Deciphering the Molecular Orchestrators of Heterochromatin-Lamina Interactions at the Nuclear Periphery

异染色质与核纤层相互作用的分子机制 外围。阿什利·M·卡内 摘要 已经确定，真核基因组在三维核空间内分离， 采用相对于特定核界标的亚核位置的特定基因组区域。这样的核 相关的标志是核周围的核层（NL）。特定基因在NL的定位 与异染色质相关的表观遗传特征的富集相关，例如赖氨酸的二甲基化 9对组蛋白H3（H3 K9 me 2）的作用，以及基因转录的抑制。外围设备的动态耦合 定位和基因沉默在指导关键的发育过程中起着关键作用， 心肌细胞谱系限制，并在心肌病和其他疾病的遗传形式中出错。 与NL接触的基因组区域被定义为核纤层相关结构域（LAD）。分布式 在所有染色体上，这些大的结构域与NL动态地相互作用，释放或附着基因， 根据细胞类型和分化状态特异性基因表达程序的调节元件。 具体地，LAD的丢失导致早熟的心脏分化。染色质与纤层的相互作用 建立和维护的机制仍然知之甚少。内源性编码序列足以 尚未鉴定出LAD的外周靶向，这强烈支持调节蛋白的存在， 表观遗传修饰或能够介导染色质-NL接触的生物分子过程。但 LAD和核外围之间的空间和时间动态的精确协调仍然是难以捉摸的。 通过将局部转录状态和表观遗传特征的靶向操作与单细胞 显微镜和基于群体的基因组学分析，我将测试的假设，异染色质- 相关的表观遗传标记H3 K9 me 2需要在核中保持隔离的基因组位点 而转录抑制用于建立染色质-纤层相互作用。这些 研究将提供关于染色质状态和基因活性如何与基因放射性结合的机理性见解。 定位通过在单细胞水平上探索外周染色质组织原则， 通过在种群水平上分析更高阶的基因组组织，我可以独特地剖析潜在的 调节基因组空间组织的机制。阐明了核组织， 人类发育和疾病病因学对于理解这些关系如何影响 器官形成和疾病

Deciphering the Molecular Orchestrators of Heterochromatin-Lamina Interactions at the Nuclear Periphery. Ashley M Karnay Abstract It is well established that the eukaryotic genome is segregated within three dimensional nuclear space, with specific genomic regions adopting subnuclear positions relative to specific nuclear landmarks. One such nuclear landmark associated is the nuclear lamina (NL) at the nuclear periphery. Positioning of specific genes at the NL correlates with enrichment in heterochromatin-associated epigenetic signatures, such as dimethylation of Lysine 9 on Histone H3 (H3K9me2), and repression of gene transcription. The dynamic coupling of peripheral positioning and gene silencing plays a key role in directing crucial developmental processes such as cardiomyocyte lineage restriction and goes awry in genetic forms of cardiomyopathy and other diseases. Genomic regions that make contact with the NL are defined as lamina-associated domains (LADs). Distributed across all chromosomes, these large domains dynamically interact with the NL to release or attach genes and regulatory elements in accordance with cell-type and differentiation state-specific gene expression programs. Specifically, loss of LADs results in precocious cardiac differentiation. How chromatin-lamina interactions are established and maintained remains poorly understood. Endogenously-encoded sequences sufficient for peripheral targeting of LADs have not been identified, strongly supporting the existence of regulatory proteins, epigenetic modifications or biomolecular processes capable of mediating chromatin-NL contacts. However, the precise orchestrators of spatial and temporal dynamics between LADs and the nuclear periphery remain elusive. By combining targeted manipulations of local transcriptional states and epigenetic signatures with single-cell microscopy and population-based genomics analysis I will test the hypothesis that the heterochromatin- associated epigenetic mark H3K9me2 is required to maintain sequestered genomic loci at the nuclear periphery while transcriptional repression serves to establish chromatin-lamina interactions. These studies will provide mechanistic insights into how chromatin states and gene activity are coupled to gene radial positioning. By probing peripheral chromatin organizational principles at the single-cell level while simultaneously analyzing higher-order genome organization at the population level, I can uniquely dissect the underlying mechanism mediating the spatial organization of the genome. Elucidating the link between nuclear organization, human development and disease etiology is crucial to understanding how these relationships impact organogenesis and disease.