Spectrin-based membrane skeleton supports ciliogenesis.

Ru Jia,Liuju Li,Chao Xie,Yufan Liu,Liangyi Chen,Wei Li,Ming Li,Xiaoshuai Huang,Yongping Chai,Wenxin Shao,Zhongyun Xie,Dongdong Li,Guangshuo Ou,Piali Sengupta

doi:10.1371/journal.pbio.3000369

Abstract

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.

Highlights

Cilia are evolutionarily conserved organelles that generate forces to drive cell motility and transduce chemical and physical signals to modulate cell behaviors [1,2,3,4]
Embryo lengths are the distance from the embryo head to the tail. (G) Scale bar, 5 μm; comparisons were between the WT and mutants, p < 0.001. (H) Representative images of SPC-1::green fluorescence protein (GFP) or GFP::UNC-70 in neuronal processes of motor neurons in live C. elegans at the young-adult stage
Data associated with this figure can be found in S1 Data. a.u, arbitrary unit; C, C terminus; CH3, calponin homology domains type 3; CRISPR-Cas9, clustered regularly interspaced short palindromic repeats-Cas9; EF-hand calciumbinding motifs (EF), EF-hand calcium-binding motifs; Emb, embryo; GFP, green fluorescence protein; KI, knock-in; N, N terminus; PH, Pleckstrin homology domain; SCA-5, spinocerebellar ataxia type 5; SH3, Src homology domain 3; WT, wild type

Summary

Introduction

Cilia are evolutionarily conserved organelles that generate forces to drive cell motility and transduce chemical and physical signals to modulate cell behaviors [1,2,3,4]. Many ciliary functions are known as mechanical in nature [5], and defects in mechanobiology of cilia lead to ciliopathies, ranging from primary ciliary dyskinesia to polycystic kidney disease to situs inversus [4]. National Natural Science Foundation of China, http://www.nsfc.gov.cn/, grants 31671444 and 31871352, W. Li. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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Conclusion