Epigenetic determinants of beta cell development and function

项目总结/摘要 胰岛β细胞产生的胰岛素是葡萄糖代谢的关键刺激物，因此至关重要。 胰岛素分泌会随着能量状态的变化而调整。胰岛素分泌受营养素的强烈调节 以及随着进食而变化的激素。如果进食状态持续，如营养过剩，适应性控制 这些机制使胰岛素分泌反应越来越敏感，以满足增加的胰岛素需求。 然而，长期营养过剩也会变得适应不良，并导致β细胞衰竭和2型糖尿病 （T2D）。β细胞如何读取营养信号并将这些信号转化为适应性和适应不良反应 是很难理解的。在这项资助的支持下，我们已经证明，营养敏感的组蛋白去甲基化酶 LSD 1介导β细胞表观基因组的营养诱导变化，以调节适应性胰岛素分泌。 具体地说，我们发现LSD 1修饰了与β细胞相关的基因调控元件的表观遗传状态， 营养反应基因，从而调节胰岛素分泌反应的幅度。因此，LSD 1 作为β细胞营养环境、表观基因组和转录因子之间的整合枢纽， 输出.我们的初步研究进一步表明，LSD 1抑制在瘦状态下是适应性的，但在瘦状态下， 适应不良并促进肥胖症中的β细胞衰竭。本提案的目的是确定 LSD 1感知营养物质的机制，并深入了解代谢线索如何汇聚在LSD 1上 和表观基因组以使适应性β细胞反应适应不良。我们将采用最先进的 方法，包括新的小鼠模型，人类胰岛实验，单细胞分辨映射， 染色质状态和基因表达，以及尖端的计算分析。在目标1中，我们将确定 LSD 1如何感知营养物质并调节β细胞中的染色质状态。为了研究营养感应 机制，我们将操纵LSD 1的代谢调节辅因子FAD和测量对LSD 1的影响。 β细胞中的调节过程。此外，我们将剖析LSD 1的酶和非酶功能， 调节β细胞表观基因组，使用新的小鼠模型和体外实验。在目标2中，我们将确定 LSD 1抑制触发加速β细胞失代偿的适应不良过程的机制 在T2 D。采用代谢应激的遗传小鼠和胰岛模型，我们将操纵LSD 1活性， 研究这些操作如何影响β细胞染色质状态、基因表达和表型。在目标3中， 将研究LSD 1在人类β细胞中的作用。在这里，我们将利用转录组和染色质图谱， 从非糖尿病、前驱糖尿病和T2 D供体胰岛的集合中产生，以确定LSD 1- 受调节的程序导致T2 D中的β细胞衰竭。通过揭示β细胞 解释营养信号，这一建议将被证明是至关重要的，以确定战略，以防止或扭转 适应不良过程和β细胞衰竭。

PROJECT SUMMARY/ABSTRACT Insulin produced by pancreatic β-cells is the key stimulus for glucose metabolism, and therefore it is critical that insulin secretion is adjusted to changes in energy state. Insulin secretion is acutely regulated by nutrients and hormones that change in response to feeding. If the fed state persists, as in overnutrition, adaptive control mechanisms increasingly sensitize the insulin secretory response to meet the increased insulin demand. However, long-term overnutrition can also become maladaptive and lead to β-cell failure and type 2 diabetes (T2D). How β-cells read nutrient signals and translate these signals into adaptive and maladaptive responses is poorly understood. Supported by this grant, we have shown that the nutrient-sensitive histone demethylase LSD1 mediates nutrient-induced changes to the β-cell epigenome to regulate adaptative insulin secretion. Specifically, we found that LSD1 modifies the epigenetic state of gene regulatory elements linked to β-cell nutrient response genes, thereby modulating the amplitude of the insulin secretory response. Thus, LSD1 functions as an integration hub between the β-cell’s nutrient environment, the epigenome and transcriptional output. Our preliminary studies further show that LSD1 inhibition is adaptive in a lean state, but becomes maladaptive and promotes β-cell failure in obesity. The objective of this proposal is to determine the mechanisms by which LSD1 senses nutrients and to gain insight into how metabolic cues converge on LSD1 and the epigenome to render the adaptive β-cell response maladaptive. We will employ state-of-the-art approaches, encompassing novel mouse models, human islet experiments, single cell resolved mapping of chromatin state and gene expression, and cutting-edge computational analyses. In Aim 1, we will determine how LSD1 senses nutrients and regulates chromatin state in β-cells. To investigate the nutrient sensing mechanism, we will manipulate LSD1’s metabolically regulated co-factor FAD and measure effects on LSD1- regulated processes in β-cells. Furthermore, we will dissect LSD1’s enzymatic and non-enzymatic functions in regulating the β-cell epigenome, using novel mouse models and in vitro experiments. In Aim 2, we will identify mechanisms by which LSD1 inhibition triggers maladaptive processes that accelerate β-cell decompensation in T2D. Employing genetic mouse and islet models of metabolic stress, we will manipulate LSD1 activity and study how these manipulations affect β-cell chromatin state, gene expression, and phenotypes. In Aim 3, we will examine the role of LSD1 in human β-cells. Here, we will leverage transcriptomic and chromatin maps we generated from a collection of nondiabetic, prediabetic, and T2D donor islets to determine whether the LSD1- regulated program contributes to β-cell failure in T2D. By unveiling fundamental mechanisms by which β-cells interpret nutrient signals, this proposal will prove critical for identifying strategies to prevent or reverse maladaptive processes and β-cell failure.