Role of Multi-enzyme Complex in ApoBCL Secretion

多酶复合物在 ApoBCL 分泌中的作用

• 批准号: 10332597
• 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
• 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/10332597
• 关键词: ADD-1 protein; ATP Citrate (pro-S)-Lyase; Acetyl-CoA Carboxylase; Acyltransferase; Apolipoproteins B; Cardiovascular system; Complement; Complex; Coronary heart disease; Cytoplasm; Cytosol; Data; Development; Dyslipidemias; Endoplasmic Reticulum; Enzymes; Event; Fatty-acid synthase; Genes; Genetic Transcription; Genetic study; Goals; Hepatic; Hepatocyte; Hypertriglyceridemia; In Vitro; Individual; LDL Cholesterol Lipoproteins; Lead; Lipids; Lipoproteins; Liver; Location; Metabolic; Metabolism; Mitochondria; Molecular; Multienzyme Complexes; Mus; New Agents; Organelles; Outcome; Palmitates; Physiological; Plasma; 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 function; gene synthesis; heart disease risk; hormonal signals; in vivo; inhibitor; insight; lipid metabolism; mitochondrial membrane; novel strategies; polymerization; protein protein interaction; stem; transcription factor

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抑制剂降低了LDL-胆固醇（LDL-C）水平，并降低心血管 事件，即使在血浆较低的最大治疗个体中，冠心病的显着残留风险仍然存在 LDL-C。多种证据支持了升高血浆甘油三酸酯（TG）-RICH的争论 含APOB的脂蛋白（APOBCL）对这种残留风险产生了重大贡献。以前，我们有 表明转录因子SREBP-1C导致所有编码涉及酶的基因的激活 在FA合成中。 SREBP-1C在肝脏中的过度激活导致高水平的FA和TG合成，VLDL 分泌，最终是高甘油三酯血症。该项目中的研究将表征一个新的后 调节FA和TG合成以及VLDL生产的翻译调节机制。 合成棕榈酸盐（C16：0）的三种酶 - ATP-CITRATE裂解酶（ACL），乙酰-COA羧化酶 （ACC）和脂肪酸合酶（FAS） - 驻留在细胞质中。拉长和/或的两个酶 去饱和棕榈酸酯，elovl6和scd1位于ER中，是合成中的第一种酶 甘油脂肪，3-磷酸酰基转移酶1（GPAM）位于线粒体膜中。这 这些酶的不同亚细胞位置为有效合成而产生独特的空间挑战 FAS和TGS由于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合成酶形成复合物。这个发现 源自SREBP-1C调节的指定Mig12的表征。我们发现Mig12 直接与ACC结合，促进ACC聚合并增加肝脏中FA合成的总体速率。 Mig12在结构上与另一种指定的S14的小蛋白质相似。我们随后的研究表明 S14共免疫沉淀的MIG12，ACC和FA，这表明这些蛋白质在细胞质中形成复合物。 在这里，我们将识别并表征FA合成复合物中所有蛋白质的表征，并确定这些蛋白质 蛋白质相互关联以及ER和/或线粒体。接下来，我们将确定是否 FA合成复合物的形成和分离由体外和体内的激素信号调节。 最后，我们将通过一系列研究来表征体内脂肪生成复合物的物理功能 缺乏FA合成复合物形成所需的关键蛋白质的小鼠。结合了这些研究 将提供重要的新见解，以了解胞质脂肪生成复合物最终如何为ER提供FAS 用于进一步的伸长和/或去饱和以及用于TG合成和VLDL分泌的GPAM。