Microtubules are polymers of α/β-tubulin, with microtubule organization being regulated by microtubule-associated proteins (MAPs). Herein, we describe a novel role for the epithelial gene repressor, zinc finger E-box-binding homeobox 1 (ZEB1), that "switches" from a chromatin-associated protein during interphase, to a MAP that associates with α-, β- and γ-tubulin during mitosis. Additionally, ZEB1 was also demonstrated to associate with γ-tubulin at the microtubule organizing center (MTOC). Using confocal microscopy, ZEB1 localization was predominantly nuclear during interphase, with α/β-tubulin being primarily cytoplasmic and the association between these proteins being minimal. However, during the stages of mitosis, ZEB1 co-localization with α-, β-, and γ-tubulin was significantly increased, with the association commonly peaking during metaphase in multiple tumor cell-types. ZEB1 was also observed to accumulate in the cleavage furrow during cytokinesis. The increased interaction between ZEB1 and α-tubulin during mitosis was also confirmed using the proximity ligation assay. In contrast to ZEB1, its paralog ZEB2, was mainly perinuclear and cytoplasmic during interphase, showing some co-localization with α-tubulin during mitosis. Considering the association between ZEB1 with α/β/γ-tubulin during mitosis, studies investigated ZEB1's role in the cell cycle. Silencing ZEB1 resulted in a G2-M arrest, which could be mediated by the up-regulation of p21Waf1/Cip1 and p27Kip1 that are known downstream targets repressed by ZEB1. However, it cannot be excluded the G2/M arrest observed after ZEB1 silencing is not due to its roles as a MAP. Collectively, ZEB1 plays a role as a MAP during mitosis and could be functionally involved in this process.

中文翻译：

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在有丝分裂期间，ZEB1从“与染色质结合的上皮基因阻遏物”“转换”为微管相关蛋白。

微管是α/β-微管蛋白的聚合物，微管的组织受微管相关蛋白（MAP）的调控。在本文中，我们描述了上皮基因阻遏物锌指E-box-homeobox 1（ZEB1）的新作用，它在相间期从染色质相关蛋白“切换”到与α-，β-和有丝分裂期间的γ-微管蛋白。此外，ZEB1在微管组织中心（MTOC）也被证明与γ-微管蛋白相关。使用共聚焦显微镜，在相间期，ZEB1的定位主要为核，α/β-微管蛋白主要为细胞质，而这些蛋白之间的关联最小。但是，在有丝分裂阶段，ZEB1与α-，β-和γ-微管蛋白的共定位显着增加，在多种肿瘤细胞类型的中期，这种关联通常会达到顶峰。还观察到ZEB1在胞质分裂过程中积累在切割沟中。使用邻近结扎法也证实了有丝分裂期间ZEB1和α-微管蛋白之间的相互作用增加。与ZEB1相反，它的旁系同源物ZEB2在相间期主要为核周和细胞质，在有丝分裂期与α-微管蛋白共定位。考虑到有丝分裂期间ZEB1与α/β/γ-微管蛋白之间的关联，研究调查了ZEB1在细胞周期中的作用。沉默ZEB1导致G2-M停滞，这可能是由p21Waf1 / Cip1和p27Kip1的上调介导的，p21Waf1 / Cip1和p27Kip1是ZEB1抑制的下游靶标。但是，不能排除ZEB1沉默后观察到的G2 / M停滞不是由于其作为MAP的作用。