Mammalian H3K4 Methylases, Chromosomal Translocations and Human Leukemia

哺乳动物 H3K4 甲基化酶、染色体易位和人类白血病

• 批准号: 8041000
• 负责人: Ali Shilatifard
• 金额: $ 46.55万
• 依托单位: STOWERS INSTITUTE FOR MEDICAL RESEARCH
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-09 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8041000
• 关键词: Address; Applications Grants; Biochemical; Biochemical Genetics; Biological; Cells; Chimera organism; Chromatin; Chromosomal Rearrangement; Chromosomal translocation; Complex; DNA Sequence Rearrangement; Detection; Development; Diagnosis; Elongation Factor; Embryo; Etiology; Family; Family member; Gene Expression Alteration; Gene Targeting; Genes; Genetic Screening; Goals; Hematologic Neoplasms; Histone H3; Homologous Gene; Human; Knowledge; Life; Lysine; MLL gene; Malignant Neoplasms; Mammalian Cell; Methylation; Methyltransferase; Modification; Molecular; Molecular Genetics; Pathogenesis; Phenotype; Play; Polymerase; Post-Translational Protein Processing; Property; Protein Family; Proteins; RNA Polymerase II; Research Personnel; Role; Site; Specificity; Therapeutic; Transcription Elongation; Yeasts; base; cell growth; design; enzyme activity; leukemia; public health relevance; tool

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: The focus of this application is on a group of proteins (MLL1-4 and Set1A/B) that regulate the posttranslational modification of the chromatin of living cells by methylation. This modification can alter cell growth, division, and differentiation properties. Importantly, one of these genes, the MLL1 is found in translocation-based leukemia. Therefore, detailed knowledge of the molecular functions of MLL and its family members will be critical for the detection, diagnosis and treatment of human leukemia.

描述(申请人提供)：导致基因表达改变的染色体重排是血液系统恶性肿瘤的主要原因。这项资助申请集中于MLL蛋白家族及其嵌合体的分子功能和生化性质的表征，以期促进我们对重排白血病分子机制的理解。在过去的五年中，我们的研究极大地扩展了我们对MLL1及其易位伙伴之一ELL蛋白的作用的分子理解。我们和其他人已经鉴定了MLL、MLL相关蛋白及其复合体为组蛋白H3赖氨酸4(H3K4)甲基酶。通过我们的生化和遗传筛选，我们还确定了H3K4甲基酶正常酶活性所需的分子机制。我们还证明了ELL蛋白是白血病中MLL1的伙伴之一，是一种真正的RNA聚合酶II伸长因子，调节着伸长形式的RNA聚合酶II的转录特性。这些研究有助于建立染色质通过甲基化和转录伸长控制的翻译后修饰参与白血病病因的范式。在这些发现的基础上，这项建议的目标是表征哺乳动物H3K4甲基酶的基因靶标，并通过MLL嵌合体了解易位白血病的分子机制。这些目标将通过两个具体目标积极实现。具体目标1集中于确定六种哺乳动物H3K4甲基酶的基因靶标，并确定这些甲基酶是如何获得其基因靶标特异性的，并了解这些位点上H3K4甲基化的生物学意义。具体目标2集中在对几个MLL易位嵌合体的生化分离和确定它们的分子组成，以期确定嵌合体之间的分子共性，这可能导致白血病表型的发病。我们将利用各种生化、分子和遗传工具来解决这一应用中提出的目标。拟议的研究应该(I)对我们理解MLL易位如何导致血液系统恶性肿瘤的发病机制产生根本性的影响；(Ii)有助于我们理解哺乳动物H3K4甲基酶机制在发育和分化过程中所扮演的不同角色。这些研究提供的信息有可能在某一天被证明对试图设计合理的方法来使用靶向特定疗法治疗某些人类恶性肿瘤的研究人员有帮助。 公共卫生相关性：这项应用的重点是一组蛋白质(MLL1-4和Set1A/B)，它们通过甲基化来调节活细胞染色质的翻译后修饰。这种修饰可以改变细胞的生长、分裂和分化特性。重要的是，其中一个基因MLL1在易位白血病中被发现。因此，对MLL及其家族成员分子功能的详细了解对人类白血病的检测、诊断和治疗具有重要意义。