JNK1-dependent PUMA Expression Contributes to Hepatocyte Lipoapoptosis
JNK1-dependent PUMA Expression Contributes to Hepatocyte Lipoapoptosis
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DOI：
10.1074/jbc.m109.022491
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发表时间：
2009-09-25
影响因子：
4.8
通讯作者：
Gores, Gregory J.
中科院分区：
文献类型：
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作者：
Cazanave, Sophie C.;Mott, Justin L.;Gores, Gregory J.
游离脂肪酸(FFA)通过c-Jun氨基末端激酶(JNK)依赖的机制诱导肝细胞脂凋亡。然而，JNK在脂毒过程中参与核心的细胞凋亡机制，特别是激活BH3-唯一的蛋白的细胞过程仍然不完全清楚。因此，我们的目的是确定JNK是否在肝细胞脂肪凋亡过程中介导了BH3-Only蛋白的诱导。饱和脂肪酸棕榈酸酯，而不是单不饱和脂肪酸油酸酯，诱导PUMA基因和蛋白水平的增加。在原代小鼠肝细胞中，棕榈酸酯对PUMA的诱导是JNK1依赖的。棕榈酸酯介导的PUMA表达被显性负性c-jun抑制，并通过凝胶迁移率改变分析和染色质免疫沉淀实验证明含有激活蛋白1复合体的磷酸化c-jun直接与PUMA启动子结合。短发夹状RNA靶向敲除PUMA可减弱Bax活性、caspase3/7活性和细胞死亡。同样，彪马的遗传缺陷使小鼠肝细胞对脂类凋亡产生抵抗力。与单纯脂肪变性或对照组相比，非酒精性脂肪性肝炎患者的肝活检标本中PUMA的表达也增加。总体而言，这些数据暗示JNK1依赖的PUMA表达是导致肝细胞脂凋亡的机制之一。
Free fatty acids (FFA) induce hepatocyte lipoapoptosis by a c-Jun N-terminal kinase (JNK)-dependent mechanism. However, the cellular processes by which JNK engages the core apoptotic machinery during lipotoxicity, especially activation of BH3-only proteins, remain incompletely understood. Thus, our aim was to determine whether JNK mediates induction of BH3-only proteins during hepatocyte lipoapoptosis. The saturated FFA palmitate, but not the monounsaturated FFA oleate, induces an increase in PUMA mRNA and protein levels. Palmitate induction of PUMA was JNK1-dependent in primary murine hepatocytes. Palmitate-mediated PUMA expression was inhibited by a dominant negative c-Jun, and direct binding of a phosphorylated c-Jun containing the activator protein 1 complex to the PUMA promoter was identified by electrophoretic mobility shift assay and a chromatin immunoprecipitation assay. Short hairpin RNA-targeted knockdown of PUMA attenuated Bax activation, caspase 3/7 activity, and cell death. Similarly, the genetic deficiency of Puma rendered murine hepatocytes resistant to lipoapoptosis. PUMA expression was also increased in liver biopsy specimens from patients with non-alcoholic steatohepatitis as compared with patients with simple steatosis or controls. Collectively, the data implicate JNK1-dependent PUMA expression as a mechanism contributing to hepatocyte lipoapoptosis.