Effects of Ethanol TNF Induced Cytotoxicity

描述（由申请人提供）：酒精性肝病（ALD）是一系列肝脏结构和功能紊乱。ALD的改变大致分为酒精诱导的脂肪变性、脂肪性肝炎和肝硬化。肿瘤坏死因子（TNF）在ALD的发展中起着关键作用，部分原因是它能够导致肝细胞的损伤和死亡。在之前的支持阶段，我们发现暴露于乙醇的肝细胞对TNF诱导的细胞毒性表现出增加的敏感性，这是由线粒体对损伤的敏感性增强驱动的，这反过来又被乙醇暴露细胞中TNF引起的信号通路的改变所利用。在本申请中，我们打算缩小和扩大我们的研究范围。首先，我们提出肝细胞脂肪生成的修饰有助于增加对TNF诱导的损伤的脆弱性，这是乙醇暴露细胞的线粒体的特征。具体地，在乙醇暴露的细胞中酰基CoA结合蛋白（ACBP）和外周苯二氮受体（PBR）（参与脂质和胆固醇代谢的蛋白质）的表达增加，建立了线粒体对TNF诱导的损伤的增强的易感性。此外，由乙醇暴露引起的PI 3-激酶/Akt途径的紊乱导致电压依赖性阴离子载体（VDAC）的磷酸化，对线粒体功能和对损伤的抵抗力具有有害后果。初步数据还显示，通过乙醇暴露对线粒体施加的改变可能通过阻碍脂联素诱导的AMPK通路的激活来减轻脂联素对TNF诱导的细胞毒性的有益作用。该提议的工作假设是，由乙醇暴露引发的脂肪生成的紊乱引起线粒体功能的改变，特别是通过酰基CoA结合蛋白、外周苯二氮卓受体、电压依赖性阴离子载体（VDAC）的磷酸化和内质网应激的表达增加，所有这些都使得线粒体和细胞对TNF诱导的损伤更敏感。此外，乙醇的这些作用可以通过激活AMPK来改善。

DESCRIPTION (provided by applicant): Alcoholic liver disease (ALD) constitutes a spectrum of disorders in liver structure and function. The alterations in ALD are broadly categorized into alcohol induced steatosis, steatohepatitis and cirrhosis. Tumor necrosis factor (TNF) has been shown to play a critical role in the progression of ALD, partly through it ability to bring about the injury and death of hepatocytes. In the preceding period of support we have uncovered that hepatocytes exposed to ethanol display an increased sensitivity to TNF induced cytotoxicity and that this is driven by an enhanced susceptibility of the mitochondria to injury, which in turn is exploited by alterations in signaling pathways elicited by TNF in ethanol exposed cells. In the present application we intend to both narrow and broaden the scope of our studies. Firstly, we propose that modifications to hepatocyte lipogenesis contribute to the increased vulnerability to TNF induced damage that characterizes the mitochondria of ethanol exposed cells. Specifically, increased expression of acyl CoA binding protein (ACBP) and the peripheral benzodiazepine receptor (PBR) in ethanol exposed cells, proteins involved in lipid and cholesterol metabolism, establish an enhanced susceptibility of the mitochondria to TNF induced damage. Also, derangements of the PI3-kinase/Akt pathway brought about by ethanol exposure results in phosphorylation of the voltage dependent anion carrier (VDAC), with detrimental consequences for mitochondrial function and resistance to injury. The preliminary data also reveal that the alterations imposed on mitochondria by ethanol exposure may mitigate the beneficial effects of adiponectin against TNF induced cytotoxicity, potentially by impeding adiponectin induced activation of the AMPK pathway. The working hypothesis for this proposal is that the derangement of lipogenesis triggered by ethanol exposure causes alterations in mitochondrial function, particularly through an increased expression of acyl CoA binding protein, the peripheral benzodiazepine receptor, phosphorylation of the voltage dependent anion carrier (VDAC) and endoplasmic reticulum stress, all of which render the mitochondria and cell more sensitive to TNF induced injury. Moreover these effects of ethanol can be ameliorated by activation of AMPK.