Mammalian H3K4 Methylases, Chromosomal Translocations and Human Leukemia

项目摘要/摘要 导致基因表达改变的染色体重排是导致 恶性血液病。这项拨款申请的重点是分子的表征。 MLL蛋白家族及其嵌合体的功能和生化性质 促进我们对重排白血病分子机制的理解。我们的 在过去的五年中，研究极大地扩展了我们对分子生物学的理解。 MLL1和它的一个易位伙伴ELL蛋白。我们和其他人已经确认了MLL， MLL相关蛋白及其复合体，如组蛋白H3赖氨酸4(H3K4)甲基酶。通过我们的 在生物化学和基因筛查方面，我们还确定了 H3K4甲基酶的合适的酶活性。我们还证明了ELL蛋白， MLL1在白血病中的伙伴之一，是一种真正的RNA聚合酶II延长因子，调节 延长形式的RNA聚合酶II的转录特性。这些研究有助于 创建通过甲基化和转录对染色质进行翻译后修饰的范例 延伸率控制参与了白血病的发病机制。 在这些发现的基础上，这项提议的目标是表征人的基因靶标 哺乳动物H3K4甲基酶及其易位相关分子机制的研究 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。特定的 目的1着重于确定六种哺乳动物H3K4甲基酶的基因靶点，并定义 这些甲基酶是如何获得其基因靶标特异性并理解其生物学意义的 H3K4在这些位点上的甲基化。具体目标2集中在生化分离的几个 MLL易位嵌合体及其分子组成的研究 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。 我们将利用各种生化、分子和遗传工具来解决 在本申请中提出的AIMS。建议的研究应(I)对我们的 了解MLL易位如何导致血液系统恶性肿瘤的发病机制；以及 (Ii)有助于我们理解哺乳动物H3K4甲基酶的不同作用 机械在发育和分化过程中发挥作用。这些研究提供的资料 有朝一日可能会对试图设计合理方法的调查人员有所帮助 用于使用靶向特定疗法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.