Katanin调节G2/M期微管重构和抑制中心粒过度复制的分子机制研究

Microtubules have fundamental roles in many essential biological processes, including intracellular transport and cell division. During the transition from G2 to M phase, microtubule cytoskeleton remodeling is accomplished through disassembly of interphase microtubules and assembly of bipolar mitotic spindle. However, little is known about the molecular mechanisms that govern disassembly of interphase microtubules, especially those stable ones, upon entry into mitosis. The precise assembly of mitotic spindle relies on accurate centriole duplication. Centriole overduplication could result in formation of multipolar spindle and lead to defects of chromosome segregation. Although the signaling pathway of centriole duplication has been extensively studied, the mechanisms restricting centriole overduplication are poorly understood. Our unpublished preliminary results have demonstrated that microtubule severing protein katanin plays important roles in both clearing interphase stable microtubule and inhibiting centriole overduplication. In this project we will investigate the function and mechanism of katanin during these two processes in detail through a combination of live-cell imaging, in vitro reconstitution assays and genome editing in cells. This study will shed new light on how katanin severs cellular microtubules, define a new katanin related signaling pathway of centriole duplication and contribute to a better understanding of cell division.

微管骨架参与了许多关键的生物学过程，如胞内运输和细胞分裂。在从间期到有丝分裂期转换（G2/M）的过程中微管骨架发生重构，包括原有间期微管解聚和有丝分裂期双极纺锤体的组装。目前对于间期稳定微管如何在进入有丝分裂期之前完全清除的机理知之甚少。此外，纺锤体的正确组装依赖于中心粒的精确复制，其过度复制会导致多极纺锤体形成进而影响染色体分离。虽然现在对于中心粒复制的信号通路有较多研究，但对于抑制中心粒过度复制分子机制的解析还不详尽。我们预实验结果初步表明微管切割蛋白katanin在清除间期稳定微管和抑制中心粒过度复制这两方面均发挥关键作用。我们将利用活细胞实时成像、体外重组和基因编辑等方法深入探讨katanin在这两方面的详实功能及分子机制。我们希望通过本项目进一步揭示细胞内katanin切割微管的工作机理并描绘出一条全新的调节中心粒复制的信号通路，从而提升我们对于细胞分裂这一生命基本过程的理解。

微管骨架在囊泡运输和细胞分裂等过程中起到至关重要的作用，而微管骨架的形态和动态性受到大量微管结合蛋白的调控。在本项目资助下，我们主要围绕微管切割蛋白katanin展开研究。鉴定高尔基微管结合蛋白MTCL2和蛋白激酶NEK1为katanin新的接头蛋白。揭示了katanin一方面通过MTCL2调节微管重构和囊泡运输过程，一方面通过NEK1抑制中心体过度复制，并阐明了具体分子机制。此外，另一在中心体复制过程中发挥关键作用的蛋白复合物γ-TuRC也是本项目的研究对象。我们深入阐述了γ-TuRC如何与其招募因子 augmin复合物协同促进微管分支成核过程的分子机制。此项目在分子机制层面加深了我们对于多个微管骨架相关生命过程的理解。