The role of PTP1B in leptin receptor-dependent and -independent regulation of ene

描述（由申请人提供）：肥胖是美国和国外的主要健康问题。美国最近的估计将超过30%的成年人口归类为肥胖（BMI > 30）。由于肥胖增加了其他相关代谢和非代谢疾病的健康风险，因此日益增加的肥胖流行是公共卫生的主要问题。大脑在控制体重、调节食物摄入和能量消耗方面起着有组织的综合中心的作用。瘦素是一种从外周脂肪组织分泌的激素，主要在大脑中起作用，以抑制食物摄入并增加能量消耗。编码瘦素的基因发生突变的小鼠（ob/ob）是肥胖的和糖尿病的。蛋白酪氨酸磷酸酶1B（PTP 1B）已被证明负调节瘦素信号传导，全身和脑特异性PTP 1B-/-小鼠对饮食诱导的肥胖有抵抗力，并且对瘦素超敏感。有趣的是，瘦素和PTP 1B双基因敲除（PTP 1B-/- ob/ob）小鼠比ob/ob单基因敲除小鼠更瘦，这表明PTP 1B可能调节额外的非瘦素信号传导途径，这些途径调节体重和代谢。因此，PTP 1B是否需要完整的瘦素信号转导来发挥其代谢作用仍不清楚。其他非瘦素循环因子与能量稳态的控制有关。白细胞介素-6（IL-6）是一种循环细胞因子，与瘦素一样，其水平与脂肪量相关。中枢注射低剂量IL-6可增加大鼠的能量消耗，长期每日注射IL-6可抑制体重。已显示IL- 6通过与瘦素类似的细胞内途径发出信号。该途径涉及Janus激酶2（JAK 2）的下游活性，JAK 2是PTP 1B的已知底物。该提案的目的是在各种分子生物学技术、小鼠遗传学和体内生理学方面培训研究金申请人，以检验PTP 1B的代谢作用由瘦素依赖性和瘦素非依赖性信号传导介导的假设。此外，该提案旨在测试PTP 1B调节IL-6信号传导的假设。第一个目的是确定PTP 1B是否通过瘦素受体依赖性或非依赖性的方式在中枢神经系统中调节能量平衡。这将通过产生CNS特异性瘦素受体和PTP 1B双突变体并将它们的代谢表型与单突变体和野生型对照的代谢表型进行比较来用小鼠遗传学进行。第二个目的是确定PTP 1B是否调节参与代谢中枢控制的IL-6信号传导。将通过病毒介导的shRNA敲低培养细胞中的PTP 1B表达，并测量IL-6（pJAK、pSTAT）下游效应子的激活。此外，将根据体外结果评估体内IL-6敏感性。 公共卫生相关性：这项工作是旨在阐明蛋白酪氨酸磷酸酶1B（PTP 1B）在能量稳态中枢控制中的作用的基础研究。了解PTP 1B在大脑中的功能和途径可能会为治疗肥胖和2型糖尿病等代谢紊乱提供新的靶点和新的途径。

DESCRIPTION (provided by applicant): Obesity is a major health concern in the United States and abroad. Recent estimates within the US classify more than 30% of the adult population as obese (BMI > 30). Since obesity increases the health risks for other associated metabolic and non-metabolic disorders, the increasing obesity epidemic is a major concern for public health. The brain functions as an organized and integrative center in the control of body weight, regulating both food intake and energy expenditure. Leptin is a hormone secreted from the peripheral adipose tissue that acts primarily in the brain to suppress food intake and increase energy expenditure. Mice with a mutation in the gene encoding leptin (ob/ob) are obese and diabetic. Protein tyrosine phosphatase 1B (PTP1B) has been shown to negatively regulate leptin signaling, and whole body and brain-specific PTP1B -/- mice are resistant to diet-induced obesity and are leptin hyper-sensitive. Interestingly, leptin and PTP1B double knockouts (PTP1B-/- ob/ob) mice are leaner than ob/ob single knockouts, suggesting that PTP1B may regulate additional non-leptin signaling pathways which regulate body weight and metabolism. Thus, whether PTP1B requires intact leptin signaling for its metabolic effects remains unclear. Other non-leptin circulating factors have been implicated in the control of energy homeostasis. Interleukin-6 (IL-6) is a circulating cytokine that, like leptin, is found at levels which correlate with adipose mass. Central injection of low dose IL-6 was shown to increase energy expenditure in rats, and chronic daily injections of IL-6 suppressed body weight. IL- 6 has been shown to signal through an intracellular pathway similar to that of leptin. This pathway involves downstream activity by Janus kinase 2 (JAK2), a known substrate of PTP1B. The goal of this proposal is to train the fellowship applicant in a variety of molecular biology techniques, mouse genetics, and in vivo physiology in order to test the hypothesis that PTP1B's metabolic effects are mediated by both leptin- dependent and leptin-independent signaling. Additionally, this proposal aims to test the hypothesis that PTP1B regulates IL-6 signaling. The first aim is to determine whether PTP1B regulates energy balance through a leptin receptor-dependent or -independent manner in the CNS. This will be done with mouse genetics by generating CNS-specific leptin receptor and PTP1B double mutants and comparing their metabolic phenotypes with those of single mutants and wild type controls. The second aim is to determine whether PTP1B regulates IL-6 signaling involved in the central control of metabolism. PTP1B expression will be knocked down in cultured cells via viral-mediated shRNA, and activation of downstream effectors of IL-6 (pJAK, pSTAT) will be measured. Additionally, IL-6 sensitivity in vivo will be assessed based upon the in vitro results. PUBLIC HEALTH RELEVANCE: The proposed work is basic research designed to elucidate the role of protein tyrosine phosphatase 1B (PTP1B) in the central control of energy homeostasis. Understanding the function and pathways of PTP1B in the brain may shed light on new targets and novel pathways for treating metabolic disorders such as obesity and type 2 diabetes.