Insulin Action on GLUT4 and FOXO1 in the Brain

胰岛素对大脑中 GLUT4 和 FOXO1 的作用

• 批准号: 8397806
• 负责人: Garrett Heinrich
• 金额: $ 5.22万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8397806
• 关键词: Ablation; Address; Adipose tissue; Affect; Alleles; Brain; Cell membrane; Cells; Cerebellum; Cues; Cytoplasm; Deoxyglucose; Diabetes Mellitus; Event; Exhibits; Fatty acid glycerol esters; Fluorescence Microscopy; Gluconeogenesis; Glucose; Glucose Transporter; Goals; Hand; Hepatic; Hippocampus (Brain); Hormones; Human; Hypoglycemia; Hypothalamic structure; Immunohistochemistry; Impairment; Insulin; Insulin Receptor; Insulin Resistance; Knock-out; Knockout Mice; Label; Leptin; Liver; Location; Measures; Metabolic; Microscopy; Modeling; Monitor; Mus; Muscle; Neuraxis; Neuroblastoma; Neurons; Non-Insulin-Dependent Diabetes Mellitus; Organ; Pancreas; Pathogenesis; Pathway interactions; Peripheral; Phenotype; Physiological; Play; Primary Cell Cultures; Process; Reagent; Resolution; Risk Factors; Role; Signal Transduction; Site; Skeletal Muscle; Surface; Synapses; System; Techniques; Tissues; Transcription factor genes; Virus; blood glucose regulation; cell type; diabetic; gain of function; glucose analog; glucose disposal; glucose production; glucose uptake; insulin secretion; insulin sensitivity; loss of function; mouse model; neuron loss; neuronal cell body; olfactory bulb; research study; response; type I and type II diabetes

DESCRIPTION (provided by applicant): Impairment in insulin-stimulated glucose uptake is a major risk factor for developing Type 2 Diabetes. Insulin promotes glucose uptake through translocation of the facilitative glucose transporter 4 (GLUT4). GLUT4 is localized to the main insulin-responsive tissues, skeletal muscle and fat, but also to organs and cell types that do not require insulin for glucose uptake, such as CNS neurons. Deletion of insulin receptors in GLUT4-expressing tissues of mice (GIRKO) causes insulin-resistant diabetes and substantial insulin resistance in liver. This project studies whether the same mechanisms allowing GLUT4 translocation from the cytoplasm to the plasma membrane in the adipose tissue and muscle contribute to glucose uptake in the brain. Single cell microscopy and a fluorescent glucose analog will be used to visualize the uptake of glucose at the plasma membrane location where GLUT4 is expressed and determine whether glucose uptake occurs in a specific region of the neuron (e.g. synapses vs. soma). These experiments will be performed in primary cultures of neurons from the mouse hypothalamus. A high-resolution microscopy technique, total internal reflection microscopy (TIRF), will visualize a virus containing labeled GLUT4 in primary neuronal culture. Quantitation of labeled GLUT4 at the plasma membrane can be performed before and after insulin stimulation to determine the insulin responsiveness of these GLUT4 expressing cells. In the second part of the proposal, loss- or gain-of-function of hypothalamic insulin action mouse models will be generated by deleting the insulin receptor or Foxo1, respectively, in cells that express Nkx2.1. These models are expected to aid in the study of hypothalamic insulin action and its effects on insulin secretion from the pancreas and hepatic glucose production. GLUT4 localization in the primary neurons from these loss- and gain-of-function models will also be determined. The goals of these studies are to determine whether neuronal GLUT4 translocates to the plasma membrane and under what conditions, and how the loss or gain of insulin sensitivity in the hypothalamus affects the function of GLUT4-expressing neurons and the resulting effects on the periphery. PUBLIC HEALTH RELEVANCE: In Type 1 and Type 2 Diabetes, the ability to mount a proper counterregulatory response in the face of hypoglycemia as well as maintain sufficient glucose uptake is critical in avoiding dangerous high and low glucose levels. This project studies the function of neurons in the brain that express the glucose transporter GLUT4 and gene transcription factor FOXO1 and how insulin action in those neurons maintains peripheral glucose homeostasis.

描述（由申请人提供）：胰岛素刺激的葡萄糖摄取损伤是发生2型糖尿病的主要危险因素。胰岛素通过促进性葡萄糖转运蛋白4 （GLUT4）的易位促进葡萄糖摄取。GLUT4定位于主要的胰岛素反应组织，骨骼肌和脂肪，但也定位于不需要胰岛素来摄取葡萄糖的器官和细胞类型，如中枢神经系统神经元。小鼠glut4表达组织（GIRKO）中胰岛素受体的缺失导致胰岛素抵抗性糖尿病和肝脏中大量的胰岛素抵抗。本项目研究允许GLUT4在脂肪组织和肌肉中从细胞质转运到质膜的相同机制是否有助于大脑中的葡萄糖摄取。单细胞显微镜和荧光葡萄糖模拟物将用于可视化GLUT4表达的质膜位置的葡萄糖摄取，并确定葡萄糖摄取是否发生在神经元的特定区域（例如突触与体细胞）。这些实验将在小鼠下丘脑神经元的原代培养中进行。一种高分辨率显微镜技术，全内反射显微镜（TIRF），将在原代神经元培养中看到含有标记GLUT4的病毒。可以在胰岛素刺激前后定量质膜上标记的GLUT4，以确定这些GLUT4表达细胞的胰岛素反应性。在建议的第二部分，下丘脑胰岛素作用的功能丧失或获得