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

摘要： 急性髓系白血病(AML)是一种侵袭性和致命性疾病，其特点是幼稚细胞的积聚。 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， 因为它们是初发AML中最常见的基因突变类别之一，并且是小分子靶标。 组蛋白阅读器，含溴结构域蛋白4(BRD4)和辅活化子相关的精氨酸甲基转移酶1 (CARM1)已被证明在白血病中都有恶性作用。此外，这些蛋白质的扰动具有 展示了治疗急性髓系白血病的治疗潜力。最近，集中力量发展 针对这些蛋白及其相关途径治疗AML的有效治疗药物。CARM1抑制剂是 正在进行临床前开发研究，而几种BET抑制剂目前正在进行临床研究 审判。 一些研究已经确定了BRD4的翻译后修饰，尽管这些修饰的功能与 对修饰的研究很少。我们的初步发现确定了一种新的依赖于CARM1的不对称精氨酸 BRD4基因甲基化。此外，我们的数据表明，CARM1-BRD4信号轴功能正常，其中CARM1 二甲基BRD4，它导致BRD4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CARM1在调节急性髓系白血病细胞BRD4功能中的作用。 为了了解BRD4的这种翻译后修饰是否在白血病的启动和维持中是必需的 这种疾病的小鼠模型。根据我们的初步数据，我们假设CARM1介导的精氨酸甲基化 增加了BRD4的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BRD4，进而通过抑制转录导致提高存活率 驱动AML发病机制的致癌基因。 虽然我们已经发现了CARM1作为AML的有效靶点，并显示了其对耗竭的有利作用 癌基因信号转导，CARM1抑制阻碍AML发展的确切机制仍然是 问题。通过研究CARM1的底物和相互作用的蛋白，如BRD4，并定义其下游 生物事件，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拟议的研究将提供实验支持。 BET和CARM1抑制剂作为急性髓细胞白血病治疗药物的进展以及 新的急性髓系白血病靶向治疗。

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.