Regulation of alpha-cell glucagon secretion by mitochondrial anaplerosis-cataplerosis

项目摘要 2型糖尿病（T2 D）在美国是一种非常普遍的疾病，影响大约1 在10个成年人中，估计到2040年将有6.4亿人被诊断患有糖尿病。虽然T2 D 与β细胞衰竭相关，胰岛分泌胰岛素和胰高血糖素的缺陷导致 导致血糖失调由于目前靶向β细胞以增加胰岛素分泌的疗法有限， 成功，创新的想法，重点是新的机制，调节血糖是必要的， 创造新的治疗方法来对抗T2 D。α细胞的胰高血糖素分泌对血糖的大小有很强的控制作用。 胰岛素分泌，使α细胞成为新疗法的有吸引力的靶点。第二信使cAMP是一种强有力的 胰高血糖素分泌的决定因素。葡萄糖已被证明可以内在地调节α细胞cAMP， 非常的初步研究表明，亮氨酸强烈降低α-细胞cAMP独立于胰岛旁分泌 信号传导、KATP通道效应或钙。此外，以类似的方式，葡萄糖和亮氨酸可以抑制 氨基酸刺激的胰高血糖素分泌。葡萄糖和亮氨酸都具有强烈的回补作用，并且是初步的 数据表明，线粒体酶磷酸烯醇式丙酮酸羧激酶（PCK 2），一种重要的效应因子， 线粒体回补-解体，在调节氨基酸依赖性 胰高血糖素分泌。我们假设，回补燃料，如亮氨酸和葡萄糖将减少cAMP 通过PCK 2抑制胰高血糖素释放。为了研究这个假设，我们将：1）确定内在与。 亮氨酸对α-细胞cAMP的旁分泌（通过β/δ-细胞）作用和2）确定α-细胞PCK 2是否介导 回补燃料的抑制作用。这些目标将通过TIRF和光片显微镜进行研究， 结合新的遗传小鼠模型和生物传感器，研究回补燃料对α细胞的作用， cAMP和胰高血糖素分泌。该项目的成功完成将使以下方面建立新的联系： 回补和cAMP信号传导，在代谢研究的最新技术中培训PI， 潜在地解锁了一种新的靶向治疗T2 D的途径。

Project Summary Type 2 diabetes (T2D) is an extremely prevalent disease in the United States, affecting approximately 1 in 10 adults, and it is estimated that 640 million people will be diagnosed with diabetes by 2040. While T2D is associated with β-cell failure, defects in both insulin and glucagon secretion from the pancreatic islet contribute to dysregulated blood glucose. As current therapies that target β-cells to increase insulin secretion have limited success, innovative ideas that focus on novel mechanisms for regulation of blood glucose are necessary to create new therapeutics to combat T2D. Glucagon secretion by α-cells has strong control over the magnitude of insulin secretion, making α-cells an attractive target for new therapies. The second messenger cAMP is a strong determinant of glucagon secretion. Glucose has been shown to regulate α-cell cAMP intrinsically and extrinsically. Preliminary studies show that leucine strongly reduces α-cell cAMP independently of islet paracrine signaling, KATP channel effects, or calcium. Furthermore, in a similar fashion, glucose and leucine can dampen amino acid-stimulated glucagon secretion. Glucose and leucine are both strongly anaplerotic, and preliminary data suggests that the mitochondrial enzyme phosphoenolpyruvate carboxykinase (PCK2), an essential effector of mitochondrial anaplerosis-cataplerosis, plays an important role in the regulation of amino acid-dependent glucagon secretion. We hypothesize that anaplerotic fuels such as leucine and glucose will decrease cAMP through PCK2 to inhibit glucagon release. To study this hypothesis we will: 1) Determine the intrinsic vs. paracrine (via β/δ-cells) effects of leucine on α-cell cAMP and 2) Determine whether α-cell PCK2 mediates the inhibitory effects of anaplerotic fuels. These aims will be studied by TIRF and lightsheet microscopy in combination with novel genetic mouse models and biosensors, to examine role of anaplerotic fuels on α-cell cAMP and glucagon secretion. Successful completion of this project will characterize new connections between anaplerosis and cAMP signaling, train the PI in state of the art techniques for the study of metabolism, and potentially unlock a new pathway to target for the treatment of T2D.