Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
Federal Research and Clinical Center of Physical-Chemical Medicine of the Federal Medical Biological Agency, Moscow, 119435, Russia.
Biochemistry (Mosc). 2020 Sep;85(9):1072-1063. doi: 10.1134/S0006297920090072.
We investigated distribution and functions of beta- and gamma-cytoplasmic actins (CYAs) at different stages of non-neoplastic epithelial cell division using laser scanning microscopy (LSM). Here, we demonstrated that beta- and gamma-CYAs are spatially segregated in the early prophase, anaphase, telophase, and cytokinesis. Small interfering RNA (siRNA) experiments revealed that in both beta-CYA- and gamma-CYA-depleted cells, the number of cells was significantly reduced compared with the siRNA controls. Beta-CYA depletion resulted in an enlargement of the cell area in metaphase and high percentage of polynuclear cells compared with the siRNA control, indicating a potential failure of cytokinesis. Gamma-CYA depletion resulted in a reduced percentage of mitotic cells. We also observed the interdependence between the actin isoforms and the microtubule system in mitosis: (i) a decrease in the gamma-CYA led to impaired mitotic spindle organization; (ii) suppression of tubulin polymerization caused impaired beta-CYA reorganization, as incubation with colcemid blocked the transfer of short beta-actin polymers from the basal to the cortical compartment. We conclude that both actin isoforms are essential for proper cell division, but each isoform has its own specific functional role in this process.
我们使用激光扫描显微镜（LSM）研究了非肿瘤上皮细胞分裂不同阶段β-和γ-胞质肌动蛋白（CYAs）的分布和功能。在这里，我们证明β-CYA 和 γ-CYA 在早前期、后期、末期和胞质分裂中是空间分离的。小干扰 RNA（siRNA）实验表明，与 siRNA 对照相比，在β-CYA 和 γ-CYA 耗尽的细胞中，细胞数量明显减少。β-CYA 耗尽导致中期细胞面积增大，多核细胞比例高，表明胞质分裂可能失败。γ-CYA 耗尽导致有丝分裂细胞比例降低。我们还观察到有丝分裂中肌动蛋白同工型与微管系统之间的相互依赖性：（i）γ-CYA 的减少导致有丝分裂纺锤体组织受损；（ii）微管聚合的抑制导致β-CYA 重组受损，因为秋水仙素孵育阻止了短 β-肌动蛋白聚合物从基底向皮质区的转移。我们得出结论，两种肌动蛋白同工型对于正常的细胞分裂都是必不可少的，但每种同工型在这个过程中都有其特定的功能作用。
