The Role of SKIDA1 in Acute Myeloid Leukemia Initiation and Maintenance

摘要 涉及MLL1基因的染色体易位通常会导致婴儿急性髓系白血病(AML)。MLL 融合蛋白(如MLL-ENL、MLL-AF9、MLL-AF10)激活造血干细胞的自我更新程序 和祖细胞，最终导致转化。婴儿MLL1重排的高频率研究 白血病表明，新生儿的祖细胞对这些突变具有独特的转化能力。 事实上，我们最近已经表明，MLL-enl在新生儿祖细胞中启动AML比在 成年祖先。这就提出了一个问题：MLL-ENL是否会更多地诱导关键的转化效应因子 在新生儿祖细胞中比在成年祖细胞中有效。我们确定Ski/Dach域包含%1 作为一种基因，MLL-enl在新生儿中高度诱导，但在成人造血祖细胞中不能。 SKIDA1也在人类MLL1重排的AML中高表达。表达在很大程度上限于 伴有MLL1重排的白血病。为了测试斯基达1是否促进白血病的发生，我们生成了一个 生殖系功能丧失的小鼠等位基因。Schia1基因缺失本身对正常的影响可以忽略不计 造血性，与正常造血祖细胞缺乏表达一致。此外， Systa1缺失不影响正常的HSC功能。然而，当我们诱导MLL-ENL在细胞中表达时 斯基达1-/-新生儿，我们观察到几乎完全丧失了HSCs，所承诺的血统严重减少 造血祖细胞(HPC)。因此，作为MLL-ENL的结果，出现了对斯基达1的依赖 表情。接下来，我们产生了一个条件功能丧失的小鼠等位基因。中的有条件删除SCIDA1 造血系统在任何年龄段都不会干扰正常的造血。我们目前正在跨越 对我们的MLL-ENL小鼠模型进行有条件的SCADA1小鼠实验，以测试SKIDA1是否促进白血病的发生 表达MLL-enl的祖细胞的背景。因此，我假设斯基达1号维持白血病前期的造血干细胞。 和HPC，并在新生儿阶段促进AML。Aim 1将使用斯基达1条件淘汰赛 小鼠，询问Systa1如何维持MLL-enl表达的HSC和HPC。我也会测试一下 Systa1是维持AML细胞完全转化所必需的。目标2在目标1的基础上增加了机械性 研究确定依赖于斯基达1的基因表达变化和细胞命运。我将测试SKIDA1是否 结合染色质来调节白血病的发生，我将确定SKIDA1结合伙伴。这样做的目的是 提案将评估SKIDA1作为特定年龄转录计划和急性髓细胞白血病之间的潜在联系 启动，并为治疗婴儿白血病提供了一种新的治疗脆弱性。

ABSTRACT Chromosomal translocations involving the MLL1 gene often drive infant acute myeloid leukemia (AML). MLL fusion proteins (e.g., MLL-ENL, MLL-AF9, MLL-AF10) activate self-renewal programs in hematopoietic stem and progenitor cells, ultimately leading to transformation. The high frequency of MLL1 rearrangements in infant leukemias suggests that neonatal progenitors are uniquely poised to transform in response to these mutations. Indeed, we have recently shown that MLL-ENL initiates AML more efficiently in neonatal progenitors than in adult progenitors. This raises the question of whether MLL-ENL induces key effectors of transformation more efficiently in neonatal progenitors than in adult progenitors. We identified Ski/Dach Domain Containing 1 (Skida1) as a gene that is highly induced by MLL-ENL in neonatal, but not adult hematopoietic progenitors. SKIDA1 is also highly expressed in human pediatric MLL1 rearranged AML. Expression is largely restricted to leukemias with MLL1 rearrangements. To test whether Skida1 promotes leukemogenesis, we generated a germline loss-of-function mouse allele. Skida1 deletion by itself had negligible effects on normal hematopoiesis, consistent with the lack of expression in normal hematopoietic progenitors. Furthermore, Skida1 deletion did not affect normal HSC function. However, when we induced MLL-ENL expression in Skida1-/- neonates, we observed near complete loss of HSCs and a severe reduction in lineage committed hematopoietic progenitor cells (HPCs). Thus, Skida1-dependence emerges as a consequence of MLL-ENL expression. Next, we generated a conditional loss-of-function mouse allele. Skida1 conditional deletion in the hematopoietic system did not perturb normal hematopoiesis at any age. We are currently crossing the conditional Skida1 mouse to our MLL-ENL mouse model to test whether Skida1 promotes leukemogenesis in the context of MLL-ENL-expressing progenitors. Thus, I hypothesize that Skida1 sustains pre-leukemic HSCs and HPCs and promotes AML during neonatal stages of life. Aim 1 will use a Skida1 conditional knockout mouse to interrogate how Skida1 sustains MLL-ENL-expressing HSCs and HPCs. I will also test whether Skida1 is necessary to maintain fully transformed AML cells. Aim 2 builds upon Aim 1 by adding mechanistic studies to identify Skida1-dependent changes in gene expression and cell fate. I will test whether SKIDA1 binds chromatin to regulate leukemogenesis, and I will identify SKIDA1 binding partners. The aims of this proposal will evaluate SKIDA1 as a potential link between age-specific transcriptional programs and AML initiation, as well as offer a novel therapeutic vulnerability for treating infant leukemia.