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（由申请人提供）：导致基因表达改变的染色体重排是血液恶性肿瘤的主要原因。该赠款的应用集中在MLL蛋白质及其嵌合体的分子功能和生化特性的表征上，以期促进我们对基于重排的白血病的分子机制的理解。在过去的五年中，我们的研究大大扩展了我们对MLL1和其转运伙伴之一ELL蛋白的作用的分子理解。我们和其他人已经将MLL，MLL相关蛋白及其复合物确定为组蛋白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甲基酶正确酶促活性所需的分子机械。我们还证明，ELL蛋白是白血病中的MLL1伴侣之一，是一种真正的RNA聚合酶II伸长因子，可调节RNA聚合酶II的延伸形式的转录特性。这些研究有助于创建范例，即通过甲基化和转录伸长控制对染色质的翻译后修饰参与白血病的病因。 在这些发现的基础上，该提案的目标是表征哺乳动物H3K4甲基酶的基因靶标，并通过MLL-Chimeras了解基于易位性白血病的分子机制。这些目标将通过两个具体目标积极追求。具体目标1的重点是识别六种哺乳动物H3K4甲基酶的基因靶标，并定义这些甲基化合物如何获得其基因靶标特异性并了解此类位点H3K4甲基化的生物学意义。具体目标2的重点是对几种MLL-转置嵌合体的生化分离，并定义其分子组成，以期识别嵌合体之间的分子共同点，这可能会导致白血病表型的发病机理。 我们将利用各种生化，分子和遗传工具来解决本应用中提出的目标。拟议的研究应（i）对我们对MLL易位如何导致血液恶性肿瘤发病的理解有根本的影响； （ii）对我们理解哺乳动物H3K4甲基酶机械在发育和分化过程中发挥作用的多种作用有助于我们。这些研究提供的信息有可能有可能证明对试图设计合理方法来治疗某些人类恶性肿瘤的研究人员使用目标特定的治疗方法有所帮助。 公共卫生相关性：该应用的重点是通过甲基化调节活细胞染色质的一组蛋白质（MLL1-4和SET1A/B）。这种修饰可以改变细胞的生长，分裂和分化特性。重要的是，其中一种基因是在基于易位的白血病中发现的MLL1。因此，对MLL及其家人的分子功能的详细了解对于人类白血病的检测，诊断和治疗至关重要。