Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China.
Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing, China.
EMBO J. 2024 Jul;43(13):2606-2635. doi: 10.1038/s44318-024-00118-0. Epub 2024 May 28.
Microtubule-based kinesin motor proteins are crucial for intracellular transport, but their hyperactivation can be detrimental for cellular functions. This study investigated the impact of a constitutively active ciliary kinesin mutant, OSM-3CA, on sensory cilia in C. elegans. Surprisingly, we found that OSM-3CA was absent from cilia but underwent disposal through membrane abscission at the tips of aberrant neurites. Neighboring glial cells engulf and eliminate the released OSM-3CA, a process that depends on the engulfment receptor CED-1. Through genetic suppressor screens, we identified intragenic mutations in the OSM-3CA motor domain and mutations inhibiting the ciliary kinase DYF-5, both of which restored normal cilia in OSM-3CA-expressing animals. We showed that conformational changes in OSM-3CA prevent its entry into cilia, and OSM-3CA disposal requires its hyperactivity. Finally, we provide evidence that neurons also dispose of hyperactive kinesin-1 resulting from a clinic variant associated with amyotrophic lateral sclerosis, suggesting a widespread mechanism for regulating hyperactive kinesins.
微管动力蛋白是细胞内运输的关键,但它们的过度激活可能对细胞功能有害。本研究探讨了组成型激活的纤毛动力蛋白突变体 OSM-3CA 对秀丽隐杆线虫感觉纤毛的影响。令人惊讶的是,我们发现 OSM-3CA 不存在于纤毛中,但在异常神经突的尖端通过膜分离进行处理。邻近的神经胶质细胞吞噬并消除释放的 OSM-3CA,这一过程依赖于吞噬受体 CED-1。通过遗传抑制子筛选,我们鉴定了 OSM-3CA 马达结构域的基因内突变和抑制纤毛激酶 DYF-5 的突变,这两种突变都恢复了 OSM-3CA 表达动物中正常的纤毛。我们表明,OSM-3CA 的构象变化阻止其进入纤毛,而 OSM-3CA 的处理需要其高活性。最后,我们提供的证据表明,神经元也处理由与肌萎缩侧索硬化症相关的临床变异引起的过度激活的驱动蛋白-1,这表明存在一种广泛的调节过度激活的驱动蛋白的机制。
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