Control of Beta Cell Function by Co-activators

描述（由申请人提供）： 这项拨款建议是为了回应RFA DK 02014，题为：“β细胞生物学综合计划。“我的实验室研究核激素受体的转录调节机制，最近对基于胰岛素信号传导的核靶点研究的β细胞中共激活因子的特定作用产生了兴趣。该提议以几种方式响应RFA：1）我是糖尿病领域的新研究者，对胰岛素对β细胞的转录调节感兴趣; 2）提出转基因和敲除（KO）动物模型来研究β细胞蛋白在其生理环境中的作用; 3）提出研究两种共激活剂在β细胞中的作用，CBP和p300;和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。胰腺中胰岛素基因转录的调节涉及特定的正和负顺式作用元件。位于5'侧翼区。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）。这种蛋白质在小鼠中首次表达于e8.5，在胰腺发育和β细胞功能中具有主要作用，如分别在全身性和条件性PDX-1 KO小鼠中所证明的。胰岛素转录和β细胞发育的第二个主要调节因子是碱性螺旋-环-螺旋（bHLH）蛋白NeuroDI 43 -2，其与广泛表达的E2 A蛋白形成DNA结合复合物。PDX-1和NeuroDI/β 3-2均显示与高度相关的CBP和p300共激活蛋白相互作用。这些共激活因子已被证明在哺乳动物发育的许多方面至关重要，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，尚不清楚它们在β细胞生长和功能中起什么作用，以及它们的功能在β细胞中是组成性的还是受调节的。提出了三个目标：1）确定通过AP-1复合物的胰岛素信号传导在胰腺β细胞增殖反应中的作用; 2）确定在胰腺β细胞中重要的CBP和p300中的组成型和激素调节的相互作用结构域;和3）确定CBP和p300在携带CBP或p300的细胞特异性敲除的小鼠中的成人β细胞中的作用。本提案的总体目标是确定CBP和p300在调节胰腺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