Regulation of cAMP-Dependent Protein Kinase Genes

描述（由申请人提供）：最近的工作继续挑战和扩展我们对体重的神经控制的看法。瘦素受体已被证明以神经元特异性模式参与多种信号通路。我们建议的总体目标是解读cAMP/PKA信号系统和瘦素受体启动的信号之间的串扰，这些信号在调节摄食和能量消耗的神经元通路中。小鼠遗传技术使我们能够在生理环境中研究这个问题，也为我们提供了在分子水平上定义调控的新工具。我们建议使用我们新开发的核糖体标记方法（RiboTag）来定量下丘脑神经元特定亚型的翻译组（积极参与多核糖体的mrna）。我们的重点将放在那些对脂肪细胞合成的激素、瘦素和表达PKA的RIIb调节亚基有反应的神经元群上。RIIb-PKA KO小鼠系瘦且抵抗饮食引起的肥胖，我们最近的结果表明这是由于下丘脑瘦素敏感性的增加。本课题的具体目的是：(1)分析饮食和激素对下丘脑特定细胞类型mRNA表达/翻译的调控；(2)确定下丘脑中PKA激活的营养调节因子；(3)制定通过cAMP/PKA通路的药理调节来提高下丘脑神经元对瘦素敏感性的策略。在这些研究的结论中，我们将完成对下丘脑关键神经元群中对营养信号作出反应的mRNA转录物的全面分析。我们也希望更好地了解PKA活性调节瘦素信号和肥胖的机制。下丘脑反应网络对瘦素的敏感性是决定生物体以脂肪形式储存多少能量的最终决定因素之一。cAMP/PKA系统非常适合于g蛋白偶联受体的激动剂和拮抗剂、磷酸二酯酶抑制剂、激酶激活剂和抑制剂的药理学操作。我们的建议旨在确定下丘脑神经元内的潜在靶点，这些靶点可能被用来调节瘦素敏感性，作为治疗肥胖的一种治疗方法。

DESCRIPTION (provided by applicant): Recent work has continued to challenge and expand our views on the neural control of body weight. Leptin receptors have been shown to engage multiple signaling pathways in a neuron-specific pattern. The overall goals of our proposal are to decipher the crosstalk between the cAMP/PKA signaling system and the leptin receptor-initiated signals in neuronal pathways that regulate feeding and energy expenditure. Mouse genetic techniques allow us to investigate this problem in a physiological setting and also provide us with novel tools for defining regulation at the molecular level. We propose to use our newly developed ribosome-tagging approaches (RiboTag) to quantitate the translatome (mRNAs actively engaged on polyribosomes) in specific subtypes of hypothalamic neurons. Our focus will be on those groups of neurons that respond to the adipocyte-synthesized hormone, leptin, and also express the RIIb regulatory subunit of PKA. The RIIb-PKA KO mouse line is lean and resistant to diet-induced obesity and our recent results indicate that this is because of an increase in leptin sensitivity in the hypothalamus. The specific aims of this proposal are: (1) Analyze the regulation of mRNA expression/translation in specific hypothalamic cell types by diet and hormones (2) Identify the nutritional regulators of PKA activation in the hypothalamus (3) Develop a strategy to increase the sensitivity of hypothalamic neurons to leptin by pharmacological regulation of the cAMP/PKA pathway. At the conclusion of these studies we will have completed a comprehensive analysis of mRNA transcripts in key hypothalamic neuronal populations as they respond to nutritional signals. We also expect to gain a better understanding of the mechanisms by which PKA activity can modulate leptin signaling and adiposity. The sensitivity of the hypothalamic response network to leptin is one of the ultimate determinants of how much energy an organism will store as fat. The cAMP/PKA system is well suited to pharmacological manipulation by agonists and antagonists of G-protein coupled receptors, phosphodiesterase inhibitors, and kinase activators and inhibitors. Our proposal seeks to identify potential targets within hypothalamic neurons that might be exploited to modulate leptin sensitivity as a therapeutic approach to the treatment of obesity.