Mechanisms of Leukemogenic Transformation by MLL-CALM

MLL-CALM 转化白血病的机制

• 批准号: 6929520
• 负责人: DANIEL STEVEN WECHSLER
• 金额: $ 27.2万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6929520
• 关键词: acute myelogenous leukemia; athymic mouse; carcinogenesis; chimeric proteins; chromosome aberrations; chromosome translocation; clathrin; endocytosis; gene expression profiling; gene rearrangement; genetic manipulation; genetic regulation; genetic transcription; genetically modified animals; immunoprecipitation; leukocyte activation /transformation; neoplasm /cancer genetics; polymerase chain reaction; protein protein interaction; protein structure function; site directed mutagenesis; western blottings

DESCRIPTION (provided by applicant): Chromosomal rearrangements involving the Mixed Lineage Leukemia (MLL) gene at chromosome 11q23 are frequently seen in leukemias. Although more than 40 translocation partner genes have been identified for MLL, the precise mechanisms by which MLL-fusion partner proteins lead to leukemia remain unclear. We recently identified a novel chromosome 11 inversion in an infant with acute myeloid leukemia (AML) that juxtaposed MLL to the Clathrin Assembly Lymphoid Myeloid Leukemia (CALM) gene at 11q14. CALM was first identified as a translocation partner for AF10 - itself an MLL partner - in acute leukemias and lymphomas. The CALM protein directly interacts with clathrin and membrane lipids, and plays a key role in endocytosis and intracellular vesicle trafficking. Recently, mutations in the murine calm gene have been shown to account for the phenotype of the fill mouse, which has significant abnormalities in hematopoiesis and iron metabolism. The involvement of CALM as a translocation partner for two distinct genes in hematopoietic malignancies, together with its involvement in normal hematopoiesis, suggests that perturbation of normal CALM function contributes to the development of leukemia. The overall objective of this proposal is to study the biology of the MLL-CALM fusion protein in leukemogenesis. We hypothesize that the MLL-CALM translocation contributes to the development of myeloid leukemia by perturbing the normal function of both CALM and MLL. To begin to understand mechanisms by which the MLL-CALM protein is involved in the pathogenesis of AML, our first aim is to determine whether MLL-CALM expression results in transformation in vitro and leukemia in vivo. We will use the murine hematopoietic progenitor transformation assay to rigorously demonstrate that MLL-CALM expression results in transformation in vitro, and establish in vivo murine models of MLL-CALM-dependent leukemia. In addition, to more faithfully mimic the MLL-CALM leukemia phenotype, we will prepare an mll-CALM transgenic mouse. Finally, we will examine leukemogenesis in the context of fit1 -derived hematopoietic precursors. Our second overall aim is to identify mechanisms involved in MLL-CALM-dependent transformation. In these studies, we will focus on the role of three specific mechanisms - dimerization, transcriptional regulation and endocytosis - in MLL-CALM- and CALM-AF10-dependent transformation. Insights gained regarding CALM function may be generalizable to the large number of leukemias and lymphomas with CALM-AF10 translocations, and, in a broader sense, will contribute to our understanding of normal CALM biology.

描述（由申请人提供）：涉及11q23染色体的混合谱系白血病（MLL）基因的染色体重排，在白血病中经常看到。尽管已经确定了MLL的40多个易位伴侣基因，但MLL融合伴侣蛋白导致白血病的确切机制尚不清楚。最近，我们发现了一个新型的患有急性髓样白血病（AML）婴儿的新型染色体反转，该染色体在11q14上将MLL与网格蛋白组装淋巴髓样白血病（CALM）并列。 CALM首先被确定为AF10的转运伙伴 - 本身是MLL伴侣 - 急性白血病和淋巴瘤。平静的蛋白质直接与网格蛋白和膜脂质相互作用，并在内吞作用和细胞内囊泡运输中起关键作用。最近，鼠平静基因中的突变已被证明是填充小鼠的表型，该表型在造血和铁代谢中具有显着异常。镇静作为造血恶性肿瘤中两个不同基因的转运伴侣的参与，以及它参与正常造血作用，表明正常镇静功能的扰动有助于白血病的发展。该提案的总体目的是研究白血病中MLL-CALM融合蛋白的生物学。我们假设MLL-CALM易位通过扰动平静和MLL的正常功能来促进髓样白血病的发展。为了开始理解MLL-CALM蛋白参与AML的发病机理的机制，我们的第一个目的是确定MLL-CALM表达是否导致体内体外和白血病转化。我们将使用鼠造血祖细胞转化测定法来严格证明MLL-CALM表达会导致体外转化，并在MLL-CALM依赖性白血病的体内鼠模型中建立。此外，为了更忠实地模仿MLL-CALM白血病表型，我们将准备MLL-CALM转基因小鼠。最后，我们将在FIT1衍生的造血前体的背景下检查白血病。我们的第二个总体目的是确定与MLL-CALM依赖性转化有关的机制。在这些研究中，我们将重点关注三种特定机制的作用 - 二聚体，转录调控和内吞作用 - 在MLL-CALM-和CALM-AF-10依赖性转化中的作用。 关于平静功能获得的见解可能可以推广到具有CALS-AF10易位的大量白血病和淋巴瘤，从广义上讲，将有助于我们对正常镇静生物学的理解。