Analysis of a murine model of the AML1-ETO translocation

描述（由申请人提供）：t(8;21)（q22;q22）易位，将人类8号染色体上的ETO基因与21号染色体上的AML1基因融合，是与急性髓性白血病（AML）相关的最常见的细胞遗传学异常之一。它在大约12- 15%的AML病例中可见，在大约40%的M2表型AML中存在。我们通过逆转录病毒转导纯化的造血干细胞（HSC），建立了小鼠t（8;21）模型。用表达AML 1- ETO的HSC重组的小鼠在干细胞室和髓系谱系中表现出明显的发育异常。移植后10个月，原始成髓细胞增加到骨髓的大约10%。与这一观察结果一致的是，体外培养的骨髓集落形成细胞增加了50倍。表现出异常嗜碱性肉芽的嗜酸性粒细胞也增加。10月龄重建动物骨髓中的HSC数量是移植匹配对照小鼠的29倍，这表明AML1-ETO的表达覆盖了正常的HSC池大小的遗传控制。总之，表达aml1 - eto的动物再现了人类t患者的许多（也许是全部）发育异常（8;21），尽管这些动物不会在肝或脾等外周组织中发展为白血病或播散性疾病。这表明发展为急性白血病需要继发性突变。本提案的主要目的是了解HSC中AML1-ETO表达引起的发育功能障碍的潜在分子和细胞基础。具体目标将集中在(1)，表达成髓细胞的AML1-ETO的表型和功能表征(2)，确定AML1-ETO对HSC自我更新的影响和候选自我更新基因的鉴定(3)，与AML1-ETO合作诱导AML的继发突变的表征(4)，ETO内负责HSC和成髓细胞中观察到的发育表型的结构域的功能定位。

DESCRIPTION (provided by applicant): The t(8;21)(q22;q22) translocation, which fuses the ETO gene on human chromosome 8 with the AML1 gene on chromosome 21, is one of the most frequent cytogenetic abnormalities associated with acute myeloid leukemia (AML). It is seen in approximately 12-15 percent of AML cases and is present in about 40 percent of AML with an M2 phenotype. We have generated a murine model of the t(8;21) by retroviral transduction of purified hematopoietic stem cells (HSC). Mice reconstituted with HSC that express AML 1- ETO show distinct developmental abnormalities in the stem cell compartment and within the myeloid lineages. Primitive myeloblasts were increased to approximately 10 percent of bone marrow by ten months post-transplant. Consistent with this observation was a 50-fold increase in myeloid colony forming cells in vitro. Eosinophil myelocytes that exhibited abnormal basophilic granulation were also increased. HSC numbers in the bone marrow of 10-month-old reconstituted animals were 29-fold greater than in transplant-matched control mice, suggesting that AML1-ETO expression overrides the normal genetic control of HSC pool size. In summary, AML1-ETO-expressing animals recapitulate many (and perhaps all) of the developmental abnormalities seen in human patients with the t(8;21), although the animals do not develop leukemia or disseminated disease in peripheral tissues like the liver or spleen. This suggests that secondary mutations are required to progress to acute leukemia. The primary goal of this proposal is to understand the underlying molecular and cellular basis for the developmental dysfunction caused by AML1-ETO expression in HSC. The specific aims will focus on (1), phenotypic and functional characterization of AML1-ETO expressing myeloblasts (2), determining the influence of AML1-ETO on HSC self renewal and identification of candidate self-renewal genes (3), characterization of secondary mutations that cooperate with AML1-ETO to induce AML and (4), functional mapping of domains within ETO that are responsible for the developmental phenotypes observed in HSC and myeloblasts.