MLL in Hematopoiesis and Leukemia in the Zebrafish Model

MLL 在斑马鱼模型中的造血和白血病中的作用

• 批准号: 8434760
• 负责人: Carolyn A Felix
• 金额: $ 37.53万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8434760
• 关键词: 11q23; Adult; Affect; Alleles; Anemia; Animal Model; Animals; Antineoplastic Agents; Apoptosis; Automobile Driving; Biological; Blood Cells; Cell Lineage; Cells; Chromosome Band; Clinical; Complementary DNA; Complex; Complication; DNA Sequence Rearrangement; Development; Developmental Process; Disease; Drug resistance; Dysmorphology; Embryo; Embryonic Development; Employee Strikes; Erythrocytes; Erythroid; Future; Gene Expression; Gene Expression Regulation; Gene Targeting; Genes; HRX protein; Hematopoiesis; Hematopoietic; Hematopoietic System; Homeobox; Human; Imagery; In Situ; Infant; Life; Link; Longevity; MLL gene; Malignant - descriptor; Mammals; Messenger RNA; Modeling; Molecular; Morbidity - disease rate; Mus; Myelogenous; Oncogene Proteins; Orthologous Gene; Patients; Pattern; Phenocopy; Phenotype; Poison; Population; Proteins; Regulation; Repression; Role; Stem Cell Development; Time; Tissues; Topoisomerase II; Toxic effect; Transcript; Transcription Regulatory Protein; Transcription factor genes; Transcriptional Activation; Transcriptional Regulation; Transgenic Organisms; Whole Organism; Zebrafish; cdc Genes; cell type; chemotherapy; cofactor; fluorescence imaging; gene repression; hematopoietic tissue; in utero; in vivo; knock-down; leukemia; leukemogenesis; mortality; overexpression; patient population; progenitor; programs; promoter; public health relevance; research study

DESCRIPTION (provided by applicant): Infant leukemias and chemotherapy related leukemias characterized by translocations of the MLL gene at chromosome band 11q23 are devastating, often fatal diseases with unique clinical and biological features. MLL encodes a complex oncoprotein with transcriptional repression and activation functions. The translocations involve many partner genes and generate 5'-MLL-Partner-3' rearrangements, 5'-Partner-MLL-3' rearrangements and MLL haploinsufficiency due to involvement of one allele in the translocation. Unique attributes of zebrafish embryos enable in vivo visualization of normal and abnormal hematopoietic developmental processes in intact animals like no other animal models. Moreover, zebrafish embryos are well suited to model MLL because MLL translocations in infant leukemogenesis originate in utero. Until now, no studies of mll had been done in zebrafish. We cloned the zebrafish mll ortholog and showed high conservation of all of the critical functional domains of human MLL. We found that mll transcripts are maternally supplied to the embryo, expressed during the entire zebrafish lifespan, and detectable in hematopoietic cells and other tissues where Mll is expresed in mice. We demonstrated that mll morpholino knockdown phenocopies the external phenotype, apoptosis and anemia of Mll-/- mice. We made the striking observations that the resulting mll depletion caused not only reduced homeobox cofactor and altered cell cycle gene expression, but also overexpression and underexpression of many hematopoietic genes in different blood cell compartments, suggesting new links of mll to previously unknown targets. Furthermore, the changes in blood cell gene expression caused profound blood cell dysmorphologies. While overexpressed genes in the precursor/myeloid compartment featured lmo2, scl, cmyb, ikaros, rag2 and gata1, reduced expression of gata1 and other red cell genes was detected in the erythroid fraction, linking the anemia from mll depletion to deregulation of an entire erythroid program. This leads to the hypothesis that MLL has profound multi-lineage roles in the developmental control of the hematopoietic system, that temporal and cell-type specific regulation of gene expression by MLL including repression and activation is required for orderly specification of hematopoietic progenitor and stem cell development, and that loss of MLL causes ectopic and asynchronous overexpression and underexpression of blood cell lineage genes and ineffective development of the hematopoietic system. This project endeavors to investigate this hypothesis by exploiting whole organism studies and cellular and molecular studies on cells from whole organisms that are only possible in zebrafish to pinpoint the cells where MLL is most important and when MLL translocations first become transforming.

描述（由申请人提供）：婴儿白血病和化学疗法相关的白血病，其特征在于染色体带11Q23上MLL基因的易位是毁灭性的，通常具有独特的临床和生物学特征的致命疾病。 MLL编码具有转录抑制和激活功能的复杂癌蛋白。这些易位涉及许多伴侣基因，并产生5'-MLL-PARTNER-3'重排，5'-Partner-Mll-3'重排和由于一个等位基因参与转运而导致的MLL单倍不足。斑马鱼胚胎的独特属性可以在完整动物（如其他动物模型）（如其他动物模型）中对正常和异常造血发育过程的体内可视化。此外，斑马鱼胚胎非常适合于MLL建模，因为婴儿白血病发生的MLL易位起源于子宫内。到目前为止，在斑马鱼中尚未对MLL进行研究。我们克隆了斑马鱼MLL直系同源物，并显示了人类MLL的所有关键功能领域的高保守性。我们发现，在整个斑马鱼寿命中表达的MLL转录本可母性提供给胚胎，并在造血细胞和其他小鼠中MLL的组织中检测到。我们证明了MLL Morpholino敲低表型外部表型，凋亡和MLL - / - 小鼠的贫血。我们对所产生的MLL耗竭不仅引起了同源性辅助因子和细胞周期基因表达的改变，而且还导致了不同血细胞室中许多造血基因的过表达和不渗透，这表明MLL与以前未知靶标的新连接表明许多造血基因。此外，血细胞基因表达的变化引起了严重的血细胞畸形。在前体/髓样室中的过度表达基因以LMO2，SCL，CMYB，IKAROS，RAG2和GATA1为特征，但在红细胞分数中检测到GATA1和其他红细胞基因的表达降低，从而将MLL DEPLETION的贫血与整个Eryrodrods Progmpon的消耗相关联。这导致了以下假设：MLL在造血系统的发育控制中具有深远的多条件作用，即通过MLL（包括抑制和激活）对基因表达的时间和细胞类型的特异性调节，才能有序地规定血液上的祖细胞的祖先和干细胞的发育，以及过分的室外室外及其层次的层次和层次的疾病，尤其是层次的层次及其流失的层次及其层次及其层次及其层次及其层次及其层次及其层次及其级别的层次及其层次及其层次及其层次及其层次及其层次的层次。基因和造血系统的无效发展。该项目通过利用整个生物体研究以及对整个生物体细胞的细胞和分子研究来努力研究这一假设，这些细胞只有在斑马鱼中才有可能查明MLL最重要的细胞以及MLL易位首先转化时的细胞。