Insulin Secretion in Hyperinsulinism Human Islets

项目总结 先天性高胰岛素血症(HI)婴儿胰腺分离人胰岛的研究 之前的资金周期为我们提供了一个独特的机会来研究KATPHI的胰岛表型 整合功能、代谢组学和基因组学。我们的发现揭示了一种复杂的病理生理学 初级KATP通道缺陷导致继发性后果影响基因表达、燃料代谢、 以及触发和放大胰岛素分泌的途径。然而，许多关键问题对于 解决未满足的HI治疗需求和对正常生理机制的理解 关于胰岛素分泌的问题仍未得到回答。我们对研究两个离子的作用特别感兴趣。 胰岛素分泌正常调节中HI胰岛差异表达的通道及其机制 HI：TMEM16A是一种由ANO1编码的钙激活的氯离子通道，它在HI：TMEM16A的病理生理中可能起到作用 在KATPHI胰岛和KCNQ1编码的Kv7.1中显著上调，其表达显著 Beckwith Wiedemann综合征和HI患儿胰腺分离的胰岛减少。在……里面 初步研究发现，这些通道的药物调节改变了胰岛素的分泌。我们的 总体假设是Kv7.1和TMEM16A在终止胰岛素的过程中都起着关键作用 静息β细胞Vm超极化和促进β细胞Vm复极化的分泌 刺激。为了检验这一假说，我们提出了两个目标来检验Kv7.1和TMEM16A在 正常和HI胰岛胰岛素分泌的调节。为了实现这些目标，我们将利用基因和 调节正常和缺氧缺血人和小鼠上述通道活动的药理学途径 小岛。我们将研究：1)TMEM16A和Kv7.1在静息和刺激条件下对β-cell VM的贡献 2)TMEM16A和Kv7.1的激活和抑制对细胞内钙和胰岛素分泌的影响 3)TMEM16A和Kv7.1基因失活对血糖的影响 转基因胰岛体内动态平衡和燃料刺激的胰岛素分泌 老鼠模型。这项研究将扩大我们对HI的病理生理学的理解，并将有助于 确定这种毁灭性疾病的新遗传原因和潜在的新治疗靶点。这个 这项研究也可能对理解进行性β细胞的机制有一定的意义 导致2型糖尿病的失败。

PROJECT SUMMARY The study of human islets isolated from the pancreas of infants with congenital hyperinsulinism (HI) during the previous funding cycle has afforded us the unique opportunity to examine the islet phenotype in KATPHI integrating function, metabolomics, and genomics. Our findings revealed a complex pathophysiology in which the primary KATP channel defect leads to secondary consequences affecting gene expression, fuel metabolism, and both the triggering and amplifying pathways of insulin secretion. However, many critical questions for addressing unmet needs for the treatment of HI and for the understanding of normal physiological mechanisms of insulin secretion remain unanswered. We are particularly interested in examining the role of two ion channels that are differentially expressed in HI islets in the normal regulation of insulin secretion and their potential role in the pathophysiology of HI: TMEM16A, a Ca2+-activated Cl– channel encoded by ANO1 which is markedly upregulated in KATPHI islets, and Kv7.1, encoded by KCNQ1, whose expression is markedly decreased in islets isolated from the pancreases of children with Beckwith Wiedemann syndrome and HI. In preliminary studies we found that pharmacological modulation of these channels alters insulin secretion. Our overall hypothesis is that both Kv7.1 and TMEM16A play critical roles in the termination of insulin secretion by keeping β-cell Vm hyperpolarized at rest and facilitating β-cell Vm repolarization after stimulation. To test this hypothesis, we propose two aims to examine the role of Kv7.1 and TMEM16A in the regulation of insulin secretion in normal and HI islets. To accomplish these aims we will use genetic and pharmacological approaches to modulate the activity of these channels in normal and HI human and mouse islets. We will examine: 1) the contribution of TMEM16A and Kv7.1 to β-cell Vm at resting and stimulated states; 2) the effect of TMEM16A and Kv7.1 activation and inhibition on cytosolic calcium and insulin secretion in normal human and mouse islets; 3) the effect of genetic inactivation of TMEM16A and Kv7.1 on glucose homeostasis in vivo and fuel-stimulated insulin secretion in vivo and in isolated islets using genetically modified mouse models. This study will expand our understanding of the pathophysiology of HI and will facilitate the identification of new genetic causes and potential new therapeutic targets for this devastating disease. The study may also have implications for the understanding of the mechanisms implicated in the progressive β-cell failure that leads to type 2 diabetes.