Abstract：
The Ran-GTP/importin β pathway has been implicated in a diverse array of mitotic functions in somatic mitosis; however, the possible meiotic roles of Ran-GTP/importin β in mammalian oocyte meiosis are still not fully understood. In the present study, importazole (IPZ), a small molecule inhibitor of the interaction between Ran and importin β was used to explore the potential meiotic roles of Ran-GTP/importin β in porcine oocytes undergoing meiosis. After IPZ treatment, the extrusion rate of the first polar body (PB1) was significantly decreased, and a higher proportion of the oocytes were arrested at the germinal vesicle breakdown (GVBD) stage. Moreover, IPZ treatment led to severe defects in metaphase I (MI) spindle assembly and chromosome alignment during the germinal vesicle (GV)-to-MI stage, as well as failure of metaphase II (MII) spindle reassembly and homologous chromosome segregation during the MI-to-MII stage. Notably, IPZ treatment decreased TPX2 expression and abnormal subcellular localization. Furthermore, the expression levels of aurora kinase A (AURKA) and transforming acidic coiled-coil 3 (TACC3) were significantly reduced after IPZ treatment. Collectively, these data indicate that the interaction of Ran-GTP and importin β is essential for proper spindle assembly and successful chromosome segregation during two consecutive meiotic divisions in porcine oocytes, and regulation of this complex might be related to its effect on the TPX2 signaling cascades.
摘要：
Ran-GTP/importinβ途径与体细胞有丝分裂的多种有丝分裂功能有关；然而，Ran-GTP/importinβ在哺乳动物卵母细胞减数分裂中的可能减数分裂作用尚不完全清楚。在本研究中,进口唑（IPZ），使用Ran和importinβ相互作用的小分子抑制剂来探索Ran-GTP/importinβ在正在进行减数分裂的猪卵母细胞中的潜在减数分裂作用。IPZ治疗后，第一极体(PB1)的挤出率显著下降，并且更高比例的卵母细胞在生发囊泡破裂（GVBD）阶段被阻滞。此外，IPZ治疗导致生发囊泡（GV）至MI期中期I（MI）纺锤体组装和染色体排列严重缺陷，以及MI到MII阶段中期II（MII）纺锤体重组和同源染色体分离的失败。值得注意的是,IPZ处置下降TPX2表达和亚细胞定位异常。此外，IPZ处理后，极光激酶A（AURKA）和转化酸性卷曲螺旋3（TACC3）的表达水平显着降低。总的来说，这些数据表明，Ran-GTP和导入蛋白β的相互作用对于猪卵母细胞连续两次减数分裂过程中正确的纺锤体组装和成功的染色体分离至关重要，并且该复合物的调节可能与其对TPX2信号级联的影响有关。
