自噬在对乙酰氨基酚诱导的肝损伤中保护性作用的研究
摘要：背景与目的：自噬可以选择性清除受损的细胞器,比如受损的线粒体,从而防止线粒体损伤诱导的细胞死亡。过量的对乙酰氨基酚(APAP)会导致人类或动物肝细胞的线粒体受损，进而使肝细胞发生坏死造成肝损伤。虽然很多APAP导致肝损伤的机制已经被报道，但是目前尚不清楚APAP是否可以通过自噬来调控肝细胞损伤的程度，本研究的目的是为了验证自噬在APAP诱导的肝细胞损伤中是否起重要的保护性作用。方法：我们用APAP处理原代培养小鼠肝细胞和绿色荧光蛋白-微管相关蛋白轻链3（GFP-LC3）转基因小鼠，通过形态学和生物化学的方法检测自噬的变化。结果：我们发现APAP能够诱导原代培养的肝细胞和转基因小鼠的肝细胞自噬增多，我们还发现，APAP可以抑制肝细胞的雷帕霉素靶蛋白从而诱导自噬的发生，而这种自噬可以被乙酰半胱氨酸抑制，由此推断APAP代谢物与线粒体蛋白结合及随后活性氧的产生是自噬增多的主要原因，自噬自噬抑制剂3-甲基腺嘌呤或氯喹能够加重APAP导致的肝细胞毒性，而自噬促进剂雷帕霉素能够减轻APAP导致的肝细胞毒性。结论：过量的APAP能够诱导自噬，而自噬可以通过清除受损的线粒体来限制肝细胞的死亡。首都医科大学附属北京佑安医院中西医结合科 丁剑波 李秀惠 摘译
本文首次发表于［Hepatology，2012，55(1)：222-232］
Activation of Autophagy Protects Against Acetaminophen-Induced Hepatotoxicity
Autophagy can selectively remove damaged organelles, including mitochondria, and, in
turn, protect against mitochondria-damage–induced cell death. Acetaminophen (APAP)
overdose can cause liver injury in animals and humans by inducing mitochondria damage
and subsequent necrosis in hepatocytes. Although many detrimental mechanisms have
been reported to be responsible for APAP-induced hepatotoxicity, it is not known whether
APAP can modulate autophagy to regulate hepatotoxicity in hepatocytes. To test the hypothesis
that autophagy may play a critical protective role against APAP-induced hepatotoxicity,
primary cultured mouse hepatocytes and green fluorescent protein/light chain 3
transgenic mice were treated with APAP. By using a series of morphological and biochemical
autophagic flux assays, we found that APAP induced autophagy both in the in vivo
mouse liver and in primary cultured hepatocytes. We also found that APAP treatment
might suppress mammalian target of rapamycin in hepatocytes and that APAP-induced
autophagy was suppressed by N-acetylcysteine, suggesting APAP mitochondrial protein
binding and the subsequent production of reactive oxygen species may play an important
role in APAP-induced autophagy. Pharmacological inhibition of autophagy by
3-methyladenine or chloroquine further exacerbated APAP-induced hepatotoxicity. In
contrast, induction of autophagy by rapamycin inhibited APAP-induced hepatotoxicity.
Conclusion: APAP overdose induces autophagy, which attenuates APAP-induced liver cell
death by removing damaged mitochondria.
