Department of Gynecology and Obstetrics, School of Medicine, J. W. Goethe-University, Theodor-Stern-Kai 7, D-60590, Frankfurt, Germany.
Solvadis distribution GmbH, Am Hafen 4, 64579, Gernsheim, Germany.
Oncogene. 2019 May;38(22):4199-4214. doi: 10.1038/s41388-019-0716-7. Epub 2019 Jan 31.
The mitotic kinase Aurora A is crucial for various mitotic events. Its activation has been intensively investigated and is not yet completely understood. RITA, the RBP-J interacting and tubulin-associated protein, has been shown to modulate microtubule dynamics in mitosis. We asked if RITA could be related to the activation of Aurora A. We show here that RITA is colocalized with Aurora A and its activator TPX2 at spindle poles during mitosis. FLAG-RITA is precipitated with the complex of Aurora A, TPX2 and tubulin. Depletion of RITA increases exclusively active Aurora A and TPX2 at spindle poles in diverse cancer cell lines and in RITA knockout mouse embryonic fibroblasts. The enhanced active Aurora A, its substrate p-TACC3 and TPX2 are restored by adding back of RITA but not its Δtub mutant with an impaired tubulin-binding capability, indicating that RITA's role as Aurora A's modulator is mediated through its interaction with tubulin. Also, the mitotic failures in cells depleted of RITA are rescued by the inhibition of Aurora A. RITA itself does not directly interfere with the catalytic activity of Aurora A, instead, affects the microtubule binding of its activator TPX2. Moreover, Aurora A's activation correlates with microtubule stabilization induced by the microtubule stabilizer paclitaxel, implicating that stabilized microtubules caused by RITA depletion could also account for increased active Aurora A. Our data suggest a potential role for RITA in the activation of Aurora A at spindle poles by modulating the microtubule binding of TPX2 and the microtubule stability during mitosis.
有丝分裂激酶 Aurora A 对于各种有丝分裂事件至关重要。其激活已被深入研究，但仍不完全清楚。RITA（与 RBP-J 相互作用和微管相关的蛋白）已被证明可调节有丝分裂中的微管动力学。我们想知道 RITA 是否与 Aurora A 的激活有关。我们在这里表明，RITA 在有丝分裂期间与 Aurora A 和其激活剂 TPX2 一起在纺锤体极共定位。FLAG-RITA 与 Aurora A、TPX2 和微管的复合物共沉淀。在各种癌细胞系和 RITA 敲除的小鼠胚胎成纤维细胞中，RITA 的耗竭仅增加纺锤体极处的活性 Aurora A 和 TPX2。添加 RITA 而非其微管结合能力受损的 Δtub 突变体可恢复增强的活性 Aurora A、其底物 p-TACC3 和 TPX2，表明 RITA 作为 Aurora A 调节剂的作用是通过其与微管的相互作用介导的。此外，RITA 耗竭的细胞中的有丝分裂失败可通过抑制 Aurora A 得到挽救。RITA 本身不会直接干扰 Aurora A 的催化活性，而是影响其激活剂 TPX2 的微管结合。此外，Aurora A 的激活与微管稳定剂紫杉醇诱导的微管稳定相关，表明 RITA 耗竭引起的微管稳定增加也可能导致活性 Aurora A 增加。我们的数据表明，RITA 通过调节 TPX2 的微管结合和有丝分裂期间的微管稳定性，在纺锤体极处 Aurora A 的激活中发挥潜在作用。
