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Marshall WF. Chlamydomonas as a model system to study cilia and flagella using genetics, biochemistry, and microscopy. Front Cell Dev Biol 2024; 12:1412641. [PMID: 38872931 PMCID: PMC11169674 DOI: 10.3389/fcell.2024.1412641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/13/2024] [Indexed: 06/15/2024] Open
Abstract
The unicellular green alga, Chlamydomonas reinhardtii, has played a central role in discovering much of what is currently known about the composition, assembly, and function of cilia and flagella. Chlamydomonas combines excellent genetics, such as the ability to grow cells as haploids or diploids and to perform tetrad analysis, with an unparalleled ability to detach and isolate flagella in a single step without cell lysis. The combination of genetics and biochemistry that is possible in Chlamydomonas has allowed many of the key components of the cilium to be identified by looking for proteins that are missing in a defined mutant. Few if any other model organisms allow such a seamless combination of genetic and biochemical approaches. Other major advantages of Chlamydomonas compared to other systems include the ability to induce flagella to regenerate in a highly synchronous manner, allowing the kinetics of flagellar growth to be measured, and the ability of Chlamydomonas flagella to adhere to glass coverslips allowing Intraflagellar Transport to be easily imaged inside the flagella of living cells, with quantitative precision and single-molecule resolution. These advantages continue to work in favor of Chlamydomonas as a model system going forward, and are now augmented by extensive genomic resources, a knockout strain collection, and efficient CRISPR gene editing. While Chlamydomonas has obvious limitations for studying ciliary functions related to animal development or organ physiology, when it comes to studying the fundamental biology of cilia and flagella, Chlamydomonas is simply unmatched in terms of speed, efficiency, cost, and the variety of approaches that can be brought to bear on a question.
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Affiliation(s)
- Wallace F. Marshall
- Department Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, United States
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Grossman-Haham I, Coudray N, Yu Z, Wang F, Zhang N, Bhabha G, Vale RD. Structure of the radial spoke head and insights into its role in mechanoregulation of ciliary beating. Nat Struct Mol Biol 2021; 28:20-28. [PMID: 33318704 PMCID: PMC7855469 DOI: 10.1038/s41594-020-00519-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/16/2020] [Indexed: 11/14/2022]
Abstract
Motile cilia power cell locomotion and drive extracellular fluid flow by propagating bending waves from their base to tip. The coordinated bending of cilia requires mechanoregulation by the radial spoke (RS) protein complexes and the microtubule central pair (CP). Despite their importance for ciliary motility across eukaryotes, the molecular function of the RSs is unknown. Here, we reconstituted the Chlamydomonas reinhardtii RS head that abuts the CP and determined its structure using single-particle cryo-EM to 3.1-Å resolution, revealing a flat, negatively charged surface supported by a rigid core of tightly intertwined proteins. Mutations in this core, corresponding to those involved in human ciliopathies, compromised the stability of the recombinant complex, providing a molecular basis for disease. Partially reversing the negative charge on the RS surface impaired motility in C. reinhardtii. We propose that the RS-head architecture is well-suited for mechanoregulation of ciliary beating through physical collisions with the CP.
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Affiliation(s)
- Iris Grossman-Haham
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Nicolas Coudray
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA
- Applied Bioinformatics Laboratories, New York University School of Medicine, New York, NY, USA
| | - Zanlin Yu
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Feng Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Nan Zhang
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Gira Bhabha
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, USA
| | - Ronald D Vale
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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Gui M, Ma M, Sze-Tu E, Wang X, Koh F, Zhong ED, Berger B, Davis JH, Dutcher SK, Zhang R, Brown A. Structures of radial spokes and associated complexes important for ciliary motility. Nat Struct Mol Biol 2021; 28:29-37. [PMID: 33318703 PMCID: PMC7855293 DOI: 10.1038/s41594-020-00530-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/28/2020] [Indexed: 12/20/2022]
Abstract
In motile cilia, a mechanoregulatory network is responsible for converting the action of thousands of dynein motors bound to doublet microtubules into a single propulsive waveform. Here, we use two complementary cryo-EM strategies to determine structures of the major mechanoregulators that bind ciliary doublet microtubules in Chlamydomonas reinhardtii. We determine structures of isolated radial spoke RS1 and the microtubule-bound RS1, RS2 and the nexin-dynein regulatory complex (N-DRC). From these structures, we identify and build atomic models for 30 proteins, including 23 radial-spoke subunits. We reveal how mechanoregulatory complexes dock to doublet microtubules with regular 96-nm periodicity and communicate with one another. Additionally, we observe a direct and dynamically coupled association between RS2 and the dynein motor inner dynein arm subform c (IDAc), providing a molecular basis for the control of motor activity by mechanical signals. These structures advance our understanding of the role of mechanoregulation in defining the ciliary waveform.
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Affiliation(s)
- Miao Gui
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Meisheng Ma
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, School of Medicine, St. Louis, MO, USA
| | - Erica Sze-Tu
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Xiangli Wang
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, School of Medicine, St. Louis, MO, USA
| | - Fujiet Koh
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Thermo Fisher Scientific, Eindhoven, Netherlands
| | - Ellen D Zhong
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bonnie Berger
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Joseph H Davis
- Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Susan K Dutcher
- Department of Genetics, Washington University in St. Louis, St. Louis, MO, USA
| | - Rui Zhang
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, School of Medicine, St. Louis, MO, USA.
| | - Alan Brown
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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Abdelhamed Z, Lukacs M, Cindric S, Ali S, Omran H, Stottmann RW. A novel hypomorphic allele of Spag17 causes primary ciliary dyskinesia phenotypes in mice. Dis Model Mech 2020; 13:dmm045344. [PMID: 32988999 PMCID: PMC7648611 DOI: 10.1242/dmm.045344] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/24/2020] [Indexed: 12/22/2022] Open
Abstract
Primary ciliary dyskinesia (PCD) is a human condition of dysfunctional motile cilia characterized by recurrent lung infection, infertility, organ laterality defects and partially penetrant hydrocephalus. We recovered a mouse mutant from a forward genetic screen that developed many of the hallmark phenotypes of PCD. Whole-exome sequencing identified this primary ciliary dyskinesia only (Pcdo) allele to be a nonsense mutation (c.5236A>T) in the Spag17 coding sequence creating a premature stop codon (K1746*). The Pcdo variant abolished several isoforms of SPAG17 in the Pcdo mutant testis but not in the brain. Our data indicate differential requirements for SPAG17 in different types of motile cilia. SPAG17 is essential for proper development of the sperm flagellum and is required for either development or stability of the C1 microtubule structure within the central pair apparatus of the respiratory motile cilia, but not the brain ependymal cilia. We identified changes in ependymal ciliary beating frequency, but these did not appear to alter lateral ventricle cerebrospinal fluid flow. Aqueductal stenosis resulted in significantly slower and abnormally directed cerebrospinal fluid flow, and we suggest that this is the root cause of the hydrocephalus. The Spag17Pcdo homozygous mutant mice are generally viable to adulthood but have a significantly shortened lifespan, with chronic morbidity. Our data indicate that the c.5236A>T Pcdo variant is a hypomorphic allele of Spag17 that causes phenotypes related to motile, but not primary, cilia. Spag17Pcdo is a useful new model for elucidating the molecular mechanisms underlying central pair PCD pathogenesis in the mouse.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Zakia Abdelhamed
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Anatomy and Embryology, Faculty of Medicine (Girl's Section), Al-Azhar University, Cairo 11651, Egypt
| | - Marshall Lukacs
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Medical Scientist Training Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Sandra Cindric
- Department of General Pediatrics, University Children's Hospital Münster, 48149 Münster, Germany
| | - Saima Ali
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Heymut Omran
- Department of General Pediatrics, University Children's Hospital Münster, 48149 Münster, Germany
| | - Rolf W Stottmann
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Medical Scientist Training Program, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH 45229, USA
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Poghosyan E, Iacovache I, Faltova L, Leitner A, Yang P, Diener DR, Aebersold R, Zuber B, Ishikawa T. The structure and symmetry of the radial spoke protein complex in Chlamydomonas flagella. J Cell Sci 2020; 133:jcs245233. [PMID: 32694165 DOI: 10.1242/jcs.245233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/25/2020] [Indexed: 12/27/2022] Open
Abstract
The radial spoke is a key element in a transducer apparatus controlling the motility of eukaryotic cilia. The transduction biomechanics is a long-standing question in cilia biology. The radial spoke has three regions - a spoke head, a bifurcated neck and a stalk. Although the neck and the stalk are asymmetric, twofold symmetry of the head has remained controversial. In this work we used single particle cryo-electron microscopy (cryo-EM) analysis to generate a 3D structure of the whole radial spoke at unprecedented resolution. We show the head region at 15 Å (1.5 nm) resolution and confirm twofold symmetry. Using distance constraints generated by cross-linking mass spectrometry, we locate two components, RSP2 and RSP4, at the head and neck regions. Our biophysical analysis of isolated RSP4, RSP9, and RSP10 affirmed their oligomeric state. Our results enable us to redefine the boundaries of the regions and propose a model of organization of the radial spoke component proteins.
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Affiliation(s)
- Emiliya Poghosyan
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
- ETH Zurich, Department of Biology, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
| | - Ioan Iacovache
- University of Bern, Institute of Anatomy, Baltzerstrasse 2, 3012 Bern, Switzerland
| | - Lenka Faltova
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Alexander Leitner
- ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Dennis R Diener
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Ruedi Aebersold
- ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
- University of Zurich, Faculty of Science, Rämistrasse 71, 8006 Zürich, Switzerland
| | - Benoit Zuber
- University of Bern, Institute of Anatomy, Baltzerstrasse 2, 3012 Bern, Switzerland
| | - Takashi Ishikawa
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
- ETH Zurich, Department of Biology, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
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Rare Human Diseases: Model Organisms in Deciphering the Molecular Basis of Primary Ciliary Dyskinesia. Cells 2019; 8:cells8121614. [PMID: 31835861 PMCID: PMC6952885 DOI: 10.3390/cells8121614] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/02/2019] [Accepted: 12/10/2019] [Indexed: 12/17/2022] Open
Abstract
Primary ciliary dyskinesia (PCD) is a recessive heterogeneous disorder of motile cilia, affecting one per 15,000-30,000 individuals; however, the frequency of this disorder is likely underestimated. Even though more than 40 genes are currently associated with PCD, in the case of approximately 30% of patients, the genetic cause of the manifested PCD symptoms remains unknown. Because motile cilia are highly evolutionarily conserved organelles at both the proteomic and ultrastructural levels, analyses in the unicellular and multicellular model organisms can help not only to identify new proteins essential for cilia motility (and thus identify new putative PCD-causative genes), but also to elucidate the function of the proteins encoded by known PCD-causative genes. Consequently, studies involving model organisms can help us to understand the molecular mechanism(s) behind the phenotypic changes observed in the motile cilia of PCD affected patients. Here, we summarize the current state of the art in the genetics and biology of PCD and emphasize the impact of the studies conducted using model organisms on existing knowledge.
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Osinka A, Poprzeczko M, Zielinska MM, Fabczak H, Joachimiak E, Wloga D. Ciliary Proteins: Filling the Gaps. Recent Advances in Deciphering the Protein Composition of Motile Ciliary Complexes. Cells 2019; 8:cells8070730. [PMID: 31319499 PMCID: PMC6678824 DOI: 10.3390/cells8070730] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 12/15/2022] Open
Abstract
Cilia are highly evolutionarily conserved, microtubule-based cell protrusions present in eukaryotic organisms from protists to humans, with the exception of fungi and higher plants. Cilia can be broadly divided into non-motile sensory cilia, called primary cilia, and motile cilia, which are locomotory organelles. The skeleton (axoneme) of primary cilia is formed by nine outer doublet microtubules distributed on the cilium circumference. In contrast, the skeleton of motile cilia is more complex: in addition to outer doublets, it is composed of two central microtubules and several diverse multi-protein complexes that are distributed periodically along both types of microtubules. For many years, researchers have endeavored to fully characterize the protein composition of ciliary macro-complexes and the molecular basis of signal transduction between these complexes. Genetic and biochemical analyses have suggested that several hundreds of proteins could be involved in the assembly and function of motile cilia. Within the last several years, the combined efforts of researchers using cryo-electron tomography, genetic and biochemical approaches, and diverse model organisms have significantly advanced our knowledge of the ciliary structure and protein composition. Here, we summarize the recent progress in the identification of the subunits of ciliary complexes, their precise intraciliary localization determined by cryo-electron tomography data, and the role of newly identified proteins in cilia.
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Affiliation(s)
- Anna Osinka
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Martyna Poprzeczko
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Magdalena M Zielinska
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Hanna Fabczak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Ewa Joachimiak
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
| | - Dorota Wloga
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
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