Cilium formation and regeneration requires new protein synthesis, but the underlying cytosolic translational reprogramming remains largely unknown. Using ribosome footprinting, we performed global translatome profiling during cilia regeneration in Chlamydomonas and uncovered that flagellar genes undergo an early transcriptional activation but late translational repression. This pattern guided our identification of sphingolipid metabolism enzymes, including serine palmitoyltransferase (SPT), as essential regulators for ciliogenesis. Cryo-electron tomography showed that ceramide loss abnormally increased the membrane-axoneme distance and generated bulged cilia. We found that ceramides interact with intraflagellar transport (IFT) particle proteins that IFT motors transport along axoneme microtubules (MTs), suggesting that ceramide-IFT particle-IFT motor-MT interactions connect the ciliary membrane with the axoneme to form rod-shaped cilia. SPT-deficient vertebrate cells were defective in ciliogenesis, and SPT mutations from patients with hereditary sensory neuropathy disrupted cilia, which could be restored by sphingolipid supplementation. These results reveal a conserved role of sphingolipid in cilium formation and link compromised sphingolipid production with ciliopathies.

中文翻译：

---

纤毛发生需要依赖鞘脂的膜和轴丝相互作用。

纤毛的形成和再生需要新的蛋白质合成，但潜在的细胞溶质翻译重编程在很大程度上仍然未知。使用核糖体足迹，我们在衣藻纤毛再生过程中进行了全局翻译组分析，发现鞭毛基因经历了早期转录激活但晚期翻译抑制。这种模式指导我们鉴定鞘脂代谢酶，包括丝氨酸棕榈酰转移酶 (SPT)，作为纤毛发生的重要调节剂。低温电子断层扫描显示神经酰胺丢失异常增加了膜轴丝距离并产生了膨出的纤毛。我们发现神经酰胺与 IFT 马达沿轴丝微管 (MT) 运输的鞭毛内转运 (IFT) 颗粒蛋白相互作用，表明神经酰胺-IFT 颗粒-IFT 马达-MT 相互作用将睫状膜与轴丝连接起来形成杆状纤毛。缺乏 SPT 的脊椎动物细胞在纤毛发生方面存在缺陷，遗传性感觉神经病患者的 SPT 突变破坏了纤毛，而纤毛可以通过补充鞘脂来恢复。这些结果揭示了鞘脂在纤毛形成中的保守作用，并将受损的鞘脂产生与纤毛病联系起来。