Regulation of Insulin Gene Expression in Liver Cells

肝细胞中胰岛素基因表达的调控

• 批准号: 6672572
• 负责人: Sabire Ozcan
• 金额: $ 14.69万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6672572
• 关键词: SDS polyacrylamide gel electrophoresis; acylation; cell line; gene expression; genetic promoter element; genetic transcription; glucose; histones; hormone regulation /control mechanism; immunoprecipitation; insulin; liver cells; pancreatic islets; polymerase chain reaction; tissue /cell culture; transcription factor

DESCRIPTION (provided by applicant): Transcriptional regulation plays an important role in determining tissue specificity and every tissue is characterized by a set of specific transcription factors. In the pancreas, the major transcription factor that restricts insulin gene expression to the pancreatic beta cells is the homeodomain protein Pdx-1. Insulin production is essential for maintaining glucose homeostasis and defects in glucose-regulated insulin gene transcription result in diabetes. We have recently discovered that glucose regulates insulin gene expression in beta cells by hyperacetylation of histone H4. Interestingly, in liver cells where the insulin gene is transcriptionally silent, no significant histone acetylation is associated with the insulin gene promoter. However, introduction of Pdx-1 into liver cells caused increased histone H4 acetylation at the normally silent insulin gene promoter in a glucose-dependent manner and stimulated insulin production. Based on these data, we hypothesize that introduction of Pdx-1 into liver cells activates the normally silent insulin gene in response to high levels of glucose by increasing histone H4 acetylation. The major goal of this proposal is to understand how introduction of Pdx-1 into the liver cells stimulates the transcription of the normally silent insulin gene, by addressing the following questions: 1. Does introduction of Pdx-1 into liver cells cause glucose-regulated changes in histone modification, at the normally silent insulin gene locus? 2. Does Pdx-1 change histone H4 acetylation levels in liver cells by recruiting co-activators or co-repressors to the insulin gene promoter in a glucose-dependent manner? 3. Does the introduction of the beta-cell specific transcription factor Ribe3b1 into the liver cells cause changes in histone modification as observed with Pdx-1? Understanding of how Pdx-1 stimulates the transcription of the normally silent insulin gene in liver cells, will facilitate the development of liver cell lines that can produce insulin in a glucose-dependent manner. The development of such non-beta cell lines will be important for the treatment of type I and as well as type II diabetes.

描述（由申请人提供）：转录调节在决定组织特异性方面起着重要作用，每个组织都有一组特定的转录因子。在胰腺中，限制胰岛素基因向胰腺细胞表达的主要转录因子是同源结构域蛋白Pdx-1。胰岛素的产生对于维持葡萄糖稳态至关重要，而葡萄糖调节胰岛素基因转录的缺陷会导致糖尿病。我们最近发现葡萄糖通过组蛋白H4的超乙酰化调节β细胞中的胰岛素基因表达。有趣的是，在胰岛素基因转录沉默的肝细胞中，没有显著的组蛋白乙酰化与胰岛素基因启动子相关。然而，将Pdx-1引入肝细胞，以葡萄糖依赖的方式增加了通常沉默的胰岛素基因启动子上的组蛋白H4乙酰化，并刺激了胰岛素的产生。基于这些数据，我们假设将Pdx-1引入肝细胞通过增加组蛋白H4乙酰化来激活通常沉默的胰岛素基因，以响应高水平的葡萄糖。本提案的主要目标是通过解决以下问题，了解将Pdx-1引入肝细胞如何刺激通常沉默的胰岛素基因的转录：