Role and regulation of heterochromatin proteins in the functional organization of the mammalian nucleus

蛋白质和核酸在细胞核中不是自由扩散的，而是在没有分裂膜的情况下形成的动态高阶结构和亚核室中组织起来的。由于这些亚核区室通常与转录，RNA加工和DNA复制等核功能相关，这些观察导致了细胞核功能组织的概念。我们之前已经确定了几个表观遗传调节剂，有助于这种功能组织，并确定了负责调节的蛋白质结构域。此外，我们还通过荧光光漂白/活化和单分子跟踪来探测它们在细胞核中的迁移率。最近，我们发现HP1 β和Mecp2也在体外形成相分离的液滴。我们现在要确定促进或阻止液滴形成的参数。此外，我们希望研究异染色质蛋白HP1 β和Mecp2在体外形成相分离液滴的能力如何有助于细胞核的功能组织，翻译后修饰或相互作用因子如何调节这一过程，以及这一特性对细胞核功能调节的功能后果。

Proteins and nucleic acids are not freely diffusing in the nucleus but are organized in dynamic higher order structures and subnuclear compartments that form in the absence of dividing membranes. As these subnuclear compartments often correlate with nuclear functions like transcription, RNA processing and DNA replication, these observations led to the concept of the functional organization of the nucleus.We have previously identified several epigenetic regulators that contribute to this functional organization and have identified the responsible regulatory protein domains. Furthermore, we have probed their mobility in the nucleus by fluorescence photobleaching/activation and single molecule tracking.Most recently, we found that HP1 beta and Mecp2 also form phase separated droplets in vitro. We now want to determine the parameters that either promote or prevent droplet formation. Moreover, we want to investigate how the ability of the heterochromatin proteins HP1 beta and Mecp2 to form phase separated droplets in vitro contributes to the functional organization of the nucleus, how posttranslational modifications or interacting factors modulate this process and what functional consequences this property has for the regulation of nuclear functions.