Role of BAP1/ASXL3 complex in transcriptional regulation and development

BAP1/ASXL3 复合物在转录调控和发育中的作用

• 批准号: 10669750
• 负责人: Lu Wang
• 金额: $ 40万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-22 至 2027-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10669750
• 关键词: Attenuated; Biochemical; Biological Markers; Bromodomain; Cells; Chromatin; Chromatin Structure; Complex; Development; Developmental Process; Disease; Enhancers; Epigenetic Process; Equilibrium; Functional disorder; Gene Expression; Genes; Genetic; Genetic Transcription; Goals; Histone H2A; Histones; Lysine; Malignant Neoplasms; Mammalian Cell; Mammals; Mediating; Modification; Molecular; Multiprotein Complexes; Mus; Mutation; Neurons; PRC1 Protein; Patients; Play; Polycomb; Prognostic Marker; Proteins; Role; Scaffolding Protein; Therapeutic; Transcription Coactivator; Transcriptional Regulation; Ubiquitination; developmental disease; driver mutation; embryonic stem cell; gene repression; histone modification; human disease; nerve stem cell; new therapeutic target; novel; novel therapeutics; recruit; screening; small molecule; small molecule inhibitor; stem cell differentiation; transcriptome; ubiquitin isopeptidase

Project Summary Recent advances have shown that dysfunctions prevalent in epigenetic factors play an important role in the developing human diseases, including developmental disorders and cancers. Therefore, understanding the roles of these epigenetic factors may aid in identifying new epigenetic prognostic markers or targetable biomarkers that could contribute towards the establishment of novel therapeutics. Histone H2A lysine 119 ubiquitination (H2AK119ub) is one of the most functional histone marks that plays an essential role in establishing repressive chromatin domains and mediating Polycomb induced transcriptional repression during development. The evolutionarily conserved H2AK119ub histone modification is mainly catalyzed by the Polycomb repressive complex 1 (PRC1) and deubiquitinated by Polycomb repressive-deubiquitinase (PR-DUB) complex (also known as the BAP1 complex in mammals) that antagonizes PRC1’s function. In mammalian cells, the BAP1 complex functions as a multi-protein complex, containing as many as ten different subunits, which are responsible for the chromatin recruitment, protein stability, and enzymatic activity of BAP1. Mutations and dysregulations within subunits in the BAP1 complex are found in patients with developmental diseases, neuronal disorders, and cancer. Therefore, it is critical to understand the molecular basis of how genes are turned on/off by the BAP1/PRC1 epigenetic balance. Our previous studies have characterized a functional epigenetic axis comprised of both BAP1 and Bromodomain and Extraterminal (BET)-containing protein 4 (BRD4), which are physically bridged together by the scaffold protein ASXL3—the largest subunit within the BAP1 complex. Genetic depletion of the linker, ASXL3, dramatically attenuates the establishment of the BAP1/ASXL3/BRD4 epigenetic axis machinery at active enhancers, leading towards a significant reduction in the enhancer-nearby gene expression. In our current studies, we have employed biochemical, molecular, and small-molecule screening approaches to mechanistically understand how the ASXL3/BAP1/BRD4 epigenetic axis regulates transcription and determines cell fate and differentiation ability. Our first goal for this study is to uncover the BAP1/ASXL3 sub-complex’s role at active enhancers and assess the impact of the BAP1/ASXL3/BRD4 epigenetic axis on enhancer activity, chromatin structure, and gene expression. As a major H2AK119 deubiquitinase, the BAP1 complex functions as a general transcriptional activator, antagonizing PRC1’s function and is involved in PRC1-dependent transcriptional regulation. Therefore, our second project is to elucidate the relationship between BAP1 and a distinct PRC1 sub-complex in regulating H2AK119ub levels by utilizing our newly developed BAP1-specific small-molecule inhibitor. Mutations within ASXL3 have been demonstrated to be driver mutations in multiple neuronal diseases. Therefore, we will define the role of ASXL3 in mediating ESC differentiation into neuronal progenitor cells (NPC), and then investigate how ASXL3 and its associated epigenetic factors determine the transcriptome landscape during developmental processes.

项目概要 最近的进展表明，表观遗传因素中普遍存在的功能障碍在 发展人类疾病，包括发育障碍和癌症，因此，了解其作用。 这些表观遗传因素可能有助于识别新的表观遗传预后标记或可靶向的生物标记 这可能有助于建立新的组蛋白 H2A 赖氨酸 119 泛素化疗法。 (H2AK119ub) 是最具功能性的组蛋白标记之一，在建立抑制性中发挥重要作用 染色质结构域和介导 Polycomb 在发育过程中诱导转录抑制。 进化上保守的 H2AK119ub 组蛋白修饰主要由 Polycomb 抑制催化 复合物 1 (PRC1) 并被 Polycomb 抑制性去泛素酶 (PR-DUB) 复合物（也称为 如哺乳动物中的 BAP1 复合物）拮抗 PRC1 的功能。 作为多蛋白质复合物发挥作用，包含多达十个不同的亚基，这些亚基负责 BAP1 内的染色质募集、蛋白质稳定性和酶活性。 BAP1 复合体中的亚基存在于患有发育性疾病、神经元疾病和 因此，了解基因如何打开/关闭的分子基础至关重要。 我们之前的研究已经描述了 BAP1/PRC1 表观遗传平衡的功能性表观遗传轴。 BAP1 和含 Bromodomain 和 Extraterminal (BET) 的蛋白 4 (BRD4) 的物理结构 通过支架蛋白 ASXL3（BAP1 基因缺失复合物中最大的亚基）桥接在一起。 连接子 ASXL3 的作用显着减弱 BAP1/ASXL3/BRD4 表观遗传轴的建立 活性增强子的机制，导致增强子附近的基因表达显着减少。 在我们目前的研究中，我们采用了生化、分子和小分子筛选方法 从机制上理解 ASXL3/BAP1/BRD4 表观遗传轴如何调节转录并决定 我们这项研究的首要目标是揭示 BAP1/ASXL3 亚复合物的作用。 在活性增强子上并评估 BAP1/ASXL3/BRD4 表观遗传轴对增强子活性的影响， 作为主要的 H2AK119 去泛素酶，BAP1 复合物的功能如下。 一种通用转录激活剂，拮抗 PRC1 的功能并参与 PRC1 依赖性 因此，我们的第二个项目是阐明 BAP1 和 a 之间的关系。 利用我们新开发的 BAP1 特异性来调节 H2AK119ub 水平的独特 PRC1 子复合物 ASXL3 内的突变已被证明是多种疾病的驱动突变。 因此，我们将定义 ASXL3 在介导 ESC 分化为神经元中的作用。 祖细胞 (NPC)，然后研究 ASXL3 及其相关的表观遗传因子如何决定 发育过程中的转录组景观。