The role of membrane protein phase separation in nuclear membrane sealing and fusion

膜蛋白相分离在核膜密封和融合中的作用

• 批准号: 506340646
• 负责人: Dr. Alexander von Appen
• 金额: --
• 依托单位: Max-Planck-Institut für molekulare Zellbiologie und Genetik (MPI-CBG)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/506340646?language=en
• 关键词: role; membrane; protein; phase; separation

Membrane remodeling is essential to life. The self-assembly of the nucleus at the end of vertebrate mitosis exemplifies how efficiently and robustly cells reshape membranes, even up to the point of building an entire organelle from solubilized pieces. Our recent work suggests that nuclear membrane reformation at the end of mitosis proceeds via the complete fusion of incoming sheets and tubules of the endoplasmic reticulum (ER) on the surface of decondensing chromatin – a prerequisite for nuclear compartmentalization – by coupling membrane protein phase separation to the work of the cell’s membrane fusion machinery endosomal sorting complexes required for transport-III (ESCRT-III). In this proposal, we aim to investigate the yet undefined structural and biophysical principles by which the condensed intrinsically disordered domain (IDD)-containing membrane proteins LEM2 and MAN1 recruit the structured ESCRT-III machinery protein CHMP7 to form filaments and seal and finally fuse the nuclear membrane to complete nuclear reformation. We will reconstitute the LEM2/MAN1-ESCRT-III pathway components on membranes to study their properties using cryo electron microscopy (cryo-EM) and biophysics. Established assays monitoring nuclear self-assembly in mitosis will allow us to validate our models in vivo. A growing body of work links the LEM2-ESCRT-III pathway, and potentially MAN1, to a variety of age-related pathologies underscoring its critical role for cellular physiology and its therapeutic potential. Generating a first mechanistic framework of how protein phase separation controls nuclear membrane assembly will hence not only address fundamental questions of membrane organelle self-organization but will also be of medical relevance.

膜重塑是生命的关键。脊椎动物有丝分裂末期细胞核的自我组装证明了细胞重塑细胞膜的效率和稳健性，甚至达到了从溶解的碎片构建整个细胞器的程度。我们最近的工作表明，核膜重组在有丝分裂结束后，通过完全融合的传入片和内质网（ER）的表面上的去致密染色质-核区室化的先决条件-通过耦合膜蛋白相分离的细胞的膜融合机器转运-III（ESCRT-III）所需的内体分选复合物的工作进行。在这个建议中，我们的目标是调查尚未确定的结构和生物物理原理，其中凝聚的内在无序结构域（IDD）含有膜蛋白LEM 2和MAN 1招聘结构ESCRT-III机器蛋白CHMP 7形成细丝和密封，并最终融合核膜，完成核改造。我们将在膜上重建LEM 2/MAN 1-ESCRT-III途径组分，使用冷冻电子显微镜（cryo-EM）和生物物理学研究其特性。有丝分裂中核自组装的检测方法将使我们能够在体内验证我们的模型。越来越多的工作将LEM 2-ESCRT-III通路和可能的MAN 1与各种年龄相关的病理学联系起来，强调其对细胞生理学及其治疗潜力的关键作用。因此，产生蛋白质相分离如何控制核膜组装的第一个机械框架不仅解决了膜细胞器自组织的基本问题，而且还具有医学意义。