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: 8963439
• 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/8963439
• 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; Vesicle Transport Pathway; Veterans; Work; absorption; apolipoprotein B-48; design; feeding; inhibitor/antagonist; long chain fatty acid; male; 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，退伍军人中的肥胖症已经上升到流行病的程度。33%的男性退伍军人和37%的女性退伍军人根据CDC指南分类为肥胖。多年来的研究试图解决肥胖的原因。虽然我们对这一问题的认识大大增加，但没有有效的措施取得成功，肥胖率继续上升。 这里提出的计划旨在通过抑制肠道水平的膳食脂肪吸收来治疗肥胖症。目前，已经开发出一种名为四氢lipstatin的化合物来抑制胰脂肪酶，胰脂肪酶是一种在吸收之前分解膳食脂肪所需的酶。虽然这可以减少脂肪的吸收，但其腹胀，气体和腹泻的副作用限制了它的有用性。拟议的计划抑制脂肪吸收后，脂肪被吸收到肠道，但在它进入身体，使许多症状的脂肪酶抑制剂是静音。我们的计划是在肠道吸收细胞的水平上阻止吸收的脂肪。这种类型的阻断是在一种罕见的人类疾病称为无β脂蛋白血症。在这种情况下，脂肪被吸收不良，但这种吸收不良的症状减轻的事实，肠细胞持有的脂肪，只有释放到肠腔，然后到结肠时，肠细胞死亡。每个细胞存活2到4天。 我们的实验室已经确定了大鼠膳食脂肪吸收的限速步骤。发现Tis位于内质网（ER）水平。接下来，我们发现脂肪以囊泡形式离开ER，即前乳糜微粒转运囊泡（PCTV）。我们知道选择货物乳糜微粒包含在囊泡和启动这一过程的蛋白质。 乳糜微粒是脂蛋白，膳食脂肪通过它进入循环。我们的建议解决了我们研究中的一个难题。肝脏脂肪酸结合蛋白（FABP 1）本身可以产生PCTV，而无需添加由ATP提供的蛋白磷酸化。相比之下，肠细胞胞质溶胶，其中有相当大的FABP 1，不能产生PCTV没有ATP。为什么？为什么？ 我们在初步研究中发现，L-FABP在胞质溶胶中不是以单一蛋白质的形式存在，而是与3种其他蛋白质形成蛋白质复合物，每种蛋白质我们都知道。我们的第一个目标是确定在脂肪吸收过程中，复合物中的哪种蛋白质被磷酸化，并表明阻断这种磷酸化事件可以有效地阻止FABP 1附着在ER膜上，从而启动PCTV出芽级联反应。如果我们成功了，那么我们将确定这个过程中受到药物攻击的一个步骤。 我们的第二个目的是鉴定ER表面上被ATP磷酸化的蛋白质，并且这样做增加了L-FABP从胞质蛋白复合物到ER膜的结合。阻断该磷酸化步骤也可以抑制PCTV的产生。同样，这种蛋白质可能会受到药物攻击。 我们的第三个目标是将ER或高尔基体中蛋白质磷酸化的变化与由于饮食变化或磷脂酰胆碱向肠的输送而导致的乳糜微粒输出到淋巴中的变化相关联。这些变化也将与ER的PCTV产生活性相关。这将给出我们在体外发现的生理构象。