Effects of Ethanol TNF Induced Cytotoxicity

描述（由申请人提供）：酒精性肝病（ALD）构成了一系列肝脏结构和功能紊乱。ALD的改变大致分为酒精性脂肪变性、脂肪性肝炎和肝硬化。肿瘤坏死因子（TNF）已被证明在ALD的进展中发挥关键作用，部分是通过其导致肝细胞损伤和死亡的能力。在之前的研究中，我们已经发现，暴露于乙醇中的肝细胞对TNF诱导的细胞毒性表现出更高的敏感性，这是由于线粒体对损伤的易感性增强所致，而线粒体对损伤的易感性反过来又被乙醇暴露的细胞中TNF引起的信号通路的改变所利用。在目前的应用中，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改变有助于增加乙醇暴露细胞线粒体对TNF诱导损伤的脆弱性。具体来说，在乙醇暴露的细胞中，酰基辅酶a结合蛋白（ACBP）和外周苯二氮卓受体（PBR）的表达增加，参与脂质和胆固醇代谢的蛋白质，建立了线粒体对TNF诱导损伤的增强易感性。此外，乙醇暴露导致pi3 -激酶/Akt通路紊乱，导致电压依赖性阴离子载体（VDAC）磷酸化，对线粒体功能和抗损伤能力产生不利影响。初步数据还显示，乙醇暴露对线粒体施加的改变可能会减轻脂联素对TNF诱导的细胞毒性的有益作用，可能是通过阻碍脂联素诱导的AMPK通路的激活。该提议的工作假设是，乙醇暴露引发的脂肪生成紊乱会导致线粒体功能的改变，特别是通过酰基辅酶a结合蛋白、外周苯二氮卓类受体、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，所有这些都使线粒体和细胞对TNF诱导的损伤更敏感。此外，乙醇的这些影响可以通过活化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.