Department of Biology, University of Hawai'i at Hilo, Hilo, HI 96720, USA.
Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
Sci Signal. 2023 Jul 4;16(792):eadh0601. doi: 10.1126/scisignal.adh0601.
During cytokinesis, the cell membrane furrows inward along a cleavage plane. The positioning of the cleavage plane is critical to faithful cell division and is determined by the Rho guanine nucleotide exchange factor (RhoGEF)-mediated activation of the small guanosine triphosphatase RhoA and the conserved motor protein complex centralspindlin. Here, we explored whether and how centralspindlin mediates the positioning of RhoGEF. In dividing neuroblasts from , we observed that immediately before cleavage, first centralspindlin and then RhoGEF localized to the sites where cleavage subsequently initiated. Using in vitro assays with purified proteins and stabilized microtubules, we found that centralspindlin directly transported RhoGEF as cargo along single microtubules and sequestered it at microtubule plus-ends for prolonged periods of time. In addition, the binding of RhoGEF to centralspindlin appeared to stimulate centralspindlin motor activity. Thus, the motor activity and microtubule association of centralspindlin can translocate RhoGEF to areas where microtubule plus-ends are abundant, such as at overlapping astral microtubules, to locally activate RhoA and accurately position the cleavage plane during cell division.
在胞质分裂过程中，细胞膜沿着分裂平面向内凹陷。分裂平面的定位对忠实的细胞分裂至关重要，这取决于 Rho 鸟嘌呤核苷酸交换因子（RhoGEF）介导的小 GTP 酶 RhoA 的激活和保守的马达蛋白复合物中心体纺锤体。在这里，我们探讨了中心体纺锤体是否以及如何介导 RhoGEF 的定位。在分裂的神经母细胞中，我们观察到，在分裂之前，首先是中心体纺锤体，然后是 RhoGEF，定位在随后开始分裂的部位。使用纯化的 和稳定的微管进行体外测定，我们发现中心体纺锤体可直接作为货物沿单根微管运输 RhoGEF，并将其在微管正极上长时间隔离。此外，RhoGEF 与中心体纺锤体的结合似乎刺激了中心体纺锤体的马达活性。因此，中心体纺锤体的马达活性和微管结合可以将 RhoGEF 转移到微管正极丰富的区域，例如在重叠的星体微管上，以局部激活 RhoA 并在细胞分裂过程中准确定位分裂平面。
