The Role of eIF4G1 and eIF4G2 in Translational Control of Adipogenesis and Obesity

eIF4G1 和 eIF4G2 在脂肪生成和肥胖转化控制中的作用

• 批准号: 10464460
• 负责人: Rachel Elizabeth Turn
• 金额: $ 6.72万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10464460
• 关键词: 3T3-L1 Cells; Address; Adipocytes; Adipose tissue; Adult; BODIPY; Binding; Binding Sites; Biological; Biological Assay; Biological Models; Cell Proliferation; Cell physiology; Cells; Chronic; Cilia; Clustered Regularly Interspaced Short Palindromic Repeats; Complex; Cues; Cyclic AMP; Data; Degenerative polyarthritis; Deposition; Development; Diabetes Mellitus; Disease; Event; Failure; Fatty Acids; Fatty acid glycerol esters; Future; G-Protein-Coupled Receptors; Gene Targeting; Generations; Genes; Genetic Models; Genetic Transcription; Goals; Harvest; Health; Heart Diseases; Histology; Homologous Protein; Hormones; Human; Hypertension; Hypertrophy; In Vitro; Incidence; Inflammation; Inflammatory; Insulin; Insulin Resistance; Kinetics; Knock-out; Knockout Mice; Lead; Life; Ligands; Link; Lipids; Maintenance; Malignant Neoplasms; Mammals; Mediating; Mesenchymal Stem Cells; Messenger RNA; Metabolic; Metabolic Diseases; Metabolism; Modification; Morbid Obesity; Non-Insulin-Dependent Diabetes Mellitus; Obese Mice; Obesity; Omega-3 Fatty Acids; Pancreatitis; Parkinson Disease; Pathology; Pathway interactions; Patients; Peptide Initiation Factors; Population; Prevalence; Process; Proteins; Regulation; Ribosomes; Risk; Role; Signal Transduction; Sorting - Cell Movement; Source; Stains; Supplementation; Surface; Symptoms; System; Techniques; Testing; Therapeutic; Time; Tissues; Training; Transcript; Translation Initiation; Translations; Triglycerides; United States; Weight Gain; Work; adipocyte differentiation; base; chemokine; cytokine; fatty liver disease; genome wide screen; genome-wide; in vivo; inhibitor; insight; lipid biosynthesis; mouse genetics; mouse model; neurotransmission; novel; predictive test; prevent; programs; receptor; recruit; reduce symptoms; screening; targeted treatment; therapeutic development; therapeutic target; vision development

PROJECT SUMMARY Obesity, a disease caused by elevated fat mass, has increased in prevalence over the past few decades. Over 30% of the population suffers from obesity, and over time it can lead to increased incidence of life- threatening pathologies, including Type II Diabetes, heart disease, and cancer. Much study has been devoted to finding new treatments, which remain ineffective because 1) obesity is highly polygenic, and 2) they ameliorate symptoms rather than target the disease source. It is urgent to identify pathways disrupted in obesity to develop better therapeutics that more precisely treat the case-specific source of fat mass expansion. My lab contributed to this effort by performing a genome-wide screen for fat mass-regulating GPCRs and discovered FFAR4, a ciliary GPCR that binds ω-3 fatty acids to promote preadipocyte differentiation into new adipocytes (adipogenesis) instead of depositing lipids in existing tissue, causing inflammation (hypertrophy). This discovery is especially useful to human health because even though adipogenesis and hypertrophy both cause weight gain, hypertrophy is ultimately much more pernicious because the chronic inflammation leads to complications, including hypertension and diabetes. Therefore, understanding how FFAR4 drives preadipocyte differentiation may help us circumvent hypertrophic obesity and downstream pathology. The mechanism by which FFAR4 drives adipogenesis has yet to be elucidated. To do so, the Jackson lab performed the first genome-wide CRISPR knockout screen for FFAR4-pathway adipogenesis regulators using preadipocytes harvested at different time points post-differentiation. Our lab discovered that translation initiation factors eIF4G1 and eIF4G2, highly homologous proteins that compete for the same ribosomal binding site to drive transcript recruitment, have opposite effects on adipogenesis downstream of FFAR4: eIF4G2 was the strongest inhibitor and eIF4G1 was one of the strongest drivers of adipogenesis. I will test my central hypothesis that the switch from eIF4G2-dependent to eIF4G1-dependent translation (by degradation of eIF4G2 and activation of eIF4G1), downstream of FFAR4-induced cAMP signaling, drives fate change through converting to the translation of transcripts that specifically promote adipogenesis. I will use a combination of 3T3-L1 preadipocytes and mouse genetic models to gain mechanistic insight into eIF4G1/2 functions on a cellular and systemic level. In Aim 1, I will determine the mechanism of eIF4G1/2 function in preadipocyte differentiation in vitro. I will tease apart the pathway(s) through which eIF4G1 and eIF4G2 act by probing mechanism, tracking their kinetics in adipogenesis, determining if they are necessary/sufficient to drive adipogenesis, and identifying the transcripts they each regulate. In Aim 2, I will determine the role of eIF4G1/2 in fat expansion and metabolism in vivo using mouse model systems to see how eIF4G1 and eIF4G2 function relates to multicellular systems. Taken together, my work will pave the way for exploring the network of signaling events that drive adipogenesis downstream of the cilium and may pave the way for therapeutics targeting monogenic sources of obesity.

项目总结 肥胖是一种由脂肪质量增加引起的疾病，在过去的几十年里，肥胖症的患病率有所上升。 超过30%的人口患有肥胖症，随着时间的推移，它可能会导致寿命的增加- 具有威胁性的病理，包括II型糖尿病、心脏病和癌症。已经投入了大量的研究 寻找新的治疗方法，这些方法仍然无效，因为1)肥胖是高度多基因的，2)它们改善了 而不是针对病源。当务之急是找出肥胖发展的受阻途径 更好的治疗方法，更精确地治疗特定病例的脂肪肿块扩大的来源。 我的实验室为这项工作做出了贡献，进行了全基因组的脂肪质量调节GPCRs和 发现FFAR4，一种纤毛状GPC，结合ω-3脂肪酸促进前脂肪细胞分化为新的 脂肪细胞(脂肪生成)而不是在现有组织中沉积脂肪，导致炎症(肥大)。 这一发现对人类健康特别有用，因为即使脂肪生成和肥大都 导致体重增加，肥大最终更有害，因为慢性炎症导致 并发症，包括高血压和糖尿病。因此，了解FFAR4如何驱动前脂肪细胞 分化可能有助于我们绕过肥厚性肥胖和下游病理。这个机制是通过 FFAR4驱动脂肪生成的机制尚不清楚。为了做到这一点，杰克逊实验室进行了第一次 利用前脂肪细胞对FFAR4途径脂肪生成调控因子进行全基因组CRISPR基因敲除筛选 分化后不同时间点收获。我们的实验室发现翻译起始因子eIF4G1 和eIF4G2，高度同源的蛋白质，竞争相同的核糖体结合位点来驱动转录本 对FFAR4下游的脂肪形成有相反的影响：eIF4G2是最强的抑制剂 EIF4G1是脂肪形成的最强驱动力之一。我将验证我的中心假设，即 从eIF4G2依赖到eIF4G1依赖的翻译(通过eIF4G2的降解和eIF4G1的激活)， 在FFAR4诱导的cAMP信号的下游，通过转换为 专门促进脂肪生成的转录本。我将使用3T3-L1前脂肪细胞和小鼠的组合 遗传模型，以获得对eIF4G1/2在细胞和系统水平上的功能的机械性洞察。在目标1中，我 将确定eIF4G1/2在体外诱导前脂肪细胞分化中的作用机制。我会梳理出 EIF4G1和EIF4G2通过探测机制发挥作用的途径(S)，追踪它们在脂肪形成中的动力学， 确定它们是否是推动脂肪生成所必需的/足够的，并确定它们各自的转录本 监管。在目标2中，我将利用小鼠来确定eIF4G1/2在体内脂肪扩张和代谢中的作用 建立系统模型，了解eIF4G1和eIF4G2的功能与多细胞系统的关系。加在一起，我的 这项工作将为探索驱动脂肪生成下游的信号事件网络铺平道路。 纤毛，并可能为针对肥胖的单基因来源的治疗铺平道路。