Role of taste signaling elements in enteroendocrine cells

味觉信号元件在肠内分泌细胞中的作用

• 批准号: 8067065
• 负责人: Robert F. Margolskee
• 金额: $ 30.42万
• 依托单位: MONELL CHEMICAL SENSES CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8067065
• 关键词: Affect; Amino Acids; Artificial Sweeteners; Beryllium; Brush Cell; CD36 gene; Cell Line; Cell physiology; Cells; Defect; Desire for food; Detection; Diabetes Mellitus; Diet; Digestion; Distal; Elements; Energy Metabolism; Enterocytes; Enteroendocrine Cell; Esthesia; Exhibits; FABP1 gene; Failure; Fatty Acids; Fatty acid glycerol esters; GNAI2 gene; GTP-Binding Proteins; Genes; Genetic; Glucose; Hormones; Human; Indium; Infusion procedures; Insulin; Intestines; Killer Cells; Knock-out; Knockout Mice; L Cells; Location; Macronutrients Nutrition; Mediator of activation protein; Medical; Methods; Molecular; Mus; Nature; Obesity; Oral; Pattern; Pharmacology; Physiological; Plasma; Play; Regulation; Research; Resistance; Role; Satiation; Secretin; Signal Transduction; Signaling Molecule; Small Intestines; Stimulus; Stomach; Sugar Acids; Sweetening Agents; Taste Perception; Testing; Tissues; Transducin; Transgenic Mice; Transgenic Organisms; Up-Regulation; Villus; blood glucose regulation; cell type; energy balance; glucagon-like peptide 1; in vivo; insight; interdisciplinary approach; knockout gene; mouse Neurog3 protein; nerve supply; promoter; public health relevance; rat Gnat3 protein; receptor; research study; response; sugar

DESCRIPTION (provided by applicant): We have determined that gustducin, T1R3 and several other signaling elements that underlie taste detection/transduction also are expressed in L and K subtypes of enteroendocrine cells. One function of gustducin and T1R3 in L cells is to sense glucose or sweeteners within the lumen of the gut. 1-Gustducin knockout mice do not secrete GLP-1 from their enteroendocrine L cells in response to infusion of glucose into the gut lumen. Because of this defect these mice have dysfunctional regulation of their plasma insulin and glucose levels. Studies with minced duodenal tissue or isolated duodenal villi from 1-gustducin knockout mice show that the defect in GLP-1 secretion is independent of innervation. Studies with human and mouse enteroendocrine cell lines and antisense blockade of gustducin or pharmacological inhibition of T1R3 indicate that both gustducin and T1R3 are required for enteroendocrine cell release of GLP-1, suggesting that the defect in 1-gustducin knockout mice in vivo is at the level of glucose sensation. The experiments proposed here aim to further characterize the functions of gustducin, T1R3 and other taste signaling elements in enteroendocrine cells. We have combined molecular, cellular, transgenic, physiological and pharmacological methods to: 1. Determine which key taste signaling molecules are expressed in which enteroendocrine cells; 2. Determine if hormone release from enteroendocrine cells depends on their expression of taste signaling elements and elicits upregulation of sugar and fatty acid transporters in enterocytes; 3. Determine if pharmacologic or genetic block of enteroendocrine cell-expressed taste signaling elements alters hormone release from enteroendocrine cells; 4. Generate conditional knockout mice selectively lacking 1-gustducin, T1r3 or Trpm5 in gut; 5. Determine if conditional knockout mice lacking 1- gustducin, T1r3 or Trpm5 in gut are resistant to diet-induced obesity, show defective 2 cell function on a high fat diet, and exhibit increased energy expenditure. We will be testing the following key hypotheses: 1. Specific types of enteroendocrine cell type express multiple taste signaling elements; 2. Macronutrients and tastants elicit release of GLP-1 and other hormones from enteroendocrine cell by activating gustducin and taste receptors expressed in subtypes of enteroendocrine cells; 3. Conditional Knockout mice lacking enteroendocrine cell-expressed taste signaling elements will have defects in regulating their plasma levels of GLP-1, GIP and other hormones - leading to: (a) failure to upregulate certain enterocyte transporters, (b) dysregulation of glucose homeostasis, (c) resistance to diet-induced obesity, (d) disruption of 2 cell functions, (e) increased energy expenditure. This multidisciplinary approach has promise for providing significant new insights into the nature of enteroendocrine cell function. In particular, how enteroendocrine cells sense macronutrients (e.g. glucose and sugars) and tastants (e.g. artificial sweeteners) in the gut lumen, and how this leads to stimulation of release of GLP-1 and other hormones to regulate gut functions. This proposal has medical relevance to appetite, satiety, obesity, and diabetes. PUBLIC HEALTH RELEVANCE: Many of the same signaling elements that underlie taste detection/transduction also are expressed in enteroendocrine cells. Gustducin and T1R3, expressed in enteroendocrine L cells, are required for the release of GLP-1 in response to glucose or sweeteners within the lumen of the small intestine. The experiments proposed to functionally characterize the roles of gustducin and other taste signaling elements in enteroendocrine cells have medical relevance to appetite, satiety, diabetes and obesity.

描述（由申请人提供）：我们已经确定味觉素、T1R3和作为味觉检测/转导基础的几种其他信号元件也在肠内分泌细胞的L和K亚型中表达。 L 细胞中味素和 T1R3 的功能之一是感知肠腔内的葡萄糖或甜味剂。 1-Gustducin 敲除小鼠不会响应葡萄糖注入肠腔而从肠内分泌 L 细胞中分泌 GLP-1。由于这种缺陷，这些小鼠的血浆胰岛素和葡萄糖水平调节功能失调。对 1-gustducin 敲除小鼠切碎的十二指肠组织或分离的十二指肠绒毛进行的研究表明，GLP-1 分泌的缺陷与神经支配无关。对人和小鼠肠内分泌细胞系的研究以及 gustducin 的反义阻断或 T1R3 的药理学抑制表明，gustducin 和 T1R3 都是肠内分泌细胞释放 GLP-1 所必需的，这表明 1-gustducin 敲除小鼠体内的缺陷在于葡萄糖感觉水平。 这里提出的实验旨在进一步表征味觉素、T1R3 和其他味觉信号元件在肠内分泌细胞中的功能。我们结合了分子、细胞、转基因、生理和药理学方法来： 1. 确定哪些关键味觉信号分子在哪些肠内分泌细胞中表达； 2. 确定肠内分泌细胞释放的激素是否取决于味觉信号元件的表达并引起肠上皮细胞中糖和脂肪酸转运蛋白的上调； 3. 确定肠内分泌细胞表达的味觉信号元件的药理学或遗传阻断是否会改变肠内分泌细胞的激素释放； 4. 生成肠道选择性缺乏1-gustducin、T1r3或Trpm5的条件敲除小鼠； 5. 确定肠道中缺乏 1-味素、T1r3 或 Trpm5 的条件敲除小鼠是否能够抵抗饮食诱导的肥胖，在高脂肪饮食下是否表现出有缺陷的 2 细胞功能，并表现出能量消耗增加。我们将测试以下关键假设： 1. 特定类型的肠内分泌细胞类型表达多种味觉信号元件； 2.大量营养素和促味剂通过激活肠内分泌细胞亚型表达的味觉素和味觉受体，引起肠内分泌细胞释放GLP-1和其他激素； 3. 缺乏肠内分泌细胞表达的味觉信号元件的条件性基因敲除小鼠在调节血浆 GLP-1、GIP 和其他激素水平方面存在缺陷，导致：(a) 无法上调某些肠上皮细胞转运蛋白，(b) 葡萄糖稳态失调，(c) 对饮食引起的肥胖的抵抗力，(d) 2 种细胞功能破坏，(e) 能量增加 支出。 这种多学科方法有望为肠内分泌细胞功能的本质提供重要的新见解。特别是，肠内分泌细胞如何感知肠腔中的大量营养素（例如葡萄糖和糖）和促味剂（例如人工甜味剂），以及这如何导致刺激 GLP-1 和其他激素的释放以调节肠道功能。该提议与食欲、饱腹感、肥胖和糖尿病具有医学相关性。 公共卫生相关性： 许多构成味觉检测/转导基础的相同信号元件也在肠内分泌细胞中表达。肠内分泌 L 细胞中表达的味导素和 T1R3 是小肠腔内响应葡萄糖或甜味剂释放 GLP-1 所必需的。这些实验旨在从功能上表征肠内分泌细胞中味觉素和其他味觉信号元件的作用，这些实验与食欲、饱腹感、糖尿病和肥胖症具有医学相关性。