Metabolically Coupled Ion Channel Interactions in Islets

描述(申请人提供)：2型糖尿病患者(T2 DM)和他们的一级亲属以及该疾病的动物模型中，依赖葡萄糖的胰岛素分泌的脉动性被扰乱。尽管β细胞中功能失调的电和钙振荡可能导致胰岛素分泌缺陷，但这种振荡功能障碍的本质尚不清楚，正常β细胞振荡的机制也尚未完全阐明。前一时期进行的研究支持这一假设，即分泌的振荡是胰岛β细胞固有的电(EO)和代谢振荡器(MO)之间复杂相互作用的结果(‘双振荡器模型’；DOM)。使用一种新的实验范式获得的试点数据表明，代谢振荡可以主导电子振荡器，与其他模型的预测不同，具有独特的时间进程，并且可以与钙脱钩。在此基础上，我们建议：检查EO和MO的性质，阐明EO和MO如何相互作用产生振荡，并测试双重振荡器框架的有效性(目标1)；调查促成DOM的其他离子机制，包括新型离子电流(目标2)；确定胰岛代谢振荡源于糖酵解还是线粒体，并设计新颖的FRET探针和质谱学方法来测量活的胰岛内燃料代谢物(目标3)；以及确定双振荡器是否解释了正常人类胰岛或缺乏KCNQ1的小鼠的振荡特性(KCNQ1是一种可能与T2 DM相连的β细胞钾通道；4)。这些目标的完成将是迄今为止理解胰岛潜在振荡机制的最全面的努力，并将增加我们对胰岛功能在健康和疾病中的洞察力。

DESCRIPTION (provided by applicant): The pulsatility of glucose-dependent insulin secretion is disrupted in Type 2 diabetics (T2DM) and their first-degree relatives, and in animal models of the disease. Although dysfunctional electrical and calcium oscillations in beta cells likely contribute to insulin secretory deficits, the nature of this oscillatory dysfunction is not known; nor have the mechanisms underlying normal beta cell oscillations been fully elucidated. Research conducted during the previous period supports the hypothesis that oscillations in secretion result from complex interactions between electrical (EO) and metabolic oscillators (MO) intrinsic to islet beta cells (the 'Dual Oscillator Model'; DOM). Pilot data obtained using a new experimental paradigm show that metabolic oscillations can dominate the electrical oscillator, have a distinctive time course unlike the predictions of other models, and can be decoupled from calcium. Building on this progress, we propose to: examine the properties of the EO and MO, elucidate how EO and MO interact to produce oscillations, and test the validity of the dual oscillator framework (Aim 1); investigate additional ionic mechanisms contributing to the DOM, including novel ion currents (Aim 2); determine whether islet metabolic oscillations are glycolytic or mitochondrial in origin, and design novel FRET probes and mass spectrometry approaches to measure intracellular fuel metabolites in living islets (Aim 3); and determine whether the dual oscillator accounts for the oscillatory properties of normal human islets or a mouse lacking KCNQ1, a putative beta cell potassium channel linked to T2DM; Aim 4). Completion of these aims will represent the most comprehensive effort to date to understand the underlying oscillatory mechanisms of pancreatic islets, and will increase our insight into islet function in both health and disease.