LIPID METABOLISM IN FAT CELLS

中链脂肪酸摄入（MCFA）导致动物和人类脂肪储存减少，而长链脂肪酸（LCFA）摄入量相似则导致体重增加。 我们项目的目标是研究这种现象背后的细胞机制。 我们的假设是MCFA替代LCFA将下调脂肪形成蛋白的表达，降低脂肪细胞的脂质储存能力，促进脂肪酸从储存的脂肪中释放，并且可能还降低脂肪细胞前体的分化能力。本研究的具体目的是：1）MCFA的代谢命运以及LCFA、葡萄糖和胰岛素如何影响MCFA的代谢命运，2）MCFA对脂肪储存和脂解的影响，以及对亚细胞组分的膜脂组成的影响（质膜、线粒体和内质网）; 3）MCFA对分化过程中脂肪形成蛋白表达的影响;和4）作为长期MCFA饮食适应的结果的脂肪细胞功能的变化。 一个综合的方法将被用来表征MCFA的代谢终产物，寻找未识别的终产物，并解释MCFA治疗导致的过量能量消耗。我们将通过NMR鉴定和定量脂肪酸（脂质和CO2）的主要代谢终产物。 13 C同位素标记的底物将用于适当的实验。 这大大提高了NMR分析的选择性和灵敏度。 我们将通过测量耗氧量和氧化还原状态来比较适应MCFA或LCFA的细胞的产热;通过HPLC定量重要代谢产物（乙酰辅酶A和乙酰肉毒碱），并通过GLC分析脂肪酸组成。 如果发现MCFA处理导致亚细胞膜组成发生显著变化，则将通过固态NMR分析对膜结构和流动性的后续影响。其他标准生化测定将用于测量酮体、总甘油三酯、胆固醇、DNA、蛋白质等。分化依赖性脂肪形成基因的mRNA产物将通过北方分析测定。 脂肪细胞形态将通过相差显微镜表征。 使用这种综合方法，我们预计将开发重要的新信息，以帮助阐明通过MCFA管理控制肥胖和肥胖相关健康疾病的分子机制。

Medium chain fatty acid ingestion (MCFA) results in diminished fat storage in animals and humans, while similar intake of long chain fatty acids (LCFA) results in weight-gain. The goal of our project is to examine the cellular mechanisms underlying this phenomenon. Our hypothesis is that substitution of MCFA for LCFA will down-regulate the expression of adipogenic proteins, lower the lipid storage capacity of adipose cells, facilitate fatty acid release from stored fat, and probably also reduce the capacity for differentiation of adipose cell precursors. The specific aims of this study focus on: 1) the metabolic fate of MCFA and how this is influenced by LCFA, glucose and insulin, 2) the effects of MCFA on fat storage and lipolysis, and on membrane lipid composition of sub-cellular components (plasma membrane, mitochondria, and endoplasmic reticulum); 3) the effects of MCFA on the expression of adipogenic proteins during the differentiation process; and 4) changes in fat cell function as a result of long-term MCFA dietary adaptation. An integrated approach will be used to characterize the metabolic end products of MCFA, to search for unidentified end products, and to explain the excess energy expenditure that results from MCFA treatment. We will identify and quantify, the major metabolic end products of fatty acids (lipids and CO2) by NMR. 13C isotope labeled substrates will be used in appropriate experiments. This greatly enhances the selectivity and sensitivity of NMR analysis. We will compare heat generation by cells adapted to MCFA or LCFA by measuring oxygen consumption and redox state; quantify the important metabolites (acetylCoA and acetylcarnitine) by HPLC, and analyze the fatty acid compositions by GLC. If significant changes in sub-cellular membrane composition are found as a result of MCFA treatment, subsequent effects on membrane structure and fluidity will be analyzed by solid state NMR. Other standard biochemical assays will be used for the measurement of ketone bodies, total triglycerides, cholesterol, DNA, protein, etc. The mRNA products of differentiation- dependent adipogenic genes will be determined by Northern analysis. Fat cell morphology will be characterized by phase- contrast microscopy. Using this integrated approach, we anticipate developing important new information to help shed light on the molecular mechanisms of the control of obesity and obesity-related health disorders afforded through MCFA administration.