Role of Multi-enzyme Complex in ApoBCL Secretion

多酶复合物在 ApoBCL 分泌中的作用

基本信息

批准号：
10543873
负责人：
JAY D. HORTON
金额：
$ 57.4万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-01-01 至 2026-12-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10543873
关键词：
ADD-1 protein ATP Citrate (pro-S)-Lyase Acetyl-CoA Carboxylase Acyltransferase Apolipoproteins B Binding Cardiovascular system Cholesterol Co-Immunoprecipitations Complement Complex Coronary heart disease Cytoplasm Cytosol Data Development Dyslipidemias Endoplasmic Reticulum Enzymes Event Fatty-acid synthase Genes Genetic study Goals Hepatic Hepatocyte Hypertriglyceridemia In Vitro Individual LDL Cholesterol Lipoproteins Lipids Lipoproteins Liver Location Low-Density Lipoproteins Metabolic Metabolism Mitochondria Molecular Multienzyme Complexes Mus New Agents Organelles Outcome Palmitates Physiological Plasma Polymers Production Program Research Project Grants Proteins Regulation Research Project Grants Residual state Risk Role Series Signal Transduction Structural Protein Triglycerides Very low density lipoprotein alpha-glycerophosphoric acid cardiovascular risk factor density enzyme activity gene synthesis heart disease risk hormonal signals in vivo inhibitor insight lipid metabolism mitochondrial membrane novel strategies polymerization posttranscriptional protein protein interaction stem transcription factor

项目摘要

Project 2. Role of Multi-Enzyme Complexes in ApoBCL Secretion SUMMARY/ABSTRACT Although statins and PCSK9 inhibitors decrease LDL-Cholesterol (LDL-C) levels and reduce cardiovascular events, significant residual risk of CHD remains even in maximally treated individuals with low plasma levels of LDL-C. Multiple lines of evidence support the contention that elevated plasma levels of triglyceride (TG)-rich ApoB-Containing Lipoproteins (ApoBCLs) contribute significantly to this residual risk. Previously, we have shown that the transcription factor, SREBP-1c, leads to activation of all genes encoding the enzymes involved in FA synthesis. Excessive activation of SREBP-1c in liver results in high levels of FA and TG synthesis, VLDL secretion, and ultimately hypertriglyceridemia. The studies in this project will characterize a new post- translational regulatory mechanism that modulates FA and TG synthesis as well as VLDL production. The three enzymes that synthesize palmitate (C16:0) — ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) — reside in the cytoplasm. The two enzymes that elongate and/or desaturate palmitate, ELOVL6 and SCD1, are located in the ER, and the first enzyme in the synthesis of glycerolipids, glycerol-3-phosphate acyltransferase 1 (GPAM), is located in the mitochondrial membrane. The distinct subcellular locations of these enzymes produce a unique spatial challenge for the efficient synthesis of FAs and TGs since the product of one enzyme is the substrate for the next. Our preliminary data suggest that the cytosolic FA synthesis enzymes form a complex. This discovery stemmed from the characterization of a SREBP-1c-regulated gene designated MIG12. We found that MIG12 bound directly to ACCs, facilitated ACC polymerization, and increased overall rates of FA synthesis in liver. MIG12 is structurally similar to another small protein designated S14. Our subsequent studies have shown that S14 co-immunoprecipitated MIG12, ACC, and FAS suggesting that these proteins form a complex in the cytosol. Here, we will identify and characterize all proteins in the FA synthesis complex and determine how these proteins associate with each other and with the ER and/or mitochondria. Next, we will determine whether the formation and disassociation of the FA synthesis complex is regulated by hormonal signals in vitro and in vivo. Finally, we will characterize the physiological function of lipogenic complex in vivo through a series of studies in mice that lack the key proteins required for the formation of the FA synthesis complex. Combined, these studies will provide important new insights into how the cytosolic lipogenic complex ultimately provides FAs to the ER for further elongation and/or desaturation as well as to GPAM for TG synthesis and VLDL secretion.

项目2.多酶复合物在ApoBCL分泌中的作用摘要/摘要尽管他汀类药物和 PCSK9 抑制剂可降低低密度脂蛋白胆固醇 (LDL-C) 水平并减少心血管疾病即使在血浆中低水平的最大程度治疗的个体中，冠心病的显着残余风险仍然存在多种证据支持血浆中富含甘油三酯 (TG) 水平升高的论点。此前，我们发现含 ApoB 的脂蛋白 (ApoBCL) 对这种残留风险有显着影响。结果表明，转录因子 SREBP-1c 会激活编码相关酶的所有基因肝脏中 SREBP-1c 的过度激活导致 FA 和 TG 合成、VLDL 水平升高。该项目的研究将描述一种新的后甘油三酯血症的特征。调节 FA 和 TG 合成以及 VLDL 产生的翻译调节机制。合成棕榈酸 (C16:0) 的三种酶 — ATP-柠檬酸裂解酶 (ACL)、乙酰辅酶A羧化酶（ACC）和脂肪酸合酶（FAS）——存在于细胞质中的两种酶，可以延长和/或延长。去饱和棕榈酸 ELOVL6 和 SCD1 位于内质网，是合成棕榈酸的第一个酶甘油脂，即 3-磷酸甘油酰基转移酶 1 (GPAM)，位于线粒体膜上。这些酶的不同亚细胞位置对有效合成产生了独特的空间挑战 FA 和 TG，因为一种酶的产物是下一种酶的底物。我们的初步数据表明，胞质 FA 合成酶形成了复合物。源于 SREBP-1c 调控基因 MIG12 的表征，我们发现 MIG12。直接与 ACC 结合，促进 ACC 聚合，并提高肝脏中 FA 合成的总体速率。 MIG12 在结构上与另一种称为 S14 的小蛋白相似。我们随后的研究表明， S14 免疫共沉淀 MIG12、ACC 和 FAS，表明这些蛋白质在胞质溶胶中形成复合物。在这里，我们将鉴定和表征 FA 合成复合物中的所有蛋白质，并确定这些蛋白质如何蛋白质之间以及与 ER 和/或线粒体之间的关联接下来，我们将确定是否存在关联。 FA 合成复合物的形成和解离受体外和体内激素信号的调节。最后，我们将通过一系列研究来表征脂肪生成复合物在体内的生理功能。这些研究结合了缺乏形成 FA 合成复合物所需关键蛋白质的小鼠。将为细胞溶质脂肪生成复合物如何最终向内质网提供 FA 提供重要的新见解用于进一步延伸和/或去饱和，以及用于 TG 合成和 VLDL 分泌的 GPAM。