Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
Regenerative Biosciences Center (RBC), University of Georgia, Athens, Georgia, USA.
Reproduction. 2020 Apr;159(4):383-396. doi: 10.1530/REP-19-0494.
Accurate chromosome segregation relies on correct chromosome-microtubule interactions within a stable bipolar spindle apparatus. Thus, exposure to spindle disrupting compounds can impair meiotic division and genomic stability in oocytes. The endocrine disrupting activity of bisphenols such as bisphenol A (BPA) is well recognized, yet their damaging effects on spindle microtubules (MTs) is poorly understood. Here, we tested the effect(s) of acute exposure to BPA and bisphenol F (BPF) on assembled spindle stability in ovulated oocytes. Brief (4 h) exposure to increasing concentrations (5, 25, and 50 µg/mL) of BPA or BPF disrupted spindle organization in a dose-dependent manner, resulting in significantly shorter spindles with highly unfocused poles and fragmented pericentrin. The chromosomes remained congressed in an abnormally elongated metaphase-like configuration, yet normal end-on chromosome-MT attachments were reduced in BPF-treated oocytes. Live-cell imaging revealed a rapid onset of bisphenol-mediated spindle MT disruption that was reversed upon compound removal. Moreover, MT stability and regrowth were impaired in BPA-exposed oocytes, with few cold-stable MTs and formation of multipolar spindles upon MT regrowth. MT-associated kinesin-14 motor protein (HSET/KIFC1) labeling along the spindle was also lower in BPA-treated oocytes. Conversely, cold stable MTs and HSET labeling persisted after BPF exposure. Notably, inhibition of Aurora Kinase A limited bisphenol-mediated spindle pole widening, revealing a potential interaction. These results demonstrate rapid MT disrupting activity by bisphenols, which is highly detrimental to meiotic spindle stability and organization. Moreover, we identify an important link between these defects and altered distribution of key spindle associated factors as well as Aurora Kinase A activity.
准确的染色体分离依赖于稳定的双极纺锤体装置中正确的染色体-微管相互作用。因此，暴露于纺锤体破坏化合物会损害卵母细胞中的减数分裂和基因组稳定性。双酚类物质（如双酚 A（BPA））的内分泌干扰活性已得到充分认识，但它们对纺锤体微管（MT）的破坏作用尚不清楚。在这里，我们测试了急性暴露于 BPA 和双酚 F（BPF）对已组装的纺锤体稳定性的影响。短暂（4 小时）暴露于递增浓度（5、25 和 50 µg/mL）的 BPA 或 BPF 以剂量依赖性方式破坏纺锤体组织，导致极显著变短且焦点高度分散的纺锤体，以及碎片化的中心体。染色体仍然在异常拉长的中期样构象中保持联会，但 BPF 处理的卵母细胞中正常的端对染色体-MT 附着减少。活细胞成像揭示了双酚介导的纺锤体 MT 破坏的快速发作，在化合物去除后逆转。此外，BPA 暴露的卵母细胞中的 MT 稳定性和再生受到损害，冷稳定的 MT 很少，并且在 MT 再生后形成多极纺锤体。在 BPA 处理的卵母细胞中，沿纺锤体的 MT 相关驱动蛋白-14 马达蛋白（HSET/KIFC1）标记也较低。相反，BPF 暴露后冷稳定的 MT 和 HSET 标记仍然存在。值得注意的是，Aurora Kinase A 的抑制限制了双酚介导的纺锤体极变宽，揭示了潜在的相互作用。这些结果表明双酚具有快速的 MT 破坏活性，这对减数分裂纺锤体的稳定性和组织有很大的危害。此外，我们确定了这些缺陷与关键纺锤体相关因子的改变分布以及 Aurora Kinase A 活性之间的重要联系。
