非中心体微管自身调控机制以及其调控胞内细胞器定位的分子机制的研究

微管作为细胞骨骼的一个重要成员，对维持细胞以至机体的正常的生理功能有不可缺少的作用。微管分为中心体微管与非中心体微管。由于非中心体微管具有很高的动态特征，难以观察，目前对非中心体微管的认识和研究非常有限。在近来的研究中，我们首次发现了非中心体微管负端蛋白并命名为 Nezha。前期研究结果表明，Nezha显示出了对非中心体微管的负端安定机制的维持起着至关重要的作用，利用此蛋白不仅可以标识非中心体微管，与中心体微管进行区分，还为我们继续深入研究非中心体微管提供了一个难得的切入点。同时，我们研究发现Nezha家族蛋白不仅对于非中心体微管的安定有重要的作用，在其敲降细胞中还发现高尔基体、线粒体和内质网等细胞小器官的定位异常，因此，我们拟通过其作为模型来进一步研究非中心体微管的功能。. 本项研究目标在于揭示非中心体微管在细胞内的功能的分子机制，为研究其在机体中的作用打下基础。

In animal cells, two populations of microtubules, centrosomal and non-centrosomal, are detected at the interphase of cell cycle. Centrosomal microtubules are radially nucleated from the centrosome via the??-tubulin ring complex, with their minus ends anchored to this subcellular structure. Their plus ends, on the other hand, are subjected to dynamic instability, and the stability of the plus ends is regulated by +TIPs or plus-end tracking proteins. Non-centrosomal microtubules are produced by various mechanisms, and their minus ends are located in the cytoplasm. How these minus ends are stabilized is, however, little understood. A centrosomal protein, ninein, has been shown to relocate into the non-centrosomal sites, and anchors MT minus ends there. Recent studied identified novel proteins that bind to the minus ends, Nezha and Drosophila Patronin, which are structurally related to one another. It was shown that Nezha tethers non-centrosomal microtubules to the cell junctions, although a non-junctional cytoplasmic population of Nezha/CAMSAP was also detectable; and Patronin can stabilize the minus ends by protecting them against Kinesin 13-mediated depolymerization. .In the present study, we analyzed the functions of Nezha, whi, using Caco2 epithelial cells. We found that Nezha is important for nucleating non-centrosomal microtubules. Depletion of Nezha affected microtubule assembly, causing an increase of centrosomal microtubules. In Nezha depleted cells, the Golgi apparatus was fragmented, and other organelles, such as mitochondria and endosomes, also displayed altered distributions. Further analysis revealed that Nezha depletion caused the suppression of active migration of ERGIC components between Golgi and ERES. From these observations, we conclude that the Nezha fimily/CAMSAPs-tethered microtubules play a crucial role for organelle assembly, whose actions are distinct from those of centrosomal microtubules. In future studies, we are going to deepen the current findings and to study the molecular mechanisms of its regulation.