The Role of Asymmetric Histone Inheritance in Establishing Distinct Cell Identities

不对称组蛋白遗传在建立不同细胞身份中的作用

• 批准号: 10347379
• 负责人: Emily Hope Zion
• 金额: $ 3.52万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-16 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10347379
• 关键词: Academia; Address; Affect; Biological; Candidate Disease Gene; Cell Differentiation process; Cell Lineage; Cell division; Cells; Chromatin; Chromatin Fiber; Color; Complex; DNA; DNA Methylation; DNA Sequence; DNA biosynthesis; Data; Defect; Deposition; Differentiated Gene; Disease; Drosophila genus; Enterocytes; Enteroendocrine Cell; Epigenetic Process; Gene Expression; Genes; Germ Cells; Goals; Heritability; Histone H2A; Histone H3; Histones; Homeostasis; Inheritance Patterns; Inherited; Intestines; Kinetochores; Label; Laboratories; Lead; Maintenance; Malignant Neoplasms; Methods; Mitosis; Mitotic; Molecular; Mutate; Mutation; Pattern; Phenotype; Phosphorylation; Phosphorylation Site; Play; Post-Translational Protein Processing; Process; Proteins; RNA; Research; Research Training; Role; Sister Chromatid; Specific qualifier value; Structure; System; Tail; Techniques; Tissue-Specific Gene Expression; Tissues; Transgenes; Transgenic Organisms; Tumor Tissue; Universities; Variant; Work; adult stem cell; career; cell type; daughter cell; genomic locus; germline stem cells; histone modification; insight; male; mutant; neoplastic cell; segregation; self-renewal; skills; stem cell division; stem cells; stemness; tissue degeneration

Project Summary Cells are required to divide and organize into tissues. One method of tissue homeostasis is the utilization of adult stem cells that are able to replace cells by undergoing asymmetric cell division (ACD) to produce a renewed stem cell and a differentiating cell. Disruptions to this division can lead to cancers or tissue degeneration. Although ACD is a vital part of tissue homeostasis, the underlying mechanisms involved in specifying two unique cell identities during this process are unknown. Previous work studying the epigenetic mechanisms of ACD in the Drosophila male germline found that, by labeling old and new histones distinctively, old H3 histones are retained in the renewed stem cell, whereas new H3 histones are preferentially segregated to the differentiating cell. To investigate whether asymmetric histone inheritance is an important mechanism of ACD, I will study histone inheritance in the intestinal stem cells (ISCs) of Drosophila. The ISCs undergo ACD to produce two differentiated cell types, enterocyte and enteroendocrine cells. The ISCs are also able to undergo symmetric cell division (SCD) to produce two ISCs. The ISC lineage is ideal to study histone inheritance as it is high throughput as there are many ISCs in one intestine, the ISC is the only cell in the lineage to undergo mitosis, and transgenes can be expressed in only the progenitor cells. I will take advantage of a two-color transgenic system to label old and new histones differentially and track their segregation during ISC division. My preliminary data suggest that H3 histones are segregated asymmetrically during the ACD of ISCs, while H3 histones are segregated symmetrically during SCD. In contrast, H2A histones are segregated symmetrically in both ACD and SCD. This suggests that H3 may be important for establishing different cell identities. To investigate the cellular and molecular mechanisms of histone inheritance, I will first look at old and new histone deposition in recently replicated sister chromatids and then study the segregation of the sister chromatids during mitosis. I will use a chromatin fiber technique to study the incorporation of histones following DNA replication in ISCs. I will then analyze components of the mitotic machinery that recognizes and segregates these epigenetically distinct sister chromatids during cell division. Further, I will investigate a mutation in the tail of the H3 histone, which has been previously found to cause aberrant histone inheritance and cellular defects such as tumors and tissue degeneration in the Drosophila germline. After characterizing the mechanism of H3 inheritance during cell division, I will investigate how H3 inheritance influences cell identity. To study this, I will examine the chromatin context at gene loci that are important for cell identity to determine if different chromatin contexts are established and inherited through cell division. I will also investigate gene expression in a wildtype and mutant H3 background to determine if mis-inheritance of H3 causes aberrant gene expression. This will provide understanding of how histones affect cell identity and the roles they may play in diseases such as cancer. The excellent research and training at Johns Hopkins University and in the Chen laboratory will allow me to both complete the proposed research and develop the skills necessary to pursue a career in academia.

项目摘要 需要细胞分裂并组织成组织。组织稳态的一种方法是成人的利用 能够通过不对称细胞分裂（ACD）来替代细胞的干细胞以产生新的干细胞和 一个区分细胞。对这种分裂的破坏会导致癌症或组织变性。虽然ACD是至关重要的部分 在组织稳态中，在此过程中指定两个独特的细胞身份涉及的基本机制是 未知。先前研究果蝇雄性种系ACD表观遗传机制的工作发现，通过 旧的H3组蛋白保留在新的H3组蛋白上，保留在新的H3干细胞中，而新的H3组蛋白保留了旧的H3组蛋白 优先隔离到分化细胞。 为了研究不对称组蛋白遗传是否是ACD的重要机制，我将研究组蛋白 果蝇的肠道干细胞（ISC）的遗传。 ISC经历ACD产生两个分化的细胞 类型，肠细胞和肠内分泌细胞。 ISC还能够进行对称细胞分裂（SCD）产生 两个ISC。 ISC谱系是研究组蛋白遗传的理想选择，因为它具有很高的吞吐量，因为一个ISC中有许多ISC 肠道，ISC是谱系中唯一经历有丝分裂的细胞，只能在祖细胞中表达转基因 细胞。我将利用一个两色的转基因系统来差异标签，并跟踪他们 ISC部门期间的隔离。我的初步数据表明，在 ISC的ACD，而H3组蛋白在SCD期间对称隔离。相反，H2A组蛋白被分离 在ACD和SCD中对称。这表明H3对于建立不同的细胞身份可能很重要。 为了研究组蛋白遗传的细胞和分子机制，我将首先看一下新旧组蛋白 在最近复制的姐妹染色单体中沉积，然后研究有丝分裂过程中姐妹染色单体的分离。我 将使用染色质纤维技术研究ISC中DNA复制后组蛋白的掺入。然后我会 分析有丝分裂机制的组件，这些组件识别并隔离了这些表观遗传差异的姐妹染色质被 在细胞分裂期间。此外，我将研究H3组蛋白尾部的突变，以前已发现该突变 引起异常的组蛋白遗传和细胞缺陷，例如果蝇种系中的肿瘤和组织变性。 在表征了细胞分裂过程中H3遗传的机理后，我将研究H3的遗传 影响细胞身份。为了研究这一点，我将检查基因基因座的染色质环境，这对于细胞身份很重要 确定是否通过细胞分裂建立和遗传了不同的染色质环境。我还将研究基因 在野生型和突变体H3背景中的表达以确定H3的误传是否引起异常基因表达。 这将提供对组蛋白如何影响细胞身份的理解以及它们在癌症等疾病中的作用。 约翰·霍普金斯大学和陈实验室的出色研究和培训将使我同时 完成拟议的研究，并发展从事学术界所需的技能。