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Meng X, Xu C, Li J, Qiu B, Luo J, Hong Q, Tong Y, Fang C, Feng Y, Ma R, Shi X, Lin C, Pan C, Zhu X, Yan X, Cong Y. Multi-scale structures of the mammalian radial spoke and divergence of axonemal complexes in ependymal cilia. Nat Commun 2024; 15:362. [PMID: 38191553 PMCID: PMC10774353 DOI: 10.1038/s41467-023-44577-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/19/2023] [Indexed: 01/10/2024] Open
Abstract
Radial spokes (RS) transmit mechanochemical signals between the central pair (CP) and axonemal dynein arms to coordinate ciliary motility. Atomic-resolution structures of metazoan RS and structures of axonemal complexes in ependymal cilia, whose rhythmic beating drives the circulation of cerebrospinal fluid, however, remain obscure. Here, we present near-atomic resolution cryo-EM structures of mouse RS head-neck complex in both monomer and dimer forms and reveal the intrinsic flexibility of the dimer. We also map the genetic mutations related to primary ciliary dyskinesia and asthenospermia on the head-neck complex. Moreover, we present the cryo-ET and sub-tomogram averaging map of mouse ependymal cilia and build the models for RS1-3, IDAs, and N-DRC. Contrary to the conserved RS structure, our cryo-ET map reveals the lack of IDA-b/c/e and the absence of Tektin filaments within the A-tubule of doublet microtubules in ependymal cilia compared with mammalian respiratory cilia and sperm flagella, further exemplifying the structural diversity of mammalian motile cilia. Our findings shed light on the stepwise mammalian RS assembly mechanism, the coordinated rigid and elastic RS-CP interaction modes beneficial for the regulation of asymmetric ciliary beating, and also facilitate understanding on the etiology of ciliary dyskinesia-related ciliopathies and on the ependymal cilia in the development of hydrocephalus.
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Affiliation(s)
- Xueming Meng
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Cong Xu
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Jiawei Li
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Benhua Qiu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Jiajun Luo
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Qin Hong
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yujie Tong
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Chuyu Fang
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
| | - Yanyan Feng
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Institute of Early Life Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China
| | - Rui Ma
- Shanghai Nanoport, Thermofisher Scientific, Shanghai, China
| | - Xiangyi Shi
- Shanghai Nanoport, Thermofisher Scientific, Shanghai, China
| | - Cheng Lin
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Chen Pan
- National Facility for Protein Science in Shanghai, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
| | - Xiumin Yan
- Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Institute of Early Life Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, China.
| | - Yao Cong
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.
- Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
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Vasudevan KK, Song K, Alford LM, Sale WS, Dymek EE, Smith EF, Hennessey T, Joachimiak E, Urbanska P, Wloga D, Dentler W, Nicastro D, Gaertig J. FAP206 is a microtubule-docking adapter for ciliary radial spoke 2 and dynein c. Mol Biol Cell 2014; 26:696-710. [PMID: 25540426 PMCID: PMC4325840 DOI: 10.1091/mbc.e14-11-1506] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Radial spokes are conserved macromolecular complexes that are essential for ciliary motility. Little is known about the assembly and functions of the three individual radial spokes, RS1, RS2, and RS3. In Tetrahymena, a conserved ciliary protein, FAP206, docks RS2 and dynein c to the doublet microtubule. Radial spokes are conserved macromolecular complexes that are essential for ciliary motility. A triplet of three radial spokes, RS1, RS2, and RS3, repeats every 96 nm along the doublet microtubules. Each spoke has a distinct base that docks to the doublet and is linked to different inner dynein arms. Little is known about the assembly and functions of individual radial spokes. A knockout of the conserved ciliary protein FAP206 in the ciliate Tetrahymena resulted in slow cell motility. Cryo–electron tomography showed that in the absence of FAP206, the 96-nm repeats lacked RS2 and dynein c. Occasionally, RS2 assembled but lacked both the front prong of its microtubule base and dynein c, whose tail is attached to the front prong. Overexpressed GFP-FAP206 decorated nonciliary microtubules in vivo. Thus FAP206 is likely part of the front prong and docks RS2 and dynein c to the microtubule.
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Affiliation(s)
| | - Kangkang Song
- Department of Biology, Rosenstiel Center, Brandeis University, Waltham, MA 02454
| | - Lea M Alford
- Department of Cell Biology, Emory University, Atlanta, GA 30303
| | - Winfield S Sale
- Department of Cell Biology, Emory University, Atlanta, GA 30303
| | - Erin E Dymek
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - Elizabeth F Smith
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - Todd Hennessey
- Department of Biological Sciences, State University of New York, Buffalo, NY 14260
| | - Ewa Joachimiak
- Department of Cell Biology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland Department of Animal Physiology, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland
| | - Paulina Urbanska
- Department of Cell Biology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Dorota Wloga
- Department of Cell Biology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - William Dentler
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045
| | - Daniela Nicastro
- Department of Biology, Rosenstiel Center, Brandeis University, Waltham, MA 02454
| | - Jacek Gaertig
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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Heuser T, Dymek EE, Lin J, Smith EF, Nicastro D. The CSC connects three major axonemal complexes involved in dynein regulation. Mol Biol Cell 2012; 23:3143-55. [PMID: 22740634 PMCID: PMC3418309 DOI: 10.1091/mbc.e12-05-0357] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
This study reveals the 3D structure of the CSC and its connections to three major axonemal complexes involved in dynein regulation, including the distal radial spoke and the nexin-DRC. The findings corroborate radial spoke heterogeneity and suggest a unique role for the distal spoke in calcium-mediated signal transduction and flagellar motility. Motile cilia and flagella are highly conserved organelles that play important roles in human health and development. We recently discovered a calmodulin- and spoke-associated complex (CSC) that is required for wild-type motility and for the stable assembly of a subset of radial spokes. Using cryo–electron tomography, we present the first structure-based localization model of the CSC. Chlamydomonas flagella have two full-length radial spokes, RS1 and RS2, and a shorter RS3 homologue, the RS3 stand-in (RS3S). Using newly developed techniques for analyzing samples with structural heterogeneity, we demonstrate that the CSC connects three major axonemal complexes involved in dynein regulation: RS2, the nexin–dynein regulatory complex (N-DRC), and RS3S. These results provide insights into how signals from the radial spokes may be transmitted to the N-DRC and ultimately to the dynein motors. Our results also indicate that although structurally very similar, RS1 and RS2 likely serve different functions in regulating flagellar motility.
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Affiliation(s)
- Thomas Heuser
- Biology Department, Rosenstiel Center, Brandeis University, Waltham, MA 02454, USA
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Lin J, Heuser T, Carbajal-González BI, Song K, Nicastro D. The structural heterogeneity of radial spokes in cilia and flagella is conserved. Cytoskeleton (Hoboken) 2012; 69:88-100. [PMID: 22170736 DOI: 10.1002/cm.21000] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 12/02/2011] [Accepted: 12/05/2011] [Indexed: 01/05/2023]
Abstract
Radial spokes (RSs) are ubiquitous components of motile cilia and flagella and play an essential role in transmitting signals that regulate the activity of the dynein motors, and thus ciliary and flagellar motility. In some organisms, the 96 nm axonemal repeat unit contains only a pair of spokes, RS1 and RS2, while most organisms have spoke triplets with an additional spoke RS3. The spoke pairs in Chlamydomonas flagella have been well characterized, while spoke triplets have received less attention. Here, we used cryoelectron tomography and subtomogram averaging to visualize the three-dimensional structure of spoke triplets in Strongylocentrotus purpuratus (sea urchin) sperm flagella in unprecedented detail. Only small differences were observed between RS1 and RS2, but the structure of RS3 was surprisingly unique and structurally different from the other two spokes. We observed novel doublet specific features that connect RS2, RS3, and the nexin-dynein regulatory complex, three key ciliary and flagellar structures. The distribution of these doublet specific structures suggests that they could be important for establishing the asymmetry of dynein activity required for the oscillatory movement of cilia and flagella. Surprisingly, a comparison with other organisms demonstrated both that this considerable RS heterogeneity is conserved and that organisms with RS pairs contain the basal part of RS3. This conserved RS heterogeneity may also reflect functional differences between the spokes and their involvement in regulating ciliary and flagellar motility.
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Affiliation(s)
- Jianfeng Lin
- Department of Biology, Rosenstiel Center, MS029, Brandeis University, Waltham, Massachusetts 02454-9110, USA
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Barber CF, Heuser T, Carbajal-González BI, Botchkarev VV, Nicastro D. Three-dimensional structure of the radial spokes reveals heterogeneity and interactions with dyneins in Chlamydomonas flagella. Mol Biol Cell 2011; 23:111-20. [PMID: 22072792 PMCID: PMC3248890 DOI: 10.1091/mbc.e11-08-0692] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Cryo–electron tomography of Chlamydomonas flagella reveals previously uncharacterized features of the radial spokes, including structural heterogeneity and direct interactions with dyneins and between the spoke heads. A “radial spoke 3 stand-in” occupies what would be the site of a third spoke in organisms with spoke triplets. Radial spokes (RSs) play an essential role in the regulation of axonemal dynein activity and thus of ciliary and flagellar motility. However, few details are known about the complexes involved. Using cryo–electron tomography and subtomogram averaging, we visualized the three-dimensional structure of the radial spokes in Chlamydomonas flagella in unprecedented detail. Unlike many other species, Chlamydomonas has only two spokes per axonemal repeat, RS1 and RS2. Our data revealed previously uncharacterized features, including two-pronged spoke bases that facilitate docking to the doublet microtubules, and that inner dyneins connect directly to the spokes. Structures of wild type and the headless spoke mutant pf17 were compared to define the morphology and boundaries of the head, including a direct RS1-to-RS2 interaction. Although the overall structures of the spokes are very similar, we also observed some differences, corroborating recent findings about heterogeneity in the docking of RS1 and RS2. In place of a third radial spoke we found an uncharacterized, shorter electron density named “radial spoke 3 stand-in,” which structurally bears no resemblance to RS1 and RS2 and is unaltered in the pf17 mutant. These findings demonstrate that radial spokes are heterogeneous in structure and may play functionally distinct roles in axoneme regulation.
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Affiliation(s)
- Cynthia F Barber
- Biology Department, Rosenstiel Center, Brandeis University, Waltham, MA 02454, USA
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Dentler W. Intraflagellar transport (IFT) during assembly and disassembly of Chlamydomonas flagella. ACTA ACUST UNITED AC 2007; 170:649-59. [PMID: 16103230 PMCID: PMC2171492 DOI: 10.1083/jcb.200412021] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intraflagellar transport (IFT) of particles along flagellar microtubules is required for the assembly and maintenance of eukaryotic flagella and cilia. In Chlamydomonas, anterograde and retrograde particles viewed by light microscopy average 0.12-microm and 0.06-microm diameter, respectively. Examination of IFT particle structure in growing flagella by electron microscopy revealed similar size aggregates composed of small particles linked to each other and to the membrane and microtubules. To determine the relationship between the number of particles and flagellar length, the rate and frequency of IFT particle movement was measured in nongrowing, growing, and shortening flagella. In all flagella, anterograde and retrograde IFT averaged 1.9 microm/s and 2.7 microm/s, respectively, but retrograde IFT was significantly slower in flagella shorter than 4 mum. The number of flagellar IFT particles was not fixed, but depended on flagellar length. Pauses in IFT particle entry into flagella suggest the presence of a periodic "gate" that permits up to 4 particles/s to enter a flagellum.
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Affiliation(s)
- William Dentler
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66049, USA.
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Dentler WL. Microtubule-membrane interactions in cilia and flagella. INTERNATIONAL REVIEW OF CYTOLOGY 1981; 72:1-47. [PMID: 7019129 DOI: 10.1016/s0074-7696(08)61193-6] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Abstract
The cilia in ctenophore swimming plates are organized into long rows and the cilia within each of the rows are connected to one another by interciliary bridges. The interciliary bridges form a type of intracellular junction and are periodically spaced at 15 nm intervals along the long axis of a cilium. The bridges bind adjacent cilia together even after dissolution of the ciliary membrane by non-ionic detergent. Interciliary bridges are attached to the compartmenting lamellae, which are paracrystalline structures composed of spherical particles which are periodically attached to the outer doublet microtubules at the sites to which the microtubule-membrane bridges are bound. It is proposed that the compartmenting lamellae are modifications of the ciliary microtubule-membrane bridge found in other eukaryotic cilia and that it is associated with a junctional complex that binds adjacent cilia together in swimming plates.
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Dentler WL, Pratt MM, Stephens RE. Microtubule-membrane interactions in cilia. II. Photochemical cross-linking of bridge structures and the identification of a membrane-associated dynein-like ATPase. J Biophys Biochem Cytol 1980; 84:381-403. [PMID: 6445910 PMCID: PMC2110547 DOI: 10.1083/jcb.84.2.381] [Citation(s) in RCA: 83] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Photochemical cross-linking of both Tetrahymena and Aequipecten ciliary membrane proteins with the lipophilic reagent 4,4'-dithiobisphenylazide links together a high molecular weight dynein-like ATPase, membrane tubulin, and at least two other proteins. Electron microscopy of detergent-extracted cilia reveals that the cross-linked complex remains attached to the outer-doublet microtubules by a microtubule-membrane bridge. Cleavage of the reagent's disulfide bond releases the bridge-membrane complex and the dynein-like membrane-associated ATPase. Electron microscopy was used to ensure that the dynein-like protein did not result from the solubilization of the dynein arms attached to the outer-doublet microtubules. The dynein-like protein has been isolated using sucrose gradients and is similar to axonemal dynein with respect to its sedimentation characteristics nucleotide specificity, and divalent cation requirements. Photochemical cross-linking of ciliary membrane porteins in vivo results initially in the modification of ciliary beat and, eventually, in the cessation of ciliary movement. These results suggest that a dynein-like ATPase comprises the bridge which links the ciliary membrane to the outer-doublet microtubules and that this bridge is involved in the modulation of normal ciliary movement.
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Dentler WL. Fine structural localization of phosphatases in cilia and basal bodies of Tetrahymena pyriformis. Tissue Cell 1977; 9:209-22. [PMID: 20678 DOI: 10.1016/0040-8166(77)90017-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cytochemical localization of ATPase activities in cilia and basal bodies of Tetrahymena pyriformis revealed a number of possible sites of ATPases. In basal bodies, reaction product was localized on the periphery of basal body microtubules, in the core of the B-microtubules, on the dense basal body core, and on the basal plate; some reaction product was associated with the postciliary and basal microtubules. In the cilium, reaction product was associated with the ciliary membrane, the basal granule, the periphery of the outer doublet microtubules, in the core of the B-microtubules, and on the arms and either the central microtubules or the radial spoke heads. Reaction product deposition required ATP and either Ca2+ or Mg2+ or ADP and Mg2+. When incubated in the presence of ATP and Na+, reaction product was only found at the base of the cilium in the region of the ciliary necklace. Implications of the various sites of activity are discussed with respect to possible mechanisms of ciliary motility.
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