GABP Transcription Factor in Myeloid Differentiation

描述（由申请人提供）：本提案的目标是全面表征转录因子GA结合蛋白（GABP）的作用。在骨髓分化和基因表达方面。转录因子调节骨髓细胞（粒细胞和单核细胞）从造血祖细胞的发育，并且转录因子的缺陷与急性髓性白血病相关。GABP是一个有限数量的转录因子，调节髓系基因。它是一种四聚体复合物，由2种不同的蛋白质组成：1）GABPa，一种结合DNA的ets因子，和2）GABPbeta，一种含有转录激活和多聚化结构域的Notch相关蛋白。GABP转录激活CD 18（β 2白细胞整联蛋白）和其他骨髓基因;它是响应视黄酸的CD 18转录激活所必需的。随着粒细胞和单核细胞分化，具有特异性转录激活特性的不同GABP β亚型表达;条件表达某些GABP β亚型诱导粒细胞分化和特征基因表达。该提案将测试GABP介导粒细胞分化的替代途径以及髓系分化过程中需要特定的GABP β亚型的假设。GABP与PU.1、Sp1、RAR α和p300协同激活CD 18。该提案将使用下拉分析，免疫共沉淀和染色质免疫沉淀来定义GABP与其他关键骨髓转录因子和共激活因子的物理和功能相互作用。它将测试GABP参与增强体-一种调节髓系基因表达的多蛋白复合物的假设。产生具有侧接GABPalpha ets结构域的loxP重组位点的小鼠。GABPalpha在体内和体外被有效地删除;小鼠中GABPalpha的纯合缺失导致早期胚胎致死缺陷。骨髓细胞中GABPa的选择性破坏表明它们需要GABP用于存活和/或分化。已经鉴定了GABP的下游靶标，其可以解释GABPalpha空细胞的细胞缺陷。该提案将检验GABP是粒细胞存活和/或分化所需的假设，并将定义GABP驱动髓系细胞发育的机制。这些研究将提供一个全面的证明GABP在髓系基因表达的作用，并提供重要的新信息，转录因子和共激活因子的相互作用，调节髓系分化。

DESCRIPTION (provided by applicant): The goal of this proposal is to comprehensively characterize the role of the transcription factor, GA-Binding Protein (GABP). in myeloid differentiation and gene expression. Transcription factors regulate development of myeloid cells (granulocytes and monocytes) from hematopoietic progenitor cells, and defects in transcription factors are associated with acute myelogenous leukemia. GABP is 1 of a limited number of transcription factors that regulate myeloid genes. It is a tetrameric complex that consists of 2 distinct proteins: 1) GABPalpha, an ets factor which binds to DNA, and 2) GABPbeta, a Notch-related protein which contains transcription activation and multimerization domains. GABP transcriptionally activates CD 18 (beta2 leukocyte integrin) and other myeloid genes; it is required for transcriptional activation of CD18 in response to retinoic acid. As granulocytes and monocytes differentiate, distinct isoforms of GABPbeta with specific transcriptional activation properties are expressed; conditional expression some GABP beta isoforms induces granulocytic differentiation and characteristic gene expression. The proposal will test the hypothesis that GABP mediates an alternative pathway to granulocytic differentiation and that specific GABPbeta isoforms are required during myeloid differentiation. GABP cooperates with PU.1, Sp1, RARalpha, and p300 to activate CD18. This proposal will use pull-down assays, co-immunoprecipitation, and chromatin immunoprecipitation to define the physical and functional interactions of GABP with other key myeloid transcription factors and co-activators. It will test the hypothesis that GABP participates in an enhanceosome - a multiprotein complex that regulates myeloid gene expression. Mice were generated with loxP recombination sites that flank the GABPalpha ets domain. GABPalpha is efficiently deleted in vivo and in vitro; homozygous deletion of GABPalpha in mice causes an early embryonic lethal defect. Selective disruption of GABPalpha in myeloid cells indicates that they require GABP for survival and/or differentiation. Downstream targets of GABP that may account for cellular defects of GABPalpha null cells have been identified. The proposal will test the hypothesis that GABP is required for granulocytic survival and/or differentiation and it will define mechanisms by which GABP drives myeloid cell development. These studies will provide a comprehensive demonstration of the role of GABP in myeloid gene expression and provide important new information regarding transcription factor and co-activator interactions that regulate myeloid differentiation.