TRANSCRIPTIONAL REGULATION BY X CHROMOSOME INACTIVATION

X 染色体失活的转录调控

• 批准号: 2684945
• 负责人: THOMAS P YANG
• 金额: $ 18.75万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2684945
• 关键词: DNA binding protein; DNA footprinting; DNA methylation; DNA replication; azacitidine; biochemical evolution; cell transformation; chromosome aberrations; gel mobility shift assay; gene expression; gene induction /repression; gene interaction; genetic promoter element; genetic regulatory element; genetic transcription; hybrid cells; hypoxanthine phosphoribosyltransferase; laboratory mouse; linkage mapping; nucleic acid sequence; sex chromosomes

Female eutherian mammals have evolved a mechanism which equalizes the dosage of functional X-linked genes in each somatic cell to that of males. This dosage compensation is accomplished by transcriptionally inactivating genes on one of the two X chromosomes in females. Thus, for most X-linked genes in female somatic cells, an active and inactive allele reside within the same nucleus but are differentially regulated and expressed. The process of X chromosome inactivation is developmentally regulated in female embryogenesis and involves the coordinate and chromosome-wide silencing of X-linked genes in cis. The long-term goal of this project is to determine the molecular mechanism of X chromosome inactivation. This proposal will investigate the molecular basis for establishing and maintaining the differential expression of a single X-linked gene, the hypoxanthine phosphribosyltransferase (HPRT) gene, on the active and inactive X chromosomes. We postulate that transcriptional regulation of the HPRT gene by X inactivation will involve a complex hierarchy of inter- dependent regulatory mechanisms, from long-range effects of higher order chromatin structure, to local nucleosome structure within the promoter and other regulatory regions, to individual sequence-specific DNA-protein interactions, each of which is crucial to the establishment and maintenance of differential expression of the HPRT gene on the active and inactive X chromosomes. We further postulate that the process of X chromosome inactivation will function through this hierarchy of mechanisms that regulate transcription of individual genes on the X chromosome. Thus, we will undertake a detailed study of the full range of mechanisms that influence HPRT gene transcription. The experiments proposed in this application will investigate two aspects of regulation of the HPRT gene by X chromosome inactivation. First, we will continue our detailed analysis of the HPRT promoter region on the active and inactive X chromosomes, and the effects of DNA methylation, local chromatin structure, and sequence- specific DNA-protein interactions on promoter function. Secondly, we will begin a long-term investigation of the structure and role of the HPRT chromatin domain in regulating expression of the HPRT gene on the active and inactive X chromosomes. This will involve defining the borders of the domain, then identifying and characterizing elements within the domain that regulate its chromatin structure. Understanding the mechanisms that regulate transcription of an individual X-linked gene by X inactivation should provide insights and experimental approaches to investigate the chromosomal and developmental aspects of this unique genetic process.

雌性eutherian哺乳动物已经发展了一种机制 每个体细胞中功能性X连锁基因的剂量与男性的剂量。 这种剂量补偿是通过转录灭活而实现的 女性中两个X染色体之一的基因。 因此，对于大多数X连锁 雌性体细胞中的基因，活性和非活性等位基因位于 相同的核，但受到差异调节和表达。 这 X染色体灭活过程在发育中受到调节 女性胚胎发生，涉及坐标和染色体 X连锁基因在顺式中的沉默。 这个项目的长期目标是 确定X染色体灭活的分子机制。 这 提案将调查建立和 维持单个X连锁基因的差异表达， 在活性和 无活性X染色体。 我们假设该转录的调节 X灭活的HPRT基因将涉及相互之间的复杂层次结构 依赖的调节机制，来自高阶的远程影响 染色质结构，启动子内的局部核小体结构 其他调节区域，到单个序列特异性DNA-蛋白 互动，每种互动对机构和 维持HPRT基因在活性和 无活性X染色体。 我们进一步假设x的过程 染色体灭活将通过这种机制的层次结构起作用 调节X染色体上各个基因的转录。 因此，我们将对全部机制进行详细研究 这会影响HPRT基因转录。 提出的实验 应用将通过调查HPRT基因调节的两个方面 X染色体灭活。 首先，我们将继续我们的详细分析 在活性和非活动X染色体上的HPRT启动子区域以及 DNA甲基化，局部染色质结构和序列的影响 - 在启动子功能上的特定DNA蛋白相互作用。 其次，我们会的 开始对HPRT的结构和作用的长期调查 调节HPRT基因在活性上的表达中的染色质结构域 和无活性X染色体。 这将涉及定义边界 域，然后识别和表征域内的元素 调节其染色质结构。 了解该机制 通过X灭活调节单个X连锁基因的转录 应该提供见解和实验方法来研究 这种独特的遗传过程的染色体和发育方面。