The role of Pdx1-recruited Chd4:NuRD complex in controlling mature #-cell function

项目总结 郎格罕胰岛内的胰腺β细胞是葡萄糖刺激的胰岛素分泌所必需的 和葡萄糖动态平衡。β细胞活性和特性失调会导致糖尿病，这是一种不断增长的疾病 影响数以百万计的美国人，从而造成巨大的财政和健康负担。改进的策略 越来越多的糖尿病患者的结局需要了解复杂的计划， 协调适当的胰岛素释放，以应对血糖水平的变化。在现有基础上发展 了解胰岛丰富的转录因子(TF)如何协调影响基因调控的信号 这些程序将使我们了解在糖尿病的胰岛β细胞中这些程序是如何戏剧性地改变的 病人。PDX1是发育中和出生后β细胞中最重要的转录因子之一，已被证明可以招募 一组不同的联合监管机构，可能会调节其活动。这项提案的重点是如何 PDX1与核小体重塑和脱乙酰酶(NuRD)复合体的相互作用对正常 β-细胞功能，并在与2型疾病发展相关的病理生理条件下发生改变 糖尿病(T2D)。 NuRD复合体的中央ATPase亚单位CHD4被发现与一个子集相互作用并控制一个子集 Pdx1靶基因，并被招募到对体外正常β细胞功能重要的基因。初步研究 证明有条件地从成熟的胰岛β-细胞中去除CHD4显著影响 活着。这一提议将检验Pdx1结合的CHD4：NuRD复合体控制染色质的总体假设 可获得性和对生理β细胞功能重要的基因表达程序受到损害 在糖尿病的发展过程中。在目标1中，我们将充分描述β细胞功能障碍是如何由于 在一种新的条件性CHD4缺失的小鼠模型中缺少CHD4，在目标2中，我们将揭示其机制 CHD4在利用无偏全基因组RNA控制染色质可及性和基因表达中的作用 ATAC和芯片测序方法。CHD4：NuRD对人Pdx1和β-细胞功能的影响 被调查。AIM 3将评估T2D相关应激源如何影响Pdx1：CHD4相互作用 来自啮齿动物和人胰岛的生化和原位方法，T2D和原代人体组织的活体模型。 在成功完成这笔赠款后，我们将确定CHD4：NuRD的机械性行动 关于控制Pdx1活性和β细胞功能，并定义了应激源如何与糖尿病发展相关 影响至关重要的Pdx1：CHD4调控机制。这项研究将确定有助于 T2D的发病机制，将为糖尿病的研究开辟新的途径。

PROJECT SUMMARY Pancreatic β-cells within the islets of Langerhans are required for glucose-stimulated insulin secretion and glucose homeostasis. Dysfunctional β-cell activity and identity results in diabetes, a growing disease affecting millions of Americans, thus creating an enormous fiscal and health burden. Strategies to improve outcomes for the mounting number of diabetic patients requires understanding the complex programs that coordinate a proper insulin release in response to changing blood glucose levels. Developing upon existing knowledge of how islet enriched transcription factors (TFs) coordinate signals that influence gene regulatory programs will allow us to understand how such programs are dramatically altered in islet β-cells of diabetes patients. Pdx1, one of the most important TFs in the developing and postnatal β-cell, has been shown to recruit a diverse set of coregulators which could potentially modulate its activity. This proposal is focused around how Pdx1 interactions with the Nucleosome Remodeling and Deacetylase (NuRD) complex are influential to normal β-cell function and are altered in pathophysiological conditions associated with the development of Type 2 diabetes (T2D). The central ATPase subunit of the NuRD complex, Chd4, was found to interact with and control a subset of Pdx1 target genes and is recruited to genes important for normal β-cell function in vitro. Preliminary studies demonstrate that conditional removal of Chd4 from mature islet β-cells significantly impacts glucose tolerance in vivo. This proposal will test the overall hypothesis that Pdx1-bound Chd4:NuRD complex controls chromatin accessibility and gene expression programs important for physiological β-cell function which are compromised during the development of diabetes. In Aim 1, we will fully characterize how β-cell dysfunction occurs due to the absence of Chd4 in a new conditional Chd4-deleted mouse model and in Aim 2 we will uncover the mechanistic actions of Chd4 in controlling chromatin accessibility and gene expression using unbiased genome-wide RNA-, ATAC- and ChIP-Sequencing approaches. The influence of Chd4:NuRD on human Pdx1 and β-cell action will be investigated. Aim 3 will evaluate how T2D associated stressors influence Pdx1:Chd4 interactions using biochemical and in situ methods from rodent and human islets, in vivo models of T2D and primary human tissues. Upon successful completion of this grant, we will have determined the mechanistic actions of Chd4:NuRD on controlling Pdx1 activity and β-cell function, and defined how stressors associated with diabetes development impact the vital Pdx1:Chd4 regulatory mechanisms. This research will identify critical targets that contribute to the pathogenesis of T2D, which will open new avenues for diabetes research.