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

描述（由申请人提供）：肥胖在美国和国外都是一个主要的健康问题。最近在美国估计超过30%的成年人属于肥胖（体重指数bb30）。由于肥胖增加了其他相关代谢性和非代谢性疾病的健康风险，日益严重的肥胖流行病是公共卫生的一个主要关切。大脑作为一个有组织的综合中心，控制体重，调节食物摄入和能量消耗。瘦素是一种由周围脂肪组织分泌的激素，主要在大脑中起抑制食物摄入和增加能量消耗的作用。编码瘦素基因（ob/ob）突变的小鼠肥胖和糖尿病。蛋白酪氨酸磷酸酶1B （PTP1B）已被证明负调控瘦素信号，并且全身和脑特异性PTP1B -/-小鼠对饮食诱导的肥胖具有抗性，并且对瘦素高度敏感。有趣的是，瘦素和PTP1B双敲除（PTP1B-/- ob/ob）的小鼠比ob/ob单敲除的小鼠更瘦，这表明PTP1B可能调节调节体重和代谢的其他非瘦素信号通路。因此，PTP1B是否需要完整的瘦素信号来实现其代谢作用尚不清楚。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，其水平与脂肪质量有关。中心注射低剂量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。IL- 6已被证明通过类似瘦素的细胞内通路发出信号。该途径涉及到Janus激酶2 （JAK2）的下游活性，JAK2是PTP1B的已知底物。本课题的目标是对奖学金申请者进行各种分子生物学技术、小鼠遗传学和体内生理学的培训，以验证PTP1B的代谢作用是由瘦素依赖性和瘦素非依赖性信号介导的这一假设。此外，本提案旨在验证PTP1B调节IL-6信号传导的假设。第一个目的是确定PTP1B是否通过瘦素受体依赖或不依赖的方式调节中枢神经系统的能量平衡。这将通过产生cns特异性瘦素受体和PTP1B双突变体，并将其代谢表型与单突变体和野生型对照进行比较，从而实现小鼠遗传学。第二个目的是确定PTP1B是否调节参与代谢中枢控制的IL-6信号。在培养细胞中，通过病毒介导的shRNA敲除PTP1B的表达，并测量IL-6下游效应物（pJAK, pSTAT）的激活。此外，体内IL-6敏感性将根据体外结果进行评估。

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.