MKL in megakaryocytopoiesis

MKL 巨核细胞生成

• 批准号: 8544467
• 负责人: Diane S Krause
• 金额: $ 32.81万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8544467
• 关键词: Accounting; Acute Megakaryocytic Leukemias; Affect; Blood; Blood Circulation; Blood Platelets; Bone Marrow Cells; Cells; Child; Chimeric Proteins; Chromosomes, Human, Pair 1; Chromosomes, Human, Pair 22; Data; Disease; Down-Regulation; Erythroid; Future; Genes; Genetic; Goals; Guanine Nucleotide Exchange Factors; Hematopoiesis; Hemorrhage; Hemostatic function; Human; Human Cell Line; In Vitro; Knockout Mice; Laboratories; Life; Malignant - descriptor; Megakaryoblast; Megakaryocytes; Mus; Newborn Infant; Platelet Count measurement; Ploidies; Polyploidy; Prevention; Process; Publishing; Role; Staging; Testing; Translations; Work; base; cancer cell; clinically relevant; effective therapy; in vivo; insight; leukemia; notch protein; overexpression; promoter; public health relevance; rho

DESCRIPTION (provided by applicant): Megakaryocytopoiesis is the process by which egakaryocytes differentiate from biphenotypic megakaryocyte-erythroid precursors, to megakaryoblasts, which undergo endomitosis to become polyploid, and subsequently undergo maturation to mature megakaryocytes that can release platelets into the circulation. Each of these stages is critical for the cells to produce function platelets, which are critical for hemostasis. Despite great advances in our understanding of hematopoiesis, relatively little is known regarding how megakaryocytopoiesis is regulated, and how this may go awry in diseases of megakaryocytes affecting platelet formation and in acute megakaryoblastic leukemia (AMKL). This proposal is focused on determining the mechanism(s) by which MKL1 promotes megakaryocytic differentiation. MKL1 was first identified by its involvement in the t(1;22) translocation, which occurs almost exclusively in AMKL of newborns. To understand the mechanism by which the RBM15-MKL1 fusion protein encoded by the t(1;22) translocation promotes leukemia, we must understand the normal functions of RBM15 and MKL1 in hematopoiesis, which have only recently begun to be elucidated. My laboratory has discovered several important clues regarding the normal function(s) of MKL1: 1) MKL1 is differentially expressing during megakaryocytic differentiation with the highest levels in the most mature polyploid megakaryocytes (Mks), 2) overexpression of wildtype (WT) MKL1 promotes Mk differentiation of human cell lines as well as primary murine and human cells with increased numbers of Mk and increased ploidy of Mk, 3) MKL1 knockout mice have impaired megakaryocytic differentiation and decreased platelet numbers, 4) notch stimulation promotes Mk differentiation and 5) MKL and notch act synergistically on both SRF and notch responsive promoters. The aims of this proposal build upon these observations to elucidate the mechanisms by which MKL1 promotes megakaryocytopoiesis. Aim 1 is to determine the functional interactions of MKL1 with SRF and MKL2 in megakaryocytopoiesis using in vivo and in vitro approaches. Aim 2 is to test hypothesis that MKL1 and notch act synergistically to promote megakaryocytic differentiation. Aim 3 is to assess the mechanism by which MKL1 promotes polyploidization of megakaryocytes. The clinical relevance of the proposed work is clear - these studies will help to elucidate the mechanisms underlying normal megakaryocytopoiesis, which is key for normal formation of functional platelets. In addition, these studies will form the basis for future studies on the RBM15-MKL fusion protein found uniquely in AMKL, which accounts for 10% of AML cases in children. PUBLIC HEALTH RELEVANCE: The platelets in our blood are critical for prevention f bleeding. Platelets are formed in the bone marrow from cells called megakaryocytes. The work proposed is focused on a obtaining a better understanding of the process of megakaryocytopoiesis with the long-term goals of deriving effective therapies for genetic and acquired diseases affecting these cells. Acute megakaryoblastic leukemia (AMKL) affects primarily newborn infants and children during the first year of life. When AMKL is associated with a t(1;22) chromosomal translation between the RBM15 gene on chromosome 1 and the MKL1 gene on chromosome 22, there are few effective treatment options, and the disease is nearly always fatal. In this new application, we propose to build on our published work and preliminary data elucidating the role of MKL1 in normal and malignant megakaryocyte expansion, polyploidization and maturation. Specifically, we are assessing the role of MKL1 in megakaryocyte differentiation, and the mechanisms underlying its action. The results of these studies will provide new insights into the role of MKL1 in normal as well as malignant cells.)

DESCRIPTION (provided by applicant): Megakaryocytopoiesis is the process by which egakaryocytes differentiate from biphenotypic megakaryocyte-erythroid precursors, to megakaryoblasts, which undergo endomitosis to become polyploid, and subsequently undergo maturation to mature megakaryocytes that can release platelets into the circulation.这些阶段中的每个阶段对于细胞产生功能血小板至关重要，这对于止血至关重要。尽管我们对造血性的理解取得了长足的进步，但对于如何调节巨核细胞的调节以及影响血小板形成和急性巨毛毛毛毛糖细胞和急性巨型巨核细胞（AMKL）的巨核细胞（AMKL）的疾病，人们对这可能会产生相对较少的了解。该建议的重点是确定MKL1促进巨核细胞分化的机制。 MKL1首先是通过参与t（1; 22）易位来确定的，该易位几乎完全发生在新生儿的AMKL中。要了解由T（1; 22）易位编码的RBM15-MKL1融合蛋白促进白血病，我们必须了解造血中RBM15和MKL1在造血中的正常功能，这些功能最近才刚刚开始阐明。 My laboratory has discovered several important clues regarding the normal function(s) of MKL1: 1) MKL1 is differentially expressing during megakaryocytic differentiation with the highest levels in the most mature polyploid megakaryocytes (Mks), 2) overexpression of wildtype (WT) MKL1 promotes Mk differentiation of human cell lines as well as primary murine and human cells with increased numbers of Mk and increased ploidy of MK，3）MKL1基因敲除小鼠损害了巨核细胞分化和血小板数量减少，4）Notch刺激会促进MK分化，5）MKL和Notch在SRF和Notch响应式启动子上均协同作用。该提案的目的是建立在这些观察结果上，以阐明MKL1促进巨核细胞的机制。目的1是使用体内和体外方法来确定MKL1与SRF和MKL2的功能相互作用。目的2是检验MKL1和Notch协同作用以促进巨核细胞分化的假设。 AIM 3是评估MKL1促进巨核细胞多倍体化的机制。拟议工作的临床相关性很明显 - 这些研究将有助于阐明正常的巨核细胞质的机制，这对于正常形成功能性血小板是关键。此外，这些研究将构成对未来对RBM15-MKL融合蛋白的研究的基础，该蛋白在AMKL中独特发现，该蛋白占儿童AML病例的10％。 公共卫生相关性：我们血液中的血小板对于预防出血至关重要。血小板由称为巨核细胞的细胞在骨髓中形成。提出的工作集中于更好地了解巨核细胞的过程，其长期目标是为影响这些细胞的遗传和获得性疾病提供有效的疗法。急性巨型巨细胞白血病（AMKL）在生命的第一年中主要影响新生婴儿和儿童。当AMKL与1号染色体上的RBM15基因与22号染色体上的MKL1基因之间的T（1; 22）染色体翻译相关时，几乎没有有效的治疗选择，这种疾病几乎总是致命的。在此新应用程序中，我们建议建立我们已发表的工作和初步数据，阐明MKL1在正常和恶性巨核细胞扩张，多倍体化和成熟中的作用。具体而言，我们正在评估MKL1在巨核细胞分化中的作用以及其作用的基础机制。这些研究的结果将为MKL1在正常和恶性细胞中的作用提供新的见解。）