Faculty of Chemistry, University of Warsaw, 1 Pasteur Street, 02-093 Warsaw, Poland.
Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
Cells. 2022 Dec 14;11(24):4048. doi: 10.3390/cells11244048.
Motile cilia and eukaryotic flagella are specific cell protrusions that are conserved from protists to humans. They are supported by a skeleton composed of uniquely organized microtubules-nine peripheral doublets and two central singlets (9 × 2 + 2). Microtubules also serve as docking sites for periodically distributed multiprotein ciliary complexes. Radial spokes, the T-shaped ciliary complexes, repeat along the outer doublets as triplets and transduce the regulatory signals from the cilium center to the outer doublet-docked dynein arms. Using the genetic, proteomic, and microscopic approaches, we have shown that lack of Cfap91 protein affects stable docking/positioning of the radial spoke RS3 and the base of RS2, and adjacent inner dynein arms, possibly due to the ability of Cfap91 to interact with a molecular ruler protein, Ccdc39. The localization studies confirmed that the level of RS3-specific proteins, Cfap61 and Cfap251, as well as RS2-associated Cfap206, are significantly diminished in CFAP91-KO cells. Cilia of cells with knocked-out beat in an uncoordinated manner and their beating frequency is dramatically reduced. Consequently, CFAP91-KO cells swam about a hundred times slower than wild-type cells. We concluded that Cfap91 localizes at the base of radial spokes RS2 and RS3 and likely plays a role in the radial spoke(s) positioning and stability.
纤毛和鞭毛是从原生动物到人类都保守存在的特定细胞突起。它们由由独特组织的微管组成的骨架支撑，包括九个外周二联体和两个中央单体（9×2+2）。微管还作为周期性分布的多蛋白鞭毛复合物的停靠点。辐条，即 T 型鞭毛复合物，沿着外二联体以三联体重复，并将调节信号从纤毛中心传递到外二联体连接的动力蛋白臂。通过遗传、蛋白质组学和显微镜方法，我们已经表明，Cfap91 蛋白的缺乏会影响辐条 RS3 和 RS2 基部以及相邻的内动力蛋白臂的稳定停靠/定位，这可能是由于 Cfap91 与分子标尺蛋白 Ccdc39 相互作用的能力。定位研究证实，RS3 特异性蛋白 Cfap61 和 Cfap251 以及与 RS2 相关的 Cfap206 的水平在 CFAP91-KO 细胞中显著降低。敲除 的细胞的纤毛以不协调的方式跳动，其跳动频率显著降低。因此，CFAP91-KO 细胞的游动速度比野生型细胞慢约一百倍。我们得出结论，Cfap91 定位于辐条 RS2 和 RS3 的基部，可能在辐条的定位和稳定性中发挥作用。
