Transcriptional Mechanisms of Beta Cell Gene Expression

β细胞基因表达的转录机制

• 批准号: 6712224
• 负责人: ULUPI S JHALA
• 金额: $ 12.32万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-12-15 至 2005-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6712224
• 关键词: DNA binding protein; Xenopus; acetylation; acyltransferase; enzyme activity; gel mobility shift assay; gene expression; gene induction /repression; lysine; mutant; neurogenesis; pancreatic islets; posttranslational modifications; protein localization; protein protein interaction; protein structure function; reporter genes; site directed mutagenesis; transcription factor; transfection /expression vector; western blottings

DESCRIPTION (provided by applicant): Beta2 is a critical regulator of differentiation and survival of several neuro-endocrine cell types including the pancreatic beta cell, neurons and entero-endocrine cells, such that mice lacking Beta2 display severe diabetes, neuronal depletion and neonatal death. In pancreatic beta cells, Beta2 is one of the key regulators of glucose-dependent insulin gene expression, suggesting a homeostatic role of Beta2 in mature beta cells. While it is clear that Beta2 has multiple functions in both developing and mature neuro-endocrine cells, little is known about how its activity is regulated in different cellular contexts. Transcription factors that orchestrate such an important array of functions are usually tightly regulated post-translationally by highly specific, rapid and reversible covalent modifications. Recent studies suggest that Beta2 function can be regulated by phosphorylation of its transactivation domain. Here we propose to examine the effects of acetylation on Beta2. Beta2 associates with p300, a transcriptional coactivator with an intrinsic acetyltransferase (AT) enzymatic activity, and this association is required for inducing differentiation and glucose-dependent insulin gene activation. Therefore, we examined whether Beta2 is a substrate for p300 dependent AT activity and found this to be true both by in vitro acetylation assay, and in transfected cells. Based on our preliminary data, we hypothesize that acetylation of Beta2 plays an important role in regulation of its activity. The main goal of this study is to examine the impact of acetylation on Beta2 function. To address this question, we propose to: 1) Identify the specific lysine residues that undergo p-300 dependent acetylation, in vitro and in vivo; 2) Assess the impact of acetylation on the mechanism of Beta2; and 3) Examine the biological significance of Beta2 acetylation.

描述（由申请人提供）：Beta2 是多种神经内分泌细胞类型（包括胰腺 β 细胞、神经元和肠内分泌细胞）分化和存活的关键调节因子，因此缺乏 Beta2 的小鼠表现出严重的糖尿病、神经元耗竭和新生儿死亡。在胰腺β细胞中，Beta2是葡萄糖依赖性胰岛素基因表达的关键调节因子之一，表明Beta2在成熟β细胞中具有稳态作用。虽然 Beta2 在发育中和成熟的神经内分泌细胞中具有多种功能，但人们对其活性在不同细胞环境中如何调节知之甚少。协调如此一系列重要功能的转录因子通常通过高度特异性、快速和可逆的共价修饰在翻译后受到严格调节。最近的研究表明 Beta2 功能可以通过其反式激活结构域的磷酸化来调节。在这里，我们建议检查乙酰化对 Beta2 的影响。 Beta2 与 p300 结合，p300 是一种具有内在乙酰转移酶 (AT) 酶活性的转录共激活因子，这种结合是诱导分化和葡萄糖依赖性胰岛素基因激活所必需的。因此，我们检查了 Beta2 是否是 p300 依赖性 AT 活性的底物，并通过体外乙酰化测定和转染细胞发现这都是正确的。根据我们的初步数据，我们假设 Beta2 的乙酰化在其活性调节中发挥重要作用。本研究的主要目标是检查乙酰化对 Beta2 功能的影响。为了解决这个问题，我们建议：1) 鉴定在体外和体内经历 p-300 依赖性乙酰化的特定赖氨酸残基； 2）评估乙酰化对Beta2机制的影响； 3) 检查 Beta2 乙酰化的生物学意义。