Control of Beta Cell Function by Co-activators

描述(由申请人提供)： 这项拨款提案是对题为“贝塔细胞生物学综合计划”的02014丹麦克朗的回应。我的实验室研究核激素受体的转录调节机制，最近在研究胰岛素信号的核靶标的基础上，开始对辅助激活剂在β细胞中的特定作用感兴趣。这项建议以几种方式响应RFA：1)我是糖尿病领域的新研究员，对胰岛素对β细胞的转录调控感兴趣；2)建立转基因和基因敲除(KO)动物模型来研究β细胞蛋白的生理环境；3)研究两种共激活子在当时细胞中的作用，CBP和p300；以及4)将探索β细胞特异性蛋白PDX-1在胰岛素刺激的基因表达和R细胞增殖中的作用。胰岛素基因转录调控涉及特定的正负顺式作用元件。位于5‘侧翼区域。胰岛素基因表达的一个主要调节因子是同源框蛋白PDX-1(也称为IPF-1、STF-1和IDX-1)。该蛋白于e8.5在小鼠中首次表达，在胰腺发育和胰岛β细胞功能中发挥重要作用，分别在普通和条件性PDX-1 KO小鼠中得到证实。胰岛素转录和β细胞发育的第二个主要调节因子是基本螺旋-环-螺旋(BHLH)蛋白，NeuroDI43-2，它与普遍表达的E2a蛋白形成DNA结合复合体。PDX-1和NeuroDI/(3-2)都被证明与高度相关的CBP和p300共激活蛋白相互作用。这些共激活子已被证明在哺乳动物发育的许多方面都是关键的，包括它们对有丝分裂原反应基因的功能；基于体外研究，它们也被认为是胰岛素基因转录所必需的。然而，目前尚不清楚它们在(β细胞)生长和功能中扮演什么角色，以及它们的功能在(β细胞)中是结构性的还是受调节的。有三个目标被提出：1)确定通过AP-1复合体的胰岛素信号在胰腺(β细胞)增殖反应中的作用；2)确定CBP和p300中对胰腺(β细胞)重要的结构性和激素调节的相互作用结构域；以及3)确定CBP和p300在成人(β细胞)中的作用；以及(3)确定CBP和p300在成年(β细胞)中的作用。这项提案的总体目标将是确定CBP和p300在调节胰岛β细胞生长和功能中的作用机制。

DESCRIPTION (provided by applicant): This grant proposal is in response to RFA DK 02014 entitled: "Comprehensive Programs in Beta Cell Biology." My laboratory studies mechanisms of transcriptional regulation by nuclear hormone receptors and has recently become interested in the specific role of co-activators in the beta cell based on the study of nuclear targets for insulin signaling. This proposal is responsive to the RFA in several ways: 1) I am a new investigator to the diabetes field interested in transcriptional regulation of the beta-cell by insulin; 2) transgenic and knockout (KO) animal models are proposed to study beta-cell proteins in their physiological context; 3) a study of the role of two co-activators in then-cell, CBP and p300, are proposed; and 4) the role of a beta-cell-specific protein, PDX-1, in insulin-stimulated gene expression and R-cell proliferation will be explored. Regulation of insulin gene transcription in the pancreas involves specific positive and negative cis-acting elements. located in the 5' flanking region. One major regulator of insulin gene expression is the homeobox protein, PDX-1 (also referred to as IPF-1, STF-1, and IDX-1). This protein, first expressed at e8.5 in the mouse, has a major role in pancreatic development and (beta-cell function as demonstrated in both generalized and conditional PDX-1 KO mice; respectively. A second major regulator of both insulin transcription and (beta-cell development is the basic helix-loop-helix (bHLH) protein, NeuroDI43-2, which forms a DNA-binding complex with the ubiquitously expressed E2A proteins. Both PDX-1 and NeuroDI/(3-2 have been shown to interact with the highly related CBP and p300 co-activator proteins. These co-activators have proven to be critical in many aspects of mammalian development, including their function on mitogen-responsive genes; they have also been proposed to be essential for insulin gene transcription based on in vitro studies. It is unclear, however, what role they play in (beta-cell growth and function, and whether their function is constitutive or regulated in the (beta cell. Three Aims are proposed: 1) To-define the role of insulin signaling via the AP-1 complex in proliferative responses of the pancreatic (beta cell; 2) To define constitutive and hormonal regulated interaction domains in CBP and p300 important in the pancreatic (beta cell; and 3) To define the role of CBP and p300 in the adult (beta-cell in mice harboring a cell-specific knock out of either CBP or p300. The overall goal of this proposal will be to determine the mechanism of CBP and p300 action in regulating pancreatic beta-cell growth and function