Inhibition of Fat Absorption as a Mechanism to Treat Obesity

抑制脂肪吸收作为治疗肥胖的机制

• 批准号: 8333166
• 负责人: CHARLES Milton MANSBACH
• 金额: --
• 依托单位: MEMPHIS VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8333166
• 关键词: Abetalipoproteinemia; Address; Adverse effects; Affect; Animals; Binding; Blood Circulation; CD36 gene; Cells; Centers for Disease Control and Prevention (U.S.); Chylomicrons; Colon; Complex; Cytosol; Diarrhea; Diet; Dietary Fats; Effectiveness; Elements; Endoplasmic Reticulum; Enterocytes; Enzymes; Epidemic; Epithelial Cells; Event; FABP1 gene; Fatty Acid-Binding Protein 1; Fatty acid glycerol esters; Female; Gases; Generations; Goals; Golgi Apparatus; Guidelines; Human; In Vitro; Intestines; Laboratories; Lecithin; Lipase; Lipoproteins; Lymph; Measures; Mediating; Membrane; Modeling; Molecular Conformation; Obesity; One-Step dentin bonding system; Output; Pancreas; Pharmacologic Substance; Phosphorylation; Physiological; Population; Process; Proteins; Rattus; Recombinants; Site; Steatorrhea; Surface; Symptoms; Testing; Transport Vesicles; Triglycerides; Triolein; United States; Vesicle; Veterans; Work; absorption; apolipoprotein B-48; design; feeding; inhibitor/antagonist; long chain fatty acid; male; orlistat; prevent; programs; protein complex

DESCRIPTION (provided by applicant): Obesity in the Veteran population has risen to epidemic proportions in the United States. 33% of male Veterans and 37% of female Veterans are obese as classified by CDC guidelines. Studies over many years have tried to address the causes of obesity. While our understanding of this problem has greatly increased, no effective measures have been successful and obesity rates continue to rise. The program proposed here is designed to treat obesity by inhibiting dietary fat absorption at the level of the intestine. Currently, a compound called tetrahydrolipstatin has been developed to inhibit pancreatic lipase, an enzyme required to break down dietary fat prior to its absorption. While this works in reducing fat absorption, its side effects of bloating, gas, nd diarrhea limit its usefulness. The proposed program inhibits fat absorption after the fat is absorbed into the intestine but before it enters the body so that many of the symptoms of the lipase inhibitor are muted. Our plan is to block the absorbed fat at the level of the intestinal absorptive cell. This type of blockade is modeled in a rare human condition called abetalipoproteinemia. In this condition, fat is malabsorbed but the symptoms of this malabsorbtion are lessened by the fact that the intestinal cell holds the fat that is only released into the intestinal lumen and then to the colon when the intestinal cell dies. Each cell lives 2 to4 days. Our laboratory has identified the rate-limiting step in dietary fat absorption in the rat. Tis was found to be at the level of the endoplasmic reticulum (ER). Next we found that the fat exited the ER in a vesicle, the pre-chylomicron transport vesicle (PCTV). We know the proteins that select cargo chylomicrons for inclusion in the vesicle and the protein that initiates this process. Chylomicrons are the lipoprotein by which dietary fat is delivered to the circulation. Our proposal attacks a conundrum in our studies. The liver fatty acid binding protein (FABP1) can, by itself, generate PCTV without the addition of protein phosphorylation supplied by ATP. By contrast, intestinal cell cytosol, which has considerable FABP1, cannot generate PCTV without ATP. Why? We have found in preliminary studies that L-FABP in cytosol is not present as a single protein but is in a protein complex with 3 other proteins, each of which we know. Our first aim is to determine which of the proteins in the complex is phosphorylated during fat absorption and show that blocking this phosphorylation event is effective in preventing FABP1 from attaching to the ER membrane to start the PCTV budding cascade. If we are successful, then we will have identified one step in the process that is subject to pharmaceutical attack. Our second aim is to identify proteins on the ER surface that are phosphorylated by ATP and in so doing increase the binding of L-FABP from the cytosolic protein complex to the ER membrane. Blocking this phosphorylation step may also inhibit PCTV generation. Again, this protein may be open to pharmaceutical attack. Our third aim is to correlate changes in phosphorylation of proteins in the ER or Golgi with changes in chylomicron output into the lymph due to changes in diet or delivery of phosphatidylcholine to the intestine. These changes will also be correlated with PCTV generating activity of the ER. This will give physiological conformation of our in vitro findings.

描述（由申请人提供）： 在美国，退伍军人人口的肥胖已经增加了流行比例。 CDC指南归类为33％的男性退伍军人和37％的女退伍军人肥胖。多年来的研究试图解决肥胖的原因。尽管我们对这个问题的理解大大增加了，但没有成功的措施成功，肥胖率继续上升。 此处提出的该计划旨在通过抑制肠道上的饮食脂肪吸收来治疗肥胖。目前，已经开发了一种称为四氢稳定蛋白的化合物来抑制胰腺脂肪酶，胰腺脂肪酶是一种在饮食吸收之前分解脂肪所需的酶。尽管这可以减少脂肪的吸收，但其腹胀，气体，腹泻的副作用限制了其有用性。提出的程序会抑制脂肪吸收到肠中，但在进入身体之前，使脂肪酶抑制剂的许多症状被静音。我们的计划是在肠道吸收细胞的水平上阻止吸收的脂肪。这种类型的封锁是在罕见的人类疾病中建模的，称为Abetalipoymia血症。在这种情况下，脂肪被厌食，但由于肠细胞容纳仅释放到肠道内的脂肪，然后在肠道死亡时将其脂肪释放到结肠，从而减少了这种厌食症的症状。每个细胞生存2至4天。 我们的实验室已经确定了大鼠饮食脂肪吸收的限速步骤。发现TI处于内质网的水平（ER）。接下来，我们发现脂肪以囊泡为胶囊前转运囊泡（PCTV）中的ER退出。我们知道，选择货物乳糜微粒以纳入囊泡和启动该过程的蛋白质的蛋白质。 乳糜微粒是将饮食脂肪输送到循环的脂蛋白。我们的建议在我们的研究中攻击了一个难题。肝脂肪酸结合蛋白（FABP1）本身可以生成PCTV，而无需添加ATP提供的蛋白质磷酸化。相比之下，具有相当大的FABP1的肠细胞胞质不会在没有ATP的情况下产生PCTV。为什么？ 我们在初步研究中发现，细胞质中的L-FABP并非作为单一蛋白质，而是与其他3种蛋白质的蛋白质复合物中，我们知道每种蛋白质。我们的第一个目的是确定在脂肪吸收过程中磷酸化的络合物中的哪种蛋白质，并表明阻止这种磷酸化事件有效防止Fabp1附着在ER膜上以启动PCTV萌芽的级联反应。如果我们成功了，那么我们将在该过程中确定一步受到药物攻击。 我们的第二个目的是鉴定通过ATP磷酸化的ER表面上的蛋白质，因此可以增加L-FABP从胞质蛋白复合物与ER膜的结合。阻止这种磷酸化步骤也可能抑制PCTV的产生。同样，该蛋白可能对药物攻击开放。 我们的第三个目的是将ER或高尔基体蛋白质磷酸化的变化与乳糜微粒输出的变化与淋巴的变化相关联，这是由于饮食的变化或磷脂酰胆碱的递送而变化为淋巴。这些变化也将与ER的PCTV生成活性相关。这将给出我们体外发现的生理构象。