Masouminia M, Samadzadeh S, Mendoza A S, French B A, Tillman B, French S W
Harbor UCLA Medical Center, Department of Pathology, Torrance, CA, United States.
LA Biomed, Torrance, CA, United States.
Exp Mol Pathol. 2016 Aug;101(1):81-8. doi: 10.1016/j.yexmp.2016.07.002. Epub 2016 Jul 16.
There are many homeostatic mechanisms for coping with stress conditions in cells, including autophagy. In many studies autophagy, as an intracellular pathway which degrades misfolded and damaged protein, and Mallory-Denk Body (MDB) formation have been shown to be protective mechanisms against stress such as alcoholic hepatitis. Alcohol has a significant role in alteration of lipid homeostasis, sterol regulatory element-binding proteins (SREBPs) and peroxidase proliferator-activated receptors through AMP-activated protein kinase (AMPK)-dependent mechanism. AMPK is one of the kinases that regulate autophagy through the dephosphorylation of ATG1. Activation of ATG1 (ULK kinases family) activates ATG6. These two activated proteins relocate to the site of initial autophagosome and activate the other downstream components of autophagocytosis. Many other proteins regulate autophagocytosis at the gene level. CHOP (C/EBP homologous protein) is one of the most important parts of stress-inducible transcription that encodes a ubiquitous transcription factor. In this report we measure the upregulation of the gene that are involved in autophagocytosis in liver biopsies of alcoholic hepatitis and NASH. Electron microscopy was used to document the presence of autophagosomes in the liver cells. Expression of AMPK1, ATG1, ATG6 and CHOP in ASH were significantly (p value<0.05) upregulated in comparison to control. Electron microscopy findings of ASH confirmed the presence of autophagosomes, one of which contained a MDB, heretofore undescribed. Significant upregulations of AMPK-1, ATG-1, ATG-6, and CHOP, and uptrending of ATG-4, ATG-5, ATG-9, ATR, and ATM in ASH compared to normal control livers indicate active autophagocytosis in alcoholic hepatitis.
细胞中有许多应对应激条件的稳态机制,包括自噬。在许多研究中,自噬作为一种降解错误折叠和受损蛋白质的细胞内途径,以及马洛里-丹科小体(MDB)的形成已被证明是针对诸如酒精性肝炎等应激的保护机制。酒精通过AMP激活蛋白激酶(AMPK)依赖性机制在脂质稳态、固醇调节元件结合蛋白(SREBP)和过氧化物酶体增殖物激活受体的改变中起重要作用。AMPK是通过使ATG1去磷酸化来调节自噬的激酶之一。ATG1(ULK激酶家族)的激活会激活ATG6。这两种激活的蛋白质会重新定位到初始自噬体的位点,并激活自噬作用的其他下游成分。许多其他蛋白质在基因水平上调节自噬作用。CHOP(C/EBP同源蛋白)是应激诱导转录的最重要部分之一,它编码一种普遍存在的转录因子。在本报告中,我们测量了酒精性肝炎和非酒精性脂肪性肝炎(NASH)肝活检中参与自噬作用的基因的上调情况。使用电子显微镜记录肝细胞中自噬体的存在。与对照组相比,酒精性肝炎(ASH)中AMPK1、ATG1、ATG6和CHOP的表达显著上调(p值<0.05)。ASH的电子显微镜检查结果证实了自噬体的存在,其中一个自噬体含有一个此前未描述过的MDB。与正常对照肝脏相比,ASH中AMPK - 1、ATG - 1、ATG - 6和CHOP的显著上调,以及ATG - 4、ATG - 5、ATG - 9、ATR和ATM的上升趋势表明酒精性肝炎中存在活跃的自噬作用。