Basal bodies (BBs) are microtubule-based organelles that act as a template for and stabilize cilia at the cell surface. Centrins ubiquitously associate with BBs and function in BB assembly, maturation and stability. Human POC5 (hPOC5) is a highly conserved centrin-binding protein that binds centrins through Sfi1p-like repeats and is required for building full-length, mature centrioles. Here, we use the BB-rich cytoskeleton of Tetrahymena thermophila to characterize Poc5 BB functions. Tetrahymena Poc5 (TtPoc5) uniquely incorporates into assembling BBs and is then removed from mature BBs prior to ciliogenesis. Complete genomic knockout of TtPOC5 leads to a significantly increased production of BBs, yet a markedly reduced ciliary density, both of which are rescued by reintroduction of TtPoc5. A second Tetrahymena POC5-like gene, SFR1, is similarly implicated in modulating BB production. When TtPOC5 and SFR1 are co-deleted, cell viability is compromised and BB overproduction is exacerbated. Overproduced BBs display defective transition zone formation and a diminished capacity for ciliogenesis. This study uncovers a requirement for Poc5 in building mature BBs, providing a possible functional link between hPOC5 mutations and impaired cilia.

This article has an associated First Person interview with the first author of the paper.

基底体（BBs）是基于微管的细胞器，可作为模板并稳定纤毛在细胞表面。Centrins普遍与BB结合，并在BB组装，成熟和稳定中起作用。人POC5（hPOC5）是高度保守的中心蛋白结合蛋白，可通过Sfi1p-like重复序列结合中心蛋白，是构建全长，成熟中心粒所需的蛋白。在这里，我们使用嗜热四膜膜的富含BB的细胞骨架来表征Poc5 BB功能。四膜虫Poc5（TtPoc5）独特地结合到组装的BB中，然后在纤毛形成之前从成熟的BB中去除。TtPOC5的完整基因组敲除导致BB的产量显着增加，但睫毛密度显着降低，这两者都通过重新引入TtPoc5得以挽救。第二四膜虫POC5样基因SFR1类似地参与调节BB的产生。当共同删除TtPOC5和SFR1时，细胞活力受到损害，BB过度生产加剧。过量生产的BBs显示出缺陷的过渡区形成和纤毛生成能力降低。这项研究揭示了在构建成熟的BB中对Poc5的需求，从而在hPOC5突变与纤毛受损之间提供了可能的功能联系。

本文与论文的第一作者进行了第一人称访谈。