Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China.
State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China.
PLoS Biol. 2019 Jul 12;17(7):e3000369. doi: 10.1371/journal.pbio.3000369. eCollection 2019 Jul.
Cilia are remarkable cellular devices that power cell motility and transduce extracellular signals. To assemble a cilium, a cylindrical array of 9 doublet microtubules push out an extension of the plasma membrane. Membrane tension regulates cilium formation; however, molecular pathways that link mechanical stimuli to ciliogenesis are unclear. Using genome editing, we introduced hereditary elliptocytosis (HE)- and spinocerebellar ataxia (SCA)-associated mutations into the Caenorhabditis elegans membrane skeletal protein spectrin. We show that these mutations impair mechanical support for the plasma membrane and change cell shape. RNA sequencing (RNA-seq) analyses of spectrin-mutant animals uncovered a global down-regulation of ciliary gene expression, prompting us to investigate whether spectrin participates in ciliogenesis. Spectrin mutations affect intraflagellar transport (IFT), disrupt axonemal microtubules, and inhibit cilium formation, and the endogenous spectrin periodically distributes along cilia. Mammalian spectrin also localizes in cilia and regulates ciliogenesis. These results define a previously unrecognized yet conserved role of spectrin-based mechanical support for cilium biogenesis.
纤毛是一种非凡的细胞装置，能够为细胞运动和转导细胞外信号提供动力。为了组装纤毛，9 个双联微管的圆柱形阵列将细胞膜的延伸部分推出。膜张力调节纤毛的形成；然而，将机械刺激与纤毛发生联系起来的分子途径尚不清楚。我们使用基因组编辑，将遗传性椭圆形红细胞增多症（HE）和脊髓小脑共济失调（SCA）相关突变引入秀丽隐杆线虫的膜骨架蛋白 spectrin 中。我们表明，这些突变会损害对质膜的机械支撑，并改变细胞形状。spectrin 突变体动物的 RNA 测序（RNA-seq）分析发现，纤毛基因的表达被全面下调，促使我们研究 spectrin 是否参与纤毛发生。spectrin 突变影响内鞭毛运输（IFT），破坏轴丝微管，并抑制纤毛形成，而内源性 spectrin 周期性地沿纤毛分布。哺乳动物 spectrin 也定位于纤毛中并调节纤毛发生。这些结果定义了 spectrin 基于机械支撑在纤毛发生中的一个以前未被认识但保守的作用。
