Dissecting the principles guiding CTCF condensate formation in cellular ageing

人类细胞复制潜力的耗尽标志着它们致力于细胞周期停滞的不可逆转状态，即衰老。进入衰老，细胞保持代谢活跃，也伴随着基因表达和3D染色质结构的戏剧性变化。这些变化中最值得注意的是CTCF--3D染色质结构域的关键组织者--聚集成由衰老诱导的大型凝聚体。虽然相分离类型的力现在与核体(例如，斑点)和亚室(例如，核仁)的形成有关，但这构成了对染色质组织的特定老化效应的第一个例子。有了这个建议，我们提供了初步的证据，证明CTCF团簇确实是在斑点附近成核的凝聚体，并且只有在衰老时才会成核，我们接着提出了生化、功能和基因组学分析的组合，并辅之以计算机模拟，以机械地剖析它们的出现。我们还假设这些衰老诱导的CTCF簇(SICCs)的形成是为了保护特定的基因座免受过度的DNA损伤，并提出了检验这一假说的工作。最终，我们预计将获得对衰老如何改变细胞机制和相分离力重新连接人类基因组的分子理解。该项目与SPP2191优先事项非常一致，并将从与德国这一新兴研究社区的互动中受益。

Exhaustion of the replicative potential of human cells signals their commitment to an irreversible state of cell cycle arrest known as senescence. Entry into senescence, where cells remain metabolically active, is also accompanied by dramatic changes in gene expression and 3D chromatin architecture. The most notable of these changes is the clustering of CTCF – a key organizer of 3D chromatin domains – into large senescence-induced condensates. Although phase separation-type forces have now been implicated in the formation of nuclear bodies (e.g., speckles) and subcompartments (e.g., nucleoli), this constitutes the first example of an ageing-specific effect on chromatin organization. With this proposal, we present preliminary evidence that CTCF clusters are indeed condensates that nucleate in close proximity to speckles and only upon senescence, and we go on to propose a combination of biochemical, functional and genomics assays, complemented by in silico modelling, to mechanistically dissect their emergence. We also hypothesize that these senescence-induced CTCF clusters (SICCs) form to shield particular loci from excessive DNA damage, and propose work to test this hypothesis. In the end, we anticipate obtain a molecular understanding of how senescence repurposes the cellular machinery and phase separation forces to rewire the human genome. This project aligns well with the SPP2191 priorities and will benefit from interactions with this emerging research community in Germany.