Conditional Mutagenesis to Study c-Myb Function

研究 c-Myb 功能的条件诱变

• 批准号: 7891202
• 负责人: Timothy P. Bender
• 金额: $ 32.08万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-05 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7891202
• 关键词: Alleles; Anemia; Breeding; CD4 Positive T Lymphocytes; CD8B1 gene; Cell Cycle; Cell Differentiation process; Cell physiology; Cells; Development; Embryonic Development; Genetic; Goals; Helper-Inducer T-Lymphocyte; Hematopoiesis; Hematopoietic; Homeostasis; MYB gene; Mediating; Molecular; Mouse Strains; Mus; Mutagenesis; Mutation; Peripheral; Phase; Play; Process; Proliferating; Proto-Oncogene Proteins c-myb; Proto-Oncogenes; Rest; Role; Signal Pathway; Site; Staging; System; T-Cell Development; T-Lymphocyte; T-Lymphocyte Subsets; Thymus Gland; Time; V(D)J Recombination; base; recombinase; thymocyte

DESCRIPTION (provided by applicant): It is clear that the Myb protooncogene plays a crucial role during hematopoiesis. In each hematopoietic lineage, c-Myb is abundantly expressed at the immature stages of differentiation and is turned off at a relatively late time during the differentiation process. However, virtually nothing is known about what role c- Myb plays during hematopoietic maturation, how that role is mediated or what signaling pathways regulate c- Myb expression. Mice that are homozygous null at the Myb locus die at day fifteen during embryogenesis from a severe anemia. This finding graphically demonstrated the significance of c-Myb during hematopoiesis but has precluded study of c-Myb activity at the later stages of differentiation. The lack of a tractable genetic system that will allow mutation of Myb during the later stages of hematopoietic maturation has been a major impediment to understanding the role of c-Myb during hematopoiesis. During T cell development in the thymus, CD4 and CD8 double negative (DM) and double positive (DP) thymocytes contain abundant amounts of c-Myb while CD4+ and CD8+ single positive (SP) cells contain only 10 to 20% as much c-Myb. In the periphery, c-Myb is expressed at only low levels in resting T cells, but expression increases in proliferating T cells in late G1/early SD phase of the cell cycle. To begin to understand the role played by c- Myb during T cell development we have produced mice that carry a Myb allele targeted with loxP sites for deletion by the Cre recombinase. By breeding these mice to available mouse strains that direct Cre expression to different stages of T cell development in the thymus we have defined critical points during T cell development where c-Myb is required: transition from the DN to the DP stage of development, for the survival of pre-selection DP cells and the differentiation of CD4 SP thymocytes. More recently we have identified roles for c-Myb in maintaining T cell homeostasis and mediating T cell helper function. The goals of this proposal are to understand the basis for c-Myb function during the DN stage of T cell development, in peripheral T homeostasis and helper T cell function.

描述（由申请人提供）：很明显，Myb原癌基因在造血过程中起着至关重要的作用。在每个造血谱系中，c-Myb在分化的不成熟阶段大量表达，并且在分化过程中的相对较晚的时间关闭。然而，事实上对c-Myb在造血成熟过程中起什么作用，这种作用是如何介导的或什么信号通路调节c-Myb表达还一无所知。在Myb基因座处纯合无效的小鼠在胚胎发生期间的第15天死于严重贫血。这一发现生动地证明了c-Myb在造血过程中的重要性，但排除了在分化后期c-Myb活性的研究。缺乏一个易于处理的遗传系统，将允许突变的Myb在造血成熟的后期阶段一直是一个主要的障碍，以了解c-Myb在造血过程中的作用。在胸腺中T细胞发育期间，CD 4和CD 8双阴性（DM）和双阳性（DP）胸腺细胞含有大量的c-Myb，而CD 4+和CD 8+单阳性（SP）细胞仅含有10 - 20%的c-Myb。在外周，c-Myb在静息T细胞中仅以低水平表达，但在细胞周期的G1晚期/早期SD期的增殖T细胞中表达增加。为了开始理解c-Myb在T细胞发育过程中所起的作用，我们生产了携带Myb等位基因的小鼠，该等位基因被Cre重组酶用loxP位点靶向缺失.通过将这些小鼠与可获得的小鼠品系（其将Cre表达引导至胸腺中T细胞发育的不同阶段）进行育种，我们已经定义了T细胞发育期间需要c-Myb的关键点：从DN向DP发育阶段的过渡，用于预选DP细胞的存活和CD 4 SP胸腺细胞的分化。最近，我们已经确定了c-Myb在维持T细胞稳态和介导T细胞辅助功能中的作用。本研究的目的是了解c-Myb在T细胞发育的DN阶段、外周T细胞稳态和辅助性T细胞功能中的作用基础。