Mammalian H3K4 Methylases, Chromosomal Translocations and Human Leukemia

项目总结/摘要 导致基因表达改变的染色体重排是导致癌症的主要原因。 血液恶性肿瘤这项拨款申请的重点是分子的表征 MLL家族蛋白及其嵌合体的功能和生化特性， 推进我们对基于复发的白血病的分子机制的理解。我们 过去五年的研究大大扩展了我们对分子生物学作用的理解， MLL 1和它的易位伙伴之一ELL蛋白。我们和其他人已经确定了MLL， MLL相关蛋白及其复合物，如组蛋白H3赖氨酸4（H3 K4）甲基化酶。通过我们 生物化学和遗传筛选，我们还确定了所需的分子机制， H3 K4甲基化酶的适当酶活性。我们还证明了ELL蛋白， 白血病中的MLL 1伙伴之一，是一种真正的RNA聚合酶II延伸因子， RNA聚合酶II的延伸形式的转录特性。这些研究有助于 创造了通过甲基化和转录修饰染色质的翻译后修饰的范例， 延长控制参与白血病的病因学。 在这些发现的基础上，该提案的目标是表征基因靶点， 哺乳动物H3 K4甲基化酶，并了解基于易位的分子机制 白血病通过MLL-嵌合体。这些目标将通过两个具体目标积极实现。具体 目的1是确定哺乳动物H3 K4甲基化酶的靶基因， 这些甲基化酶如何获得它们的基因靶特异性，并了解 H3 K4在这些位点的甲基化。具体目标2集中在几个生物化学分离， MLL易位嵌合体，并确定其分子组成，希望确定一个 嵌合体之间的分子共性，这可能导致白血病的发病机制 表型 我们将利用各种生物化学、分子和遗传工具来解决 本申请中提出的目标。建议的研究应（i）对我们的 了解MLL易位如何导致血液恶性肿瘤的发病机制;以及 (ii)有助于我们理解哺乳动物H3 K4甲基化酶的不同作用， 机械在发育和分化中起作用。这些研究提供的信息 有可能在某一天对试图设计合理方法的研究人员有所帮助 用于使用靶特异性治疗剂治疗某些人类恶性肿瘤。

Project Summary/Abstract Chromosomal rearrangements resulting in alteration of gene expression are a major cause of hematological malignancies. This grant application is focused on the characterization of the molecular functions and biochemical properties of the MLL family of proteins and its chimeras in the hope of advancing our understanding of the molecular mechanisms of rearrangement-based leukemia. Our studies during the past five years have considerably expanded our molecular understanding of the role of MLL1 and one of its translocation partners, the ELL protein. We and others have identified MLL, MLL-related proteins and their complexes as histone H3 lysine 4 (H3K4) methylases. Through our biochemical and genetic screens, we have also identified the molecular machinery required for the proper enzymatic activity of the H3K4 methylases. We have also demonstrated that the ELL protein, one of the MLL1 partners in leukemia, is a bona fide RNA polymerase II elongation factor regulating the transcriptional properties of the elongating form of RNA polymerase II. These studies have helped to create the paradigm that posttranslational modifications of chromatin by methylation and transcriptional elongation control participate in the etiology of leukemia. Building on these discoveries, the goals of this proposal are to characterize the gene targets of the mammalian H3K4 methylases and to understand the molecular mechanism of translocation-based leukemia via MLL-chimeras. These goals will be aggressively pursued via two specific aims. Specific Aim 1 is focused on identifying the gene targets of the six mammalian H3K4 methylases and to define how these methylases acquire their gene target specificity and understand the biological significance of H3K4 methylation at such sites. Specific Aim 2 is focused on the biochemical isolation of several of the MLL-translocation chimeras and on defining their molecular composition in the hope of identifying a molecular commonality among the chimeras, which may result in the pathogenesis of a leukemic phenotype. We will take advantage of a variety of biochemical, molecular and genetic tools to address the aims proposed in this application. The proposed studies should (i) have a fundamental impact on our understanding of how MLL translocations result in the pathogenesis of hematological malignancies; and (ii) be instrumental for our understanding of the diverse roles that the mammalian H3K4 methylase machinery plays during development and differentiation. The information provided by these studies have the potential of some day proving helpful to investigators attempting to design rational approaches for the treatment of certain human malignancies using target specific therapeutics.