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

破译核内异染色质-板层相互作用的分子协调器 外围设备。阿什利·M·卡奈 摘要 众所周知，真核生物基因组是在三维核空间内分离的，具有 特定基因组区域采用相对于特定核标志的亚核位置。一个这样的核子 相关的地标是位于核外围的核层(NL)。特定基因在NL的定位 与异染色质相关表观遗传特征的丰富有关，例如赖氨酸的二甲基化 9与组蛋白H3(H3K9me2)结合，抑制基因转录。外设的动态耦合 定位和基因沉默在指导关键的发育过程中发挥着关键作用，如 心肌细胞谱系受到限制，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板层相关结构域(LAD)。分布式 在所有染色体上，这些大的结构域动态地与NL相互作用，释放或连接基因和 调控元件根据细胞类型和分化状态制定特定的基因表达计划。 具体地说，LADS的丢失会导致心脏早熟分化。染色质-板层相互作用如何 建立和维护的机制仍然知之甚少。内源编码的序列足以 LAD的外周靶向尚未确定，这有力地支持了调节蛋白的存在， 能够调节染色质-NL接触的表观遗传修饰或生物分子过程。然而， LADS和核外围之间的空间和时间动态的精确协调者仍然难以捉摸。 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相结合 显微镜和基于群体的基因组分析我将测试异染色质- 相关的表观遗传标记H3K9me2需要在核上保持隔离的基因组座位 外周，而转录抑制用于建立染色质-板层相互作用。这些 研究将提供染色质状态和基因活性如何与基因辐射相关联的机械性见解 定位。通过在单细胞水平上探索外周染色质的组织原理，同时 在种群水平上分析更高级别的基因组组织，我可以唯一地剖析潜在的 调节基因组空间组织的机制。阐明了核组织之间的联系， 人类发育和疾病病因学对于理解这些关系如何影响至关重要 器官发生与疾病。

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.