Regulation of Hepatic Lipid and Glucose Metabolism by Phosphatidylcholine Transfe

磷脂酰胆碱转染对肝脏脂质和葡萄糖代谢的调节

• 批准号: 7867935
• 负责人: DAVID E. COHEN
• 金额: $ 36.06万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7867935
• 关键词: Adipocytes; Affinity; Atherosclerosis; Attenuated; Biliary; Binding; Binding Proteins; Biogenesis; Biological; Biological Process; Brown Fat; Cell Culture System; Cell Culture Techniques; Cell membrane; Cell physiology; Cells; Cholesterol Homeostasis; Data; Development; Diet; Endoplasmic Reticulum; Evaluation; Extrahepatic; Fatty Acids; Gene Expression; Glean; Government; Grant; Heart; Hepatic; Hepatobiliary; Hepatocyte; High Density Lipoproteins; Homeostasis; In Vitro; Insulin; Insulin Resistance; Lead; Lecithin; Left; Lipid Binding; Lipids; Liver; Liver diseases; Measurement; Mediating; Membrane; Metabolic syndrome; Metabolism; Mitochondria; Molecular Target; Morphology; Mus; Non-Insulin-Dependent Diabetes Mellitus; Persons; Play; Principal Investigator; Process; Proteins; Regulation; Research; Resistance; Role; Skeletal Muscle; Testing; Therapeutic; Thermogenesis; Tissues; Wild Type Mouse; base; glucose metabolism; glucose production; high throughput screening; in vivo; inhibitor/antagonist; insight; insulin sensitivity; insulin signaling; knock-down; lipid metabolism; member; metabolic abnormality assessment; non-alcoholic fatty liver; novel strategies; phosphatidylcholine transfer protein; public health relevance; research study; small molecule; transcription factor; Adipocytes; Affinity; Atherosclerosis; Attenuated; Biliary; Binding; Binding Proteins; Biogenesis; Biological; Biological Process; Brown Fat; Cell Culture System; Cell Culture Techniques; Cell membrane; Cell physiology; Cells; Cholesterol Homeostasis; Data; Development; Diet; Endoplasmic Reticulum; Evaluation; Extrahepatic; Fatty Acids; Gene Expression; Glean; Government; Grant; Heart; Hepatic; Hepatobiliary; Hepatocyte; High Density Lipoproteins; Homeostasis; In Vitro; Insulin; Insulin Resistance; Lead; Lecithin; Left; Lipid Binding; Lipids; Liver; Liver diseases; Measurement; Mediating; Membrane; Metabolic syndrome; Metabolism; Mitochondria; Molecular Target; Morphology; Mus; Non-Insulin-Dependent Diabetes Mellitus; Persons; Play; Principal Investigator; Process; Proteins; Regulation; Research; Resistance; Role; Skeletal Muscle; Testing; Therapeutic; Thermogenesis; Tissues; Wild Type Mouse; base; glucose metabolism; glucose production; high throughput screening; in vivo; inhibitor/antagonist; insight; insulin sensitivity; insulin signaling; knock-down; lipid metabolism; member; metabolic abnormality assessment; non-alcoholic fatty liver; novel strategies; phosphatidylcholine transfer protein; public health relevance; research study; small molecule; transcription factor

DESCRIPTION (provided by applicant): Phosphatidylcholine transfer protein (PC-TP, a.k.a. StarD2) is a highly specific intracellular lipid binding protein with accentuated expression in liver and other oxidative tissues, including brown fat, heart, and skeletal muscle. Using PC-TP-deficient (Pctp-/-) mice, we have demonstrated that PC-TP regulates biliary lipid secretion, hepatic cholesterol homeostasis and high density lipoprotein (HDL) metabolism. In addition, mice lacking PC-TP expression are relatively resistant to developing atherosclerosis. In contrast to our original prediction that PC-TP transports phosphatidylcholines to the plasma membrane for export from hepatocytes, this research has suggested a more global regulatory role in hepatic lipid homeostasis. Preliminary studies in Pctp-/- mice have also revealed profound insulin-mediated decreases in hepatic glucose production, as well as altered energy substrate utilization by extrahepatic oxidative tissues. PC-TP may regulate lipid and glucose metabolism via direct interactions with the mitochondrial-associated protein thioesterase superfamily member 2 (Them2), potentially by controlling access of fatty acids to mitochondria. Specific Aim 1 will test the hypothesis that PC-TP regulates hepatic insulin sensitivity. We will examine whether lack of PC-TP expression protects against diet-induced insulin resistance and whether liver-specific expression of PC-TP reduces hepatic insulin sensitivity. Insulin signaling will be studied using cell culture systems in which PC-TP expression levels are broadly varied. We will also explore evidence both in vivo and in cell culture that PC-TP-Them2 interactions contribute to the control of insulin action. Specific Aim 2 will explore the influence of PC-TP on the differentiation and function of brown fat, which expresses both PC-TP and Them2. Gene expression, as well as cellular function and morphology will be characterized during the differentiation of brown pre-adipocytes cultured from Pctp-/- and wild type mice. Mechanisms by which PC-TP influences the maturation of brown adipocytes will be gleaned by systematically reintroducing PC-TP with or without Them2 during the process of differentiation. These data will be correlated with measurements of brown fat thermogenesis in vivo. Studies in cell culture will explore mechanisms by which PC-TP and Them2 activate key transcription factors in brown fat. Specific Aim 3 will investigate a mechanistic relationship between the in vitro and in vivo activities of PC-TP. High-throughput screening has identified small molecule inhibitors of the phosphatidylcholine transfer activity of PC-TP. This Specific Aim will continue the development of the most promising inhibitors. Mechanisms of inhibition will be elucidated and compounds will be tested in cells. Comparisons will be made to cells in which PC-TP expression is absent or knocked down. These studies should provide new insights into the regulation of lipid and glucose metabolism and may lead to a novel approach to managing insulin resistance, which constitutes the hallmark of the metabolic syndrome and non-alcoholic fatty liver disease. PUBLIC HEALTH RELEVANCE: Resistance to insulin is a hallmark of the metabolic syndrome and type II diabetes, which predispose to non-alcoholic fatty liver disease. The proposed studies will examine a key role for phosphatidylcholine transfer protein/StarD2, a highly specific lipid binding protein, in insulin- mediated regulation of lipid and glucose metabolism within the liver and energy consuming tissues of the body. It is anticipated that these experiments may establish phosphatidylcholine transfer protein/StarD2 as a molecular target for the management of insulin resistance.

描述（由申请人提供）：磷脂酰胆碱转移蛋白（PC-TP，又称stard2）是一种高度特异性的细胞内脂质结合蛋白，在肝脏和其他氧化组织中具有重音表达，包括棕色脂肪，心脏和骨骼肌。使用PC-TP缺陷型（PCTP - / - ）小鼠，我们证明了PC-TP调节胆道脂质分泌，肝胆固醇稳态和高密度脂蛋白（HDL）代谢。另外，缺乏PC-TP表达的小鼠对发展动脉粥样硬化相对抗药性。与我们最初的预测，PC-TP将磷脂酰胆碱转移到质膜中以从肝细胞出口，这项研究表明在肝脂质稳态中具有更全球的调节作用。在PCTP - / - 小鼠中的初步研究还显示，胰岛素介导的肝葡萄糖产生的降低以及肝外氧化组织的能量底物利用改变了。 PC-TP可以通过与线粒体相关蛋白硫酯酶超家族成员2（THEM2）直接相互作用来调节脂质和葡萄糖代谢，这可能是通过控制脂肪酸对线粒体的访问。具体目标1将检验PC-TP调节肝胰岛素敏感性的假设。我们将检查缺乏PC-TP表达是否可以防止饮食诱导的胰岛素抵抗以及PC-TP的肝脏特异性表达是否会降低肝胰岛素敏感性。将使用细胞培养系统研究胰岛素信号传导，其中PC-TP表达水平大致变化。我们还将探索体内和细胞培养的证据，表明PC-TP-THEM2相互作用有助于控制胰岛素作用。具体目标2将探索PC-TP对棕色脂肪的分化和功能的影响，该脂肪同时表达PC-TP和HET2。基因表达以及细胞功能和形态在分化从PCTP - / - 和野生型小鼠培养的棕色前脂肪细胞的分化过程中。 PC-TP影响棕色脂肪细胞成熟的机制将通过在分化过程中系统地重新引入PC-TP的系统重新引入PC-TP。这些数据将与体内棕色脂肪热发生的测量相关。细胞培养中的研究将探索PC-TP和THEM2激活棕色关键转录因子的机制。特定目标3将研究PC-TP的体外和体内活性之间的机械关系。高通量筛选已经确定了PC-TP的磷脂酰胆碱转移活性的小分子抑制剂。这个具体目标将继续发展最有前途的抑制剂。将阐明抑制作用机制，并将在细胞中测试化合物。将与缺乏PC-TP表达或敲低的PC-TP表达的细胞进行比较。这些研究应为调节脂质和葡萄糖代谢的调节提供新的见解，并可能导致一种新的方法来管理胰岛素抵抗，这构成了代谢综合征和非酒精性脂肪肝疾病的标志。公共卫生相关性：抗胰岛素的抗性是代谢综合征和II型糖尿病的标志，它们易于非酒精性脂肪肝病。拟议的研究将研究磷脂酰胆碱转移蛋白/stard2（一种高度特异性的脂质结合蛋白）在肝脏和人体肝脏中脂质和葡萄糖代谢的胰岛素介导的调节中的关键作用。预计这些实验可能会建立磷脂酰胆碱转移蛋白/stard2作为治疗胰岛素抵抗的分子靶标。