Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22903.
Department of Pathology, University of Virginia School of Medicine, Charlottesville, VA 22903.
Mol Biol Cell. 2023 Jan 1;34(1):br1. doi: 10.1091/mbc.E21-09-0438. Epub 2022 Nov 9.
Dynein inactivates the spindle assembly checkpoint (SAC) by transporting checkpoint proteins away from kinetochores toward spindle poles in a process known as "stripping." We find that inhibition of Aurora A kinase, which is localized to spindle poles, enables the accumulation of the spindle checkpoint activator Mad1 at poles where it is normally absent. Aurora kinases phosphorylate the dynein activator NudE neurodevelopment protein 1 like 1 (Ndel1) on Ser285 and Mad1 accumulates at poles when Ndel1 is replaced by a nonphosphorylatable mutant in human cells. The pole focusing protein NuMA, transported to poles by dynein, also accumulates at poles in cells harboring a mutant Ndel1. Phosphorylation of Ndel1 on Ser285 is required for robust spindle checkpoint activity and regulates the poles of asters in extracts. Our data suggest that dynein/SAC complexes that are generated at kinetochores and then transported directionally toward poles on microtubules are inhibited by Aurora A before they reach spindle poles. These data suggest that Aurora A generates a spatial signal at spindle poles that controls dynein transport and spindle function.
动力蛋白通过将检查点蛋白从着丝粒运输到纺锤体极，从而使纺锤体装配检查点（SAC）失活，这个过程被称为“去稳定化”。我们发现，定位于纺锤体极的 Aurora A 激酶的抑制作用使通常不存在于纺锤体极的纺锤体检查点激活因子 Mad1 在纺锤体极积累。Aurora 激酶在 Ser285 上将动力蛋白激活剂 NudE 神经发育蛋白 1 样 1（Ndel1）磷酸化，当人细胞中的 Ndel1 被不可磷酸化的突变体取代时，Mad1 在纺锤体极积累。由动力蛋白运送到纺锤体极的极定位蛋白 NuMA 也在含有突变 Ndel1 的细胞中在纺锤体极积累。Ndel1 在 Ser285 上的磷酸化对于强大的纺锤体检查点活性是必需的，并调节提取物中星状体的极。我们的数据表明，在微管上从着丝粒定向运输到纺锤体极的动力蛋白/SAC 复合物在到达纺锤体极之前被 Aurora A 抑制。这些数据表明，Aurora A 在纺锤体极产生空间信号，控制动力蛋白运输和纺锤体功能。
