The Role of JunB in Hematopoietic Stem Cell Homeostasis

描述（由申请人提供）：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。这些研究将在我们已经产生和表征的JunB缺乏症小鼠模型中进行。在特定目标1的研究将调查如何失调的细胞周期分布和增殖增加有助于junB缺陷的HSC的异常特性。我们将确定在何种程度上静止与循环junB缺陷的HSC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调调节，以确保稳态，以及如何改变innts应该增加我们的理解HSC是如何维持在他们的骨髓龛和LSC如何可以逃脱这些微环境的规定。Specific Aim 3的总体目标是鉴定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典型JunB结合位点匹配的顺式调控基序的基因，以及染色质免疫沉淀（ChIP）方法与基因组阵列平台（ChIP-chip）。这些实验应该揭示重要的调控网络控制HSC稳态和转录异常LSC生成的基础。在具体目标4中，我们将从功能上评估失控的增殖和微环境相互作用对junB缺陷HSC白血病转化的贡献。我们将测试几个重要的候选基因的作用，无论是纠正他们的缺陷调节junB缺陷的HSC或通过模仿他们的改变在正常的HSC。这些实验应该确定关键的介质，功能上有助于LSC的产生和功能。 项目叙述：总之，这些实验追求的总体目标是鉴定分子靶点，以破坏人类骨髓性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.