NeuroD function during Beta cell development and in mouse models of diabetes

描述（由申请人提供）：2型糖尿病（T2D）是由与胰岛素抵抗相关的细胞应激源导致胰腺β细胞恶化引起的，可在妊娠、衰老和肥胖期间发生。通过相对未知的机制，代谢应激通过使维持胰岛素和其他β细胞功能关键因子表达的重要转录因子失活，导致β细胞失去其功能特性。本研究探讨了基本螺旋环螺旋（bHLH）转录因子（TF） NeuroD作为T2D理想治疗靶点的潜力。NeuroD对于β细胞在发育过程中的功能成熟、生长和存活以及在成人中维持其功能至关重要。NeuroD可以直接激活胰岛素和其他对β细胞功能至关重要的因子的表达。该项目的第一个目标是确定NeuroD在发育过程中如何调节β细胞的生长和成熟。在此目标中确定的因子可能有助于将干细胞分化为功能成熟的β细胞并在培养中扩增。第二个目的是研究NeuroD在成人中维持胰岛素和其他β细胞功能重要因子表达的机制。我将研究NeuroD是否需要维持其靶蛋白启动子上的组蛋白乙酰转移酶p300，以维持附近组蛋白乙酰化标记的激活。为了研究为什么胰岛素和其他NeuroD靶点在T2D发病过程中转录沉默，我将研究肥胖T2D小鼠胰岛中p300的启动子占用、NeuroD和p300之间的相互作用以及它们的启动子附近染色质的乙酰化状态。我还建议研究在T2D发病过程中发生的翻译后修饰是否会改变NeuroD的功能。为了研究NeuroD的治疗潜力，我建议在肥胖T2D小鼠的β细胞中异位诱导NeuroD的表达，试图通过保存和重新激活胰岛素和其他对β细胞功能至关重要的NeuroD靶点的表达来保护和恢复其功能β细胞。这些实验将提供对T2D发病机制的深入了解，并为新的治疗策略提供证据。

DESCRIPTION (provided by applicant): Type 2 diabetes (T2D) results from the deterioration of pancreatic β cells by cellular stressors associated with insulin resistance that can occur during pregnancy, aging and obesity. Through relatively uncharacterized mechanisms, metabolic stress causes β cells to lose their functional identity by the inactivation of transcription factors important for maintaining the expression of insulin and other factors critica for β cell function. This proposal examines the potential of the basic helix loop helix (bHLH) transcription factor (TF) NeuroD as an ideal therapeutic target for T2D. NeuroD is critical for the functional maturation, growth and survival of β cells during development and for maintaining their function in the adult. NeuroD can directly activate the expression of insulin and other factors critical for β cell function. The 1st aim of this project is to determine how NeuroD regulates β cell growth and maturation during development. Factors identified in this aim could be useful for differentiating stem cells into functionally mature β cells and expanding them in culture. The second aim, investigates the mechanism by which NeuroD maintains the expression of insulin and other factors important for β cell function in the adult. I will examine whether NeuroD is required to maintain the histone acetyl-transferase p300 at the promoters of its targets in order to maintain activating acetylation marks on nearby histones. To investigate why insulin and other NeuroD targets are transcriptionally silenced during the pathogenesis of T2D, I will examine the promoter occupancy of p300, the interaction between NeuroD and p300 and the acetylation status of chromatin near their promoters in the islets of obese T2D mice. I also propose to examine if NeuroD's function is altered by post-translational modifications that occur during the pathogenesis of T2D. To examine the therapeutic potential of NeuroD, I propose to ectopically induce the expression of NeuroD in the β cells of obese T2D mice, to try to protect and restore their functional β cells by preserving and reactivating the expression of insulin and other NeuroD targets critical for β cell function. These experiments would provide mechanistic insight into the pathogenesis of T2D and provide evidence for a novel therapeutic strategy.