Trypanosome Cell Biology Unit, INSERM U1201, Institut Pasteur, 25 Rue du Docteur Roux, 75015 Paris, France.
Sorbonne Université école doctorale complexité du vivant, ED 515, 7, quai Saint-Bernard, case 32, 75252 Paris Cedex 05, France.
J Cell Sci. 2020 Sep 23;133(18):jcs248989. doi: 10.1242/jcs.248989.
Multicellular organisms assemble cilia and flagella of precise lengths differing from one cell to another, yet little is known about the mechanisms governing these differences. Similarly, protists assemble flagella of different lengths according to the stage of their life cycle. assembles flagella of 3 to 30 µm during its development in the tsetse fly. This provides an opportunity to examine how cells naturally modulate organelle length. Flagella are constructed by addition of new blocks at their distal end via intraflagellar transport (IFT). Immunofluorescence assays, 3D electron microscopy and live-cell imaging revealed that IFT was present in all life cycle stages. IFT proteins are concentrated at the base, and IFT trains are located along doublets 3-4 and 7-8 and travel bidirectionally in the flagellum. Quantitative analysis demonstrated that the total amount of flagellar IFT proteins correlates with the length of the flagellum. Surprisingly, the shortest flagellum exhibited a supplementary large amount of dynamic IFT material at its distal end. The contribution of IFT and other factors to the regulation of flagellum length is discussed.
多细胞生物组装出精确长度的纤毛和鞭毛，这些长度在不同细胞之间存在差异，但人们对控制这些差异的机制知之甚少。同样，原生动物也会根据生命周期的阶段组装出不同长度的鞭毛。在采采蝇的发育过程中， 会组装出 3 到 30 微米长的鞭毛。这为研究细胞如何自然调节细胞器长度提供了机会。鞭毛是通过鞭毛内运输（IFT）在其远端添加新的模块构建而成的。免疫荧光分析、3D 电子显微镜和活细胞成像显示，IFT 存在于所有生命周期阶段。IFT 蛋白集中在鞭毛的基部，IFT 列车位于二联体 3-4 和 7-8 处，并在鞭毛中双向移动。定量分析表明，鞭毛 IFT 蛋白的总量与鞭毛的长度相关。令人惊讶的是，最短的鞭毛在其远端显示出额外大量的动态 IFT 物质。IFT 及其他因素对鞭毛长度的调节作用正在讨论之中。
