Tet1 activity and function in helper T cells

描述(由申请人提供)：在细胞发育中适当建立和维持表观遗传状态的重要性是毋庸置疑的。与人类疾病相关的表观遗传修饰蛋白的突变数量突显了这一过程的关键作用，在癌症中发现的发病率特别高。同样，在免疫系统中，表观遗传事件的精确协调也是细胞分化所必需的，白血病和淋巴瘤等血癌往往具有影响表观遗传修饰复合体功能的突变。最近的研究工作集中在分析表观遗传修饰，以确定其细胞类型和激活状态的特定分布。还强调了表观遗传模式的变化与人类疾病状态的相关性。然而，我们目前知识中的一个主要空白一直是定义控制特定部位靶向的酶机制的事件，该酶机制在独特的细胞状态下调节表观遗传模式。这是一个影响很大的研究领域，因为如果不知道在不同的细胞环境中将表观遗传修饰复合体定向到独特的位置的机制，就无法解释细胞类型和激活状态特定的表观遗传模式。这项提案的重点将放在辅助T细胞中DNA去甲基酶Tet1的定点基因组靶向和功能活性上。直到最近，我还不清楚一个细胞是否拥有酶机械，有可能主动去除DNA中胞嘧啶碱基上的甲基修饰。哺乳动物细胞中发生活性DNA去甲基化的一些最早迹象来自对IL-2启动子的T细胞研究，在实验中观察到胞嘧啶甲基化修饰的DNA复制不依赖于复制的移除。Tet蛋白家族的发现首次证明胞嘧啶甲基化可以被细胞酶分解为羟甲基化状态，并有可能随后转化为非甲基化状态。值得注意的是，在一些血癌中发现了Tet蛋白的突变，这突显了该蛋白家族在免疫细胞发育中的重要性。在这项提案中，我们将首次确定Tet1靶向Helpe T细胞中特定基因组位点的机制及其在免疫反应中的重要性。这些研究将为理解Tet1在辅助T细胞发育中的位点特异性靶向以及这如何影响细胞转变以及免疫过程中细胞的功能潜力奠定基础 对病毒感染的反应。

DESCRIPTION (provided by applicant): The importance of properly establishing and maintaining epigenetic states in cellular development is unmistakable. The critical role for this process is highlighted by the number of mutations in epigenetic modifying proteins that are associated with human diseases, with a particularly high prevalence found in cancers. Similarly in the immune system, the precise coordination of epigenetic events is also required for cellular differentiation, and blood cancers such as leukemia and lymphoma often have mutations that impact the functions of epigenetic-modifying complexes. Recent research efforts have focused on profiling epigenetic modifications to define their cell-type and activation-state specific distribution. There also has been an emphasis on correlating changes in epigenetic patterns with human disease states. However, a major gap in our current knowledge has been defining the events that control the site specific targeting of the enzymatic machinery that regulates epigenetic patterns in unique cellular states. This is a high impact area of research because cell-type and activation-state specific epigenetic patterns cannot be explained without knowledge of the mechanisms that direct epigenetic-modifying complexes to unique sites in different cellular contexts. The focus of this proposal will be on the site-specific genomic targeting and functional activity of the DNA- demethylase Tet1 in helper T cells. Until recently, i was unclear if a cell possessed enzymatic machinery with the potential to actively remove the methyl modification on cytosine bases within the DNA. Some of the first hints that active DNA demethylation occurs in mammalian cells came from studies in T cells examining the IL-2 promoter, where the DNA replication-independent removal of cytosine methylation modifications was experimentally observed. The discovery of the ten-eleven-translocation (TET) protein family provided the first evidence that cytosine methylation could be broken down by a cellular enzyme into a hydroxymethylated state, with the potential to then be successively converted to the unmethylated state. Notably, mutations in TET proteins are found in a number of blood cancers, highlighting the importance of this protein family in immune cell development. In this proposal, we will for the first time define the mechanisms that target Tet1 to specific genomic loci in helpe T cells and its importance in the immune response. These studies will form the basis for understanding the site-specific targeting of Tet1 to loci in helper T cell development and how this impacts cellular transitions as well as the functional potential of the cells during an immune response to viral infection.