Lipid Stress and MC4R

脂质应激和 MC4R

• 批准号: 8816805
• 负责人: GIULIA BALDINI
• 金额: $ 32.91万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8816805
• 关键词: Address; Adverse effects; Affect; Agonist; Biochemical; Biological Assay; Body Weight decreased; Brain; Cells; Chemicals; Defect; Desire for food; Diet; Disease; Dyslipidemias; Eating; Endocytosis; Endoplasmic Reticulum; Exposure to; Fatty acid glycerol esters; Food; G-Protein-Coupled Receptors; Glucose Intolerance; Health; Hormones; Human; Hypertension; Hypothalamic structure; Inflammation; Insulin; Insulin Resistance; Knowledge; Leptin; Lipids; Macaca mulatta; Mass Spectrum Analysis; Measures; Melanocortin 4 Receptor; Membrane Lipids; Metabolic syndrome; Molecular Chaperones; Mus; Neurons; Non-Insulin-Dependent Diabetes Mellitus; Obese Mice; Obesity; Palmitates; Pathway interactions; Population; Proteins; Reducing diet; Reporter; Reporting; Research; Resistance; Risk Factors; Serum; Signal Pathway; Signal Transduction; Stress; Structure of nucleus infundibularis hypothalami; Subfamily lentivirinae; System; Testing; Ubiquitination; United States; Weight; base; cofactor; desensitization; endoplasmic reticulum stress; interest; paraventricular nucleus; prevent; public health relevance; receptor; receptor function; response; trafficking; transcription factor

DESCRIPTION (provided by applicant): Obesity is a major risk factor to develop the metabolic syndrome, characterized by hypertension, glucose intolerance, insulin resistance, dyslipidemia and increased propensity to develop diabetes type 2. A likely cofactor promoting the alarming increase in obesity in the last 10 years is the availability of food with high caloric and fat contnt. Exposure to a hypercaloric, high-fat (HF) diet induces Endoplasmic Reticulum (ER) stress and inflammation in regions of the hypothalamus controlling appetite. ?-MSH is the natural agonist of Melanocortin- 4 receptor (MC4R), a G-protein coupled receptor (GPCR) expressed by neurons of the hypothalamus that signals to decrease appetite. Because MC4R functions distally to control appetite, it has been considered as a most relevant target for anti-obesity therapies. However, even very potent MC4R agonists do not appear to treat obesity in mice and humans and the underlying mechanisms by which such agonists are ineffective are yet unclear. The overall hypothesis of this proposal is that lipid stress induces loss of MC4R function by altering the abundance (Aim 1 and Aim 2) and the traffic (Aim 3) of the receptor and that correcting such defects by chemical chaperones would facilitate weight loss by MC4R agonists. Aim 1 will determine whether adverse effects by increased palmitate on MC4R abundance observed in cultured neurons take place in the hypothalamus of mice exposed to HF-diet. The aim uses lentivirus-dependent delivery of an MC4R reporter to a region of the hypothalamus that controls appetite and measures abundance of endogenous MC4R in the hypothalamus by a mass spectrometry-based approach. Aim 2 will determine, by using biochemical and immunofluoresce-based assays, whether increased expression of transcription factors and chemical chaperones that modulate ER stress rescues MC4R abundance and function in cultured neurons exposed to elevated palmitate. The aim will also determine whether the combination of chemical chaperones and MC4R agonists promote reduced food intake and sustained weight loss in mice that are obese by being exposed to high fat diet. Aim 3 will determine whether exposure of immortalized hypothalamic neurons to elevated palmitate changes the cell lipid composition and traffic of MC4R to increase desensitization of the receptor upon prolonged exposure with the agonist, and whether such effects are blunted by a chemical chaperone. The aim will also determine whether administration of chemical chaperones restores hypothalamic lipid composition in mice obese because of HF diet (Aim 3). The proposed research will increase knowledge on an understudied topic, namely how lipid stress affects MC4R function and help identify new targets to treat obesity.

描述（由申请人提供）：肥胖是发展代谢综合征的主要危险因素，其特征是高血压，葡萄糖不耐症，胰岛素抵抗，血脂异常以及增加2型糖尿病的倾向。可能会促进高温和脂肪的肥胖症，促进肥胖症令人震惊的辅助因子。暴露于高脂肪（HF）饮食中会诱导控制食欲下丘脑区域的内质网（ER）应激和炎症。 ？-MSH是黑色素素4受体（MC4R）的天然激动剂，下丘脑神经元表达的G蛋白偶联受体（GPCR）是 信号减少食欲。由于MC4R在控制食欲的远端发挥作用，因此被认为是抗肥胖疗法的最相关靶标。但是，即使是非常有效的MC4R激动剂似乎也没有治疗小鼠和人类的肥胖症，并且这种激动剂无效的基本机制尚不清楚。该提案的总体假设是，脂质应力通过改变受体的丰度（AIM 1和AIM 2）和受体的流量（AIM 3）来诱导MC4R功能的丧失，并且化学伴侣纠正这种缺陷将促进MC4R激动剂的体重减轻。 AIM 1将确定棕榈酸盐增加对培养神经元中MC4R丰度的不利影响是否发生在暴露于HF-DIET的小鼠的下丘脑中。该目的使用慢病毒依赖性MC4R报告基因递送到下丘脑的区域，该区域控制食欲并通过基于质谱的方法来控制下丘脑中的内源性MC4R。 AIM 2将通过使用基于生化和免疫荧光的测定方法来确定转录因子的表达和化学伴侣的表达是否增加，而化学伴侣是否会在暴露于棕榈酸盐升高的培养神经元中挽救MC4R的丰度和功能。其目的还将决定化学伴侣和MC4R激动剂的组合是否会促进食物摄入量减少和持续的老鼠体重减轻 高脂饮食。 AIM 3将确定永生下丘脑神经元是否暴露于升高 棕榈酸酯会改变MC4R的细胞脂质组成和流量，以增加与激动剂的长时间暴露后受体脱敏的脱敏，以及这种作用是否被化学伴侣抑制。目的还将决定化学伴侣的给药是否由于HF饮食而恢复小鼠肥胖的下丘脑脂质组成（AIM 3）。拟议的研究将增加对研究不足的主题的知识，即脂质应力如何影响MC4R功能并帮助确定治疗肥胖症的新目标。