Molecular Basis of Centromere Specification and Inheritance

着丝粒规格和遗传的分子基础

• 批准号: 10334471
• 负责人: Fei Li
• 金额: $ 39.22万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10334471
• 关键词: Address; Affect; Aneuploidy; Animal Model; Biochemistry; Cell Cycle; Cell division; Cells; Cellular Structures; Centromere; Chromatin; Chromosome Segregation; Chromosomes; Cytology; DNA biosynthesis; Daughter; Development; Diagnosis; Disease; Down Syndrome; Ensure; Epigenetic Process; Eukaryota; Eukaryotic Cell; Fission Yeast; Foundations; Functional disorder; Gene Silencing; Genetic; Genome; Genomics; Goals; Heterochromatin; Histone H3; Human; Kinetochores; Knowledge; Lead; Light; Link; Malignant Neoplasms; Meiosis; Mitosis; Molecular; Normal Cell; Process; Regulation; Role; Ubiquitin-mediated Proteolysis Pathway; Variant; centromere protein A; chromosome number abnormality; daughter cell; design; epigenetic regulation; human disease; insight; interdisciplinary approach; prevent; segregation; structural biology

PROJECT SUMMARY/ABSTRACT A fundamental but poorly understood process in eukaryotic cells is how cells structure their genomes into distinct functional domains. This project addresses this gap in knowledge by studying the centromere, a specific chromatin domain found in all eukaryotes. This stably propagated locus guides the assembly of kinetochores to ensure proper segregation of chromosomes during mitosis and meiosis. Mis-regulation of centromeres adversely affects chromosome segregation resulting in aneuploidy, a condition found in more than 90% of all cancers. Aneuploidy contributes to the development of many diseases, such as cancer and Down syndrome. The goal of this project is to understand the molecular mechanisms underlying the specification and inheritance of centromeres. In most eukaryotes, centromeres are epigenetically governed by the centromere-specific histone H3 variant, CENP-A. CENP-A partially replaces canonical histone H3 at centromeres, and provides the foundation for the assembly of kinetochores. Centromeres are usually embedded in epigenetically distinct heterochromatin, the transcriptionally silenced chromatin domain. Assembly of CENP-A at centromeres is cell cycle-regulated. Parental CENP-A is partitioned equally among daughter centromeres following DNA replication, whereas loading of newly synthesized CENP-A to centromeres is uncoupled from DNA replication. How CENP-A chromatin at centromeres is assembled throughout the cell cycle remains poorly understood. Mislocalization of CENP-A to non-centromeric regions has a devastating impact on chromosome segregation, and has been linked to a variety of cancers. Ubiquitin- mediated proteolysis of CENP-A is a conserved mechanism to prevent CENP-A mislocalization. But how non- centromeric regions are protected from CENP-A mis-incorporation in normal cells is largely unexplored. In addition, CENP-A in centromeres is interspersed with the canonical histone H3. The histone H3 within centromeres is actually vital for proper assembly of CENP-A chromatin. How CENP-A and H3 levels are properly balanced in centromeres is unknown. We propose to use fission yeast (Schizosaccharomyces pombe) to address these outstanding questions. Fission yeast is a simple eukaryotic model organism with many aspects of centromere regulation conserved with humans. It is particularly suited to an interdisciplinary approach that includes genetics, genomics, cytology, biochemistry, and structural biology. We propose to: 1) define the mechanisms underlying cell cycle-dependent CENP-A assembly at centromeres, 2) determine how formation of ectopic CENP-A chromatin is prevented, 3) identify regulatory mechanism for how CENP-A and histone H3 levels are balanced at centromeres. Our study also provides important new insights into the role of heterochromatin in centromere function. Given that epigenetic regulation in fission yeast is conserved, our studies will shed light on the processes governing chromosome segregation in human cells, and contribute to a better understanding of human diseases resulting from centromere misregulation.

项目概要/摘要 真核细胞中一个基本但知之甚少的过程是细胞如何将其基因组构建成 不同的功能域。该项目通过研究着丝粒（一种 所有真核生物中都存在特定的染色质结构域。这个稳定传播的轨迹引导组装 着丝粒确保有丝分裂和减数分裂过程中染色体的正确分离。监管不当 着丝粒对染色体分离产生不利影响，导致非整倍性，这是一种在更多情况下发现的情况 超过 90% 的癌症。非整倍体导致许多疾病的发生，例如癌症和 唐氏综合症。该项目的目标是了解潜在的分子机制 着丝粒的规范和遗传。在大多数真核生物中，着丝粒受表观遗传控制 着丝粒特异性组蛋白 H3 变体，CENP-A。 CENP-A 部分取代经典组蛋白 H3 着丝粒，并为着丝粒的组装提供基础。着丝粒通常是 嵌入表观遗传上独特的异染色质中，即转录沉默的染色质结构域。 CENP-A 在着丝粒上的组装受细胞周期调节。亲本 CENP-A 平均分配 DNA复制后的子体着丝粒，而将新合成的CENP-A加载到 着丝粒与 DNA 复制脱钩。着丝粒处的 CENP-A 染色质如何组装 对整个细胞周期的了解仍知之甚少。 CENP-A 错误定位到非着丝粒区域 对染色体分离具有毁灭性影响，并与多种癌症有关。泛素- CENP-A 介导的蛋白水解是防止 CENP-A 错误定位的保守机制。但如何非 正常细胞中着丝粒区域是否受到 CENP-A 错误掺入的保护在很大程度上尚未被探索。在 此外，着丝粒中的 CENP-A 散布有典型的组蛋白 H3。内的组蛋白 H3 着丝粒实际上对于 CENP-A 染色质的正确组装至关重要。 CENP-A 和 H3 水平如何 着丝粒的适当平衡尚不清楚。我们建议使用裂殖酵母（Schizosaccharomyces pombe） 来解决这些悬而未决的问题。裂殖酵母是一种简单的真核模型生物，具有许多 人类保守的着丝粒调控方面。它特别适合跨学科 方法包括遗传学、基因组学、细胞学、生物化学和结构生物学。我们建议：1) 定义着丝粒上细胞周期依赖性 CENP-A 组装的机制，2) 确定如何 防止异位 CENP-A 染色质的形成，3) 确定 CENP-A 和 组蛋白 H3 水平在着丝粒处保持平衡。我们的研究还为我们的作用提供了重要的新见解 着丝粒功能中的异染色质。鉴于裂殖酵母的表观遗传调控是保守的，我们的 研究将揭示人类细胞中控制染色体分离的过程，并有助于 更好地了解由着丝粒失调引起的人类疾病。