The Role of CARM1-Dependent Arginine Methylation of BRD4 in Hematopoiesis

摘要： 急性髓系白血病（AML）是一种侵袭性和致死性疾病，其特征在于未成熟的白血病细胞聚集。 骨髓中的血细胞表观遗传修饰蛋白正在成为白血病的重要治疗靶点， 因为它们是新生AML中最常见的突变基因类型之一，并且可以用小分子靶向。 组蛋白阅读器，含溴结构域蛋白4（BRD 4）和辅激活因子相关精氨酸甲基转移酶1 （CARM 1）都已被证明在白血病中具有恶性功能。此外，这些蛋白质的扰动 证明了治疗AML的治疗潜力。最近，已作出集中努力， 靶向这些蛋白质及其相关通路的有效治疗药物来治疗AML。CARM 1抑制剂是 目前正在临床前开发中进行研究，而几种BET抑制剂目前正在临床研究中。 审判 几项研究已经鉴定了BRD 4的翻译后修饰，尽管这些修饰的功能相关性不明显。 修改的研究很少。我们的初步研究结果确定了一种新的CARM 1依赖性不对称精氨酸 BRD 4的甲基化。此外，我们的数据表明，CARM 1-BRD 4信号传导轴的功能，其中CARM 1 二甲基化BRD 4，这导致BRD 4的亚细胞定位及其与染色质的结合的调节 促进其致癌功能。我们建议研究CARM 1在AML细胞中调节BRD 4功能的作用， 为了了解BRD 4的这种翻译后修饰是否是白血病发生和维持所必需的， 疾病的小鼠模型。根据我们的初步数据，我们假设CARM 1介导的精氨酸甲基化 BRD 4的表达增加了其定位和与染色质的结合。此外，这种甲基化的扰动将导致 驱逐染色质结合的BRD 4，进而通过抑制BRD 4的转录而提高存活率。 导致AML发病的致癌基因。 尽管我们已经发现CARM 1是AML的有效靶点，并显示出其对消耗AML的有益作用， 致癌信号传导，CARM 1抑制阻碍AML发展的确切机制仍然是一个未知的问题。 问题通过研究CARM 1的底物和相互作用蛋白，如BRD 4，并确定其下游 生物学事件，我们将更充分地了解驱动AML的细胞机制，并更有效地设计 治疗策略我们有信心，成功完成我们的拟议研究将提供实验支持 对于BET和CARM 1抑制剂作为AML治疗的进展，以及告知开发 新型AML靶向治疗。

ABSTRACT: Acute myeloid leukemia (AML) is an aggressive and lethal disease characterized by the accumulation of immature blood cells in the bone marrow. Epigenetic modifying proteins are emerging as important therapeutic targets in leukemia, as they are one of the most commonly mutated class of genes in de novo AML and are targetable with small molecules. Histone reader, bromodomain containing protein 4 (BRD4) and coactivator-associated arginine methyltransferase 1 (CARM1) have both been shown to have malignant functions in leukemia. Furthermore, perturbation of these proteins has demonstrated a therapeutic potential for the treatment of AML. Recently, focused efforts have been made to develop efficacious therapeutic drugs targeting these proteins and their associated pathways to treat AML. CARM1 inhibitors are being investigated in preclinical development, while several BET inhibitors are currently being investigated in clinical trials. Several studies have identified post translational modifications of BRD4 though the functional relevance of these modifications is poorly studied. Our preliminary findings identify a novel CARM1-dependent asymmetric arginine methylation of BRD4. Moreover, our data suggest a functional CARM1-BRD4 signaling axis in which CARM1 dimethylates BRD4, which results in the regulation of subcellular localization of BRD4 and its binding to the chromatin promoting its oncogenic functions. We propose to study the role of CARM1 in regulating BRD4 function in AML cells and to understand whether this post-translation modification of BRD4 is required for leukemia initiation and maintenance in mouse models of the disease. From our preliminary data we hypothesize that the CARM1-mediated arginine methylation of BRD4 increases its localization and binding to chromatin. Furthermore, perturbations of this methylation will result in an eviction of chromatin-bound BRD4, in turn leading to improved survival through the suppression of the transcription of oncogenic genes that drive AML pathogenesis. Though we have unearthed CARM1 as an efficacious target of AML and shown its beneficial effects on depleting oncogenic signaling, the precise mechanisms in which CARM1 inhibition hinders AML development still remains a question. By studying the substrates and interacting proteins of CARM1, such as BRD4, and defining its downstream biological events, we will more fully understand the cellular machinery that drives AML and more efficiently devise therapeutic strategies. We are confident that successful completion of our proposed study will provide experimental support for the advancement of both BET and CARM1 inhibitors as a treatment for AML as well as inform the development of novel AML targeted therapies.