The Role of JunB in Hematopoietic Stem Cell Homeostasis

描述(申请人提供)：本项目的目标是阐明AP-1转录因子JunB调节正常造血的机制，并了解JunB的缺失如何改变造血干细胞(HSC)的特性并导致白血病干细胞(LSC)的产生。这些研究将在我们建立和表征的JunB缺乏症小鼠模型上进行。针对特定目标1的研究将探讨细胞周期分布失调和增殖增加是如何导致JunB缺陷的HSC异常特性的。我们将确定静止期和循环期JunB缺陷的HSC在多大程度上能够提供长期植入，研究它们对造血应激的反应，并询问控制其增殖的分子网络。这些实验应该解决的问题是，HSC的维持和增殖是如何协同调节的，以确保动态平衡，而体内基因的变化应该如何增加我们对HSC如何在其骨髓壁龛中维持以及LSC如何逃脱这些微环境调节的理解。特异性目标3的总体目标是识别HSC中的JunB靶基因。我们将利用全基因组生物信息学方法来扫描具有与规范JunB结合位点匹配的顺式调控基序的基因，以及利用基因组阵列平台的染色质免疫沉淀(CHIP)方法(CHIP-CHIP)。这些实验应该会发现控制HSC动态平衡的重要调控网络和潜在的LSC生成的转录异常。在特定的目标4中，我们将从功能上评估非调控的增殖和微环境相互作用在JunB缺陷的HSC白血病转化中的作用。我们将测试几个重要的候选基因的作用，要么纠正它们在JunB缺乏的HSC中的缺陷调控，要么通过模仿它们在正常HSC中的变化。这些实验应该确定在功能上对LSC的产生和功能起作用的关键介质。 项目简介：这些实验共同追求确定分子靶点的总体目标，以摧毁人类髓系白血病中原本具有治疗抗性的LSC群体。

DESCRIPTION (provided by applicant): The goal of this project is to elucidate the mechanisms by which the AP-1 transcription factor JunB regulates normal hematopoiesis, and to understand how loss of JunB alters hematopoietic stem cells (HSC) properties and leads to the generation of leukemic stem cells (LSC). These studies will be carried out in mouse models of JunB deficiency that we have generated and characterized. Studies in Specific Aim 1 will investigate how deregulated cell cycle distribution and increased proliferation contribute to the aberrant properties of junB- deficient HSC. We will determine to what extent quiescent vs. cycling junB-deficient HSC are able to provide long-term engraftment, investigate their response to hematopoietic stresses and interrogate the molecular networks controlling their proliferation. These experiments should address the question of how HSC maintenance and proliferation are co-coordinately regulated to ensure homeostasis and how changes innts should increase our understanding of how HSC are maintained in their bone marrow niches and how LSC can escape these microenvironmental regulations. The general goal of Specific Aim 3 is to identify junB target genes in HSC. We will exploit both genome-wide bioinformatics approach to scan for genes with cis-regulatory motifs matching canonical JunB binding sites and chromatin immunoprecipitation (ChIP) approach with genomic array platforms (ChIP-chip). These experiments should uncover important regulatory networks controlling HSC homeostasis and transcriptional abnormalities underlying LSC generation. In Specific Aim 4, we will functionally evaluate the contribution of deregulated proliferation and microenvironmental interactions to the leukemic transformation of junB-deficient HSC. We will test the role of several important candidate genes by either correcting their defective regulation in junB-deficient HSC or by mimicking their alterations in normal HSC. These experiments should identify critical mediators that functionally contribute to LSC generation and function. PROJECT NARRATIVE: Together, these experiments pursue the general goal of identifying molecular targets to destroy the otherwise therapeutically resistant LSC population in human myeloid leukemias.