Mechanistic Connection between Interorganellar Communication and Obesity-associated Diseases

细胞器间通讯与肥胖相关疾病之间的机制联系

• 批准号: 10634347
• 负责人: Xing Zeng
• 金额: $ 42.8万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2028-02-29
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10634347
• 关键词: Ablation; Adipocytes; Adipose tissue; Affect; Animal Model; Animals; Binding; Biochemical; Biochemistry; Biological Assay; Body Weight; Body mass index; Brown Fat; C-terminal; Cardiovascular Diseases; Cell model; Cells; Cellular biology; Communication; Defect; Deposition; Disease; Dissection; Elements; Endocrine System Diseases; Endoplasmic Reticulum; Event; Extravasation; Genetic Models; Goals; Health; High Fat Diet; Impairment; In Vitro; Individual; Insulin Resistance; Knockout Mice; Knowledge; Lipid Binding; Lipids; Maintenance; Mediating; Metabolic; Metabolic Diseases; Mission; Molecular; Mus; N-terminal; Names; National Institute of Diabetes and Digestive and Kidney Diseases; Nerve; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Obesity associated disease; Organ; Organelles; Outcome; Pathogenesis; Pathway interactions; Persons; Phenotype; Phospholipids; Physiological; Physiology; Play; Population; Predisposition; Process; Proteins; Public Health; Quality of life; Research; Risk; Risk Factors; Role; Severities; Site; Structure; Surface; System; Testing; Transgenic Mice; Transmembrane Domain; Variant; Wild Type Mouse; Work; density; design; feeding; improved; innovation; insight; metabolic phenotype; mouse model; nerve supply; new therapeutic target; non-alcoholic fatty liver disease; novel; obese patients; reconstitution; recruit; therapeutic target

Project Summary Obesity is a leading risk factor for type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases. A central driver of pathogenesis in obesity-associated disorders is the insufficient lipid-storing capacity of adipocytes and subsequent lipid deposition in extra-adipose organs. The lipid droplet (LD) is the organelle responsible for lipid storage and mobilization in adipocytes. It remains to be elucidated whether proteins and pathways regulating LD structure and function constitute limiting factors governing the lipid-storing capacity of adipocytes, and thus play an essential role in determining one’s susceptibility to obesity-associated disorders. We observed that mice deficient in CLSTN3B, a mammalian adipocyte-specific protein, are more prone to high-fat diet-induced metabolic disorders compared with body weight-matched wild-type mice, whereas the adipose-specific clstn3b transgenic mice display the opposite phenotype. Preliminary evidence shows that CLSTN3B localizes to endoplasmic reticulum (ER)/LD contact sites and ablation of CLSTN3B results in an impaired coating of LDs by phospholipids and proteins. Our overall objectives are to (i) establish the significance of CLSTN3B expressed in white adipocytes to the metabolic phenotype; (ii) reveal the molecular mechanism of CLSTN3B action at the ER/LD contact sites. The central hypothesis is that CLSTN3B enhances the structural and functional integrity of LDs, improves white adipocyte lipid-storing capacity, and contributes to the maintenance of metabolic health under obese conditions; mechanistically, this is achieved by replenishing LD surface phospholipids and promoting the binding of LD-targeting proteins. We will test this hypothesis by pursuing three specific aims: 1) Show that CLSTN3B expressed in white adipocytes is the main contributor to the metabolic benefits upon high-fat diet feeding; 2) Show that CLSTN3B promotes phospholipids transfer between ER and LD; 3) Probe the role of the C-terminal ER luminal segment of CLSTN3B in the formation of ER/LD contacts. For the first aim, we will construct genetic models allowing specific assessment of white adipocyte-derived CLSTN3B. For the second aim, we will design in vitro reconstituted phospholipid transfer assays and examine the functional significance of LD surface phospholipid density. For the third aim, we will use biochemical approaches to identify potential binding partners of the ER luminal C-terminal fragment of CLSTN3B, followed by assessing the significance of such interactions using cellular and animal models. The proposed research is innovative because it dissects the molecular mechanism of a novel protein and explains susceptibility to obesity-associated disorders from a novel perspective. The proposed research is significant because it aims to establish an integrated understanding encompassing interorganelle communication and metabolic physiology at the organismal level. Our long-term goal is to use CLSTN3B as a molecular handle to derive a thorough understanding of ER/LD interactions in the specific context of adipocytes and identify novel therapeutic targets for obesity-associated diseases.

项目摘要 肥胖是2型糖尿病，非酒精性脂肪肝病和心血管的主要危险因素 疾病。肥胖相关疾病中发病机理的核心驱动力是脂质储存不足 脂肪细胞和随后的脂质器官中的脂质沉积的能力。脂质液滴（LD）是 负责脂肪细胞中脂质储存和动员的细胞器。是否尚待阐明是否 调节LD结构和功能的蛋白质和途径构成了管理脂质存储的限制因素 脂肪细胞的能力，因此在确定与肥胖相关的敏感性方面起着至关重要的作用 疾病。我们观察到缺乏哺乳动物脂肪细胞特异性蛋白Clstn3b的小鼠更多 与体重匹配的野生型小鼠相比，容易发生饮食诱导的代谢性疾病， 而脂肪特异性的CLSTN3B转基因小鼠显示了相反的表型。初步证据 表明CLSTN3B本地化为内质网（ER）/LD接触位点和Clstn3b的消融 导致磷脂和蛋白质对LDS的涂层受损。我们的整体目标是（i）建立 Clstn3b在白色脂肪细胞中表达的对代谢表型的意义； （ii）揭示 Clstn3b在ER/LD接触位点作用的分子机制。中心假设是clstn3b 增强LD的结构和功能完整性，提高白色脂肪细胞脂质的能力，并 在肥胖状况下维持代谢健康；从机械上讲，这是通过 补充LD表面磷脂并促进靶向LD靶向蛋白的结合。我们将测试这个 通过追求三个特定目标：1）表明以白色脂肪细胞表达的clstn3b是主要的 高脂饮食喂养的代谢益处的贡献者； 2）证明Clstn3b促进 ER和LD之间的磷脂转移； 3）探测C末端ER腔段的作用 clstn3b在ER/LD触点的形成中。对于第一个目标，我们将构建遗传模型，允许 白色脂肪细胞衍生的Clstn3b的特定评估。为了第二个目标，我们将在体外设计 重建的磷脂转移测定法并检查LD表面磷脂的功能意义 密度。对于第三个目标，我们将使用生化方法来识别ER的潜在约束伙伴 Clstn3b的腔C末端片段，然后评估使用这种相互作用的重要性 细胞和动物模型。拟议的研究具有创新性，因为它剖析了分子机制 一种新颖的蛋白质，并从新颖的角度解释了对肥胖相关疾病的敏感性。这 拟议的研究很重要，因为它旨在建立综合理解 有机水平上的企业间通信和代谢生理学。我们的长期目标是使用 clstn3b作为分子手柄，以获取对特定的ER/LD相互作用的透彻理解 脂肪细胞的背景并确定与肥胖相关疾病的新型治疗靶标。