Defining the regulation of repressive epigenetic marks by the ubiquitin-conjugating enzyme UBE2K and its impact on cell fate decisions and organismal aging

定义泛素结合酶 UBE2K 对抑制性表观遗传标记的调节及其对细胞命运决定和生物体衰老的影响

• 批准号: 264352640
• 负责人: Professor Dr. David Vilchez
• 金额: --
• 依托单位: Institut für Genetik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/264352640?language=en
• 关键词: Defining; regulation; repressive; epigenetic; marks

The development and survival of an organism are linked to its ability to maintain the integrity of the cellular proteome. Human embryonic stem cells (hESCs) are immortal in culture. This capacity demands avoidance of any imbalance in protein homeostasis (proteostasis) that would otherwise compromise hESC identity. We have found that hESCs exhibit increase levels of UBE2K, an E2 enzyme that regulates protein ubiquitination. Notably, UBE2K is required for neuronal differentiation of hESCs. Interestingly, we found that UBE2K binds to histone H3.3 and regulates its ubiquitination. Moreover, loss of UBE2K changes the epigenetic landscape of hESCs by inducing trimethylation of H3K9. Although the histone code has a critical role in chromatin and gene regulation, the molecular mechanisms that modulate the unique chromatin pattern of hESCs remain largely unknown. Here we will seek to define how modulation of H3K9 trimethylation by UBE2K impinges upon neurogenesis of hESCs. Since cell reprogramming involves a marked reorganization of chromatin, we will examine whether changes in UBE2K levels alter the H3K9me3 landscape of somatic cells and facilitate cell reprogramming. Given the importance of histone modifications in cell function, we will define the molecular mechanisms by which UBE2K regulates H3K9 trimethylation. Epigenetic changes are not only a determinant of development but also a hallmark of aging. H3K9me3 epigenetic modifications are downregulated during the aging process. Most importantly, the epigenetic landscape can be modulated to extend lifespan in model organisms such as C. elegans. These findings highlight the role of epigenetic dysregulation as a driver of mammalian aging. Thus, defining novel modulators of age-associated epigenetic marks may provide further insights into aging research. Interestingly, we have observed that loss of UBE2K triggers H3K9me3 levels in C. elegans. We will examine whether modulation of UBE2K is sufficient to extend longevity and ameliorate the downregulation of H3K9me3 associated to biological aging. Finally, we will perform a RNAi screen to define how UBE2K modulates trimethylation of H3K9 in vivo. Thus, our experiments can define the interconnectedness between two tentative hallmarks of aging (i.e., loss of proteostasis, epigenetic changes) and uncover novel mechanisms to slow down the aging process. Taken together, our research proposal can have a big impact in several fields such as stem cell research, cell therapy, aging and age-related diseases.

生物体的发育和生存与其维持细胞蛋白质组完整性的能力有关。人类胚胎干细胞 (hESC) 在培养中是永生的。这种能力要求避免蛋白质稳态（蛋白质稳态）的任何不平衡，否则会损害 hESC 的特性。我们发现 hESC 的 UBE2K 水平增加，UBE2K 是一种调节蛋白质泛素化的 E2 酶。值得注意的是，UBE2K 是 hESC 神经元分化所必需的。有趣的是，我们发现 UBE2K 与组蛋白 H3.3 结合并调节其泛素化。此外，UBE2K 的缺失会诱导 H3K9 三甲基化，从而改变 hESC 的表观遗传景观。尽管组蛋白密码在染色质和基因调控中发挥着关键作用，但调节 hESC 独特染色质模式的分子机制仍然很大程度上未知。在这里，我们将寻求定义 UBE2K 对 H3K9 三甲基化的调节如何影响 hESC 的神经发生。由于细胞重编程涉及染色质的显着重组，因此我们将检查 UBE2K 水平的变化是否会改变体细胞的 H3K9me3 景观并促进细胞重编程。鉴于组蛋白修饰在细胞功能中的重要性，我们将定义 UBE2K 调节 H3K9 三甲基化的分子机制。表观遗传变化不仅是发育的决定因素，也是衰老的标志。 H3K9me3 表观遗传修饰在衰老过程中下调。最重要的是，可以调节表观遗传景观以延长模型生物（如秀丽隐杆线虫）的寿命。这些发现强调了表观遗传失调作为哺乳动物衰老驱动因素的作用。因此，定义与年龄相关的表观遗传标记的新型调节剂可能会为衰老研究提供进一步的见解。有趣的是，我们观察到 UBE2K 的缺失会触发线虫中的 H3K9me3 水平。我们将研究 UBE2K 的调节是否足以延长寿命并改善与生物衰老相关的 H3K9me3 下调。最后，我们将进行 RNAi 筛选，以确定 UBE2K 如何在体内调节 H3K9 三甲基化。因此，我们的实验可以定义衰老的两个暂时标志（即蛋白质稳态丧失、表观遗传变化）之间的相互关联，并揭示减缓衰老过程的新机制。总而言之，我们的研究计划可以在干细胞研究、细胞治疗、衰老和与年龄相关的疾病等多个领域产生重大影响。