LCR ACTIVATION OF THE HUMAN GROWTH HORMONE GENE

LCR 激活人类生长激素基因

• 批准号: 7863874
• 负责人: NANCY E. COOKE
• 金额: $ 1.13万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2010-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7863874
• 关键词: Address; Adult; Architecture; Binding Sites; Boundary Elements; Cells; Chromatin; Complement; Complex; Data; Development; Distal; Elements; Ensure; Epigenetic Process; Foundations; Gene Cluster; Gene Expression; Genes; Genetic; Histones; In Vitro; Life; Link; Locus Control Region; Maintenance; Maps; Mediating; Modeling; Modification; Pituitary Gland; Play; Proteins; Recruitment Activity; Role; Simplexvirus; Site; Somatropin; Specific qualifier value; Structure; Testing; Transcript; Transcriptional Regulation; Transgenes; Transgenic Organisms; base; hGH Gene; histone acetyltransferase; in vivo; promoter; reconstitution; synergism; transgene expression

DESCRIPTION (provided by applicant): A distal locus control region (LCR) regulates the human growth hormone (hGH) gene cluster. The determinants of the hGH LCR, located between 14.5 to 32 kb 5' to the hGH-N gene are marked by five DNaseI hypersensitive sites (HSI-HSV). These determinants act in concert to establish robust and appropriately regulated expression of hGH-N in pituitary somatotropes. HSI is the primary determinant of hGH-N transgene expression in somatotropes. HSI contains three essential binding sites for the pituitary-enriched transfactor Pit-1. These HSI core elements appear to function via specific recruitment of histone acetyltransferase activity, leading to the establishment of a 32 kb domain of core histone hyperacetylation that encompasses the entire hGH LCR and extends to the distal hGH-N promoter. The powerful Pit-1 array at HSI exerts unique, chromatin-based functions that are dominant over the activity of the Pit-1 sites at the hGH-N promoter. The full level of HSI activity is dependent on synergism with a closely linked determinant. HSII, a pituitary-specific HS located -1 kb 5' to HSI, may be responsible for this synergism. The terminal boundaries of the 32 kb hGH LCR domain are specific to pituitary cells and in a transgenic setting serve to insulate the hGH locus from site-of-integration effects and variegation of expression. Present data suggest that the boundary and/or insulator activities at the 5' border of this domain may be mediated by HSV. A boundary element located 3' to the hGH-N gene may insulate the placental hCS genes from HSI-mediated activation in the pituitary. The role of the LCR in the initial activation of the hGH locus may be followed by an equally important role in maintenance of epigenetic modifications within the chromatin domain that ensure continued hGH-N expression throughout adult life. The Specific Aims of this proposal focus on these major aspects of hGH LCR function: Aim I. Characterize interactions at HSI that initiate hGH LCR activation, Aim II. Define the mechanism(s) of long-range activation of hGH-N by its LCR, Aim III. Characterize the role of HSII as an HSI facilitator, Aim IV. Identify the chromatin boundaries that establish the pituitary-specific hGH LCR domain, and Aim V. Define the role of HSI in stable maintenance of hGH-N expression. Significantly, these studies will address fundamental epigenetic mechanisms involved in the activity of LCRs, and establish a foundation for understanding normal and pathological aspects of hGH-N gene control.

描述（由申请人提供）：远端基因座控制区（LCR）调节人类生长激素（hGH）基因簇。 hGH LCR 的决定簇位于 hGH-N 基因 5' 14.5 至 32 kb 之间，由五个 DNaseI 超敏位点 (HSI-HSV) 标记。这些决定因素协同作用，在垂体生长激素中建立稳定且适当调节的 hGH-N 表达。 HSI 是生长激素中 hGH-N 转基因表达的主要决定因素。 HSI 包含富含垂体的转因子 Pit-1 的三个必需结合位点。这些 HSI 核心元件似乎通过组蛋白乙酰转移酶活性的特异性募集发挥作用，从而导致核心组蛋白超乙酰化的 32 kb 结构域的建立，该结构域包含整个 hGH LCR 并延伸至远端 hGH-N 启动子。 HSI 上强大的 Pit-1 阵列发挥独特的、基于染色质的功能，这些功能在 hGH-N 启动子上的 Pit-1 位点的活性中占主导地位。 HSI 活动的全部水平取决于与密切相关的决定因素的协同作用。 HSII 是一种位于 HSI -1 kb 5' 处的垂体特异性 HS，可能是这种协同作用的原因。 32 kb hGH LCR 结构域的末端边界是垂体细胞特有的，在转基因环境中可将 hGH 基因座与整合位点效应和表达多样性隔离开来。目前的数据表明，该结构域 5' 边界处的边界和/或绝缘体活性可能是由 HSV 介导的。位于 hGH-N 基因 3' 的边界元件可以将胎盘 hCS 基因与垂体中 HSI 介导的激活隔离。 LCR 在 hGH 基因座初始激活中的作用可能在维持染色质结构域内的表观遗传修饰中发挥同样重要的作用，从而确保在整个成年生命中持续表达 hGH-N。该提案的具体目标侧重于 hGH LCR 功能的这些主要方面： 目标 I. 表征启动 hGH LCR 激活的 HSI 相互作用，目标 II。定义通过 LCR 远程激活 hGH-N 的机制，目标 III。描述 HSII 作为 HSI 促进者的作用，目标 IV。确定建立垂体特异性 hGH LCR 结构域的染色质边界，以及目标 V。定义 HSI 在稳定维持 hGH-N 表达中的作用。值得注意的是，这些研究将解决涉及 LCR 活性的基本表观遗传机制，并为理解 hGH-N 基因控制的正常和病理方面奠定基础。