Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain.
Oregon Health and Science University, Portland, Oregon.
Gastroenterology. 2019 Aug;157(2):552-568. doi: 10.1053/j.gastro.2019.04.023. Epub 2019 Apr 25.
BACKGROUND & AIMS: Acetaminophen (APAP) overdose is a major cause of acute liver failure (ALF). Mitochondrial SH3BP5 (also called SAB) and phosphorylation of c-Jun N-terminal kinase (JNK) mediate the hepatotoxic effects of APAP. We investigated the involvement of steroidogenic acute regulatory protein (STARD1), a mitochondrial cholesterol transporter, in this process and sensitization by valproic acid (VPA), which depletes glutathione and stimulates steroidogenesis.
Nonfasted C57BL/6J mice (control) and mice with liver-specific deletion of STARD1 (Stard1), SAB (Sab), or JNK1 and JNK2 (Jnk1+2) were given VPA with or without APAP. Liver tissues were collected and analyzed by histology and immunohistochemistry and for APAP metabolism, endoplasmic reticulum (ER) stress, and mitochondrial function. Adult human hepatocytes were transplanted into Fah/Rag2/Il2rg/NOD (FRGN) mice to create mice with humanized livers.
Administration of VPA before administration of APAP increased the severity of liver damage in control mice. The combination of VPA and APAP increased expression of CYP2E1, formation of NAPQI-protein adducts, and depletion of glutathione from liver tissues of control mice, resulting in ER stress and the upregulation of STARD1. Livers from control mice given VPA and APAP accumulated cholesterol in the mitochondria and had sustained mitochondrial depletion of glutathione and mitochondrial dysfunction. Inhibition of ER stress, by administration of tauroursodeoxycholic acid to control mice, prevented upregulation of STARD1 in liver and protected the mice from hepatoxicity following administration of VPA and APAP. Administration of N-acetylcysteine to control mice prevented VPA- and APAP-induced ER stress and liver injury. Stard1 mice were resistant to induction of ALF by VPA and APAP, despite increased mitochondrial levels of glutathione and phosphorylated JNK; we made similar observations in fasted Stard1 mice given APAP alone. Sab mice or Jnk1+2 mice did not develop ALF following administration of VPA and APAP. The ability of VPA to increase the severity of APAP-induced liver damage was observed in FRGN mice with humanized liver.
In studies of mice, we found that upregulation of STARD1 following ER stress mediates APAP hepatoxicity via SH3BP5 and phosphorylation of JNK1 and JNK2.
对乙酰氨基酚（APAP）过量是急性肝衰竭（ALF）的主要原因。线粒体 SH3BP5（也称为 SAB）和 c-Jun N 末端激酶（JNK）的磷酸化介导 APAP 的肝毒性作用。我们研究了胆固醇转运蛋白类固醇急性调节蛋白（STARD1）在该过程中的作用以及丙戊酸（VPA）的敏化作用，VPA 可耗尽谷胱甘肽并刺激类固醇生成。
非禁食 C57BL/6J 小鼠（对照组）和肝脏特异性缺失 STARD1（Stard1）、SAB（Sab）或 JNK1 和 JNK2（Jnk1+2）的小鼠给予 VPA 加或不加 APAP。收集肝组织并进行组织学和免疫组织化学分析，以及 APAP 代谢、内质网（ER）应激和线粒体功能分析。将成人肝细胞移植到 Fah/Rag2/Il2rg/NOD（FRGN）小鼠中，以创建具有人源化肝脏的小鼠。
APAP 前给予 VPA 增加了对照组小鼠肝损伤的严重程度。VPA 和 APAP 的联合使用增加了 CYP2E1 的表达、NAPQI-蛋白加合物的形成以及对照组小鼠肝组织中谷胱甘肽的耗竭，导致 ER 应激和 STARD1 的上调。给予 VPA 和 APAP 的对照组小鼠的肝脏线粒体中胆固醇积累，谷胱甘肽持续耗竭线粒体和线粒体功能障碍。给予牛磺熊脱氧胆酸可抑制 ER 应激，可防止对照组小鼠肝中 STARD1 的上调，并防止 VPA 和 APAP 给药后肝毒性。给予 N-乙酰半胱氨酸可预防 VPA 和 APAP 诱导的 ER 应激和肝损伤。Stard1 小鼠对 VPA 和 APAP 诱导的 ALF 具有抗性，尽管线粒体谷胱甘肽和磷酸化 JNK 水平升高；我们在单独给予 APAP 的禁食 Stard1 小鼠中也观察到了类似的现象。Sab 小鼠或 Jnk1+2 小鼠在给予 VPA 和 APAP 后未发展为 ALF。在具有人源化肝脏的 FRGN 小鼠中观察到 VPA 增加 APAP 诱导的肝损伤的严重程度的能力。
在小鼠研究中，我们发现 ER 应激后 STARD1 的上调通过 SH3BP5 和 JNK1 和 JNK2 的磷酸化介导 APAP 的肝毒性。
