Chromatin Cofactors in Islet Development and Function

描述（由申请人提供）：我实验室的总体目标是确定发育和成熟胰岛2细胞中基因调控的生化机制。近年来，组蛋白共价修饰在哺乳动物基因转录中的作用越来越受到重视，特别是这些修饰如何在特定的基因位点上形成开放或封闭的染色质（常染色质或异染色质）。包括我们自己在内的几个实验室的集体研究已经确定，Pdx 1是胰腺中的主要转录调节因子，部分通过招募共价修饰组蛋白的辅因子来控制基因表达。二甲基化组蛋白H3-Lys 4似乎是分化和成熟胰岛的关键常染色质标记物。因此，原则上，Pdx 1对胰腺发育和胰岛功能的许多影响可以通过其招募组蛋白甲基化辅因子来解释。我们已经确定了一个显着的胰岛富集辅因子，Set 7/9，似乎是负责二甲基化H3-Lys 4在许多Pdx 1靶基因。我们的初步研究表明，胰岛中的Set 7/9单倍不足导致许多Pdx 1靶点的转录受损，并导致胰岛功能障碍和葡萄糖耐受不良，有效地表型Pdx 1单倍不足本身。因此，该提议的总体假设是Set 7/9是一种染色质修饰辅因子，其在发育和成熟的胰岛中作为Pdx 1作用的效应子发挥作用。为了验证这一假设，我们提出了以下3个具体目标：目标1：确定Set 7/9在胰腺发育过程中指导胰岛细胞命运和质量增加的作用。目的2：确定Set 7/9在维持正常胰岛功能和葡萄糖稳态中的作用。目的3：研究Set 7/9和Pdx 1转录复合物对MafA基因转录的调控作用。 我们相信，这些目标的成功完成将确定一个重要的染色质修饰辅因子在胰岛发育和功能中的作用和机制。 公共卫生相关性：糖尿病是一种胰岛素产生和胰岛素反应细胞的紊乱，困扰着2400万美国人，其发病率正以惊人的速度上升。这项资助的具体目标是研究基因在胰岛素产生细胞中是如何调节的。总的来说，该项目旨在了解胰岛素产生细胞是如何形成的，以及如何使用特定基因重新编程其他细胞类型，使其成为糖尿病患者的胰岛素产生细胞。

DESCRIPTION (provided by applicant): The overall objective of my laboratory is to define the biochemical mechanisms underlying gene regulation in the developing and mature islet 2 cell. In recent years, a greater emphasis has been placed on the role of covalent histone modifications in mammalian gene transcription, particularly how such modifications enable states of open or closed chromatin (euchromatin or heterochromatin, respectively) at specific genetic loci. The collective studies of several laboratories including our own have established that Pdx1, a master transcriptional regulator in the pancreas, controls gene expression in part through recruitment of cofactors that covalently modify histones. Dimethylated histone H3-Lys4 appears to be a crucial euchromatin marker in differentiating and mature islets. Therefore, in principle, many of the effects of Pdx1 on pancreas development and islet function could be explained by its recruitment of histone methylating cofactors. We have identified a remarkably islet-enriched cofactor, Set7/9, that appears to be responsible for dimethylated H3-Lys4 at many Pdx1 target genes. Our preliminary studies show that Set7/9 haploinsufficiency in the islet leads to impaired transcription of many Pdx1 targets and causes islet dysfunction and glucose intolerance, effectively phenocopying Pdx1 haploinsufficiency itself. Thus, the overarching hypothesis of this proposal is that Set7/9 is a chromatin-modifying cofactor that functions as an effector of Pdx1 action in the developing and mature islet. To test this hypothesis, we propose the following 3 specific aims: Aim 1: Determine the role of Set7/9 in directing islet cell fate and mass accrual during pancreas development. Aim 2: Determine the role of Set7/9 in the maintenance of normal islet function and glucose homeostasis. Aim 3: Determine how a transcriptional complex involving Set7/9 and Pdx1 regulates MafA gene transcription in the developing and mature 2 cell. We believe that the successful completion of these aims will identify both the role and mechanisms of a crucial chromatin-modifying cofactor in islet development and function. PUBLIC HEALTH RELEVANCE: Diabetes is a disorder of insulin-producing and insulin-responsive cells that afflicts 24 million Americans, and its incidence is rising at an alarming rate. The specific goal of this grant is to investigate how genes are regulated in insulin-producing cells. Overall, this project seeks to understand how insulin-producing cells are formed and how specific genes might be used to reprogram other cell types to become insulin-producing cells for individuals with diabetes.