, 101 Longmian Avenue, Jiangsu, 211166, China.
Cell Death Differ. 2020 Jun;27(6):1924-1937. doi: 10.1038/s41418-019-0471-x. Epub 2019 Dec 11.
Acetaminophen (APAP) is the leading cause of drug-induced acute liver failure. Sphingosine-1-phosphate (S1P), whose formation is catalyzed by sphingosine kinase (SPHK)-1 or -2, is a bioactive lipid implicated in human health and disease. Here, we show that APAP-treated sphK1-deficient (sphK1) mice exhibited markedly less liver damage and reduced inflammation compared with the wild-type mice. SPHK1 deficiency alleviated APAP-induced endoplasmic reticulum (ER) stress by affecting the phosphorylation of inositol-requiring enzyme 1α (IRE1α) and protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)-eukaryotic translation initiation factor 2α (eIF2α), levels of activating transcription factor 4 (ATF4), and activation of activating transcription factor 6 (ATF6). SPHK1 deficiency also inhibited mitochondrial permeability transition (MPT), as evidenced by the impaired phosphorylation of JNK, apoptosis signal-regulated kinase 1 (ASK1), and glycogen synthase kinase 3β (GSK3β). In addition, SPHK1 deficiency reduced the levels of histone deacetylase and promoted the acetylation of p65 and STAT1, thereby impairing the transcription of inflammatory genes. Supplementation with exogenous S1P significantly reversed the activation of the PERK-eIF2α-ATF4 pathway and ATF6 during ER stress as well as the activation of GSK3β, ASK1, and JNK during MPT. Both FTY720, a functional S1P receptor antagonist, and PF543, an SPHK1 inhibitor, significantly ameliorated APAP-induced liver injury and improved animal survival. Our study reveals a critical role for SPHK1 in mediating APAP-induced hepatotoxicity by promoting ER stress and MPT.
对乙酰氨基酚（APAP）是导致药物性急性肝衰竭的主要原因。神经鞘氨醇-1-磷酸（S1P）的形成由鞘氨醇激酶（SPHK）-1 或 -2 催化，是一种与人类健康和疾病有关的生物活性脂质。在这里，我们发现与野生型小鼠相比，APAP 处理的 sphK1 缺陷（sphK1）小鼠的肝损伤明显减少，炎症反应减轻。SPHK1 缺乏通过影响肌醇需求酶 1α（IRE1α）和蛋白激酶 R（PKR）样内质网激酶（PERK）-真核起始因子 2α（eIF2α）的磷酸化、激活转录因子 4（ATF4）的水平和激活转录因子 6（ATF6）来减轻 APAP 诱导的内质网（ER）应激。SPHK1 缺乏还抑制线粒体通透性转换（MPT），这表现为 JNK、凋亡信号调节激酶 1（ASK1）和糖原合酶激酶 3β（GSK3β）的磷酸化受损。此外，SPHK1 缺乏降低组蛋白去乙酰化酶水平，促进 p65 和 STAT1 的乙酰化，从而损害炎症基因的转录。外源性 S1P 的补充显著逆转了 ER 应激过程中 PERK-eIF2α-ATF4 途径和 ATF6 的激活，以及 MPT 过程中 GSK3β、ASK1 和 JNK 的激活。功能性 S1P 受体拮抗剂 FTY720 和 SPHK1 抑制剂 PF543 均显著改善 APAP 诱导的肝损伤并提高动物存活率。我们的研究揭示了 SPHK1 通过促进 ER 应激和 MPT 介导 APAP 诱导的肝毒性的关键作用。
