Function of MTG16/ETO2 in acute leukemia

描述（由申请人提供）：染色体易位与癌症密切相关，最常见的是造血恶性肿瘤，破坏主调控基因。在急性髓系白血病（AML）中，16号染色体上的髓系易位基因（MTG16，也称为Eto2）被t（16;21）染色体易位破坏，这种易位最常与治疗相关性AML相关。此外，在最常见的乳腺癌中，高达40%的患者存在MTG16缺失。ETO/MTG8 （RUNX1T1）是一个密切相关的蛋白，它被t（8;21）破坏，这是AML中最常见的染色体易位之一。该基因家族的第三个成员Mtgrl不受易位的直接影响，但位于20号染色体的一个区域，该区域在骨髓增生性疾病中经常被删除。MTG家族成员是核蛋白，似乎作为转录共抑制因子，将调节DNA结合蛋白与组蛋白修饰酶连接起来，抑制和/或沉默基因表达。为了开始理解依赖于Mtg16的调控途径，我们从小鼠的种系中删除了这个基因。mtg16缺失小鼠大多正常，但表现出轻微的造血缺陷。然而，骨髓移植实验揭示了造血干细胞和祖细胞功能的显著缺陷，因为来自mtg16缺失小鼠的骨髓不能保护致命辐射的受体小鼠，并且在竞争性再种群实验中竞争能力差。此外，在脾脏集落形成实验中，Mtg16-null干细胞和祖细胞完全缺陷。重要的是，我们已经能够通过体外逆转录病毒转导Mtg16的再表达来补充造血干细胞功能中的这一缺陷。因此，我们有一种快速、可靠的方法来评估Mtg16在造血干细胞中的作用。此外，我们已经创建了mtgr1缺陷小鼠，并发现这些小鼠在压力下也可能在结肠中表现出干细胞缺陷的迹象。最后，我们再生了Mtg8缺失嵌合小鼠，这样我们就可以通过创造缺乏Mtg16和Mtg8或Mtgr1的小鼠来从遗传学上解剖整个基因家族的作用。因此，我们将明确Mtg16在造血干细胞中的作用，并确定这一关键调控基因家族在干细胞生物学和癌症中的功能。

DESCRIPTION (provided by applicant): The chromosomal translocations that are closely associated with cancer, most frequently hematopoietic malignancies, disrupt master regulatory genes. Myeloid Translocation Gene on chromosome 16 (MTG16, also known as Eto2) is disrupted by the t(16;21) chromosomal translocation in acute myeloid leukemia (AML), and this translocation is most commonly associated with therapy-related AML. In addition, deletion of MTG16 is observed in up to 40% of the most common form of breast cancer. ETO/MTG8 (RUNX1T1) is a closely related protein, which is disrupted by the t(8;21), which is one of the most frequent chromosomal translocations in AML. A third member of this gene family, Mtgrl, is not affected directly by translocations, but resides in a region of Chromosome 20 that is frequently deleted in myelo-proliferative disorders. MTG family members are nuclear proteins that appear to function as transcriptional co-repressors that link regulatory DNA binding proteins to histone modifying enzymes to repress and/or silence gene expression. To begin to understand the regulatory pathways that depend on Mtg16, we have deleted this gene from the germ line of mice. The Mtg16-null mice are mostly normal, but display mild hematopoietic defects. However, bone marrow transplantation assays revealed a dramatic defect in the function of hematopoietic stem cells and progenitor cells, as the bone marrow from Mtg16-null mice was unable to protect lethally irradiated recipient mice and poorly competed in competitive repopulation assays. Moreover, the Mtg16-null stem cells and progenitor cells were completely defective in spleen colony forming assays. Importantly for this proposal, we have been able to complement this defect in hematopoietic stem cell function by re- expression of Mtg16 via ex vivo retroviral transduction. Thus, we have a quick, robust method to assess Mtg16 action in HSCs in vivo. In addition, we have already created Mtgr1-deficient mice and found that these mice may also show signs of a stem cell defect in the colon upon stress. Finally, we have re- generated Mtg8-null chimeric mice, such that we can genetically dissect the action of the entire gene family by creating mice lacking Mtg16 and either Mtg8 or Mtgr1. Therefore, we will define the action of Mtg16 in the hematopoietic stem cell and determine the function of this key regulatory gene family in stem cell biology and cancer.