Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, Prague, Czech Republic.
Department of Cell Biology, Faculty of Science, Charles University, Prague, Viničná 7, Czech Republic.
Sci Rep. 2019 Apr 5;9(1):5725. doi: 10.1038/s41598-019-42056-6.
Microtubules of all eukaryotic cells are formed by α- and β-tubulin heterodimers. In addition to the well known cytoplasmic tubulins, a subpopulation of tubulin can occur in the nucleus. So far, the potential function of nuclear tubulin has remained elusive. In this work, we show that α- and β-tubulins of various organisms contain multiple conserved nuclear export sequences, which are potential targets of the Exportin 1/CRM1 pathway. We demonstrate exemplarily that these NES motifs are sufficient to mediate export of GFP as model cargo and that this export can be inhibited by leptomycin B, an inhibitor of the Exportin 1/CRM1 pathway. Likewise, leptomycin B causes accumulation of GFP-tagged tubulin in interphase nuclei, in both plant and animal model cells. Our analysis of nuclear tubulin content supports the hypothesis that an important function of nuclear tubulin export is the exclusion of tubulin from interphase nuclei, after being trapped by nuclear envelope reassembly during telophase.
所有真核细胞的微管都是由α-和β-微管蛋白异二聚体组成的。除了众所周知的细胞质微管外，微管蛋白的一个亚群也可以存在于细胞核中。到目前为止，核微管的潜在功能仍然难以捉摸。在这项工作中，我们表明，各种生物体的α-和β-微管蛋白含有多个保守的核输出序列，这些序列可能是 Exportin 1/CRM1 途径的靶标。我们举例证明，这些 NES 基序足以介导 GFP 作为模型货物的输出，并且这种输出可以被 Exportin 1/CRM1 途径的抑制剂莱普霉素 B 抑制。同样，莱普霉素 B 导致 GFP 标记的微管蛋白在间期核中的积累，在植物和动物模型细胞中都是如此。我们对核微管蛋白含量的分析支持了这样一种假设，即核微管蛋白输出的一个重要功能是在有丝分裂末期核膜重新组装时将微管蛋白从间期核中排除出去。
