Post-Developmental Adipocyte Autophagy in Control of Insulin-Glucose Homeostasis

发育后脂肪细胞自噬控制胰岛素-葡萄糖稳态

• 批准号: 8615905
• 负责人: TIMOTHY E. GRAHAM
• 金额: $ 32.41万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-13 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8615905
• 关键词: Adipocytes; Adipose tissue; Adult; Affect; Age; Animal Model; Area; Aurothioglucose; Autophagocytosis; Biogenesis; Biological Process; Body Composition; Body Weight; Cells; Cellular Stress; Communication; Death Rate; Development; Diet; Eating; Embryo; Embryonic Development; Exhibits; Fatty acid glycerol esters; Functional disorder; Genetic; Genetic Transcription; Genetically Engineered Mouse; Glucose; Glucose Intolerance; Glycogen; Glycolysis; Health; Homeostasis; Hypothalamic structure; Impairment; In Vitro; Infiltration; Inflammation; Insulin; Insulin Resistance; Islets of Langerhans; Knock-out; Knockout Mice; Life; Lipolysis; Liver; Measures; Mediating; Metabolic; Metabolic syndrome; Metabolism; Mitochondria; Modeling; Molecular; Multivesicular Body; Mus; Muscle; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Obesity; Organ; Pathogenesis; Pathway interactions; Phenotype; Play; Prevention; Production; Regulation; Reporting; Role; Signal Transduction; Skeletal Muscle; Stem cells; Stress; Structure of beta Cell of islet; Tamoxifen; Testing; Time; Time Study; Tissues; Tracer; Wild Type Mouse; Work; adipocyte biology; adipocyte differentiation; biological adaptation to stress; blood glucose regulation; feeding; glucose production; glucose transport; glucose uptake; glycogenolysis; in vivo; insulin secretion; insulin sensitivity; insulin signaling; late endosome; lipid biosynthesis; macrophage; mortality; mouse model; novel; oxidation; prevent; progenitor; public health relevance; response; trafficking; treatment strategy

Summary /Abstract Obesity, Metabolic Syndrome, and Type 2 diabetes are characterized by insulin resistance affecting multiple tissues (e.g., liver, muscle, and fat). Recent studies determined that intracellular autophagy plays an important role maintaining the metabolic health of tissues involved in the pathogenesis of insulin resistance. Autophagy is the intracellular lysosomal trafficking pathway that maintains energy homeostasis and counteracts multiple forms of cellular stress. In addition, autophagy is the sole mechanism for mitochondrial degradation and turnover in cells. Autophagy functions in skeletal muscle, liver, pancreatic beta cells, and hypothalamus to maintain insulin-glucose homeostasis; in addition, autophagy is required for lipolysis in liver. Prior studies examining the role of autophagy in adipose tissue utilized mouse models in which adipocyte autophagy was impaired during embryogenesis. These mice were lean and protected from diet-induced obesity, and exhibited enhanced insulin sensitivity and glucose intolerance. Such observations led to speculations that inhibiting autophagy in adipocytes might provide a promising strategy for treating or preventing obesity and its metabolic consequences. However, despite their apparently favorable metabolic phenotype, the mice with embryonic impairment of autophagy were not healthy: they exhibit increased rates of death (40% at 12 weeks of age) and inflammation and macrophage infiltration in adipose tissue. Due to the extreme alterations of adipocyte development and adipose tissue depot formation in these mice, they are not adequate models for assessing the post-developmental role of autophagy in the mature adipocyte. We hypothesize autophagy plays an important, protective function in mature adipocytes, and post-developmental impairment of adipocyte autophagy will induce intracellular stress and insulin-resistance via established signaling mechanisms; in addition, we predict "autophagic stress" will cause release of unique circulating factors from adipocytes that drive systemic insulin-resistance and glucose intolerance via direct effects on other organs (e.g., liver, muscle, and pancreatic beta cells). The Overall Objectives of this project are: (i) to determine the role of adipocyte autophagy in the pathogenesis of insulin-resistance and glucose intolerance in vivo by defining specific target tissues and molecular actions through which adipocyte autophagy regulates systemic metabolism in the adult; and (ii) to define the normal regulation and metabolic functions of autophagy in mature adipocytes, independently of the role of autophagy in adipocyte development/differentiation. We genetically engineered mice so that autophagy can be turned off in adulthood, after the developmental period of intense adipogenesis, via a tamoxifen- inducible genetic impairment. Preliminary findings with "mature adipocyte autophagy knockout mice" indicate autophagy does not regulate adiposity but is necessary for healthy insulin-glucose homeostasis. In the proposed work we will extend these observations to a systematic assessment of the tissue specific-mechanisms through which impairment of autophagy in mature adipocytes causes insulin resistance and glucose intolerance in mice in vivo (Aim #1); and we will make use of cultured primary adipocyte progenitor cells to study how the timing of autophagy impairment during adipogenesis influences the metabolic phenotype of adipocytes in vitro (Aim #2).

摘要/摘要 肥胖、代谢综合征和 2 型糖尿病的特点是胰岛素抵抗影响 多种组织（例如肝脏、肌肉和脂肪）。最近的研究确定细胞内自噬 在维持参与发病机制的组织的代谢健康中发挥重要作用 胰岛素抵抗。 自噬是维持能量的细胞内溶酶体运输途径 体内平衡并抵消多种形式的细胞应激。此外，自噬是唯一 细胞中线粒体降解和周转的机制。自噬在骨骼肌中发挥作用， 肝脏、胰腺β细胞和下丘脑维持胰岛素-葡萄糖稳态；此外， 肝脏的脂肪分解需要自噬。先前的研究检查了自噬在脂肪中的作用 组织利用小鼠模型，其中脂肪细胞自噬在胚胎发生过程中受损。这些 小鼠身材苗条，免受饮食引起的肥胖的影响，并且表现出增强的胰岛素敏感性和 葡萄糖不耐受。这些观察结果引发了这样的推测：抑制脂肪细胞的自噬可能 为治疗或预防肥胖及其代谢后果提供了一种有前景的策略。 然而，尽管具有明显有利的代谢表型，但具有胚胎损伤的小鼠 自噬不健康：它们表现出较高的死亡率（12 周龄时为 40%）并且 脂肪组织中的炎症和巨噬细胞浸润。由于脂肪细胞的极端改变 这些小鼠的发育和脂肪组织库的形成，它们不是足够的模型 评估自噬在成熟脂肪细胞中的发育后作用。我们假设 自噬在成熟脂肪细胞和发育后细胞中发挥重要的保护功能 脂肪细胞自噬受损将通过已建立的机制诱导细胞内应激和胰岛素抵抗 信号机制；此外，我们预测“自噬应激”将导致独特的循环释放 来自脂肪细胞的因子通过直接作用驱动全身胰岛素抵抗和葡萄糖耐受不良 其他器官（例如肝脏、肌肉和胰腺 β 细胞）。 该项目的总体目标是： (i) 确定脂肪细胞自噬在胰岛素抵抗和葡萄糖发病机制中的作用 通过定义脂肪细胞的特定靶组织和分子作用来消除体内不耐受 自噬调节成人的全身代谢； (ii) 定义正常监管和 成熟脂肪细胞中自噬的代谢功能，与自噬在脂肪细胞中的作用无关 脂肪细胞发育/分化。我们对小鼠进行了基因改造，使自噬能够 在成年期，在强烈的脂肪生成发育期之后，通过他莫昔芬- 诱导性遗传缺陷。 “成熟脂肪细胞自噬敲除小鼠”的初步发现 表明自噬不能调节肥胖，但对于健康的胰岛素-葡萄糖稳态是必需的。 在拟议的工作中，我们将把这些观察扩展到对组织的系统评估 成熟脂肪细胞自噬受损导致胰岛素产生的具体机制 小鼠体内抵抗力和葡萄糖不耐受（目标#1）；我们将利用培养初级 脂肪细胞祖细胞研究脂肪生成过程中自噬损伤的时间 影响体外脂肪细胞的代谢表型（目标#2）。