Division of Gastroenterology & Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI 02903, USA.
J Hepatol. 2013 Apr;58(4):785-91. doi: 10.1016/j.jhep.2012.11.042. Epub 2012 Dec 2.
BACKGROUND & AIMS: p53 and its transcriptional target miRNA34a have been implicated in the pathogenesis of fatty liver. We tested the efficacy of a p53 inhibitor, pifithrin-α p-nitro (PFT) in attenuating steatosis, associated oxidative stress and apoptosis in a murine model of non-alcoholic fatty liver disease (NAFLD).
C57BL/6 mice were fed a high-fat (HFD) or control diet for 8 weeks; PFT or DMSO (vehicle) was administered three times per week. Markers of oxidative stress and apoptosis as well as mediators of hepatic fatty acid metabolism were assessed by immunohistochemistry, Western blot, real-time PCR, and biochemical assays.
PFT administration suppressed HFD-induced weight gain, ALT elevation, steatosis, oxidative stress, and apoptosis. PFT treatment blunted the HFD-induced upregulation of miRNA34a and increased SIRT1 expression. In the livers of HFD-fed, PFT-treated mice, activation of the SIRT1/PGC1α/PPARα axis increased the expression of malonyl-CoA decarboxylase (MLYCD), an enzyme responsible for malonyl-CoA (mCoA) degradation. Additionally, the SIRT1/LKB1/AMPK pathway (upstream activator of MLYCD) was promoted by PFT. Thus, induction of these two pathways by PFT diminished the hepatic mCoA content by enhancing MLYCD expression and function. Since mCoA inhibits carnitine palmitoyltransferase 1 (CPT1), the decrease of hepatic mCoA in the PFT-treated, HFD-fed mice increased CPT1 activity, favored fatty acid oxidation, and decreased steatosis. Additionally, we demonstrated that PFT abrogated steatosis and promoted MLYCD expression in palmitoleic acid-treated human HepaRG cells.
The p53 inhibitor PFT diminished hepatic triglyceride accumulation and lipotoxicity in mice fed a HFD, by depleting mCoA and favoring the β-oxidation of fatty acids.
p53 及其转录靶标 miRNA34a 已被牵连到脂肪肝的发病机制中。我们测试了 p53 抑制剂 pifithrin-α p-硝基（PFT）在减轻非酒精性脂肪性肝病（NAFLD）小鼠模型中脂肪变性、相关氧化应激和细胞凋亡的功效。
C57BL/6 小鼠喂食高脂肪（HFD）或对照饮食 8 周；每周三次给予 PFT 或 DMSO（载体）。通过免疫组织化学、Western blot、实时 PCR 和生化测定评估氧化应激和细胞凋亡的标志物以及肝内脂肪酸代谢的介质。
PFT 给药抑制了 HFD 诱导的体重增加、ALT 升高、脂肪变性、氧化应激和细胞凋亡。PFT 治疗减弱了 HFD 诱导的 miRNA34a 上调，并增加了 SIRT1 表达。在 HFD 喂养、PFT 治疗的小鼠肝脏中，SIRT1/PGC1α/PPARα 轴的激活增加了丙二酰辅酶 A 脱羧酶（MLYCD）的表达，该酶负责丙二酰辅酶 A（mCoA）的降解。此外，SIRT1/LKB1/AMPK 途径（MLYCD 的上游激活剂）被 PFT 促进。因此，PFT 诱导这两条途径通过增强 MLYCD 的表达和功能来减少肝内 mCoA 含量。由于 mCoA 抑制肉碱棕榈酰转移酶 1（CPT1），PFT 治疗的 HFD 喂养小鼠肝内 mCoA 减少增加了 CPT1 活性，有利于脂肪酸氧化，并减少了脂肪变性。此外，我们证明 PFT 消除了棕榈油酸处理的人 HepaRG 细胞中的脂肪变性并促进了 MLYCD 的表达。
p53 抑制剂 PFT 通过耗竭 mCoA 和促进脂肪酸的β氧化，减少了 HFD 喂养小鼠的肝甘油三酯积累和脂毒性。
