Molecular Mechanisms for the Assembly and Regulation of the MLL1 Core Complex

MLL1 核心复合物组装和调节的分子机制

• 批准号: 8998172
• 负责人: Michael S. Cosgrove
• 金额: $ 9.97万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2015-07-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8998172
• 关键词: Accounting; Acute leukemia; Address; Amino Acids; Antineoplastic Agents; Arginine; Binding; Binding Proteins; Biochemical; Biological; Biological Models; Cells; Complex; Consensus; Development; Diagnostic; Dosage Compensation (Genetics); Electron Microscopy; Enzymes; Epigenetic Process; Eukaryota; Family; Gene Expression; Genes; Genetic Transcription; Genome; Goals; Health; Hematopoiesis; Histone H3; Histone-Lysine N-Methyltransferase; Histones; Homeobox Genes; Human; In Vitro; Investigation; Kinetics; Knowledge; Lead; Lysine; Malignant Neoplasms; Methylation; Methyltransferase; Molecular; Mono-S; Multienzyme Complexes; Mutation; Myeloid-Lymphoid Leukemia Protein; Oncogenic; Outcome; Pathogenesis; Pathway interactions; Proteins; Regulation; Research; Retinoblastoma; Role; SET Domain; Site; Specificity; Structural Protein; Structure; System; Transcriptional Activation; Transcriptional Regulation; Vertebrates; WD Repeat; Work; X-Ray Crystallography; amino group; analytical ultracentrifugation; biophysical analysis; biophysical techniques; design; follow-up; functional outcomes; histone methyltransferase; in vitro Model; in vivo; innovation; insight; leukemia; leukemia treatment; member; novel; outcome forecast; protein complex

DESCRIPTION (provided by applicant): The Mixed Lineage Leukemia protein-1 (MLL1) catalyzes histone H3 lysine 4 (H3K4) methylation, which is an epigenetic mark essential for the regulation of HOX genes in hematopoiesis and development. Translocations that disrupt the MLL1 gene are present in a unique group of acute leukemias, often predicting a poor prognosis. Other MLL1 rearrangements and amplifications increase MLL1's enzymatic activity and are oncogenic. MLL1 contains an evolutionarily conserved ~130 amino acid SET domain that catalyzes H3K4 methylation. Recent studies indicate that the enzymatic activity of MLL1 is regulated by a conserved complex of proteins including WDR5, RbBP5, and ASH2L. These proteins form an independent complex that binds to MLL1 and regulates its ability to mono-, di-, or trimethylate H3K4 substrates, a phenomenon known as 'Product Specificity'. Since different levels of methylation of H3K4 are associated with different transcriptional outcomes, it is imperative to understand the molecular mechanisms by which the product specificity of MLL1 is regulated. Despite the important biological role of MLL1 and its involvement in human leukemia, there is currently little information about the protein-structural features that are responsible for the enzymatic activity of the MLL1 core complex. The long-term goal of this research is to fully characterize the mechanisms for the regulation of H3K4 methylation by the MLL1 core complex. This proposal takes a structure-function approach to investigate the molecular mechanisms for the enzymatic activity of the MLL1 core complex. We have obtained novel preliminary results indicating that the intrinsic product specificity of the MLL1 SET domain is that of a slow monomethyltransferase, but becomes a fast dimethyltransferase when in complex with WDR5, RbBP5, and Ash2L. Here we propose to determine the mechanisms responsible for H3K4 dimethylation activity of the MLL1 core complex. In addition, we will determine the protein-structural features that account for its assembly. To address these aims, we combine molecular, biochemical, and biophysical approaches to investigate the regulation of H3K4 methylation by the MLL1 core complex. This information will increase our understanding of a key enzyme complex and how it is regulated in the pathways that control transcriptional activation in eukaryotes. This investigation is important because it may lead to better diagnostics and the rational design of anti-cancer drugs that inhibit MLL1's enzymatic activity.

描述（由申请人提供）：混合谱系白血病蛋白-1（MLL1）催化组蛋白H3赖氨酸4（H3K4）甲基化，这对于调节造血和发育中HOX基因的表观遗传标记必不可少。破坏MLL1基因的易位存在于独特的急性白血病中，通常预测预后不佳。其他MLL1重排和扩增会增加MLL1的酶活性，并且具有致癌性。 MLL1包含一个催化H3K4甲基化的进化保守的〜130个氨基酸套件。最近的研究表明，MLL1的酶活性受到蛋白质（包括WDR5，RBBP5和ASH2L）的保守性络合物的调节。这些蛋白质形成一种独立的复合物，该复合物与MLL1结合并调节其单，二甲基甲酯H3K4底物的能力，这是一种称为“产品特异性”的现象。由于H3K4的不同水平与不同的转录结果有关，因此必须了解MLL1的产品特异性的分子机制。尽管MLL1及其参与人类白血病的重要生物学作用，但目前几乎没有关于蛋白质结构特征的信息，这些特征是MLL1核心复合物的酶活性。这项研究的长期目标是充分表征通过MLL1核心复合物调节H3K4甲基化的机制。 该建议采用一种结构功能方法来研究MLL1核心复合物的酶促活性的分子机制。我们已经获得了新的初步结果，表明MLL1 SET域的固有产品特异性是缓慢的单甲基转移酶的域，但是当与WDR5，RBBP5和ASH2L复杂化时，它成为快速的二甲基转移酶。在这里，我们建议确定负责MLL1核心复合物H3K4二甲基化活性的机制。此外，我们将确定解释其组装的蛋白质结构特征。为了解决这些目标，我们结合了分子，生化和生物物理方法，以研究MLL1核心复合物对H3K4甲基化的调节。这些信息将增加我们对关键酶复合物的理解，以及如何在控制真核生物中转录激活的途径中调节它。这项研究很重要，因为它可能导致更好的诊断和抑制MLL1酶活性的抗癌药物的合理设计。