Molecular Characterization of T-bet's Role in Immunity

描述（由申请人提供）：谱系限制性转录因子在造血分化过程中起关键作用，即使是单一因子的失调也可导致疾病状态，如白血病、自身免疫和过敏反应。这是如何发生的部分原因是，一个因子的选择性丢失可以大大改变关键效应细胞群的发育。因此，识别受这些因素影响的基因表达级联将使我们能够解决有助于疾病表型的分子机制。转录因子T-bet似乎在CD 4 + T辅助细胞1的发育中起重要作用。Th 1细胞分泌IFN γ，在细胞介导的免疫的发展中很重要。Th 1反应过度活跃可导致自身免疫性疾病，如克罗恩病和1型糖尿病。除了Th 1细胞外，T-bet还在免疫系统的多个谱系中表达，并被认为有助于每个效应细胞群体中的细胞特异性功能。在缺乏T-bet的情况下，细胞特异性缺陷发生在自然杀伤细胞、树突细胞和B细胞中。还值得注意的是，克罗恩病、哮喘和狼疮的鼠疾病模型都是通过改变T-bet水平建立的。因此，可以假设T-bet在免疫应答的发展中起重要作用。该提案的主要目标是解决T-bet在个体造血效应细胞群体中的作用背后的分子机制。目的1旨在鉴定每个细胞群体中的直接T-bet靶基因。T-bet是以细胞特异性方式靶向基因座，还是在所有细胞环境中与相同的基因相互作用？为了解决这个问题，将采用靶基因鉴定策略，该策略利用对染色质免疫沉淀程序的修改。这些技术将仅识别在给定核环境中直接被T-bet结合的基因。在目标2中，将检查T-bet与选择启动子的关联的功能后果，以确定这种相互作用在不同的细胞环境中是否是有成效的。目标1和2中的研究将提供一种解决T-bet电池规格的方法。目的3和4将解决T-bet在一些选择的靶基因的转录调控中发挥的作用。T-bet是转录激活因子还是抑制因子？T-bet是否影响染色质事件或帮助RNA聚合酶II募集到启动子？一些选择的靶基因的详细的转录调控研究将有助于回答这些问题。

DESCRIPTION (provided by applicant): Lineage-restricted transcription factors play a critical role in the hematopoietic differentiation process and the deregulation of even a single factor can lead to disease states such as leukemia, autoimmunity, and allergic reactions. Part of how this occurs is that the selective loss of a factor can drastically alter the development of critical effector cell populations. Therefore, identifying the gene expression cascades influenced by these factors will allow us to address the molecular mechanisms that contribute to the disease phenotypes. The transcription factor T-bet appears to play a significant role in the development of CD4+ T helper 1 cells. Th1 cells secrete IFNgamma and are important in the development of cell-mediated immunity. A hyperactive Th1 response can contribute to autoimmune diseases such as Crohn's disease and type 1diabetes. In addition to Th1 cells, T-bet is also expressed in multiple lineages in the immune system and is thought to contribute to cell-specific functions in each effector cell population. In the absence of T-bet, cell-specific defects occur in natural killer, dendritic, and B cells. It is also worth noting that murine disease models for Crohn's disease, asthma, and lupus have all been established by altering T-bet levels. Therefore, one may hypothesize that T-bet plays an important role in the developing immune response. The main goal of this proposal is to address the molecular mechanisms behind T-bet's role in the individual hematopoietic effector cell populations. Aim 1 is designed to identify direct T-bet target genes in each cell population. Is T-bet targeted to loci in a cell-specific manner or does it interact with the same genes in all cellular settings? To address this question, target gene identification strategies will be employed that utilize modifications to the chromatin immunoprecipitation procedure. These techniques will only identify genes that are directly bound by T-bet within the context of a given nuclear environment. In Aim 2, the functional consequence of T-bet's association with select promoters will be examined to determine if this interaction is productive in the different cellular settings. The studies in Aim 1 and 2 will provide a means to address T-bet's cell-specifications. Aims 3 and 4 will address the role T-bet plays in the transcriptional regulation of a few select target genes. Does T-bet function as a transcriptional activator or repressor? Does T-bet influence chromatin events or aid in RNA polymerase II recruitment to the promoter? Detailed transcriptional regulation studies of a few select target genes will aid in answering these questions.