Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
University of Chinese Academy of Sciences, Beijing 100039, China.
J Cell Sci. 2019 Mar 15;132(6):jcs229047. doi: 10.1242/jcs.229047.
Cilia/flagella are structurally conserved and dynamic organelles; their assembly and disassembly are coordinated with the cell cycle and cell differentiation. Several post-translational modifications, including acetylation, methylation, phosphorylation and ubiquitylation, participate in ciliary disassembly. However, the detailed mechanism and the role of ubiquitylation in ciliary disassembly are unclear. This study identified 20 proteins that were ubiquitylated in shortening flagella of α-Tubulin was the most abundant ubiquitylated protein and it was labeled with K63 polyubiquitin chains primarily at K304. Expression of an α-tubulin mutant (K304R), which could not be ubiquitylated, decreased the rate of flagellar disassembly and resulted in an enrichment of the mutant form in the axoneme, suggesting that ubiquitylation of α-tubulin is required for the normal kinetics of axonemal disassembly. Immunoprecipitation and glutathione-S-transferase pulldown assays demonstrated that the retrograde intraflagellar transport (IFT) protein, IFT139, interacted with a variety of ubiquitylated proteins, including α-tubulin, suggesting that IFT-A was responsible for transporting ubiquitylated proteins out of the flagella. Our data suggest an important role for ubiquitylation and retrograde IFT in ciliary disassembly.This article has an associated First Person interview with the first author of the paper.
纤毛/鞭毛在结构上是保守的和动态的细胞器；它们的组装和拆卸与细胞周期和细胞分化相协调。几种翻译后修饰，包括乙酰化、甲基化、磷酸化和泛素化，参与了纤毛的解体。然而，详细的机制和泛素化在纤毛解体中的作用尚不清楚。本研究鉴定了 20 种在缩短的鞭毛中被泛素化的蛋白质，α-微管蛋白是最丰富的泛素化蛋白，它主要在 K304 处被 K63 多聚泛素链标记。表达一种不能被泛素化的α-微管蛋白突变体（K304R），降低了鞭毛解体的速度，并导致突变体形式在轴丝中的富集，这表明α-微管蛋白的泛素化是轴丝正常解体动力学所必需的。免疫沉淀和谷胱甘肽 S-转移酶 pulldown 测定表明，逆行纤毛内运输（IFT）蛋白 IFT139 与多种泛素化蛋白相互作用，包括α-微管蛋白，这表明 IFT-A 负责将泛素化蛋白运输出鞭毛。我们的数据表明泛素化和逆行 IFT 在纤毛解体中起着重要的作用。本文有一篇与论文第一作者的相关第一人称访谈。
