Defining epigenetic mechanisms in NPM1c mutant leukemia

项目概要/摘要 核磷蛋白（NPM1）突变是急性髓细胞白血病（AML）中最常见的畸变之一。 并导致特征性干细胞样基因表达模式，包括HOXA/B簇的上调 基因及其辅助因子MEIS1。NPM1c突变如何调节这种异常的分子机制 基因表达程序仍然知之甚少，目前没有靶向治疗方案 available.我们最近发现NPM1c突变型白血病依赖于组蛋白甲基转移酶MLL 及其衔接蛋白Menin来维持白血病基因的表达和增殖。之间的相互作用 Menin和MLL对于将MLL复合物募集到其靶基因的亚组中是必需的，例如 MEIS1，这反过来又是维持白血病自我更新所必需的。治疗靶向的脑膜炎- MLL与小分子抑制剂的相互作用导致NPM1c自我更新和分化的丧失 白血病细胞NPM1c突变与MLL复合体之间的联系仍有待解决。在 建议的项目，我们将制定一个全面的了解染色质状态发生在 NPM1c的存在特别关注Menin和MLL在该过程中的作用。为了实现这一目标，我们将 首先确定NPM1c降解后染色质状态的变化， NPM1c的结构域（Aim 1）。接下来，我们将确定哪些转录激活因子和染色质修饰因子 与NPM1c突变型白血病中的Menin-MLL复合物相关，导致异常靶基因 激活（目标2）。最后，我们将集中在染色质结合因子LEDGF，这已被证明是 与Menin-MLL结合并募集转录激活因子以控制基因表达。我们的初步数据 表明LEDGF在NPM1c突变白血病细胞中是一种依赖性，LEDGF的缺失增强了NPM1c突变白血病细胞的凋亡。 Menin抑制对细胞存活和MLL靶基因表达的有害影响（目的3）。总之， 从拟议的项目中获得的见解将有助于推进我们对NPM1c驱动的机械理解 白血病的发展，目的是改善未来的治疗策略。

Project Summary/Abstract Nucleophosmin (NPM1) mutations are among the most common aberrations in acute myeloid leukemia (AML) and cause a characteristic stem cell-like gene expression pattern including the upregulation of HOXA/B cluster genes and their co-factors MEIS1. The molecular mechanisms of how NPM1c mutations regulate this aberrant gene expression program remains poorly understood and there are currently no targeted therapy options available. We have recently found that NPM1c mutant leukemias depend on the histone methyltransferase MLL and its adaptor protein Menin to maintain leukemia gene expression and proliferation. The interaction between Menin and MLL is essential for the recruitment of the MLL complex to a subgroup of its target genes, such as MEIS1, which are in turn essential for maintaining leukemic self-renewal. Therapeutic targeting of the Menin- MLL interaction with small molecule inhibitors causes a loss of self-renewal and differentiation of NPM1c leukemia cells. The link between NPM1c mutations and the MLL-complex remains to be resolved. In the proposed project, we will develop a comprehensive understanding of the chromatin state that occurs in the presence of NPM1c specifically focusing on the role of Menin and MLL in this process. To achieve this, we will first determine the changes in chromatin state upon NPM1c degradation and determine essential protein domains of NPM1c (Aim 1). Next, we will identify which transcriptional activators and chromatin modifiers associate with the Menin-MLL complex in NPM1c mutant leukemias that lead to the aberrant target gene activation (Aim 2). Finally, we will focus on the chromatin binding factor LEDGF, which has been shown to associate with Menin-MLL and recruit transcriptional activators to control gene expression. Our preliminary data suggests that LEDGF is a dependency in NPM1c mutant leukemia cells and that LEDGF loss enhances the detrimental effects of Menin-inhibition on cell survival and MLL-target gene expression (Aim 3). In summary, the insights gained from the proposed project will help advance our mechanistic understanding of NPM1c driven leukemia development with the goal of improving treatment strategies in the future.