Role of ACSL5 in Intestinal and Liver Triacylglycerol Metabolism

ACSL5 在肠道和肝脏三酰甘油代谢中的作用

• 批准号: 9061681
• 负责人: ANDREW S GREENBERG
• 金额: $ 30.29万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9061681
• 关键词: ADD-1 protein; ASCL1 gene; Ablation; Acyltransferase; Address; Adipocytes; Applications Grants; Blood; Blood Circulation; Body fat; Carbohydrates; Cells; Cholesterol Esters; Chylomicrons; Coenzyme A Ligases; Data; Development; Diabetes Mellitus; Diet; Dietary Fats; Dietary Fatty Acid; Dietary intake; Disease; Drug or chemical Tissue Distribution; Energy Metabolism; Enterocytes; Enzymes; Epidemic; Fatty Acids; Fatty Liver; Fatty acid glycerol esters; Food; Genes; Genetic Transcription; Glycerol; Health; Hepatic; Hepatocyte; High Fat Diet; Hyperinsulinism; Incidence; Ingestion; Insulin; Insulin Resistance; Intestines; Knock-out; Knockout Mice; Link; Lipids; Liver; Liver diseases; Malabsorption Syndromes; Mediating; Messenger RNA; Metabolic; Metabolic Diseases; Metabolic syndrome; Metabolism; Mitochondria; Monoglycerides; Mus; Nuclear; Obese Mice; Obesity; Organelles; Partner in relationship; Pathway interactions; Pattern; Peroxisome Proliferator-Activated Receptors; Pharmacologic Substance; Phospholipids; Protein Isoforms; Proteins; Resistance; Risk; Role; Signal Transduction; Signaling Molecule; Sucrose; Testing; Time; Tissues; Triglycerides; Weight Gain; absorption; base; blood glucose regulation; cell type; diabetes risk; fatty acid metabolism; fatty acid oxidation; feeding; gut microbiota; inorganic phosphate; lipid biosynthesis; lipid metabolism; metabolic rate; novel therapeutics; nutritional approach; obesity treatment; overexpression; oxidation; promoter; response; trafficking; transcription factor; villin

DESCRIPTION (provided by applicant): The epidemic of obesity is associated with detrimental metabolic complications. Critical to our understanding of these metabolic complications is delineating the mechanisms that regulate the metabolic fate of fatty acids. When fatty acids enter cells they are converted to acyl-CoAs by the actions of acyl-CoA synthetases (ACSL). Emerging data suggests that each of the five ACSL isoforms directs acyl-CoAs to specific metabolic fates. In this grant application we propose to investigate the role of ACSL5 in regulating intestinal and liver triacylglycerol metabolism. ACSL5 is highly expressed in both the intestine and liver, yet our understanding of its functions in these tissues is limited. T address the role of ACSL5 in cell-specific and systemic metabolism we have generated two different lines of ACSL5 knockout mice: one in in which the gene has been constitutively disrupted in all tissues (null) and a second conditional knockout (Acsl5loxP/loxP) that allows us to disrupt ACSL5 expression in specific tissues. In the first specific aim of this application, we propose to generate mice with an intestine-specific ablation of ACSL5 in order to determine: 1) the role of intestinal ACSL5 on enterocyte fatty acid trafficking and, 2) the effects of intestinal ACSL5 on whole body metabolism and signaling, and alterations in gut microbiota 3) the mechanistic basis by which enterocyte ablation of ACSL5 modulates energy metabolism and body fat accumulation. To perform these studies, we will mate our line of conditional ACSL5 knockout mice (Acsl5loxP/loxP) to mice expressing Cre driven by a villin promoter to specifically ablate ACSL5 expression in the intestine (Acsl5int-/-). In a second specific aim, we will determine the role of ACSL5 in regulating hepatic lipid and whole-body energy metabolism and insulin resistance. Obesity and energy dense diets result in increased ACSL5 expression in livers. We hypothesize ACSL5, is upregulated in the liver by SREBP transcription factors, known to induce hepatic steatosis because it catalyzes the formation of acyl-CoAs that are utilized by mtGPAT1 the rate limiting enzyme in lipogenesis. In this aim we will generate mice in which ACSL5 expression is ablated specifically within hepatocytes (Acsl5L-/-). We will feed our line of Acsl5L-/- mice a high fat, high sucrose diet to determine how liver specific ablation of ACSL5 regulates hepatic lipid metabolism, including TAG accumulation and insulin-glucose homeostasis, and determine whether loss of ACSL5 direct fatty acids to other ACSL isoforms and oxidation. We will overexpress SREBP-1c and mtGPAT in our newly developed line of Acsl5L-/- mice to determine the role of hepatic ACSL5 expression in mediating the lipogenic actions of these two proteins. Lastly, we will determine the ability of ACSL5 ablation to alleviate steatosis in ob/ob mice. We expect these studies will result in major advancements into our understanding of fatty acid metabolism and, thereby, provide novel therapeutic avenues for the treatment of obesity, hepatic steatosis and related diseases.

描述（由申请人提供）：肥胖的流行与有害的代谢并发症有关。我们理解这些代谢并发症的关键是描述调节脂肪酸代谢命运的机制。当脂肪酸进入细胞时，它们在酰基辅酶 A 合成酶 (ACSL) 的作用下转化为酰基辅酶A。新数据表明，五种 ACSL 亚型中的每一种都将酰基辅酶A导向特定的代谢命运。在本次拨款申请中，我们计划研究 ACSL5 在调节肠道和肝脏三酰甘油代谢中的作用。 ACSL5 在肠道和肝脏中高度表达，但我们对其在这些组织中的功能的了解有限。为了解决 ACSL5 在细胞特异性和全身代谢中的作用，我们生成了两种不同的 ACSL5 敲除小鼠品系：一种是该基因在所有组织中均被组成性破坏（无效），另一种是条件性敲除（Acsl5loxP/loxP），使我们能够破坏特定组织中的 ACSL5 表达。在本申请的第一个具体目标中，我们建议生成具有肠道特异性消融 ACSL5 的小鼠，以确定：1）肠道 ACSL5 对肠上皮细胞脂肪酸运输的作用，以及 2）肠道 ACSL5 对全身代谢和信号传导以及肠道微生物群的改变 3) ACSL5 肠细胞消融调节能量代谢和身体脂肪积累的机制基础。为了进行这些研究，我们将条件性 ACSL5 敲除小鼠 (Acsl5loxP/loxP) 系与由绒毛启动子驱动的表达 Cre 的小鼠交配，以特异性消除肠道中的 ACSL5 表达 (Acsl5int-/-)。第二个具体目标是确定 ACSL5 在调节肝脂质和全身能量代谢以及胰岛素抵抗中的作用。肥胖和能量密集饮食会导致肝脏中 ACSL5 表达增加。我们假设 ACSL5 在肝脏中被 SREBP 转录因子上调，已知会诱导肝脂肪变性，因为它催化酰基辅酶 A 的形成，而酰基辅酶 A 被脂肪生成中的限速酶 mtGPAT1 利用。为此，我们将生成 ACSL5 表达在肝细胞内特异性消除的小鼠 (Acsl5L-/-)。我们将为我们的 Acsl5L-/- 小鼠系喂食高脂肪、高蔗糖饮食，以确定 ACSL5 的肝脏特异性消融如何调节肝脏脂质代谢，包括 TAG 积累和胰岛素-葡萄糖稳态，并确定 ACSL5 的损失是否会直接将脂肪酸转化为其他 ACSL 亚型和氧化。我们将在新开发的 Acsl5L-/- 小鼠品系中过度表达 SREBP-1c 和 mtGPAT，以确定肝脏 ACSL5 表达在介导这两种蛋白的脂肪生成作用中的作用。最后，我们将确定 ACSL5 消融缓解的能力 ob/ob 小鼠的脂肪变性。我们预计这些研究将极大地促进我们对脂肪酸代谢的理解，从而为肥胖、肝脂肪变性和相关疾病的治疗提供新的治疗途径。