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.

我们通过将 Gs-alpha floxed 等位基因（其 Gs-alpha 外显子 1 周围有 loxP 重组位点）的杂合雌性与具有巢蛋白启动子的雄性交配，产生了中枢神经系统母体等位基因 Gs-alpha 表达被破坏的小鼠（mBGsKO）。 cre 重组酶转基因。通过相互杂交产生中枢神经系统中父系等位基因（pBGsKO）Gs-α表达类似丧失的小鼠。通过多种实验方法（体重和组成、器官重量、血清化学和激素、葡萄糖和胰岛素耐量测试、代谢率和食物摄入量）确定，pBGsKO 小鼠具有正常的存活率和总体表型，对葡萄糖或能量代谢或血脂没有影响测量）。相比之下，mBGsKO 则出现严重肥胖、糖尿病、严重胰岛素抵抗和高甘油三酯血症。 5周后开始出现肥胖。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，这表明对葡萄糖代谢的影响与肥胖无关。对 mBGsKO 小鼠的进一步研究表明，肥胖主要是由于交感神经系统活动和能量消耗减少以及与能量耗散相关的棕色脂肪组织基因表达减少的结果，例如解偶联蛋白 1 (UCP1)，对食物没有主要影响摄入量。我们假设 mBGsKO 小鼠的黑皮质素系统刺激交感神经系统活动和能量消耗的能力可能存在缺陷。为了检验这一假设，测量了黑皮质素激动剂（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，并且MTII对mBGsKO小鼠抑制食物摄入的能力几乎没有影响。然而，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 小鼠饮食诱导的生热作用受损，心率和血压降低。总体而言，这些结果证实，中枢神经系统中的 Gs-α 通路是代谢的关键调节因子，并且小鼠（最有可能是奥尔布赖特遗传性骨营养不良患者）的母体 Gs-α 突变是由中枢神经系统中一个或多个位点的 Gs-α 印记引起的。中枢神经系统。原位杂交研究表明，Gs-α 印记于下丘脑 (PVN) 的室旁核中，这是黑皮质素作用和代谢调节的已知部位。最近，我们使用 Sf1-cre 检查了下丘脑腹侧内侧 (VMH) 中 Gs-α 缺失的小鼠，发现对葡萄糖或能量代谢没有影响。使用 Sim1-cre 的 PVN 特异性 Gs-α 缺乏的小鼠（在其他几个位点也损失了 Gs-α）对能量平衡和葡萄糖代谢表现出中等影响，在雄性中更为突出，但程度不及 mBrGsKO 小鼠。这表明除了 PVN 之外的其他区域也参与了葡萄糖代谢的亲本效应。我们还培育了 PVN 中 Gq/11 特异性缺失的小鼠，以观察这些 G 蛋白是否参与介导对中枢黑皮质素的厌食反应。我们还开始对葡萄糖兴奋性 POMC（阿黑皮素原）神经元中 Gs-α 缺失的小鼠进行实验，看看这是否对全身代谢有任何影响，特别是是否对这些神经元感知葡萄糖的能力有影响。