ATP Binding Cassette Transporters in Health and Disease

摘要 代谢性和慢性肝病是美国死亡的主要原因之一。肝脏是一个中枢 协调调节包括脂质在内的多种营养物质的代谢。肝脏不储存脂质， 长期和脂质积累在肝脏导致不同的疾病。甘油三酯蓄积 肝脏引起脂肪变性，其可以进展为非酒精性脂肪性肝炎（NASH），这两种非酒精性脂肪性肝炎的一部分都是非酒精性脂肪性肝炎。 脂肪肝疾病（NAFLD）谱。胆汁酸在肝脏中的积累，因为病毒感染，酒精 使用或更先进的肝损伤引起胆汁淤积。确定特异性的分子机制 在能够安全地针对这些途径进行疾病预防之前，确定促发疾病的途径是必不可少的一步。 我们的研究将进一步了解过氧化物酶体ABCD转运体在肝脏中的作用。我们有 使用无偏见的系统生物学方法来确定新的球员在调节脂质代谢， 肝脏通过这些方法，我们鉴定了过氧化物酶体转运蛋白ABCD 3作为一种新的肝细胞凋亡调节因子。 脂质代谢ABCD 3 −/−小鼠是部分致死的，存活动物中ABCD 3的缺失改变了肝脏的 脂质体，导致肝肿大和胆汁酸严重减少。为了在体内研究ABCD 3，我们 已经开发并验证了一种新的AAV-CRISPR策略，可以专门在肝脏中破坏Abcd 3， 我们以暂时的方式破坏成年野生型小鼠中的Abcd 3，以确定导致 ABCD 3缺失后观察到的缺陷。使用这些工具，我们发现成人肝脏ABCD 3的急性缺失 小鼠足以概括胆汁胆汁酸的急剧减少。当喂食西方饮食（WD）时， 肝脏ABCD 3的表达导致肝脏脂质积聚以及血浆肝酶和胆汁酸升高， NASH的标志。我们设计了两个具体的目标;在目标1中，我们将测试假设ABCD 3 缺乏导致胆汁淤积和NASH。在目标2中，我们将鉴定ABCD 3的特异性底物，并测试ABCD 3的活性。 过氧化物酶体脂质缺陷是NASH发展的致病性和关键的假说。我们的研究 证明ABCD 3的缺失，这是致命的人类，结果在胆汁淤积和NASH的设置， 血脂水平升高这些研究的完成将进一步了解过氧化物酶体ABCD的作用 在肝脏中的转运蛋白，并牵连过氧化物酶体脂质代谢的重要贡献者， NASH的发病机制。

ABSTRACT Metabolic and chronic liver diseases are among the leading causes of death in the US. The liver is a central hub that coordinately regulates the metabolism of many nutrients, including lipids. The liver does not store lipids in the long-term, and lipid accumulation in the liver results in different diseases. Triglyceride accumulation in the liver causes steatosis which can progress to non-alcoholic steatohepatitis (NASH), both part of the non-alcoholic fatty liver disease (NAFLD) spectrum. Accumulation of bile acids in the liver because of viral infections, alcohol use or more advanced liver damage causes cholestasis. Identification of the molecular mechanisms of specific disease-promoting pathways is an essential step before pathways can be safely targeted for disease prevention. Our studies will further the understanding of the role of peroxisomal ABCD transporters in the liver. We have used an unbiased systems biology approach to identify new players in the regulation of lipid metabolism in the liver. Through these methods, we identified the peroxisomal transporter ABCD3 as a novel regulator of hepatic lipid metabolism. Abcd3−/− mice are partially lethal and loss of ABCD3 in surviving animals alters the hepatic lipidome and results in hepatomegaly and profoundly reduced biliary bile acids. To study ABCD3 in vivo, we have developed and validated a novel AAV-CRISPR strategy to disrupt Abcd3 exclusively in the liver, allowing us to disrupt Abcd3 in adult wild-type mice in a temporal fashion to determine the sequelae of events leading to the defects observed after loss of ABCD3. Using these tools, we show that acute loss of hepatic ABCD3 in adult mice is sufficient to recapitulate the dramatic reduction in biliary bile acids. When fed a Western diet (WD), loss of hepatic ABCD3 results in liver lipid accumulation as well as elevated plasma liver enzymes and bile acids, all hallmarks of NASH. We have designed two specific aims; in Aim 1 we will test the hypothesis that ABCD3 deficiency results in cholestasis and NASH. In Aim 2, we will identify specific substrates for ABCD3 and test the hypothesis that peroxisomal lipid defects are pathogenic and key for the development of NASH. Our studies demonstrate that loss of ABCD3, which is lethal in humans, results in cholestasis and NASH in a setting of elevated lipid levels. Completion of these studies will further the understanding of the role of peroxisomal ABCD transporters in the liver, and implicate peroxisomal lipid metabolism as an important contributor in the pathogenesis of NASH.