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: 8148778
• 负责人: Lee Weinstein
• 金额: $ 42.55万
• 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/8148778
• 关键词: Acute; Agonist; Alleles; Brain region; Cyclic AMP; Development; Diabetes Mellitus; Diet; Disease; Eating; Energy Metabolism; Exons; Female; GTP-Binding Protein alpha Subunits, Gs; Genes; Genetic Recombination; Germ-Line Mutation; Glucose; Glucose Intolerance; Heart Rate; Hormones; Human; Hyperlipidemia; Hypertension; Hypertriglyceridemia; Hypothalamic structure; In Situ Hybridization; Insulin Resistance; Lipids; Measurement; Metabolic; Metabolism; Middle Hypothalamus; Morbid Obesity; Mus; Mutation; Nerve; Neurons; Obesity; Organ Weight; Parents; Pathway interactions; Patients; Phenotype; Pro-Opiomelanocortin; Pseudohypoparathyroidism; Regulation; Role; Serum; Site; Therapeutic Agents; Thermogenesis; Transgenes; glucose metabolism; male; paraventricular nucleus; 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 began 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 sympathetic nervous system activity and 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 showed that Gs-alpha is imprinted in the paraventricular nucleus of the hypothalamus (PVN), a known site of melanocortin action and metabolic regulation. We more recently examined mice with loss of Gs-alpha in the ventral medial hypothalamus (VMH) using Sf1-cre and see no effects on glucose or energy metabolism. Mice with PVN-specific Gs-alpha deficiency using Sim1-cre (also loss of Gs-alpha in a couple of other sites) show moderate effects on energy balance and glucose metabolism, more prominent in males, but not to the extent as mBrGsKO mice. This suggests that other regions in addition to the PVN are involved in the parent-of-origin effects on glucose metabolism. We are also generating mice with PVN-specific loss of Gq/11 in the PVN to see if these G proteins are involved in mediating the anorectic response to central melanocortins. We have also begun experiments on mice with loss of Gs-alpha in glucose-excitable POMC (proopiomelanocortin) neurons to see if this has any effect on whole body metabolism and specifically whether there is an effect on the ability of these neurons to sense glucose.

我们通过与GS-Alpha的FloxErele配合了女性杂合子，从而与GS-Alpha杂合子配对中枢神经系统（MBGSKO）中的GS-Alpha表达，从而与GS-Alpha Exon 1与GS-Alpha Exon围绕GS-Alpha EXON与NESTIN促进者促进蛋白促进者重新组合酶变成型GS-Alpha重新组合站点进行了交配。用相互的杂交产生了中枢神经系统（PBGSKO）中中枢神经系统中GS-Alpha表达相似的小鼠。 PBGSKO小鼠的生存率正常和总体表型，对多种实验方法（体重和组成，器官重，血清化学和激素，葡萄糖和胰岛素耐受性测试，代谢率和食物摄入量测量）确定，对葡萄糖或能量代谢或血清脂质无影响。相比之下，MBGSKO患有严重的糖尿病，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。在年轻小鼠中的研究表明，胰岛素抵抗和葡萄糖不耐症在肥胖之前开始发展，这表明对葡萄糖代谢产生了独立于肥胖的影响。在MBGSKO小鼠中的进一步研究表明，肥胖症主要是交感神经系统活性和能量消耗降低以及与能量耗散相关的棕色脂肪组织基因的表达降低的结果，例如解开蛋白1（UCP1），没有对食物摄入的主要作用。我们假设MBGSKO小鼠可能是黑色素皮质系统刺激交感神经系统活动和能量消耗的能力的缺陷。为了检验这一假设，测量了对黑色皮质素激动剂（MTII）的急性食物摄入和能量消耗的反应。 PBGSKO小鼠和对照之间没有差异，对MTII抑制MBGSKO小鼠的食物摄入的能力几乎没有影响。但是，与对照组相比，MBGSKO小鼠中MTII刺激能量消耗的能力显着降低。此外，MGSKO小鼠还损害了饮食引起的热发生，心率和血压降低。总的来说，这些结果证实，中枢神经系统中的GS-Alpha途径是代谢的关键调节剂，并且小鼠（最有可能是奥尔布赖特遗传性骨do症患者）的母体GS-Alpha突变是由GS-Alpha在中枢神经系统中一个或多个部位烙印的GS-Alpha所致。原位杂交研究表明，GS-Alpha印在下丘脑（PVN）的室室核中，该核（PVN）是黑色素质素作用和代谢调节的已知部位。我们最近使用SF1-CRE检查了腹侧下丘脑（VMH）中GS-ALPHA损失的小鼠，并且看不到对葡萄糖或能量代谢的影响。使用SIM1-CRE（在其他几个地点中丧失GS-Alpha）具有PVN特异性GS-Alpha缺乏症的小鼠对能量平衡和葡萄糖代谢的影响适度，在男性中更为突出，但在MBRGSKO小鼠中并不是如此。这表明除了PVN之外，其他区域还参与了父母对葡萄糖代谢的影响。我们还生成PVN中GQ/11的PVN特异性损失的小鼠，以查看这些G蛋白是否参与介导对中央黑色皮质蛋白的厌食症反应。我们还开始对小鼠进行实验，其中GS-Alpha在葡萄糖可取消的POMC（proopiomelanocortin）神经元中，以查看这是否对全身代谢有任何影响，并特别具体是否对这些神经元感认识葡萄糖的能力有影响。