Role of Multi-enzyme Complex in ApoBCL Secretion

多酶复合物在 ApoBCL 分泌中的作用

• 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
• 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

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 总结/摘要 尽管他汀类药物和PCSK 9抑制剂可降低LDL-胆固醇（LDL-C）水平， 即使在接受最大剂量治疗的低血浆水平的个体中， LDL-C。多种证据支持这一论点，即血浆中富含甘油三酯（TG）的 含ApoB的脂蛋白（ApoBCL）对该剩余风险有显著影响。此前，我们有 显示转录因子SREBP-1c导致所有编码相关酶的基因的激活 在FA合成中肝脏中SREBP-1c的过度激活导致高水平的FA和TG合成，VLDL 分泌，最终导致高脂血症。该项目的研究将描绘一个新的职位- 翻译调节机制，调节FA和TG合成以及VLDL的生产。 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)和脂肪酸合成酶（FAS）-存在于细胞质中。这两种酶可以延长和/或 去饱和棕榈酸酯、HPVL 6和SCD 1位于ER中，并且是合成 甘油脂质，甘油-3-磷酸酰基转移酶1（GPAM），位于线粒体膜上。的 这些酶的不同亚细胞位置产生了独特的空间挑战， 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，细胞溶质FA合成酶形成一个复杂的。这一发现 源于SREBP-1c调控基因MIG 12的特征。我们发现MIG 12 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。 MIG 12在结构上类似于另一种命名为S14的小蛋白。我们随后的研究表明， S14共免疫沉淀MIG 12，ACC和FAS，表明这些蛋白质在胞质溶胶中形成复合物。 在这里，我们将识别和表征FA合成复合物中的所有蛋白质，并确定这些蛋白质如何与FA合成复合物结合。 蛋白质彼此结合并与ER和/或线粒体结合。接下来，我们将确定 FA合成复合物的形成和解离在体外和体内受激素信号调节。 最后，我们将通过一系列的研究来表征脂肪生成复合物在体内的生理功能， 缺乏形成FA合成复合物所需的关键蛋白质的小鼠。综合起来，这些研究 将提供重要的新的见解，胞质脂肪生成复合物如何最终提供脂肪酸的ER 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。