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.

中文翻译：

---

肌动蛋白同种型对上皮细胞分裂的不同影响

我们使用激光扫描显微镜 (LSM) 研究了 β 和 γ 细胞质肌动蛋白 (CYAs) 在非肿瘤上皮细胞分裂的不同阶段的分布和功能。在这里，我们证明了β-和γ-CYAs 在早期前期、后期、末期和胞质分裂中在空间上是隔离的。小干扰 RNA (siRNA) 实验表明，与 siRNA 对照相比，在消耗了 β-CYA 和 γ-CYA 的细胞中，细胞数量显着减少。与 siRNA 对照相比，β-CYA 耗竭导致中期细胞面积扩大，多核细胞百分比较高，表明胞质分裂可能失败。Gamma-CYA 消耗导致有丝分裂细胞的百分比降低。我们还观察到有丝分裂中肌动蛋白同种型和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) 微管蛋白聚合的抑制导致受损的 β-CYA 重组，因为与秋水仙碱孵育阻止了短的 β-肌动蛋白聚合物从基底转移到皮质区室。我们得出结论，两种肌动蛋白同种型对于正确的细胞分裂都是必不可少的，但每种同种型在这个过程中都有其特定的功能作用。