Unravelling the functional role of the “epigenetic reader” MRG-1 in the spatial organization of the C. elegans genome

染色质福尔斯根据其转录状态分为两大类：活性常染色质和转录抑制和压实的异染色质。在物种之间，常染色质和异染色质的空间分布不是随机的，并且使得基因组的功能区室化成为可能。特别是，沉默的异染色质活跃地被隔离在核周边，而活跃的常染色质位于中央。尽管如此惊人的进化保守性，异染色质的空间隔离在多大程度上有助于基因组功能还没有完全理解。为了正式解决这一问题，需要确定产生核亚区室的因素和机制，并阐明其对基因表达的干扰后果。在我最近的博士后工作中，我确定了MRG-1，活性染色质区室的第一个组成部分，显示出对塑造异染色质在肠道中的空间分布至关重要。优雅尽管如此，关于如何进行这一监管的基本问题仍然悬而未决。特别是，MRG-1带有一个染色体桶结构域，可以“读取”甲基化组蛋白。然而，决定MRG-1募集和功能的染色质信号尚不清楚。此外，染色质阅读器并不单独起作用，并且通常充当复合物到靶位点的募集者。然而，负责异染色质组织的MRG-1复合物是完全未知的。在这个建议中，我们的目标是确定i）组蛋白标记，和相应的染色质修饰剂，参与MRG-1的招聘，并有助于其在异染色质结构中的作用，ii）MRG-1在异染色质组织中发挥作用的复合物/蛋白质相互作用，在C。为了实现我们的目标，我的团队将采用显微镜、遗传学和生物化学方法相结合的方法。此外，Emerin-DamID和RNAseq等最先进的分子生物学测定将为我们提供相关突变体肠道中染色质区室化和基因表达的综合景观。通过这项工作，我们将确定在整个生物体的分化组织中塑造基因组3D组织的新角色。此外，我们将能够确定它们与基因表达的相关性，在组织特异性水平上，因为MRG-1和大多数染色质因子在蠕虫和哺乳动物之间是高度保守的，这项工作很可能在表观遗传学和核结构领域产生广泛的影响。

Largely based on its transcriptional status, chromatin falls into two main classes: active euchromatin and transcriptionally repressed and compacted heterochromatin. Across species, the spatial distribution of euchromatin and heterochromatin is not random and enables a functional compartmentalization of the genome. In particular, silent heterochromatin is actively sequestered at the nuclear periphery, while active euchromatin is centrally located. Despite such a striking evolutionary conservation, to which degree the spatial sequestration of heterochromatin contributes to genome function is not fully understood. To formally address this, the factors and mechanisms that generate nuclear sub-compartments need to be identified and the consequences of their perturbation for gene expression must be elucidated.During my recent postdoctoral work, I identified MRG-1, the first component of the active chromatin compartment shown to be a critical for shaping heterochromatin spatial distribution in the intestine of C. elegans. Nonetheless, fundamental open questions remain as to how this regulation takes place. In particular, MRG-1 bears a chromo barrel domain that can “read” methylated histones. Yet, the chromatin signals that determine MRG-1 recruitment and function are not known. Furthermore, chromatin readers do not act alone and typically serve as recruiters of complexes to target sites. However, the MRG-1-containing complex responsible for heterochromatin organization is completely unknown.In this proposal, we aim to identify i) the histone marks, and corresponding chromatin modifiers, that participate in MRG-1 recruitment and contribute to its role in heterochromatin architecture and ii) the complex/protein interactors through which MRG-1 functions in heterochromatin organization, in the C. elegans intestine.To achieve our goals, my team will employ a combination of microscopy, genetic and biochemical approaches. Moreover, state-of-the-art molecular biology assays such as Emerin-DamID and RNAseq will provide us with integrated landscapes of chromatin compartmentalization and gene expression in the intestine of relevant mutants. With this work, we will identify novel players that shape the 3D organization of the genome within a differentiated tissue of a whole organism. Additionally, we will be able to determine their relevance for gene expression, at the tissue-specific level.Because MRG-1 and most chromatin factors are highly conserved between worms and mammals, this work is likely to have a broad impact in the field of epigenetics and nuclear architecture.