Stable isotope-based fate mapping to quantify adipogenesis in obesity

基于稳定同位素的命运图谱可量化肥胖中的脂肪生成

• 批准号: 8242402
• 负责人: Matthew Steinhauser
• 金额: $ 16.02万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8242402
• 关键词: 2,4-thiazolidinedione; Address; Adipocytes; Adipose tissue; Adult; Area; Beryllium; Biological; Blood Vessels; DNA biosynthesis; Data; Date of birth; Defect; Diabetes Mellitus; Diet; Disease; Epidemic; Fatty Acids; Fatty acid glycerol esters; Generations; Genetic; Genetically Engineered Mouse; Homeostasis; Human; In Vitro; Insulin; Insulin Resistance; Intervention; Isotopes; Life; Link; Maintenance; Maps; Mass Spectrum Analysis; Metabolic; Methodology; Methods; Microscope; Microscopy; Morbidity - disease rate; Morphologic artifacts; Mus; Neutrons; Non-Insulin-Dependent Diabetes Mellitus; Obesity; PPAR gamma; Pharmacotherapy; Physiologic pulse; Process; Radioactive; Radioisotopes; Randomized; Regenerative Medicine; Relative (related person); Resolution; Rodent; Role; Safety; Stable Isotope Labeling; Testing; Therapeutic; Thiazolidinediones; Thymidine; Tissues; Tracer; Visceral; Weight; Work; base; feeding; human stem cells; in vivo; insight; insulin sensitivity; isotope incorporation; lipid biosynthesis; mortality; novel; novel strategies; research study; response; stable isotope; stem cell biology; stem cell population; subcutaneous; theories; transcription factor

DESCRIPTION (provided by applicant): Recent evidence from human studies suggests that adipocytes turnover throughout adult life. While it has long been thought that adult adipocytes are generated from a stem cell population, recent lineage mapping experiments in mice provide strong evidence for an adipocyte precursor residing within adipose tissue. Many questions regarding the role of adipocyte turnover during normal homeostasis and in obesity remain incompletely elucidated, in large part because there have not been definitive methods to quantitate adipogenesis in vivo. The central hypothesis of this project is that caloric excess results in dynamic changes in precursor-dependent white adipose turnover. Deconstructing the role of adipogenesis in obesity and diabetes will not only yield important mechanistic insight into these disease processes, but may provide the rationale to directly target adipogenesis with pharmacotherapies. To address the central hypothesis, novel approaches to quantitate adipogenesis in vivo using stable isotope labeling and two mass spectrometry based platforms will be utilized. Rare stable isotopes differ in mass from more common isotopic forms of elements, but they are not radioactive, and thus are entirely safe and biologically inert. Preliminary data suggests that stable isotope-enriched thymidine is an effective tracer to detect DNA synthesis and cellular division. Using pulse-chase strategies and mass spectrometry, including multi-isotope mass spectrometry (MIMS) an exciting new microscopy methodology that can detect areas of stable isotope incorporation within tissues with sub-cellular resolution, adipogenesis can be quantified after biologically relevant interventions, in vivo. Aim 1: To test the hypothesis that high fat feeding will result in a dynamic increase in white adipose adipogenesis. Adult mice will be randomized to a normal diet or an adipogenic (high-fat) diet, and two stable isotope based approaches will be used to determine whether adipose expansion as occurs in obesity is associated with increased generation of new adipocytes. Aim 2: To test the hypothesis that prolonged high fat feeding with resultant obesity-related insulin resistance results in a relative deficiency in subcutaneous adipogenesis in favor of increased visceral adipogenesis. The rates of adipogenesis will be compared between obese and lean mice in response to a high fat diet, with the aim to answer the question of whether obesity results in depot specific defects in adipogenesis, which may contribute to coexistent insulin resistance. Aim 3: To test the hypothesis that PPAR-gamma activation will stimulate white adipose adipogenesis, in vivo. Stable isotope methods will be used to quantitate adipogenesis after pharmacologic stimulation of PPAR-gamma with a thiazolidinedione in obese and lean mice. PUBLIC HEALTH RELEVANCE: Obesity and Type 2 Diabetes Mellitus represent major causes of morbidity and mortality in the developed world. Defining the capacity to generate new fat cells in states of Obesity and Diabetes may yield a critical mechanistic link between these related diseases. This project will study the role of new fat cell formation in obesity and diabetes, an understanding of which may provide the therapeutic rationale to pharmacologically control fat cell formation.

描述（由申请人提供）：来自人类研究的最新证据表明脂肪细胞在整个成年生活中不断更新。虽然长期以来人们一直认为成体脂肪细胞是由干细胞群产生的，但最近在小鼠中进行的谱系作图实验为脂肪组织内存在脂肪细胞前体提供了强有力的证据。关于脂肪细胞更新在正常稳态和肥胖期间的作用的许多问题仍未完全阐明，很大程度上是因为还没有量化体内脂肪生成的明确方法。该项目的中心假设是热量过剩会导致前体依赖性白色脂肪周转发生动态变化。解构脂肪生成在肥胖和糖尿病中的作用不仅可以对这些疾病过程产生重要的机制见解，而且可以为通过药物疗法直接靶向脂肪生成提供理论基础。为了解决中心假设，将利用使用稳定同位素标记和两个基于质谱的平台来定量体内脂肪生成的新方法。稀有稳定同位素的质量与更常见的元素同位素形式不同，但它们不具有放射性，因此完全安全且具有生物惰性。初步数据表明，富含稳定同位素的胸苷是检测 DNA 合成和细胞分裂的有效示踪剂。使用脉冲追踪策略和质谱法，包括多同位素质谱法 (MIMS)，这是一种令人兴奋的新显微镜方法，可以以亚细胞分辨率检测组织内稳定同位素掺入的区域，可以在生物相关干预后在体内量化脂肪生成。目标 1：检验高脂肪喂养会导致白色脂肪生成动态增加的假设。成年小鼠将被随机分配到正常饮食或脂肪形成（高脂肪）饮食，并且将使用两种基于稳定同位素的方法来确定肥胖中发生的脂肪扩张是否与新脂肪细胞生成的增加有关。目标 2：检验以下假设：长期高脂肪喂养会导致肥胖相关的胰岛素抵抗，从而导致皮下脂肪生成相对不足，从而有利于内脏脂肪生成的增加。我们将比较肥胖小鼠和瘦小鼠对高脂肪饮食的反应，其脂肪生成率，目的是回答肥胖是否会导致脂肪生成中特定缺陷的问题，这可能导致共存的胰岛素抵抗。目标 3：验证 PPAR-γ 激活会刺激体内白色脂肪生成的假设。稳定同位素方法将用于定量肥胖和瘦小鼠中用噻唑烷二酮药物刺激 PPAR-γ 后的脂肪生成。 公共卫生相关性：肥胖和 2 型糖尿病是发达国家发病和死亡的主要原因。定义肥胖和糖尿病状态下生成新脂肪细胞的能力可能会在这些相关疾病之间产生关键的机制联系。该项目将研究新脂肪细胞形成在肥胖和糖尿病中的作用，了解这一点可能为药理学控制脂肪细胞形成提供治疗原理。