Post-translational regulation of MLL in leukemogenesis

MLL 在白血病发生中的翻译后调控

基本信息

批准号：
8301560
负责人：
Andrew George Muntean
金额：
--
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-07-15 至 2012-07-02
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8301560
关键词：
11q Accounting Acute leukemia Adult Acute Myeloblastic Leukemia Alleles Binding Biochemical Biological Assay Blood Cells Bone Marrow Transplantation Cell Line Cellular biology Chemicals Chimeric Proteins Chromosomal translocation Clinical Complex DNA Polymerase II DNA Sequence Rearrangement Data Development Endocrine Gland Neoplasms Family Fluorescence Resonance Energy Transfer Gene Silencing Genes Genetic Genetic Programming Genetic Transcription Goals Growth HOXA9 gene Hematopoiesis Hematopoietic Histone H2B Histone H3 Histones Homeobox Genes Human Human Cell Line Hyperparathyroidism Infant Jaw Lead Lesion Leukemic Cell Link Lymphoblastic Leukemia Lysine MEIS1 gene MLL gene MLLT3 gene Magnetic Resonance Imaging Malignant - descriptor Malignant Neoplasms Mediating Menin Methylation Methyltransferase Molecular Monitor Mono-S Mutation Myeloid Leukemia Myeloid-Lymphoid Leukemia Protein N-terminal Nuclear Magnetic Resonance Oncogenic Outcome PHD Finger Patients Pattern Peptides Polymerase Post-Translational Regulation Proteins RNA RNA Polymerase II Reporting Research Role Screening procedure Structure Surface Syndrome Testing Therapeutic Transcriptional Activation Tumor Suppressor Genes Ubiquitination Up-Regulation adult leukemia in vivo inhibitor/antagonist leukemia leukemogenesis mouse model multicatalytic endopeptidase complex novel overexpression protein function protein protein interaction small molecule small molecule libraries therapeutic development therapeutic target transcription factor tumor ubiquitin-protein ligase

项目摘要

DESCRIPTION (provided by applicant): MLL associated leukemias account for up to 80% of infant myeloid leukemias and about 10% of adult leukemias demonstrating a need for a thorough understanding of the mechanisms that lead to transformation. MLL is a histone H3 lysine 4 methyltransferase transcription factor that regulates the expression of HOX genes, which are required for MLL induced leukemia. Translocations of the MLL gene fuse the N-terminus of MLL to one of more than 60 different translocation partners resulting in a potent oncogenic fusion protein. Importantly, MLL fusion induced leukemias require expression of the non-mutated wild type MLL allele; implicating wild type MLL in MLL associated leukemias. The long term goal of the proposed research is to identify and characterize regulatory mechanisms for both wild type MLL and MLL fusion proteins which may be disrupted for therapeutic value in myeloid leukemia. Current research focuses on a novel physical interaction between MLL and the Polymerase Associated Factor complex (PAFc). PAFc is a transcription activation complex that associates with RNA polymerase II and promotes histone H2B ubiquitination (a prerequisite for H3 lysine 4 and 79 methylation). The MLL-PAFc interaction is essential for leukemogenesis by MLL fusion proteins. Mechanistically, PAFc synergizes with MLL or MLL fusion proteins to augment transcription by aiding in the recruitment of MLL to target loci. The proposed research focuses on disruption of the MLL-PAFc interaction with the use of peptides and small chemical compounds. A detailed structure of the MLL-PAFc interaction surface will be obtained by nuclear magnetic resonance (NMR) imaging. Chemical library screening will be employed to identify inhibitors of the MLL-PAFc interaction. MLL-PAFc binding will be monitored by fluorescence resonance energy transfer (FRET) and interaction of candidate chemical compounds will be verified by NMR structural analysis. In vivo bone marrow transplantation assays in mouse models will be used to assess the efficacy of peptide or chemical compound mediated disruption of the MLL-PAFc interaction in mitigating MLL fusion induced leukemia. Another current focus is determining the function of highly conserved PHD fingers in MLL. Current research identified ASB2 and an associated E3 ubiquitin ligase complex binds to the PHD fingers of MLL and promotes proteosomal dependent degradation. This is intriguing since the PHD fingers are invariably deleted from MLL fusion proteins and PHD inclusion is deleterious to transformation. The proposed research modulates ASB2 expression to determine the effects on both MLL stability and growth of HOX dependent and HOX independent human cell lines. An expression analysis of the ASB family during hematopoietic development will be performed to test whether ASB proteins degrade MLL protein in mature blood cells. Transformation assays will determine whether ASB2 mediated MLL degradation is incompatible with MLL fusion leukemia. These studies focus on the MLL-PAFc interaction and ubiquitination of MLL which are directly relevant to MLL and HOX dependent leukemias and may prove as effective therapeutic targets.

描述（由申请人提供）：MLL 相关白血病占婴儿髓系白血病的 80%，约占成人白血病的 10%，这表明需要彻底了解导致转化的机制。 MLL 是一种组蛋白 H3 赖氨酸 4 甲基转移酶转录因子，可调节 HOX 基因的表达，这是 MLL 诱导的白血病所必需的。 MLL 基因的易位将 MLL 的 N 末端与 60 多种不同的易位伙伴之一融合，从而产生有效的致癌融合蛋白。重要的是，MLL 融合诱导的白血病需要非突变野生型 MLL 等位基因的表达；暗示野生型 MLL 与 MLL 相关白血病有关。拟议研究的长期目标是确定和表征野生型 MLL 和 MLL 融合蛋白的调节机制，这些机制可能会被破坏，从而在髓性白血病中发挥治疗价值。目前的研究重点是 MLL 和聚合酶相关因子复合物 (PAFc) 之间的新型物理相互作用。 PAFc 是一种转录激活复合物，与 RNA 聚合酶 II 结合并促进组蛋白 H2B 泛素化（H3 赖氨酸 4 和 79 甲基化的先决条件）。 MLL-PAFc 相互作用对于 MLL 融合蛋白的白血病发生至关重要。从机制上讲，PAFc 与 MLL 或 MLL 融合蛋白协同作用，通过帮助将 MLL 募集到目标位点来增强转录。拟议的研究重点是使用肽和小化合物破坏 MLL-PAFc 相互作用。 MLL-PAFc相互作用表面的详细结构将通过核磁共振（NMR）成像获得。将采用化学库筛选来鉴定 MLL-PAFc 相互作用的抑制剂。 MLL-PAFc 结合将通过荧光共振能量转移 (FRET) 进行监测，候选化合物的相互作用将通过 NMR 结构分析进行验证。小鼠模型中的体内骨髓移植测定将用于评估肽或化合物介导的 MLL-PAFc 相互作用破坏在减轻 MLL 融合诱导的白血病中的功效。当前的另一个焦点是确定 MLL 中高度保守的 PHD 手指的功能。目前的研究发现 ASB2 和相关的 E3 泛素连接酶复合物与 MLL 的 PHD 指结合并促进蛋白酶体依赖性降解。这很有趣，因为 PHD 指总是从 MLL 融合蛋白中删除，并且 PHD 包含对转化有害。拟议的研究调节 ASB2 表达，以确定对 HOX 依赖性和 HOX 独立人类细胞系的 MLL 稳定性和生长的影响。将进行造血发育过程中ASB家族的表达分析，以测试ASB蛋白是否降解成熟血细胞中的MLL蛋白。转化分析将确定 ASB2 介导的 MLL 降解是否与 MLL 融合白血病不相容。这些研究重点关注 MLL-PAFc 相互作用和 MLL 泛素化，它们与 MLL 和 HOX 依赖性白血病直接相关，并可能被证明是有效的治疗靶点。