REMOTE CONTROL ELEMENTS IN SOMATOTROPE EXPRESSION

生长激素表达中的遥控元件

• 批准号: 6070080
• 负责人: YUGONG HO
• 金额: $ 3.24万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6070080
• 关键词: chromatin; gene expression; genetic regulatory element; genetically modified animals; hormone regulation /control mechanism; laboratory mouse; pituitary gland; placenta; somatotropin

The human growth hormone (hGH) gene cluster encompasses both pituitary- and placenta-specific genes that are essential for normal growth and development. A set of tissue-specific, dominantly acting distal regulatory elements, the locus control region (LCR), were mapped between 14 and 34kb 5' to the cluster on the basis of DNaseI hypersensitivity (HS) in chromatin derived from expressing tissues. These elements are involved in appropriate activation of hGH gene cluster expression in pituitary/placenta. However the specific functional role of each HS, the level of redundancy among these determinants, and their respective mechanism(s) of action are not defined. The organization of genes in the hGH gene cluster, their high-level expression and mutually exclusive tissue-specificities, and the corresponding specific sets of LCR elements make it a valuable model for studying gene expression. Aim I is to functionally analyze the subset of LCR HS restricted to either pituitary (HSI,II) or placenta (HSIV). These elements will be studied in the context of a large (P1) human transgene (hGH-P1). This 87kb hGH-P1 transgene encompasses the entire set of LCR elements (HSI-V) and most of the contiguous hGH gene cluster and the genes are expressed in appropriate tissues in the host mouse. A small, well-characterized functional segment of the HSI,II will be deleted from hGH-P1 and its impact on hGH gene cluster expression will be investigated in the transgenic mouse. In parallel the same approach will be applied to the placental-specific, HSIV to delineate its function in activating and/or restricting placental expression. The mechanism(s) of HS function will be studied in each case by characterizing the effects of these deletions on chromatin epigenetic modifications relative to the native hGH-P1. Aim II will identify and characterize corresponding LCR control elements in the mouse (m). A major goal of this aim will be to determine whether an LCR also directs mGH gene expression. Specifically we will identify the presence of HS and their sequences will be compared to the corresponding human elements. These data will be used to establish phylogenetic footprints of critical HSI,II determinants and serve as the foundation for the ongoing functional/mechanistic analyses in Aim I, including the generation of mice with corresponding targeted deletions. Significance: These studies will provide novel insight into the role(s) played by the LCR elements in the establishment and maintenance of appropriate gene expression profiles during development and in disease-related expression patterns of the hGH gene.

人类生长激素 (hGH) 基因簇包含对正常生长和发育至关重要的垂体和胎盘特异性基因。 根据源自表达组织的染色质中的 DNaseI 超敏性 (HS)，将一组组织特异性的、起主导作用的远端调节元件，即位点控制区 (LCR) 映射到簇的 14 和 34kb 5' 之间。 这些元件参与垂体/胎盘中 hGH 基因簇表达的适当激活。 然而，每个 HS 的具体功能作用、这些决定因素之间的冗余程度以及它们各自的作用机制尚未定义。 hGH 基因簇中的基因组织、它们的高水平表达和相互排斥的组织特异性以及相应的特定 LCR 元件组使其成为研究基因表达的有价值的模型。 目标 I 是对仅限于垂体 (HSI,II) 或胎盘 (HSIV) 的 LCR HS 子集进行功能分析。 这些元件将在大型 (P1) 人类转基因 (hGH-P1) 的背景下进行研究。 这个 87kb hGH-P1 转基因包含整套 LCR 元件 (HSI-V) 和大部分连续的 hGH 基因簇，并且这些基因在宿主小鼠的适当组织中表达。 HSI,II 的一个小的、特征明确的功能片段将从 hGH-P1 中删除，并将在转基因小鼠中研究其对 hGH 基因簇表达的影响。 同时，相同的方法将应用于胎盘特异性 HSIV，以描述其激活和/或限制胎盘表达的功能。 通过表征这些缺失对相对于天然 hGH-P1 的染色质表观遗传修饰的影响，将在每种情况下研究 HS 功能的机制。目标 II 将识别并表征小鼠 (m) 中相应的 LCR 控制元件。 该目标的一个主要目标是确定 LCR 是否也指导 mGH 基因表达。具体来说，我们将鉴定 HS 的存在，并将其序列与相应的人类元件进行比较。这些数据将用于建立关键 HSI,II 决定因素的系统发育足迹，并作为 Aim I 中正在进行的功能/机制分析的基础，包括生成具有相应靶向删除的小鼠。意义：这些研究将为了解 LCR 元件在发育过程中建立和维持适当的基因表达谱以及 hGH 基因的疾病相关表达模式中所发挥的作用提供新的见解。