Sun Yi, Chen Zhe, Jin Minjun, Xie Haibo, Zhao Chengtian
Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China.
Fang Zongxi Center for Marine Evo Devo, MOE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.
Elife. 2024 Dec 13;13:RP93168. doi: 10.7554/eLife.93168.
How cells regulate the size of their organelles remains a fundamental question in cell biology. Cilia, with their simple structure and surface localization, provide an ideal model for investigating organelle size control. However, most studies on cilia length regulation are primarily performed on several single-celled organisms. In contrast, the mechanism of length regulation in cilia across diverse cell types within multicellular organisms remains a mystery. Similar to humans, zebrafish contain diverse types of cilia with variable lengths. Taking advantage of the transparency of zebrafish embryos, we conducted a comprehensive investigation into intraflagellar transport (IFT), an essential process for ciliogenesis. By generating a transgenic line carrying Ift88-GFP transgene, we observed IFT in multiple types of cilia with varying lengths. Remarkably, cilia exhibited variable IFT speeds in different cell types, with longer cilia exhibiting faster IFT speeds. This increased IFT speed in longer cilia is likely not due to changes in common factors that regulate IFT, such as motor selection, BBSome proteins, or tubulin modification. Interestingly, longer cilia in the ear cristae tend to form larger IFT compared to shorter spinal cord cilia. Reducing the size of IFT particles by knocking down Ift88 slowed IFT speed and resulted in the formation of shorter cilia. Our study proposes an intriguing model of cilia length regulation via controlling IFT speed through the modulation of the size of the IFT complex. This discovery may provide further insights into our understanding of how organelle size is regulated in higher vertebrates.
细胞如何调节其细胞器的大小仍然是细胞生物学中的一个基本问题。纤毛结构简单且位于细胞表面，为研究细胞器大小控制提供了一个理想模型。然而，大多数关于纤毛长度调节的研究主要是在几种单细胞生物上进行的。相比之下，多细胞生物中不同细胞类型的纤毛长度调节机制仍然是个谜。与人类相似，斑马鱼含有多种长度各异的纤毛。利用斑马鱼胚胎的透明性，我们对鞭毛内运输（IFT）进行了全面研究，IFT是纤毛发生的一个重要过程。通过构建携带Ift88 - GFP转基因的转基因品系，我们观察了多种不同长度纤毛中的IFT。值得注意的是，不同细胞类型的纤毛表现出不同的IFT速度，较长的纤毛IFT速度更快。较长纤毛中IFT速度的增加可能并非由于调节IFT的常见因素发生变化，如马达选择、BBSome蛋白或微管蛋白修饰。有趣的是，与较短的脊髓纤毛相比，内耳嵴中的较长纤毛往往形成更大的IFT。通过敲低Ift88来减小IFT颗粒的大小会减慢IFT速度，并导致形成较短的纤毛。我们的研究提出了一个有趣的纤毛长度调节模型，即通过调节IFT复合物的大小来控制IFT速度。这一发现可能为我们理解高等脊椎动物中细胞器大小如何调节提供进一步的见解。
