Role of Gs-alpha in central regulation of energy and glucose metabolism

Gs-α 在能量和葡萄糖代谢中枢调节中的作用

• 批准号: 7734125
• 负责人: Lee Weinstein
• 金额: $ 37.73万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7734125
• 关键词: Acute; Agonist; Alleles; Blood Pressure; Body Weight; Brown Fat; Chemistry; Cyclic AMP; Development; Diabetes Mellitus; Diet; Disease; Disruption; Eating; Energy Metabolism; Exons; Female; GTP-Binding Protein alpha Subunits; GTP-Binding Protein alpha Subunits, Gs; Generations; Genes; Genetic Recombination; Germ-Line Mutation; Glucose; Glucose Intolerance; Gs alpha mutations; Heart Rate; Hormones; Human; Hyperlipidemia; Hypertension; Hypertriglyceridemia; Hypothalamic structure; In Situ Hybridization; Insulin Resistance; Lipids; Malignant Neoplasms; Measurement; Measures; Mediating; Metabolic; Metabolism; Morbid Obesity; Mus; Mutation; Neuraxis; Obesity; Organ Weight; Parents; Partner in relationship; Pathway interactions; Patients; Pattern; Phenotype; Prevalence; Pseudohypoparathyroidism; Rate; Regulation; Role; Serum; Signal Transduction; Site; Sympathetic Nervous System; System; Testing; Therapeutic Agents; Thermogenesis; Tissues; Transgenes; Transgenic Organisms; Week; energy balance; glucose metabolism; imprint; insulin tolerance; loss of function mutation; male; mouse model; nestin protein; novel therapeutics; paraventricular nucleus; promoter; receptor coupling; recombinase; response; uncoupling protein 1

We generated mice with disruption of Gs-alpha expression from the maternal allele in the central nervous system (mBGsKO) by mating females heterozygous for a Gs-alpha floxed allele with loxP recombination sites surrounding Gs-alpha exon 1 to males with a nestin promoter-cre recombinase transgene. Mice with similar loss of Gs-alpha expression in the central nervous system on the paternal allele (pBGsKO) were generated with reciprocal crosses. pBGsKO mice had normal survival and overall phenotype with no effect on glucose or energy metabolism or serum lipids as determined by multiple experimental approaches (body weight and composition, organ weights, serum chemistries and hormones, glucose and insulin tolerance tests, metabolic rate and food intake measurements). In contrast, mBGsKO developed severe obesity with diabetes, severe insulin resistance, and hypertriglyceridemia. The obesity began to develop after 5 weeks. Studies in younger mice indicate that the insulin resistance and glucose intolerance begin to develop prior to obesity, indicating an effect on glucose metabolism independent of obesity. Further studies in mBGsKO mice showed that the obesity was primarily the result of reduced energy expenditure and reduced expression of brown adipose tissue genes associated with energy dissipation, such as uncoupling protein 1 (UCP1), with no primary effect on food intake. We hypothesized that mBGsKO mice may be defective the ability of the melanocortin system to stimulate sympathetic nervous system activity and energy expenditure. To test this hypothesis, acute food intake and energy expenditure responses to a melanocortin agonist (MTII) were measured. There were no differences between pBGsKO mice and controls, and there was little effect on the ability of MTII to inhibit food intake in mBGsKO mice. However, the ability of MTII to stimulate energy expenditure was markedly reduced in mBGsKO mice as compared to controls. Moreover MGsKO mice have impaired diet-induced thermogenesis and reduced heart rate and blood pressure. Overall these results confirm that Gs-alpha pathways in the central nervous system are critical regulators of metabolism and that maternal Gs-alpha mutations in mice (and most likely Albright hereditary osteodystrophy patients) results from Gs-alpha imprinting in one or more site in the central nervous system. In situ hybridization studies suggest that Gs-alpha is imprinted in the paraventricular nucleus of the hypothalamus, a known site of melanocortin action and metabolic regulation. We are presently trying to define these sites through matings with cre transgenic lines with a more restrictive distribution pattern.

我们将含有gs - α外显子1周围loxP重组位点的gs - α柔化等位基因的雌性杂合与含有巢蛋白启动子-cre重组酶转基因的雄性杂交，获得了中枢神经系统（mBGsKO）母系gs - α表达中断的小鼠。在父本等位基因（pBGsKO）上中枢神经系统gs - α表达类似缺失的小鼠通过反向杂交产生。通过多种实验方法（体重和组成、器官重量、血清化学成分和激素、葡萄糖和胰岛素耐量试验、代谢率和食物摄入测量）确定，pBGsKO小鼠具有正常的生存和整体表型，对葡萄糖或能量代谢或血脂没有影响。相比之下，mBGsKO出现了严重的肥胖和糖尿病，严重的胰岛素抵抗和高甘油三酯血症。5周后，肥胖开始发展。对年轻小鼠的研究表明，胰岛素抵抗和葡萄糖耐受不良在肥胖之前就开始出现，表明其对葡萄糖代谢的影响独立于肥胖。对mBGsKO小鼠的进一步研究表明，肥胖主要是能量消耗减少和与能量消耗相关的棕色脂肪组织基因（如解偶联蛋白1 (UCP1)）表达减少的结果，与食物摄入无关。我们假设mBGsKO小鼠可能存在黑素皮质素系统刺激交感神经系统活动和能量消耗的能力缺陷。为了验证这一假设，测量了对黑素皮质激素激动剂（MTII）的急性食物摄入和能量消耗反应。pBGsKO小鼠与对照组之间没有差异，MTII对mBGsKO小鼠的食物摄入抑制能力影响不大。然而，与对照组相比，mBGsKO小鼠的MTII刺激能量消耗的能力明显降低。此外，MGsKO小鼠的饮食诱导产热功能受损，心率和血压降低。总的来说，这些结果证实了中枢神经系统中的gs - α通路是代谢的关键调节因子，小鼠（很可能是奥尔布赖特遗传性骨营养不良患者）母系gs - α突变是由于中枢神经系统中一个或多个部位的gs - α印记所致。原位杂交研究表明，gs - α在下丘脑室旁核中有印记，这是一个已知的黑素皮质素作用和代谢调节的部位。我们目前正试图通过与具有更严格分布模式的cre转基因系交配来确定这些位点。