Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR), c/o Sapienza University, 00185 Rome, Italy.
Unit of Cellular Networks and Molecular Therapeutic Targets; IRCCS-Regina Elena National Cancer Institute, 00144 Rome, Italy.
Cells. 2019 Jul 5;8(7):684. doi: 10.3390/cells8070684.
Abscission is the final step of cell division, mediating the physical separation of the two daughter cells. A key player in this process is the microtubule-severing enzyme spastin that localizes at the midbody where its activity is crucial to cut microtubules and culminate the cytokinesis. Recently, we demonstrated that HIPK2, a multifunctional kinase involved in several cellular pathways, contributes to abscission and prevents tetraploidization. Here, we show that HIPK2 binds and phosphorylates spastin at serine 268. During cytokinesis, the midbody-localized spastin is phosphorylated at S268 in HIPK2-proficient cells. In contrast, no spastin is detectable at the midbody in HIPK2-depleted cells. The non-phosphorylatable spastin-S268A mutant does not localize at the midbody and cannot rescue HIPK2-depleted cells from abscission defects. In contrast, the phosphomimetic spastin-S268D mutant localizes at the midbody and restores successful abscission in the HIPK2-depleted cells. These results show that spastin is a novel target of HIPK2 and that HIPK2-mediated phosphorylation of spastin contributes to its midbody localization for successful abscission.
细胞分裂的最后一步是细胞分离，介导两个子细胞的物理分离。在这个过程中，微管切割酶 spastin 是一个关键的参与者，它定位于中体，其活性对于切割微管并完成胞质分裂至关重要。最近，我们证明了多能激酶 HIPK2 参与了几个细胞通路，它有助于细胞分离并防止四倍体化。在这里，我们表明 HIPK2 结合并磷酸化 spastin 的丝氨酸 268。在胞质分裂过程中，中体定位的 spastin 在 HIPK2 丰富的细胞中在 S268 处被磷酸化。相比之下，在 HIPK2 耗尽的细胞中，中体处没有检测到 spastin。非磷酸化的 spastin-S268A 突变体不能定位于中体，并且不能从细胞分离缺陷中拯救 HIPK2 耗尽的细胞。相比之下，磷酸化模拟的 spastin-S268D 突变体定位于中体，并在 HIPK2 耗尽的细胞中恢复成功的细胞分离。这些结果表明 spastin 是 HIPK2 的一个新靶标，并且 HIPK2 介导的 spastin 磷酸化有助于其在中体的定位，从而实现成功的细胞分离。
