Molecular mechanisms of leptin receptor/Jak2 action

瘦素受体/Jak2作用的分子机制

• 批准号: 7998415
• 负责人: Martin G Myers
• 金额: $ 18.36万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-21 至 2010-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7998415
• 关键词: 1-Phosphatidylinositol 3-Kinase; Accounting; Acute; Affect; Attenuated; Award; Binding; Biology; Blood Glucose; Body Weight; Complement; Cultured Cells; Data; Defect; Endocrine; Energy Metabolism; Feedback; Funding; Future; Health Care Costs; Homeostasis; Hyperglycemia; Hypothalamic structure; Individual; Knock-in Mouse; Lead; Leptin; Life Expectancy; Mediating; Mediator of activation protein; Metabolic; Metabolic Diseases; Metabolism; Modeling; Molecular; Molecular Target; Mus; Mutant Strains Mice; Neurons; Neurophysiology - biologic function; Neurosecretory Systems; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathway interactions; Phosphorylation; Phosphorylation Site; Phosphotransferases; Physiological; Physiology; Process; Protein Isoforms; Protein Tyrosine Kinase; Recruitment Activity; Regulation; Research; Residual state; Role; STAT5A gene; Signal Pathway; Signal Transduction; Site; System; Testing; Therapeutic Intervention; Tyrosine; Tyrosine Phosphorylation; Tyrosine Phosphorylation Site; Work; attenuation; base; blood glucose regulation; energy balance; feeding; global health; glycemic control; in vivo; insight; leptin receptor; mouse model; mutant; neuroregulation; novel; public health relevance; relating to nervous system

DESCRIPTION (provided by applicant): This proposal, entitled, "Molecular Mechanisms of Leptin Receptor/Jak2 Action," is an application for competitive renewal of DK56731. The long-term outlook of our previous and future studies is to understand mechanisms of LepRb signaling and to determine how LepRb signals contribute to the regulation of neural function and thence to the control of energy balance, glucose homeostasis, and neuroendocrine function. LepRb mediates tyrosine phosphorylation (Tyr(P))-dependent signaling by means of an associated Jak2 tyrosine kinase. Leptin binding stimulates the Tyr(P) of Jak2 and tyrosine residues on LepRb; each Tyr(P) site mediates a unique complement of intracellular signals. To this point, we have defined the mechanisms of LRb/Jak2 interaction, defined the function of Jak2 Tyr(P) sites, and examined the biology of LepRb Tyr1138AESTAT3 signaling and LepRb Tyr985AESHP2/SOCS3 signaling. Recently, we defined a third Tyr(P) site on LepRb (Tyr1077), which regulates STAT5 signaling and potentially other LepRb signals, and have generated novel mouse models to probe the function of Jak2 and Tyr1077 in LepRb action in vivo. Preliminary data suggest that contributions from LepRb phosphorylation sites are required for most known leptin effects, including some actions that are independent of Tyr1138 and Tyr985. In contrast, Tyr1077 is crucial to the regulation of glycemic control and potentially other physiologic leptin effects. In the context of a variety of data that suggest the importance of the acute (non-transcriptional) effects of leptin in the short-term regulation of energy balance and glycemic control, these data suggest the hypothesis that LepRb Tyr1077 mediates cellular signals required for the acute effects of leptin. In addition to testing this core hypothesis, the proposed research will define the signals and mechanisms by which leptin mediates a variety of physiologic effects and by which leptin modulates blood glucose levels. We propose to: (1) Understand the roles for LepRb signals in the regulation of physiology, focusing on Jak2 and Tyr1077. (2) Define the leptin-mediated regulation of neural function in mouse models of altered LepRb signaling. (3) Determine the signaling mechanisms by which LepRb Tyr1077 and/or other Jak2 and LepRb Tyr(P) sites control physiology and neural function. This approach will reveal the molecular underpinnings of leptin action and delineate the role of each leptin signal in the regulation of neural and organismal physiology by leptin. The mechanistic insights derived from these studies will suggest potential molecular targets for therapeutic intervention in metabolic disease. PUBLIC HEALTH RELEVANCE: Leptin is a key regulator of body energy homeostasis and metabolism, and impaired leptin action may contribute to a variety of metabolic diseases. Understanding the molecular mechanisms of leptin action is thus crucial for our understanding of processes that may be dysregulated in metabolic diseases, as well as for defining potential targets for therapeutic intervention. We have thus been working to define the mechanisms by which the leptin receptor, LepRb, mediates cellular signaling and to understand how each of these signals contributes to the physiologic actions of leptin in vivo. While LepRb Tyr1138/STAT3 signaling is crucial for long-term energy balance, this signaling pathway fails to explain many important aspects of leptin action. LepRb Tyr985, which mediates feedback inhibition on LepRb to attenuate leptin action in vivo, cannot account for residual leptin action. Recent data from our ongoing analysis suggests important roles for LepRb Tyr1077 in leptin action in vivo; signals emanating directly from Jak2 may contribute, as well. We will thus analyze the role of Jak2 and LepRb Tyr1077 in the neural and physiologic actions of leptin by utilizing mouse models in which we have altered LepRb to specifically affect those signals. We will furthermore utilize a set of in vivo systems to define the molecular mediators that lie downstream of Jak2 and/or LepRb Tyr1077 in the regulation of these processes. Overall, these studies will define crucial mediators of leptin action and reveal specific mechanisms by which leptin controls particular physiologic endpoints.

描述（由申请人提供）：该提案题为“瘦素受体/Jak2作用的分子机制”，是DK56731竞争性更新的申请。我们之前和未来研究的长期前景是了解 LepRb 信号传导机制，并确定 LepRb 信号如何促进神经功能的调节，从而控制能量平衡、葡萄糖稳态和神经内分泌功能。 LepRb 通过相关的 Jak2 酪氨酸激酶介导酪氨酸磷酸化 (Tyr(P)) 依赖性信号传导。瘦素结合刺激 Jak2 的 Tyr(P) 和 LepRb 上的酪氨酸残基；每个 Tyr(P) 位点介导独特的细胞内信号补充。至此，我们已经定义了 LRb/Jak2 相互作用的机制，定义了 Jak2 Tyr(P) 位点的功能，并检查了 LepRb Tyr1138AESTAT3 信号传导和 LepRb Tyr985AESHP2/SOCS3 信号传导的生物学。最近，我们在 LepRb (Tyr1077) 上定义了第三个 Tyr(P) 位点，该位点调节 STAT5 信号传导和潜在的其他 LepRb 信号，并生成了新的小鼠模型来探测 Jak2 和 Tyr1077 在 LepRb 体内作用中的功能。初步数据表明，大多数已知的瘦素效应都需要 LepRb 磷酸化位点的贡献，包括一些独立于 Tyr1138 和 Tyr985 的作用。相比之下，Tyr1077 对于血糖控制和潜在的其他生理瘦素效应的调节至关重要。各种数据表明瘦素的急性（非转录）效应在能量平衡和血糖控制的短期调节中的重要性，这些数据提出了这样的假设：LepRb Tyr1077 介导瘦素急性效应所需的细胞信号。除了测试这一核心假设之外，拟议的研究还将定义瘦素介导各种生理效应以及瘦素调节血糖水平的信号和机制。我们建议：（1）了解LepRb信号在生理调节中的作用，重点关注Jak2和Tyr1077。 (2) 定义 LepRb 信号传导改变的小鼠模型中瘦素介导的神经功能调节。 (3) 确定 LepRb Tyr1077 和/或其他 Jak2 和 LepRb Tyr(P) 位点控制生理和神经功能的信号传导机制。这种方法将揭示瘦素作用的分子基础，并描述每个瘦素信号在瘦素调节神经和机体生理学中的作用。从这些研究中得出的机制见解将为代谢疾病的治疗干预提供潜在的分子靶点。公众健康相关性：瘦素是身体能量稳态和新陈代谢的关键调节剂，瘦素作用受损可能导致多种代谢疾病。因此，了解瘦素作用的分子机制对于我们了解代谢疾病中可能失调的过程以及确定治疗干预的潜在目标至关重要。因此，我们一直致力于确定瘦素受体 LepRb 介导细胞信号传导的机制，并了解这些信号如何促进瘦素在体内的生理作用。虽然 LepRb Tyr1138/STAT3 信号传导对于长期能量平衡至关重要，但该信号传导途径无法解释瘦素作用的许多重要方面。 LepRb Tyr985 介导 LepRb 的反馈抑制以减弱体内瘦素作用，但不能解释残留的瘦素作用。我们正在进行的分析的最新数据表明 LepRb Tyr1077 在体内瘦素作用中发挥重要作用；直接从 Jak2 发出的信号也可能有所贡献。因此，我们将利用小鼠模型来分析 Jak2 和 LepRb Tyr1077 在瘦素的神经和生理作用中的作用，在该模型中我们改变了 LepRb 以特异性影响这些信号。此外，我们将利用一组体内系统来定义位于 Jak2 和/或 LepRb Tyr1077 下游调节这些过程的分子介质。总的来说，这些研究将定义瘦素作用的关键介质，并揭示瘦素控制特定生理终点的具体机制。