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 细胞需要分裂和组织成组织。组织稳态的一种方法是利用成体细胞， 能够通过经历不对称细胞分裂（ACD）来替代细胞以产生更新的干细胞的干细胞， 一种分化细胞这种分裂的破坏可能导致癌症或组织变性。虽然ACD是一个重要的组成部分， 在组织内稳态中，在此过程中指定两种独特细胞身份的潜在机制是 未知先前研究果蝇雄性生殖系ACD的表观遗传机制的工作发现， 区别地标记旧的和新的组蛋白，旧的H3组蛋白保留在更新的干细胞中，而新的H3组蛋白 优先分离到分化细胞。 为了研究组蛋白不对称遗传是否是ACD的重要机制，我将研究组蛋白 果蝇肠道干细胞（ISCs）的遗传。ISC经历ACD以产生两种分化的细胞， 类型，肠上皮细胞和肠内分泌细胞。ISC还能够进行对称细胞分裂（SCD）以产生 两个ISC。ISC谱系是研究组蛋白遗传的理想方法，因为它是高通量的，因为一个细胞中有许多ISC 在肠中，ISC是谱系中唯一经历有丝分裂的细胞，并且转基因只能在祖细胞中表达。 细胞我将利用双色转基因系统来区别标记新旧组蛋白，并追踪它们的表达。 ISC分裂期间的分离。我的初步数据表明，H3组蛋白是不对称分离的， ACD的ISCs，而H3组蛋白的分离在SCD对称。相反，H2A组蛋白是分离的， 在ACD和SCD两者中对称。这表明H3可能对建立不同的细胞身份很重要。 为了研究组蛋白遗传的细胞和分子机制，我将首先研究新旧组蛋白 沉积在最近复制的姐妹染色单体中，然后研究有丝分裂期间姐妹染色单体的分离。我 将使用染色质纤维技术来研究组蛋白在ISCs中DNA复制后的掺入。然后我将 分析识别和分离这些表观遗传学上不同的姐妹染色单体的有丝分裂机制的组成部分 在细胞分裂期间。此外，我将研究H3组蛋白尾部的突变，以前已经发现它 在果蝇种系中引起异常的组蛋白遗传和细胞缺陷，如肿瘤和组织变性。 在描述了细胞分裂过程中H3遗传的机制之后，我将研究H3遗传如何在细胞分裂过程中发生。 影响细胞的特性。为了研究这一点，我将检查对细胞身份很重要的基因位点的染色质背景 以确定不同的染色质环境是否通过细胞分裂建立和遗传。我也会调查吉恩 在野生型和突变体H3背景中的表达，以确定H3的错误遗传是否引起异常基因表达。 这将有助于了解组蛋白如何影响细胞特性以及它们在癌症等疾病中可能发挥的作用。 在约翰霍普金斯大学和陈的实验室的出色的研究和培训将使我既 完成拟议的研究，并发展必要的技能，以追求在学术界的职业生涯。