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Fu G, Augspurger K, Sakizadeh J, Reck J, Bower R, Tritschler D, Gui L, Nicastro D, Porter ME. The MBO2/FAP58 heterodimer stabilizes assembly of inner arm dynein b and reveals axoneme asymmetries involved in ciliary waveform. Mol Biol Cell 2024; 35:ar72. [PMID: 38568782 DOI: 10.1091/mbc.e23-11-0439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
Cilia generate three-dimensional waveforms required for cell motility and transport of fluid, mucus, and particles over the cell surface. This movement is driven by multiple dynein motors attached to nine outer doublet microtubules that form the axoneme. The outer and inner arm dyneins are organized into 96-nm repeats tandemly arrayed along the length of the doublets. Motility is regulated in part by projections from the two central pair microtubules that contact radial spokes located near the base of the inner dynein arms in each repeat. Although much is known about the structures and protein complexes within the axoneme, many questions remain about the regulatory mechanisms that allow the cilia to modify their waveforms in response to internal or external stimuli. Here, we used Chlamydomonas mbo (move backwards only) mutants with altered waveforms to identify at least two conserved proteins, MBO2/CCDC146 and FAP58/CCDC147, that form part of a L-shaped structure that varies between doublet microtubules. Comparative proteomics identified additional missing proteins that are altered in other motility mutants, revealing overlapping protein defects. Cryo-electron tomography and epitope tagging revealed that the L-shaped, MBO2/FAP58 structure interconnects inner dynein arms with multiple regulatory complexes, consistent with its function in modifying the ciliary waveform.
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Affiliation(s)
- Gang Fu
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Katherine Augspurger
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Jason Sakizadeh
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Jaimee Reck
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Raqual Bower
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Douglas Tritschler
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
| | - Long Gui
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Daniela Nicastro
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary E Porter
- Department of Genetics, Cell Biology, and Genetics, University of Minnesota, Minneapolis, MN 55455
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Sakizadeh J, Davis MJ, Fontana L. Progressive multifocal leukoencephalopathy in a lung transplant recipient. Clin Case Rep 2024; 12:e8626. [PMID: 38464572 PMCID: PMC10923696 DOI: 10.1002/ccr3.8626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 01/23/2024] [Accepted: 02/08/2024] [Indexed: 03/12/2024] Open
Abstract
Progressive multifocal leukoencephalopathy (PML) is a rare and fatal demyelinating disease of the central nervous system (CNS). The case we describe highlights the importance of considering a diagnosis of PML early (<1 year) after lung transplant.
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Affiliation(s)
- Jason Sakizadeh
- University of Minnesota Medical School Twin Cities CampusMinneapolisMNUSA
| | - Michael J. Davis
- Division of Infectious Diseases and International MedicineUniversity of Minnesota Medical School Twin Cities Campus, Infectious DiseaseMinneapolisMNUSA
| | - Lauren Fontana
- Division of Infectious Diseases and International MedicineUniversity of Minnesota Medical School Twin Cities Campus, Infectious DiseaseMinneapolisMNUSA
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Fu G, Augspurger K, Sakizadeh J, Reck J, Bower R, Tritschler D, Gui L, Nicastro D, Porter ME. The ciliary MBO2 complex targets assembly of inner arm dynein b and reveals additional doublet microtubule asymmetries. bioRxiv 2023:2023.07.31.551375. [PMID: 37577467 PMCID: PMC10418103 DOI: 10.1101/2023.07.31.551375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Ciliary motility requires the spatiotemporal coordination of multiple dynein motors by regulatory complexes located within the 96 nm axoneme repeat. Many organisms can alter ciliary waveforms in response to internal or external stimuli, but little is known about the specific polypeptides and structural organization of complexes that regulate waveforms. In Chlamydomonas, several mutations convert the ciliary waveform from an asymmetric, ciliary-type stroke to a symmetric, flagellar-type stroke. Some of these mutations alter subunits located at the inner junction of the doublet microtubule and others alter interactions between the dynein arms and the radial spokes. These and other axonemal substructures are interconnected by a network of poorly characterized proteins. Here we re-analyze several motility mutants (mbo, fap57, pf12/pacrg) to identify new components in this network. The mbo (move backwards only) mutants are unable to swim forwards with an asymmetric waveform. Proteomics identified more than 19 polypeptides that are missing or reduced in mbo mutants, including one inner dynein arm, IDA b. Several MBO2-associated proteins are also altered in fap57 and pf12/parcg mutants, suggesting overlapping networks. Two subunits are highly conserved, coiled coil proteins found in other species with motile cilia and others contain potential signaling domains. Cryo-electron tomography and epitope tagging revealed that the MBO2 complex is found on specific doublet microtubules and forms a large, L-shaped structure that contacts the base of IDA b that interconnects multiple dynein regulatory complexes and varies in a doublet microtubule specific fashion.
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