Altered Lipid Droplet Trafficking: Role in Alcoholic Fatty Liver Disease

改变脂滴运输：在酒精性脂肪肝病中的作用

• 批准号: 9921268
• 负责人: Carol A. Casey
• 金额: $ 56.39万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-10 至 2021-09-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9921268
• 关键词: ABL1 gene; Acute; Address; Adipocytes; Affect; Agonist; Alcohol abuse; Alcoholic Fatty Liver; Alcoholic Liver Diseases; Alcoholic beverage heavy drinker; Alcoholic steatohepatitis; Alcohols; Attenuated; Autophagocytosis; Autophagosome; Award; Biological; Capsid Proteins; Catabolic Process; Catabolism; Caveolins; Cell physiology; Cells; Cellular biology; Chronic; Cirrhosis; Cyclic AMP; Cytoskeleton; Data; Defect; Dynamin; Ethanol; Ethanol Metabolism; Event; Excision; Fatty Liver; Fatty acid glycerol esters; Fibrosis; Forskolin; Foundations; Funding; G-Protein-Coupled Receptors; GTP-Binding Protein alpha Subunits, Gs; Goals; Guanosine Triphosphate Phosphohydrolases; Health; Hepatocyte; Imaging technology; Impairment; Individual; Injury; Investigation; Isoproterenol; Lead; Lipids; Lipolysis; Liver; Liver diseases; Lysosomes; Measurable; Membrane; Membrane Protein Traffic; Molecular; National Institute on Alcohol Abuse and Alcoholism; Nutrient; Organelles; Outcome; Pathway interactions; Phosphotransferases; Principal Investigator; Process; Property; Proteins; Research; Role; SRC gene; Sampling; Severities; Signal Transduction; Solid; Steatohepatitis; Stress; Surface; Therapeutic; Triglycerides; Ubiquitination; alcohol exposure; attenuation; base; innovation; insight; lipid metabolism; liver injury; medical specialties; novel; nutrient deprivation; perilipin; prevent; problem drinker; response; trafficking

ABSTRACT This proposal is a competitive renewal of a multiple-PI R01 funded through NIAAA. The goal of the application is to examine how ethanol exposure contributes to fat accumulation in the liver due to altered dynamic properties of the fat storage organelle, the lipid droplet (LD). Specifically we will examine how alcohol exposure compromises both the lipolytic and lipophagic machineries in hepatocytes via disrupting signaling cascades and membrane trafficking effectors, ultimately leading to a fatty liver. During alcoholic liver disease, almost all heavy drinkers develop fatty liver, which is marked by the aberrant and significant accumulation of intrahepatocellular triglycerides in the form of LDs. Understanding the cellular processes contributing to this fat accumulation will provide important information for preventing further progression of injury, as it is known that alcoholic fatty liver is the initial, but entirely reversible stage of liver injury. Our research in the previously- funded R01 examined how LD dynamics in hepatocytes are regulated by several GTPases (dynamins and Rabs in particular) that can act as molecular switches to regulate membrane traffic. We showed that ethanol- induced disruption of these GTPases dramatically increases accumulation of LDs in the liver cell. Preliminary data in support of this continuation application show that the lipolytic machinery of hepatocytes, is activated by agonists of cAMP kinase (isoproterenol, forskolin) but this response is markedly inhibited by ethanol exposure. Additionally, we show that the hepatocyte utilizes sequential mechanisms to catabolize LDs that entail lipolysis followed by lipophagy. Further, it appears that activation of non-receptor tyrosine kinases that reside on the LD-autophagosome (AP) surface function to drive lipophagy, and that alcohol impairs this process. Finally, in addition to engulfment of LDs by APs, removal or “sampling” of lipids away from LDs seems to occur by a transient, measurable interaction that is sensitive to ethanol exposure. These recent, novel findings provide an excellent foundation for this proposal, and support our central hypothesis that ethanol exposure compromises both the lipolytic and lipophagic machineries in the hepatocyte by disrupting signaling cascades and membrane trafficking events, leading to hepatic steatosis. The two principal investigators directing this project have complementary strengths: Dr. Casey is a biochemist whose expertise is in alcoholic-induced liver damage. Dr. McNiven is a cell biologist whose specialty is membrane-cytoskeleton dynamics. This unique collaborative effort has proven very beneficial to the field of alcoholic liver disease and will continue to result in outcomes otherwise unattainable by individual efforts. The proposed investigation will utilize state-of-the-art membrane trafficking and imaging technologies to quantify specific molecular events that contribute to alcohol- induced fatty liver. Successful completion of these studies will provide novel insights as to how ethanol affects LD dynamics in liver cells, and important information for therapeutic strategies aimed at reducing or eliminating the severity of steatosis and blocking its further progression to alcoholic steatohepatitis, fibrosis and cirrhosis.

抽象的 该提案是对通过NIAAA资助的多个PI R01的竞争续约。应用的目标 是为了检查乙醇暴露如何因动态变化而导致肝脏中的脂肪积累 脂肪存储细胞器的性质，脂质液滴（LD）。具体而言，我们将研究酒精 暴露通过破坏信号传导损害肝细胞中的脂解和脂流体机器 级联和膜贩运作用，最终导致脂肪肝。在酒精性肝病期间， 几乎所有的重饮酒者都会出现脂肪肝，这是由异常和大量积累的标志 LDS形式的ePATOCATOCAIREDES。了解导致这种脂肪的细胞过程 积累将提供重要的信息，以防止进一步的伤害进展，众所周知 酒精脂肪肝是肝损伤的初始但完全可逆的阶段。我们在以前的研究 资助的R01检查了肝细胞中的LD动力学如何受几种GTPases（Dynamins和Dynamins和 尤其是RAB）可以充当分子开关以调节膜流量。我们表明乙醇 - 这些GTP酶的诱导破坏大大增加了LDS在肝细胞中的积累。初步的 支持此延续应用的数据表明，肝细胞的脂溶剂机械被激活 营地激酶（异丙肾上腺素，福斯科林）的激动剂，但这种反应显着抑制乙醇。 此外，我们表明肝细胞利用顺序机制来分解需要脂解的LD 其次是寄生虫。此外，看来驻留在 LD-Autophagosom（AP）表面功能可驱动脂肪，并且酒精会损害这一过程。最后，在 除了APS吞噬LDS，除去LDS的LDS吞噬或“取样”似乎是通过A 对乙醇暴露敏感的瞬态，可测量的相互作用。这些最近的新发现提供了 这项建议的良好基础，并支持我们的核心假设，即乙醇暴露会妥协 通过破坏信号级联和 膜贩运事件，导致肝脂肪变性。指导该项目的两个主要调查员 具有完全的优势：凯西博士是一位生物化学家，其专业知识是在酒精诱导的肝脏中 损害。 McNiven博士是一名细胞生物学家，其专业是膜 - 骨骨骼动力学。这个独特 事实证明，协作努力对酒精性肝病领域非常有益，并将继续导致 个人努力无法实现的结果。拟议的投资将利用最先进的 膜运输和成像技术，以量化有助于酒精的特定分子事件 诱导脂肪肝。这些研究的成功完成将提供有关乙醇如何影响的新见解 肝细胞中的LD动力学以及旨在减少或消除的治疗策略的重要信息 脂肪变性的严重程度并阻止其进一步发展为酒精性脂肪性肝炎，纤维化和肝硬化。