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De Niz M, Frachon E, Gobaa S, Bastin P. Spatial confinement of Trypanosoma brucei in microfluidic traps provides a new tool to study free swimming parasites. PLoS One 2023; 18:e0296257. [PMID: 38134042 PMCID: PMC10745224 DOI: 10.1371/journal.pone.0296257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
Trypanosoma brucei is the causative agent of African trypanosomiasis and is transmitted by the tsetse fly (Glossina spp.). All stages of this extracellular parasite possess a single flagellum that is attached to the cell body and confers a high degree of motility. While several stages are amenable to culture in vitro, longitudinal high-resolution imaging of free-swimming parasites has been challenging, mostly due to the rapid flagellar beating that constantly twists the cell body. Here, using microfabrication, we generated various microfluidic devices with traps of different geometrical properties. Investigation of trap topology allowed us to define the one most suitable for single T. brucei confinement within the field of view of an inverted microscope while allowing the parasite to remain motile. Chips populated with V-shaped traps allowed us to investigate various phenomena in cultured procyclic stage wild-type parasites, and to compare them with parasites whose motility was altered upon knockdown of a paraflagellar rod component. Among the properties that we investigated were trap invasion, parasite motility, and the visualization of organelles labelled with fluorescent dyes. We envisage that this tool we have named "Tryp-Chip" will be a useful tool for the scientific community, as it could allow high-throughput, high-temporal and high-spatial resolution imaging of free-swimming T. brucei parasites.
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Affiliation(s)
- Mariana De Niz
- Trypanosome Cell Biology Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Université de Paris, INSERM U1201, Paris, France
| | - Emmanuel Frachon
- Institut Pasteur, Université de Paris, Biomaterials and Microfluidics Core Facility, Paris, France
| | - Samy Gobaa
- Institut Pasteur, Université de Paris, Biomaterials and Microfluidics Core Facility, Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Université de Paris, INSERM U1201, Paris, France
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2
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Ghanaeian A, Majhi S, McCafferty CL, Nami B, Black CS, Yang SK, Legal T, Papoulas O, Janowska M, Valente-Paterno M, Marcotte EM, Wloga D, Bui KH. Integrated modeling of the Nexin-dynein regulatory complex reveals its regulatory mechanism. Nat Commun 2023; 14:5741. [PMID: 37714832 PMCID: PMC10504270 DOI: 10.1038/s41467-023-41480-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 09/05/2023] [Indexed: 09/17/2023] Open
Abstract
Cilia are hairlike protrusions that project from the surface of eukaryotic cells and play key roles in cell signaling and motility. Ciliary motility is regulated by the conserved nexin-dynein regulatory complex (N-DRC), which links adjacent doublet microtubules and regulates and coordinates the activity of outer doublet complexes. Despite its critical role in cilia motility, the assembly and molecular basis of the regulatory mechanism are poorly understood. Here, using cryo-electron microscopy in conjunction with biochemical cross-linking and integrative modeling, we localize 12 DRC subunits in the N-DRC structure of Tetrahymena thermophila. We also find that the CCDC96/113 complex is in close contact with the DRC9/10 in the linker region. In addition, we reveal that the N-DRC is associated with a network of coiled-coil proteins that most likely mediates N-DRC regulatory activity.
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Affiliation(s)
- Avrin Ghanaeian
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Sumita Majhi
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
| | - Caitlyn L McCafferty
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX, USA
| | - Babak Nami
- Genetics and Genome Biology Program, Hospital for Sick Children, Toronto, Canada
| | - Corbin S Black
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Shun Kai Yang
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Thibault Legal
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Ophelia Papoulas
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX, USA
| | - Martyna Janowska
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
- Laboratory of Immunology, Mossakowski Institute of Experimental and Clinical Medicine, Polish Academy of Science, Pawinskiego 5, 02-106, Warsaw, Poland
| | - Melissa Valente-Paterno
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Edward M Marcotte
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, TX, USA
| | - 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.
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada.
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3
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Ghanaeian A, Majhi S, McCaffrey CL, Nami B, Black CS, Yang SK, Legal T, Papoulas O, Janowska M, Valente-Paterno M, Marcotte EM, Wloga D, Bui KH. Integrated modeling of the Nexin-dynein regulatory complex reveals its regulatory mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543107. [PMID: 37398254 PMCID: PMC10312493 DOI: 10.1101/2023.05.31.543107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Cilia are hairlike protrusions that project from the surface of eukaryotic cells and play key roles in cell signaling and motility. Ciliary motility is regulated by the conserved nexin-dynein regulatory complex (N-DRC), which links adjacent doublet microtubules and regulates and coordinates the activity of outer doublet complexes. Despite its critical role in cilia motility, the assembly and molecular basis of the regulatory mechanism are poorly understood. Here, utilizing cryo-electron microscopy in conjunction with biochemical cross-linking and integrative modeling, we localized 12 DRC subunits in the N-DRC structure of Tetrahymena thermophila . We also found that the CCDC96/113 complex is in close contact with the N-DRC. In addition, we revealed that the N-DRC is associated with a network of coiled-coil proteins that most likely mediates N-DRC regulatory activity.
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Affiliation(s)
- Avrin Ghanaeian
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Sumita Majhi
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
| | - Caitie L McCaffrey
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, United States
| | - Babak Nami
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Corbin S Black
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Shun Kai Yang
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Thibault Legal
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Ophelia Papoulas
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, United States
| | - Martyna Janowska
- Laboratory of Cytoskeleton and Cilia Biology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
- current address: Laboratory of Immunology, Mossakowski Institute of Experimental and Clinical Medicine, Polish Academy of Science, Pawinskiego 5, 02-106 Warsaw, Poland
| | - Melissa Valente-Paterno
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
| | - Edward M Marcotte
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of Texas, Austin, United States
| | - 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
| | - Khanh Huy Bui
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Québec, Canada
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Morohoshi A, Miyata H, Shimada K, Nozawa K, Matsumura T, Yanase R, Shiba K, Inaba K, Ikawa M. Nexin-Dynein regulatory complex component DRC7 but not FBXL13 is required for sperm flagellum formation and male fertility in mice. PLoS Genet 2020; 16:e1008585. [PMID: 31961863 PMCID: PMC6994161 DOI: 10.1371/journal.pgen.1008585] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 01/31/2020] [Accepted: 12/29/2019] [Indexed: 01/28/2023] Open
Abstract
Flagella and cilia are evolutionarily conserved cellular organelles. Abnormal formation or motility of these organelles in humans causes several syndromic diseases termed ciliopathies. The central component of flagella and cilia is the axoneme that is composed of the ‘9+2’ microtubule arrangement, dynein arms, radial spokes, and the Nexin-Dynein Regulatory Complex (N-DRC). The N-DRC is localized between doublet microtubules and has been extensively studied in the unicellular flagellate Chlamydomonas. Recently, it has been reported that TCTE1 (DRC5), a component of the N-DRC, is essential for proper sperm motility and male fertility in mice. Further, TCTE1 has been shown to interact with FBXL13 (DRC6) and DRC7; however, functional roles of FBXL13 and DRC7 in mammals have not been elucidated. Here we show that Fbxl13 and Drc7 expression are testes-enriched in mice. Although Fbxl13 knockout (KO) mice did not show any obvious phenotypes, Drc7 KO male mice were infertile due to their short immotile spermatozoa. In Drc7 KO spermatids, the axoneme is disorganized and the ‘9+2’ microtubule arrangement was difficult to detect. Further, other N-DRC components fail to incorporate into the flagellum without DRC7. These results indicate that Drc7, but not Fbxl13, is essential for the correct assembly of the N-DRC and flagella. In recent years, almost one in six couples face infertility, and nearly 50% of cases are attributed to male factors. It has been shown that approximately 15% of male infertility is caused by genetic factors. The conditions of male infertility mainly include spermatozoa with abnormal morphology (teratozoospermia), reduced sperm motility (asthenozoospermia), and no or low sperm count (azoospermia). Multiple morphological abnormalities of the sperm flagella (MMAF) are characterized as asthenoteratozoospermia, which is a condition with abnormal sperm tail morphology, including absent, coiled, bent, or short tails. Sperm tails are formed during spermiogenesis; however, the mechanism that govern tail formation remains unclear. Here we mutated Fbxl13 and Drc7, two genes with strong expression in mouse testis and which have been shown to be important for flagellum formation and regulation in other systems. Deletion of Drc7 leads to aberrant tail formation in mouse spermatozoa that phenocopies patients with MMAF, while deletion of Fbxl13 has no observable effect on sperm function. Our results identified DRC7 as an important factor for sperm flagellum formation.
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Affiliation(s)
- Akane Morohoshi
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Haruhiko Miyata
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Keisuke Shimada
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kaori Nozawa
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takafumi Matsumura
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Ryuji Yanase
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Kogiku Shiba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Graduate School of Medicine, Osaka University, Osaka, Japan
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
- The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- * E-mail:
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5
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Imhof S, Zhang J, Wang H, Bui KH, Nguyen H, Atanasov I, Hui WH, Yang SK, Zhou ZH, Hill KL. Cryo electron tomography with volta phase plate reveals novel structural foundations of the 96-nm axonemal repeat in the pathogen Trypanosoma brucei. eLife 2019; 8:e52058. [PMID: 31710293 PMCID: PMC6974359 DOI: 10.7554/elife.52058] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 11/11/2019] [Indexed: 12/12/2022] Open
Abstract
The 96-nm axonemal repeat includes dynein motors and accessory structures as the foundation for motility of eukaryotic flagella and cilia. However, high-resolution 3D axoneme structures are unavailable for organisms among the Excavates, which include pathogens of medical and economic importance. Here we report cryo electron tomography structures of the 96-nm repeat from Trypanosoma brucei, a protozoan parasite in the Excavate lineage that causes African trypanosomiasis. We examined bloodstream and procyclic life cycle stages, and a knockdown lacking DRC11/CMF22 of the nexin dynein regulatory complex (NDRC). Sub-tomogram averaging yields a resolution of 21.8 Å for the 96-nm repeat. We discovered several lineage-specific structures, including novel inter-doublet linkages and microtubule inner proteins (MIPs). We establish that DRC11/CMF22 is required for the NDRC proximal lobe that binds the adjacent doublet microtubule. We propose that lineage-specific elaboration of axoneme structure in T. brucei reflects adaptations to support unique motility needs in diverse host environments.
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Affiliation(s)
- Simon Imhof
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
| | - Jiayan Zhang
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
- Molecular Biology InstituteUniversity of California, Los AngelesLos AngelesUnited States
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
| | - Hui Wang
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
- Department of BioengineeringUniversity of California, Los AngelesLos AngelesUnited States
| | - Khanh Huy Bui
- Department of Anatomy and Cell BiologyMcGill UniversityMontrealUnited States
| | - Hoangkim Nguyen
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
| | - Ivo Atanasov
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
| | - Wong H Hui
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
| | - Shun Kai Yang
- Department of Anatomy and Cell BiologyMcGill UniversityMontrealUnited States
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
- Molecular Biology InstituteUniversity of California, Los AngelesLos AngelesUnited States
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
- Department of BioengineeringUniversity of California, Los AngelesLos AngelesUnited States
| | - Kent L Hill
- Department of Microbiology, Immunology and Molecular GeneticsUniversity of California, Los AngelesLos AngelesUnited States
- Molecular Biology InstituteUniversity of California, Los AngelesLos AngelesUnited States
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesUnited States
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6
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Scaffold subunits support associated subunit assembly in the Chlamydomonas ciliary nexin-dynein regulatory complex. Proc Natl Acad Sci U S A 2019; 116:23152-23162. [PMID: 31659045 DOI: 10.1073/pnas.1910960116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The nexin-dynein regulatory complex (N-DRC) in motile cilia and flagella functions as a linker between neighboring doublet microtubules, acts to stabilize the axonemal core structure, and serves as a central hub for the regulation of ciliary motility. Although the N-DRC has been studied extensively using genetic, biochemical, and structural approaches, the precise arrangement of the 11 (or more) N-DRC subunits remains unknown. Here, using cryo-electron tomography, we have compared the structure of Chlamydomonas wild-type flagella to that of strains with specific DRC subunit deletions or rescued strains with tagged DRC subunits. Our results show that DRC7 is a central linker subunit that helps connect the N-DRC to the outer dynein arms. DRC11 is required for the assembly of DRC8, and DRC8/11 form a subcomplex in the proximal lobe of the linker domain that is required to form stable contacts to the neighboring B-tubule. Gold labeling of tagged subunits determines the precise locations of the previously ambiguous N terminus of DRC4 and C terminus of DRC5. DRC4 is now shown to contribute to the core scaffold of the N-DRC. Our results reveal the overall architecture of N-DRC, with the 3 subunits DRC1/2/4 forming a core complex that serves as the scaffold for the assembly of the "functional subunits," namely DRC3/5-8/11. These findings shed light on N-DRC assembly and its role in regulating flagellar beating.
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7
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Assessment of Parasite-Microglia Interactions In Vitro. Methods Mol Biol 2019. [PMID: 31392683 DOI: 10.1007/978-1-4939-9658-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
An extensive number of parasites are able to invade the central nervous system (CNS) and cause a plethora of pathologies. Microglia, the resident macrophages of nervous tissue, are responsible for the protection against intruders, and therefore, they are an important line of defense against parasites. The phagocytosis is one of the weapons in the microglia's arsenal to fight against parasites. Several prior studies of microglia-parasite interactions and phagocytosis have been performed using microscopic techniques. As this methodology allows only a limited number of cells to be analyzed, additional approaches are required to provide a more complete picture of how microglia interact with these pathogens. Here, we describe a protocol based on flow cytometry to analyze single-celled parasites/microglia interactions in thousands of events in an accurate and reliable way. We use Trypanosoma brucei as a model organism, as it is a well-known parasite causing primary meningoencephalitis. However, the interaction/phagocytosis assay can be applied to other single-celled parasites as well.
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8
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Figarella K, Uzcategui NL, Mogk S, Wild K, Fallier-Becker P, Neher JJ, Duszenko M. Morphological changes, nitric oxide production, and phagocytosis are triggered in vitro in microglia by bloodstream forms of Trypanosoma brucei. Sci Rep 2018; 8:15002. [PMID: 30302029 PMCID: PMC6177420 DOI: 10.1038/s41598-018-33395-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/27/2018] [Indexed: 01/18/2023] Open
Abstract
The flagellated parasite Trypanosoma brucei is the causative agent of Human African Trypanosomiasis (HAT). By a mechanism not well understood yet, trypanosomes enter the central nervous system (CNS), invade the brain parenchyma, and cause a fatal encephalopathy if is not treated. Trypanosomes are fast dividing organisms that, without any immune response, would kill the host in a short time. However, infected individuals survive either 6-12 months or more than 3 years for the acute and chronic forms, respectively. Thus, only when the brain defense collapses a lethal encephalopathy will occur. Here, we evaluated interactions between trypanosomes and microglial cells, which are the primary immune effector cells within the CNS. Using co-cultures of primary microglia and parasites, we found clear evidences of trypanosome phagocytosis by microglial cells. Microglia activation was also evident; analysis of its ultrastructure showed changes that have been reported in activated microglia undergoing oxidative stress caused by infections or degenerative diseases. Accordingly, an increase of the nitric oxide production was detected in supernatants of microglia/parasite co-cultures. Altogether, our results demonstrate that microglial cells respond to the presence of the parasite, leading to parasite's engulfment and elimination.
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Affiliation(s)
- Katherine Figarella
- Interfaculty Institute for Biochemistry, University of Tübingen, Tübingen, Germany.
- Institute for Neurophysiology, University of Tübingen, Tübingen, Germany.
| | - Nestor L Uzcategui
- Institute for Anatomy, Central University of Venezuela, Caracas, Venezuela
| | - Stefan Mogk
- Interfaculty Institute for Biochemistry, University of Tübingen, Tübingen, Germany
| | - Katleen Wild
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany and Department of Cellular Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Petra Fallier-Becker
- Institute of Pathology and Neuropathology, University Hospital of Tübingen, Tübingen, Germany
| | - Jonas J Neher
- German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany and Department of Cellular Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Michael Duszenko
- Interfaculty Institute for Biochemistry, University of Tübingen, Tübingen, Germany
- Faculty of Medicine, Tongji University, Shanghai, China
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9
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Bower R, Tritschler D, Mills KV, Heuser T, Nicastro D, Porter ME. DRC2/CCDC65 is a central hub for assembly of the nexin-dynein regulatory complex and other regulators of ciliary and flagellar motility. Mol Biol Cell 2017; 29:137-153. [PMID: 29167384 PMCID: PMC5909927 DOI: 10.1091/mbc.e17-08-0510] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 02/01/2023] Open
Abstract
DRC2 is a subunit of the nexin–dynein regulatory complex linked to primary ciliary dyskinesia. Little is known about the impact of drc2 mutations on axoneme composition and structure. We used proteomic and structural approaches to reveal that DRC2 coassembles with DRC1 to attach the N-DRC to the A-tubule and mediate interactions with other regulatory structures. The nexin–dynein regulatory complex (N-DRC) plays a central role in the regulation of ciliary and flagellar motility. In most species, the N-DRC contains at least 11 subunits, but the specific function of each subunit is unknown. Mutations in three subunits (DRC1, DRC2/CCDC65, DRC4/GAS8) have been linked to defects in ciliary motility in humans and lead to a ciliopathy known as primary ciliary dyskinesia (PCD). Here we characterize the biochemical, structural, and motility phenotypes of two mutations in the DRC2 gene of Chlamydomonas. Using high-resolution proteomic and structural approaches, we find that the C-terminal region of DRC2 is critical for the coassembly of DRC2 and DRC1 to form the base plate of N-DRC and its attachment to the outer doublet microtubule. Loss of DRC2 in drc2 mutants disrupts the assembly of several other N-DRC subunits and also destabilizes the assembly of several closely associated structures such as the inner dynein arms, the radial spokes, and the calmodulin- and spoke-associated complex. Our study provides new insights into the range of ciliary defects that can lead to PCD.
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Affiliation(s)
- Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Douglas Tritschler
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Kristyn VanderWaal Mills
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Thomas Heuser
- Biology Department and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.,Vienna Biocenter Core Facilities, 1030 Vienna, Austria
| | - Daniela Nicastro
- Biology Department and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454.,Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary E Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
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10
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Insect stage-specific adenylate cyclases regulate social motility in African trypanosomes. EUKARYOTIC CELL 2014; 14:104-12. [PMID: 25416239 DOI: 10.1128/ec.00217-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sophisticated systems for cell-cell communication enable unicellular microbes to act as multicellular entities capable of group-level behaviors that are not evident in individuals. These group behaviors influence microbe physiology, and the underlying signaling pathways are considered potential drug targets in microbial pathogens. Trypanosoma brucei is a protozoan parasite that causes substantial human suffering and economic hardship in some of the most impoverished regions of the world. T. brucei lives on host tissue surfaces during transmission through its tsetse fly vector, and cultivation on surfaces causes the parasites to assemble into multicellular communities in which individual cells coordinate their movements in response to external signals. This behavior is termed "social motility," based on its similarities with surface-induced social motility in bacteria, and it demonstrates that trypanosomes are capable of group-level behavior. Mechanisms governing T. brucei social motility are unknown. Here we report that a subset of receptor-type adenylate cyclases (ACs) in the trypanosome flagellum regulate social motility. RNA interference-mediated knockdown of adenylate cyclase 6 (AC6), or dual knockdown of AC1 and AC2, causes a hypersocial phenotype but has no discernible effect on individual cells in suspension culture. Mutation of the AC6 catalytic domain phenocopies AC6 knockdown, demonstrating that loss of adenylate cyclase activity is responsible for the phenotype. Notably, knockdown of other ACs did not affect social motility, indicating segregation of AC functions. These studies reveal interesting parallels in systems that control social behavior in trypanosomes and bacteria and provide insight into a feature of parasite biology that may be exploited for novel intervention strategies.
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Abstract
Trypanosoma brucei is a pathogenic unicellular eukaryote that infects humans and other mammals in sub-Saharan Africa. A central feature of trypanosome biology is the single flagellum of the parasite, which is an essential and multifunctional organelle that facilitates cell propulsion, controls cell morphogenesis and directs cytokinesis. Moreover, the flagellar membrane is a specialized subdomain of the cell surface that mediates attachment to host tissues and harbours multiple virulence factors. In this Review, we discuss the structure, assembly and function of the trypanosome flagellum, including canonical roles in cell motility as well as novel and emerging roles in cell morphogenesis and host-parasite interactions.
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Affiliation(s)
- Gerasimos Langousis
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095
| | - Kent L. Hill
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095
- Molecular Biology Institute, University of California, Los Angeles, CA90095
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