Alcohol alters hepatic microtubule and membrane dynamics

描述（由申请人提供）： 每年有超过20，000人死于酒精性肝病，这是美国人的第七大死因。由于肝脏是乙醇代谢的主要场所，因此它是最易受酒精诱导损伤的器官。在疾病的早期阶段，脂肪肝的发展导致肝细胞坏死，肝纤维化，并最终导致肝硬化。虽然疾病进展在临床上得到了很好的描述，但酒精性肝损伤的分子基础尚不清楚。我们的长期目标是了解导致酒精诱导的肝毒性的机制。我们最近的研究是在培养的WIF-B细胞中进行的。这些肝细胞高度分化，并在培养中保持肝脏特异性活性，包括有效代谢乙醇的能力。因此，这些细胞是一个很好的模型，以检查酒精诱导的肝毒性，并允许我们进行机制的研究，不能在动物中进行。最近，我们发现乙醇处理的细胞中微管更稳定，乙酰化程度是对照组的2-3倍。我们在乙醇喂养大鼠的肝细胞中证实了这些结果，表明这些发现具有生理学意义。我们进一步确定，在WIF-B细胞中增加的微管乙酰化依赖于乙醇代谢。本建议侧重于从这些最近的结果中出现的两个主要问题。首先，导致乙醇处理细胞中微管过度乙酰化和稳定性增加的机制是什么，其他肝脏蛋白质是否通过类似机制过度乙酰化？其次，我们将测试是否微管超乙酰化;有助于酒精诱导的蛋白质运输中观察到的缺陷。我们在培养和使用WIF-B细胞方面的专业知识以及我们在极化肝细胞蛋白运输方面的专业知识完美地帮助我们进行这些探索性的机制实验。这些新的研究领域将为我们未来的肝毒性研究提供新的方法和假设。

DESCRIPTION (provided by applicant): More than 20,000 people each year die of alcoholic liver disease, the seventh largest cause of death in Americans. Because the liver is the major site of ethanol metabolism, it is the most susceptible organ to alcohol-induced injury. In the early stages of the disease, a fatty liver develops which leads to hepatocyte necrosis, liver fibrosis, and ultimately to cirrhosis. Although the disease progression is well described clinically, the molecular basis for alcohol-induced liver injury is not understood. Our long-term goal is to understand the mechanisms that lead to alcohol-induced hepatotoxicity. Our recent studies have been performed in cultured WIF-B cells. These hepatic cells are highly differentiated and maintain liver-specific activities in culture, including the ability to efficiently metabolize ethanol. Thus, these cells are an excellent model to examine alcohol-induced hepatotoxicity and allow us to perform mechanistic studies that cannot be done in animals. Recently, we found that microtubules are more stable and acetylated 2-3-fold more in ethanol-treated cells than in control. We confirmed these results in hepatocytes from ethanol-fed rats indicating the findings have physiologic importance. We further determined that increased microtubule acetylation in WIF-B cells is dependent on ethanol metabolism. This proposal focuses on two major questions emerging from these recent results. First, what is the mechanism that leads:; to microtubule hyperacetylation and increased stability in ethanol-treated cells and are other hepatic proteins hyperacetylated via similar mechanisms? Secondly, we will test whether microtubule hyperacetylation ;contributes to alcohol-induced defects observed in protein trafficking. Our considerable expertise in the culture and use of WIF-B cells and our expertise in polarized hepatocyte protein trafficking situate us perfectly to perform these exploratory, mechanistic experiments. These novel research areas will open the door to novel approaches and hypotheses that we will apply to our future studies of hepatotoxicity.