A hallmark of cell division in eukaryotic cells is the formation and elongation of a microtubule (MT)‐based mitotic spindle. Proper positioning of the spindle is critical to ensure equal segregation of the genetic material to the resulting daughter cells. Both the timing of spindle elongation and constriction of the actomyosin contractile ring must be precisely coordinated to prevent missegregation or damage to the genetic material during cellular division. Here, we show that Sds23, an inhibitor of protein phosphatases, contributes to proper positioning of elongating spindles in fission yeast cells. We found that sds23∆ mutant cells exhibit asymmetric spindles that initially elongate asymmetrically toward one end of the dividing cell. Spindle asymmetry in sds23∆ cells results from a defect that is distinct from previously identified mechanisms, including MT protrusions and enlarged vacuoles. Combined with our previous work, this study demonstrates that Sds23, an inhibitor of PP2A‐family protein phosphatases, promotes proper positioning of both the bipolar spindle and cytokinetic ring during fission yeast cell division. These two steps ensure the overall symmetry and fidelity of the cell division process.

中文翻译：

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磷酸酶抑制剂 Sds23 促进裂殖酵母中纺锤体的对称定位

真核细胞细胞分裂的一个标志是基于微管（MT）的有丝分裂纺锤体的形成和延长。纺锤体的正确定位对于确保遗传物质与所得子细胞的平等分离至关重要。纺锤体伸长和肌动球蛋白收缩环收缩的时间必须精确协调，以防止细胞分裂过程中遗传物质的错误分离或损坏。在这里，我们证明 Sds23（一种蛋白磷酸酶抑制剂）有助于裂殖酵母细胞中伸长纺锤体的正确定位。我们发现sds23Δ突变细胞表现出不对称纺锤体，最初向分裂细胞的一端不对称地伸长。sds23Δ细胞中的纺锤体不对称是由与先前确定的机制不同的缺陷引起的，包括 MT 突出和扩大的液泡。结合我们之前的工作，本研究表明，PP2A 家族蛋白磷酸酶抑制剂 Sds23 在裂殖酵母细胞分裂过程中促进双极纺锤体和细胞因子环的正确定位。这两个步骤确保了细胞分裂过程的整体对称性和保真度。