Fatty acid metabolism and DGAT1 deficiency

描述（由申请人提供）：肥胖是II型糖尿病和心脏病的主要危险因素，在美国已达到流行病的比例。肥胖是由能量输入和输出之间的不平衡引起的，其中多余的卡路里以甘油三酯的形式储存。缺乏DGAT 1（一种参与三酰甘油合成的酶）的小鼠能量消耗增加，因此具有抗肥胖性。增加的能量消耗可归因于增加的产热和身体活动。本研究的目的是探讨DGAT 1缺乏改变脂肪酸代谢的机制。我推测DGAT 1缺乏会减少脂肪酸的合成，增加脂肪酸的氧化。我的具体目标是： 具体目的1：确定Dgat 14-小鼠中脂肪酸合成是否减少。 目标1.1：通过测量氚化水掺入脂肪酸中，确定喂食高脂肪饮食的Dgatl 4-小鼠的肝脏中体内脂肪酸合成是否减少。 目标1.2：确定LXR-α的活化降低（可能由于不饱和脂肪酸水平升高）是否是脂肪酸合成基因表达降低的原因。 目标1.3：通过用LXR-α激动剂处理Dgatl -/-小鼠来确定SREBP-Ic的表达降低对肥胖抗性表型的贡献。 具体目的2：确定Dgatl _-小鼠中脂肪酸氧化是否增加。 目标2.1：通过测量[1-1“C]棕榈酸酯形成[1- 14 C] CO2和测量酮体血清水平，确定脂肪酸氧化是否增加。 目的2.2：确定是否存在与脂肪酸氧化有关的基因的表达增加。 目标2.3：确定Dgat 1-/-小鼠的肥胖抵抗表型是否需要脂肪酸氧化的主要转录调节因子PPAR_。

DESCRIPTION (provided by applicant): Obesity, a major dsk factor for type II diabetes and heart disease, has reached epidemic proportions in the U.S. Obesity results from an imbalance between energy input and output, where excess calories are stored as triglycerides. Mice lacking DGAT1, an enzyme involved in triacylglycerol synthesis, have increased energy expenditure and are therefore obesity resistant. The increased energy expenditure can be attributed to increased thermogenesis and physical activity. The objectives of this study are to investigate the mechanisms by which DGAT1 deficiency alters fatty acid metabolism. I hypothesize that DGAT1 deficiency decreases fatty acid synthesis and increases fatty acid oxidation. My specific aims are: Specific Aim 1: To determine if fatty acid synthesis is decreased in Dgatl 4- mice. Aim 1.1: Determine if in vivofatty acid synthesis is decreased in livers of Dgatl 4- mice fed a high-fat diet by measuring the incorporation of tritiated water into fatty acids. Aim 1.2: Determine whether decreased activation of LXR-alpha, possibly due to increased levels of unsaturated fatty acids, is responsible for the decreased expression of fatty acid synthesis genes. Aim 1.3: Determine the contribution of decreased expression of SREBP-lc to the obesity-resistance phenotype by treating Dgatl -/- mice with an LXR-alpha agonist. Specific Aim 2: Determine if fatty acid oxidation is increased in Dgatl _- mice. Aim 2.1: Determine if there is increased fatty acid oxidation by measuring the formation of [1-14C] CO2 from [1-1"C] palmitate and measuring the serum levels of ketone bodies. Aim 2.2: Determine if there is increased expression of genes implicated in fatty acid oxidation. Aim 2.3: Determine if PPAR_, a master transcriptional regulator of fatty acid oxidation, is required for the obesity resistance phenotype of Dgat1-/-mice.