ANALYSIS OF MULTIPLE CHIMERIC TRANSCRIPTS IN THE T(3;21)

复发性染色体易位（3;21）（q26;q22）与新发或治疗相关的急性和慢性髓性白血病有关。 这种易位是不寻常的，因为它导致三个不同的融合基因。每个融合基因的作用尚不清楚。 其中之一，AML 1/MDS 1/EVI 1，是由易位后两个转录激活因子的框内连接引起的。 它们分别是位于染色体21 q22带的胎儿肝脏造血所必需的AML 1和位于染色体3q 26带的MDS 1/EVI 1。 MDS 1/EVI 1在造血组织中未检测到，但在分化的造血干细胞中瞬时表达。 与作为非常强的转录激活因子的AML 1和MDS 1/EVI 1相反，AML 1/MDS 1/EVI 1是阻遏物，并且可以抑制由AML 1和MDS 1/EVI 1激活的启动子。本研究的目的是探讨融合蛋白AML 1/MDS 1/EVI 1改变白血病造血细胞分化进程的分子机制。 我们已经开发了几种模型，表明在造血前体细胞中，AML 1/MDS 1/EVI 1抑制对控制细胞复制和分化的因子的反应。 基于初步结果，我们假设融合蛋白通过破坏造血过程中由AML 1和MDS 1/IM 1调节的基因的正常调节而起作用，导致对造血分化和复制至关重要的谱系特异性因子的表达水平不适当。 在这个提议中解决的问题是：如何抑制介导的，融合蛋白的目标是什么？ 通过使用生物化学和分子技术的组合，以及组织培养研究，我们将确定由AML 1/MDS 1/EVI 1调节的靶蛋白，并评估它们在细胞转化中的作用。 我们获得的信息将有助于设计新的治疗方案，用于髓性白血病和t（3;21）患者。 此外，我们的研究结果将为AML 1或MDS 1/EVI 1重排的白血病研究提供见解。

The recurring chromosomal translocation (3;21)(q26;q22) has been associated with de novo or therapy related acute and chronic myeloid leukemias. This translocation is unusual in that it results in three different fusion genes. The role of each fusion gene is not known. One of them, AML1/MDS1/EVI1, results from the in-frame joining of two transcription activators following the translocation. They are AML1, which is necessary to fetal liver hematopoiesis and is located at chromosome band 21q22, and MDS1/EVI1, located at chromosome band 3q26. MDS1/EVI1 is not detected in hematopoietic tissues, but is transiently expressed in differentiating hematopoietic stem cells. In contrast to AML1 and MDS1/EVI1, which are very strong transcription activators, AML1/MDS1/EVI1 is a repressor, and can inhibit promoters activated by AML1 and MDS1/EVI1. The objective of this proposal is to dissect the molecular mechanisms by which the fusion protein AML1/MDS1/EVI1 alters the progress of the hematopoietic differentiation leading to leukemia. We have developed several models showing that, in hematopoietic precursor cells, AML1/MDS1/EVI1 inhibits the response to factors that control cell replication and differentiation. Based on preliminary results, we hypothesize that the fusion protein acts by disrupting the normal regulation of genes regulated by AML1 and MDS1/EVI1 during hematopoiesis, resulting in inappropriate level of expression of lineage- specific factors critical for hematopoietic differentiation and replication. The questions addressed in this proposal are: How is the repression mediated, and what are the targets of the fusion protein? By using a combination of biochemical and molecular techniques, and tissue culture studies, we will identify the target proteins regulated by AML1/MDS1/EVI1 and assess their role in cell transformation. The information we obtain will be useful in the design of new treatments for patients with myeloid leukemia and a t(3;21). In addition, our results will provide insight in the study of leukemias in which either AML 1 or MDS1/EVI1 are rearranged.