Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, Japan.
Cytoskeleton (Hoboken). 2023 Nov-Dec;80(11-12):448-460. doi: 10.1002/cm.21784. Epub 2023 Aug 31.
Accurate placement of the cleavage furrow is crucial for successful cell division. Recent advancements have revealed that diverse mechanisms have evolved across different branches of the phylogenetic tree. Here, we employed Dictyostelium cells to validate previous models. We observed that during metaphase and early anaphase, mitotic spindles exhibited random rotary movements which ceased when the spindle elongated by approximately 7 μm. At this point, astral microtubules reached the polar cell cortex and fixed the spindle axis, causing cells to elongate by extending polar pseudopods and divide along the spindle axis. Therefore, the position of the furrow is determined when the spindle orientation is fixed. The distal ends of astral microtubules stimulate the extension of pseudopods at the polar cortex. One signal for pseudopod extension may be phosphatidylinositol trisphosphate in the cell membrane, but there appears to be another unknown signal. At the onset of polar pseudopod extension, cortical flow began from both poles toward the equator. We suggest that polar stimulation by astral microtubules determines the furrow position, induces polar pseudopod extension and cortical flow, and accumulates the elements necessary for the construction of the contractile ring.
准确地定位分裂沟对于成功的细胞分裂至关重要。最近的研究进展表明，不同的分支在进化过程中形成了多样化的机制。在这里，我们使用盘基网柄菌细胞来验证之前的模型。我们观察到，在有丝分裂中期和早期后期，有丝分裂纺锤体表现出随机的旋转运动，当纺锤体延长约 7μm 时停止。此时，星体微管到达极细胞皮质并固定纺锤体轴，使细胞通过延伸极性伪足并沿着纺锤体轴分裂而伸长。因此，当纺锤体取向固定时，分裂沟的位置就确定了。星体微管的远端刺激极性皮质处伪足的延伸。细胞膜中磷酸肌醇三磷酸可能是伪足延伸的一个信号，但似乎还有另一个未知信号。在极性伪足延伸开始时，皮质流从两极开始向赤道方向流动。我们认为，星体微管对极的刺激决定了分裂沟的位置，诱导极性伪足延伸和皮质流，并积累了构建收缩环所需的元素。
