Critical roles of GA binding protein in HSC maintenance and ageing

GA 结合蛋白在 HSC 维持和衰老中的关键作用

• 批准号: 8040990
• 负责人: Hai-Hui Xue
• 金额: $ 37.5万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-07 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8040990
• 关键词: Address; Affect; Age; Animals; Apoptosis; Binding Proteins; Biochemical; Biological Assay; Blood; Blood Cells; Bone Marrow; C-terminal; Cell Aging; Cell Cycle; Cell Cycle Regulation; Cell Maintenance; Cell Survival; Cell physiology; Chromatin; Complex; Coupled; DNA Binding; DNA Repair; Ectopic Expression; Embryo; Enzymes; Equilibrium; Family; Frequencies; GA-binding protein transcription factor; Gene Targeting; Genes; Goals; Health; Hematopoietic Neoplasms; Hematopoietic stem cells; Homeostasis; Human; Kinetics; Knockout Mice; Knowledge; Lead; Leucine Zippers; Life; Link; Maintenance; Malignant - descriptor; Maps; Mediating; Molecular; Mouse Strains; Mus; Names; Natural regeneration; Nucleic Acid Regulatory Sequences; Pathway interactions; Phenotype; Production; Protein Binding; Protein Isoforms; Proteins; RNA; Reactive Oxygen Species; Regulation; Regulator Genes; Resistance; Role; Severities; Signal Transduction; Stem cells; Structure; Testing; Tissues; Transactivation; Transplantation; age related; aged; base; cell age; chromatin immunoprecipitation; genome-wide; meetings; prevent; protein complex; regenerative; self-renewal; stem cell biology; transcription factor

DESCRIPTION (provided by applicant): Hematopoietic stem cells (HSCs) have two defining features. One is the ability to self-renew, maintaining a constant number under steady state, and the other is the potential to differentiate into multiple lineages in blood, meeting the regenerative needs. The maintenance of HSC homeostasis and multipotency is stipulated by transcription factors such as Bmi1, Zfx, and Foxo proteins. However, it is unknown if these factors interact with each other and if they form a hierarchical gene regulatory network in HSCs. In this project, we will investigate the roles of GA binding protein (GABP) in regulating HSC homeostasis and repopulation capacity. We will further characterize its interplay with other transcription factors in controlling different aspects of HSC biology. A functional GABP complex contains one DNA binding subunit, GABP1, and one transactivation subunit, GABP2. Two of GABP2 isoforms contribute to the formation of GABP 1222 tetramers. Inactivation of GABP1 abrogates the activity of entire GABP complex, causing early embryonic lethality. In contrast, mice with deletion of both tetramer-forming GABP2 isoforms were viable. Both strains of animals showed diminished HSC frequency and numbers, but differed in onset and kinetics of the phenotypes. We hypothesize that the GABP complex controls different pathways regulating HSC homeostasis and function and the 1222 tetramers regulate a subset of GABP target gene and have a specific role in regulating HSC self- renewal and ageing. Our long-term goal is to elucidate the interplay between GABP and other key transcription factors and how such interplay balances self-renewal and differentiation of HSCs. This project will generate critical information for a better understanding of HSC plasticity, hematopoietic malignancy, and stem cell ageing. We will approach these objectives through the following specific aims: SPECIFIC AIM 1. To investigate the roles of GABP complex in HSC self-renewal and repopulation capacity. We will use a tissue-specific GABP1-targeted mouse strain, induce inactivation of GABP1 in the bone marrow, and determine the impact on HSC self-renewal and repopulation capacity. We will also investigate if HSC cell cycle and survival pathways are affected by GABP1 deficiency. SPECIFIC AIM 2. To identify GABP direct target genes which mediate its regulation of HSC function. We have obtained a genome-wide GABP binding map in HSCs and found direct GABP binding to regulatory regions of a number of transcription factors. We will characterize the interplay between GABP and these transcription factors to construct a gene regulatory network maintaining HSC homeostasis and multipotency. SPECIFIC AIM 3. To determine a specific role of GABP 1222 tetramers in DNA damage repair and HSC ageing. We will use the mouse strain that is deficient for both tetramer-forming GABP2 isoforms and determine the specific aspect of HSC biology that is controlled by GABP 1222 tetramers. We will also investigate the direct link of tetramers to DNA damage repair and HSC ageing. PUBLIC HEALTH RELEVANCE: Hematopoietic stem cells (HSCs) are responsible for sustained production of all blood cells throughout one's life, and HSCs have two defining features, self-renewal to maintain a constant number and plasticity to generate multiple blood lineages. Aberrant regulation of HSCs can either lead to defective regeneration of blood cells or result in hematopoietic malignancy. This project will investigate critical roles of a transcription factor name GA binding protein and characterize the interplay between GA binding protein and other factors in regulating HSC self-renewal and repopulation capacity, and these studies will lead to a better understanding on how HSC homeostasis and multi-potency are controlled, and provide a molecular basis on how to maintain HSCs to meet regenerative needs and prevent malignant transformation.

描述（由申请人提供）：造血干细胞（HSC）有两个定义特征。一是自我更新的能力，在稳定状态下保持恒定的数量，二是在血液中分化成多种谱系的潜力，满足再生的需要。 HSC 稳态和多能性的维持是由 Bmi1、Zfx 和 Foxo 蛋白等转录因子决定的。然而，这些因素是否相互作用以及它们是否在造血干细胞中形成分层基因调控网络尚不清楚。在这个项目中，我们将研究 GA 结合蛋白 (GABP) 在调节 HSC 稳态和增殖能力中的作用。我们将进一步表征其与其他转录因子在控制 HSC 生物学不同方面的相互作用。功能性 GABP 复合物包含一个 DNA 结合亚基 GABP1 和一个反式激活亚基 GABP2。两种 GABP2 同工型有助于 GABP 1222 四聚体的形成。 GABP1 失活会消除整个 GABP 复合物的活性，导致早期胚胎死亡。相比之下，缺失两种形成四聚体的 GABP2 同工型的小鼠是可以存活的。两种动物品系均显示 HSC 频率和数量减少，但表型的起始和动力学不同。我们假设 GABP 复合物控制调节 HSC 稳态和功能的不同途径，而 1222 四聚体调节 GABP 靶基因的子集，并在调节 HSC 自我更新和衰老中具有特定作用。我们的长期目标是阐明 GABP 与其他关键转录因子之间的相互作用，以及这种相互作用如何平衡 HSC 的自我更新和分化。该项目将为更好地了解造血干细胞可塑性、造血系统恶性肿瘤和干细胞衰老提供重要信息。我们将通过以下具体目标来实现这些目标： 具体目标 1. 研究 GABP 复合物在 HSC 自我更新和增殖能力中的作用。我们将使用组织特异性 GABP1 靶向小鼠品系，诱导骨髓中 GABP1 失活，并确定其对 HSC 自我更新和增殖能力的影响。我们还将研究 HSC 细胞周期和生存途径是否受到 GABP1 缺陷的影响。具体目标 2. 鉴定介导其调节 HSC 功能的 GABP 直接靶基因。我们获得了 HSC 中的全基因组 GABP 结合图谱，并发现 GABP 与许多转录因子的调控区域直接结合。我们将表征 GABP 和这些转录因子之间的相互作用，以构建维持 HSC 稳态和多能性的基因调控网络。具体目标 3. 确定 GABP 1222 四聚体在 DNA 损伤修复和 HSC 老化中的具体作用。我们将使用缺乏形成四聚体的 GABP2 同工型的小鼠品系，并确定由 GABP 1222 四聚体控制的 HSC 生物学的具体方面。我们还将研究四聚体与 DNA 损伤修复和 HSC 老化的直接联系。公共健康相关性：造血干细胞 (HSC) 负责人一生中所有血细胞的持续生成，HSC 有两个显着特征：自我更新以保持恒定数量，可塑性以产生多种血统。造血干细胞的异常调节可能导致血细胞再生缺陷或导致造血系统恶性肿瘤。该项目将研究转录因子GA结合蛋白的关键作用，并表征GA结合蛋白与其他因子在调节HSC自我更新和增殖能力中的相互作用，这些研究将有助于更好地理解HSC稳态和多效性是如何控制的，并为如何维持HSC满足再生需求和防止恶性转化提供分子基础。