1
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Ott CM, Torres R, Kuan TS, Kuan A, Buchanan J, Elabbady L, Seshamani S, Bodor AL, Collman F, Bock DD, Lee WC, da Costa NM, Lippincott-Schwartz J. Ultrastructural differences impact cilia shape and external exposure across cell classes in the visual cortex. Curr Biol 2024; 34:2418-2433.e4. [PMID: 38749425 PMCID: PMC11217952 DOI: 10.1016/j.cub.2024.04.043] [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: 11/06/2023] [Revised: 03/27/2024] [Accepted: 04/22/2024] [Indexed: 06/06/2024]
Abstract
A primary cilium is a membrane-bound extension from the cell surface that contains receptors for perceiving and transmitting signals that modulate cell state and activity. Primary cilia in the brain are less accessible than cilia on cultured cells or epithelial tissues because in the brain they protrude into a deep, dense network of glial and neuronal processes. Here, we investigated cilia frequency, internal structure, shape, and position in large, high-resolution transmission electron microscopy volumes of mouse primary visual cortex. Cilia extended from the cell bodies of nearly all excitatory and inhibitory neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) but were absent from oligodendrocytes and microglia. Ultrastructural comparisons revealed that the base of the cilium and the microtubule organization differed between neurons and glia. Investigating cilia-proximal features revealed that many cilia were directly adjacent to synapses, suggesting that cilia are poised to encounter locally released signaling molecules. Our analysis indicated that synapse proximity is likely due to random encounters in the neuropil, with no evidence that cilia modulate synapse activity as would be expected in tetrapartite synapses. The observed cell class differences in proximity to synapses were largely due to differences in external cilia length. Many key structural features that differed between neuronal and glial cilia influenced both cilium placement and shape and, thus, exposure to processes and synapses outside the cilium. Together, the ultrastructure both within and around neuronal and glial cilia suggest differences in cilia formation and function across cell types in the brain.
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Affiliation(s)
- Carolyn M Ott
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
| | - Russel Torres
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Tung-Sheng Kuan
- Department of Physics, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Aaron Kuan
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - JoAnn Buchanan
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | - Leila Elabbady
- Allen Institute for Brain Science, Seattle, WA 98109, USA; University of Washington, Seattle, WA 98195, USA
| | | | - Agnes L Bodor
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| | | | - Davi D Bock
- Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Wei Chung Lee
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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2
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Mercey O, Mukherjee S, Guichard P, Hamel V. The molecular architecture of the ciliary transition zones. Curr Opin Cell Biol 2024; 88:102361. [PMID: 38648677 DOI: 10.1016/j.ceb.2024.102361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/28/2024] [Accepted: 03/30/2024] [Indexed: 04/25/2024]
Abstract
Cilia and flagella are specialized eukaryotic organelles projecting from the surface of eukaryotic cells that play a central role in various physiological processes, including cell motility, sensory perception, and signal transduction. At the base of these structures lies the ciliary transition zone, a pivotal region that functions as a gatekeeper and communication hub for ciliary activities. Despite its crucial role, the intricacies of its architecture remain poorly understood, especially given the variations in its organization across different cell types and species. In this review, we explore the molecular architecture of the ciliary transition zone, with a particular focus on recent findings obtained using cryotomography and super-resolution imaging techniques.
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Affiliation(s)
- Olivier Mercey
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Souradip Mukherjee
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Paul Guichard
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
| | - Virginie Hamel
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
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3
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Ott CM, Torres R, Kuan TS, Kuan A, Buchanan J, Elabbady L, Seshamani S, Bodor AL, Collman F, Bock DD, Lee WC, da Costa NM, Lippincott-Schwartz J. Nanometer-scale views of visual cortex reveal anatomical features of primary cilia poised to detect synaptic spillover. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.31.564838. [PMID: 37961618 PMCID: PMC10635062 DOI: 10.1101/2023.10.31.564838] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
A primary cilium is a thin membrane-bound extension off a cell surface that contains receptors for perceiving and transmitting signals that modulate cell state and activity. While many cell types have a primary cilium, little is known about primary cilia in the brain, where they are less accessible than cilia on cultured cells or epithelial tissues and protrude from cell bodies into a deep, dense network of glial and neuronal processes. Here, we investigated cilia frequency, internal structure, shape, and position in large, high-resolution transmission electron microscopy volumes of mouse primary visual cortex. Cilia extended from the cell bodies of nearly all excitatory and inhibitory neurons, astrocytes, and oligodendrocyte precursor cells (OPCs), but were absent from oligodendrocytes and microglia. Structural comparisons revealed that the membrane structure at the base of the cilium and the microtubule organization differed between neurons and glia. OPC cilia were distinct in that they were the shortest and contained pervasive internal vesicles only occasionally observed in neuron and astrocyte cilia. Investigating cilia-proximal features revealed that many cilia were directly adjacent to synapses, suggesting cilia are well poised to encounter locally released signaling molecules. Cilia proximity to synapses was random, not enriched, in the synapse-rich neuropil. The internal anatomy, including microtubule changes and centriole location, defined key structural features including cilium placement and shape. Together, the anatomical insights both within and around neuron and glia cilia provide new insights into cilia formation and function across cell types in the brain.
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Affiliation(s)
- Carolyn M. Ott
- Janelia Research Campus, Howard Hughes Medical Institute
| | | | | | - Aaron Kuan
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Current address Department of Neuroscience, Yale School of Medicine, New Haven, CT, USA
| | | | - Leila Elabbady
- Allen Institute for Brain Science
- University of Washington, Seattle, WA, USA
| | | | | | | | - Davi D. Bock
- Larner College of Medicine, University of Vermont, Burlington, VT, USA
| | - Wei Chung Lee
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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4
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. Curr Biol 2023; 33:4174-4186.e7. [PMID: 37708887 PMCID: PMC10578079 DOI: 10.1016/j.cub.2023.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/17/2023] [Accepted: 08/16/2023] [Indexed: 09/16/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the overlying aECM from a solid sheet to an ∼200 nm pore, thus allowing a male sensory neuron to access the environment. Using cell-specific genetic sex reversal, we find that this switch reflects an inherent sex difference in the glial cell that is independent of the sex identity of the surrounding neurons. Through candidate and unbiased genetic screens, we find that this glial sex difference is controlled by factors shared with neurons (mab-3, lep-2, and lep-5) as well as previously unidentified regulators whose effects may be glia specific (nfya-1, bed-3, and jmjd-3.1). The switch results in male-specific glial expression of a secreted Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites where aECM pores will form. Using electron microscopy, we find that blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific glial gene expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure. Our results highlight that aECM is not a simple homogeneous meshwork, but instead is composed of discrete local features that reflect the identity of the underlying cells.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Taralyn M Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children's Hospital, Boston, MA 02115, USA.
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5
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Fung W, Tan TM, Kolotuev I, Heiman MG. A sex-specific switch in a single glial cell patterns the apical extracellular matrix. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.17.533199. [PMID: 36993293 PMCID: PMC10055199 DOI: 10.1101/2023.03.17.533199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Apical extracellular matrix (aECM) constitutes the interface between every tissue and the outside world. It is patterned into diverse tissue-specific structures through unknown mechanisms. Here, we show that a male-specific genetic switch in a single C. elegans glial cell patterns the aECM into a ∼200 nm pore, allowing a male sensory neuron to access the environment. We find that this glial sex difference is controlled by factors shared with neurons ( mab-3, lep-2, lep-5 ) as well as previously unidentified regulators whose effects may be glia-specific ( nfya-1, bed-3, jmjd-3.1 ). The switch results in male-specific expression of a Hedgehog-related protein, GRL-18, that we discover localizes to transient nanoscale rings at sites of aECM pore formation. Blocking male-specific gene expression in glia prevents pore formation, whereas forcing male-specific expression induces an ectopic pore. Thus, a switch in gene expression in a single cell is necessary and sufficient to pattern aECM into a specific structure.
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Affiliation(s)
- Wendy Fung
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Taralyn M. Tan
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
| | - Irina Kolotuev
- Electron Microscopy Facility, University of Lausanne, 1015 Lausanne, Switzerland
| | - Maxwell G. Heiman
- Department of Genetics, Blavatnik Institute, Harvard Medical School and Boston Children’s Hospital, Boston, MA 02115, USA
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6
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Life-Saver or Undertaker: The Relationship between Primary Cilia and Cell Death in Vertebrate Embryonic Development. J Dev Biol 2022; 10:jdb10040052. [PMID: 36547474 PMCID: PMC9783631 DOI: 10.3390/jdb10040052] [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: 10/29/2022] [Revised: 12/02/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
The development of multicellular organisms requires a tightly coordinated network of cellular processes and intercellular signalling. For more than 20 years, it has been known that primary cilia are deeply involved in the mediation of intercellular signalling and that ciliary dysfunction results in severe developmental defects. Cilia-mediated signalling regulates cellular processes such as proliferation, differentiation, migration, etc. Another cellular process ensuring proper embryonic development is cell death. While the effect of cilia-mediated signalling on many cellular processes has been extensively studied, the relationship between primary cilia and cell death remains largely unknown. This article provides a short review on the current knowledge about this relationship.
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7
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Maurya AK. Structural diversity in a stereotypic organelle - Sensory cilia of Caenorhabditis elegans. J Cell Physiol 2022; 237:2668-2672. [PMID: 35686462 DOI: 10.1002/jcp.30732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/25/2022] [Accepted: 03/21/2022] [Indexed: 11/07/2022]
Abstract
Sensory cilia, an ancient organelle, displays a high degree of conservation in its structure and functioning. Sensory cilia also fulfill a wide range of sensory functions, from sensing environmental signals (light, sound, chemicals, and mechanical forces) to interpreting intercellular developmental signals. One way they appear to fulfill these diverse and specialized roles is by adopting a variety of shapes and sizes. We are only beginning to document and appreciate this complexity. Here in this review, using the varied and specialized cilia found on Caenorhabditis elegans sensory neurons, I highlight some of the most obvious examples of this structural diversity and the underlying mechanisms if known. Such structural diversity appears to arise from the modulation of deeply conserved molecular pathways and also from cell- and species-specific mechanisms. Studying these ciliary specializations will thus provide for a comprehensive understanding of ciliary biology and might uncover understudied aspects of ciliary disease biology.
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Affiliation(s)
- Ashish K Maurya
- Department of Biology, Brandeis University, Waltham, Massachusetts, USA
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8
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Bezler A, Woglar A, Schneider F, Douma F, Bürgy L, Busso C, Gönczy P. Atypical and distinct microtubule radial symmetries in the centriole and the axoneme of Lecudina tuzetae. Mol Biol Cell 2022; 33:ar75. [PMID: 35544302 DOI: 10.1091/mbc.e22-04-0123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The centriole is a minute cylindrical organelle present in a wide range of eukaryotic species. Most centrioles have a signature 9-fold radial symmetry of microtubules that is imparted onto the axoneme of the cilia and flagella they template, with 9 centriolar microtubule doublets growing into 9 axonemal microtubule doublets. There are exceptions to the 9-fold symmetrical arrangement of axonemal microtubules in some species, with lower or higher fold symmetries. In the few cases where this has been examined, such alterations in axonemal symmetries are grounded in likewise alterations in centriolar symmetries. Here, we examine the question of microtubule number continuity between centriole and axoneme in flagellated gametes of the gregarine Lecudina tuzetae, which have been reported to exhibit a 6-fold radial symmetry of axonemal microtubules. We used time-lapse differential interference microscopy to identify the stage at which flagellated gametes are present. Thereafter, using electron microscopy and ultrastructure-expansion microscopy coupled to STimulated Emission Depletion (STED) super-resolution imaging, we uncover that a 6- or 5-fold radial symmetry in the axoneme is accompanied by an 8-fold radial symmetry in the centriole. We conclude that the transition between centriolar and axonemal microtubules can be characterized by unexpected plasticity. [Media: see text] [Media: see text] [Media: see text].
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Affiliation(s)
- Alexandra Bezler
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Alexander Woglar
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Fabian Schneider
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Friso Douma
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Léo Bürgy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Coralie Busso
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
| | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, CH-1015
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9
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De-Castro ARG, Rodrigues DRM, De-Castro MJG, Vieira N, Vieira C, Carvalho AX, Gassmann R, Abreu CMC, Dantas TJ. WDR60-mediated dynein-2 loading into cilia powers retrograde IFT and transition zone crossing. J Cell Biol 2022; 221:212746. [PMID: 34739033 PMCID: PMC8576871 DOI: 10.1083/jcb.202010178] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 09/20/2021] [Accepted: 10/13/2021] [Indexed: 12/30/2022] Open
Abstract
The dynein-2 motor complex drives retrograde intraflagellar transport (IFT), playing a pivotal role in the assembly and functions of cilia. However, the mechanisms that regulate dynein-2 motility remain poorly understood. Here, we identify the Caenorhabditis elegans WDR60 homologue, WDR-60, and dissect the roles of this intermediate chain using genome editing and live imaging of endogenous dynein-2/IFT components. We find that loss of WDR-60 impairs dynein-2 recruitment to cilia and its incorporation onto anterograde IFT trains, reducing retrograde motor availability at the ciliary tip. Consistent with this, we show that fewer dynein-2 motors power WDR-60–deficient retrograde IFT trains, which move at reduced velocities and fail to exit cilia, accumulating on the distal side of the transition zone. Remarkably, disrupting the transition zone’s NPHP module almost fully restores ciliary exit of underpowered retrograde trains in wdr-60 mutants. This work establishes WDR-60 as a major contributor to IFT, and the NPHP module as a roadblock to dynein-2 passage through the transition zone.
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Affiliation(s)
- Ana R G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Diogo R M Rodrigues
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Maria J G De-Castro
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Neide Vieira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus Gualtar, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Cármen Vieira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Ana X Carvalho
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Reto Gassmann
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Carla M C Abreu
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Tiago J Dantas
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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10
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Wang J, Nikonorova IA, Silva M, Walsh JD, Tilton PE, Gu A, Akella JS, Barr MM. Sensory cilia act as a specialized venue for regulated extracellular vesicle biogenesis and signaling. Curr Biol 2021; 31:3943-3951.e3. [PMID: 34270950 DOI: 10.1016/j.cub.2021.06.040] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/30/2021] [Accepted: 06/14/2021] [Indexed: 02/07/2023]
Abstract
Ciliary extracellular vesicle (EV) shedding is evolutionarily conserved. In Chlamydomonas and C. elegans, ciliary EVs act as signaling devices.1-3 In cultured mammalian cells, ciliary EVs regulate ciliary disposal but also receptor abundance and signaling, ciliary length, and ciliary membrane dynamics.4-7 Mammalian cilia produce EVs from the tip and along the ciliary membrane.8,9 This study aimed to determine the functional significance of shedding at distinct locations and to explore ciliary EV biogenesis mechanisms. Using Airyscan super-resolution imaging in living C. elegans animals, we find that neuronal sensory cilia shed TRP polycystin-2 channel PKD-2::GFP-carrying EVs from two distinct sites: the ciliary tip and the ciliary base. Ciliary tip shedding requires distal ciliary enrichment of PKD-2 by the myristoylated coiled-coil protein CIL-7. Kinesin-3 KLP-6 and intraflagellar transport (IFT) kinesin-2 motors are also required for ciliary tip EV shedding. A big unanswered question in the EV field is how cells sort EV cargo. Here, we show that two EV cargoes- CIL-7 and PKD-2-localized and trafficked differently along cilia and were sorted to different environmentally released EVs. In response to mating partners, C. elegans males modulate EV cargo composition by increasing the ratio of PKD-2 to CIL-7 EVs. Overall, our study indicates that the cilium and its trafficking machinery act as a specialized venue for regulated EV biogenesis and signaling.
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Affiliation(s)
- Juan Wang
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA.
| | - Inna A Nikonorova
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Malan Silva
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Jonathon D Walsh
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Peter E Tilton
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Amanda Gu
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Jyothi S Akella
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA.
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11
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Lambert J, Lloret-Fernández C, Laplane L, Poole RJ, Jarriault S. On the origins and conceptual frameworks of natural plasticity-Lessons from single-cell models in C. elegans. Curr Top Dev Biol 2021; 144:111-159. [PMID: 33992151 DOI: 10.1016/bs.ctdb.2021.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
How flexible are cell identities? This problem has fascinated developmental biologists for several centuries and can be traced back to Abraham Trembley's pioneering manipulations of Hydra to test its regeneration abilities in the 1700s. Since the cell theory in the mid-19th century, developmental biology has been dominated by a single framework in which embryonic cells are committed to specific cell fates, progressively and irreversibly acquiring their differentiated identities. This hierarchical, unidirectional and irreversible view of cell identity has been challenged in the past decades through accumulative evidence that many cell types are more plastic than previously thought, even in intact organisms. The paradigm shift introduced by such plasticity calls into question several other key traditional concepts, such as how to define a differentiated cell or more generally cellular identity, and has brought new concepts, such as distinct cellular states. In this review, we want to contribute to this representation by attempting to clarify the conceptual and theoretical frameworks of cell plasticity and identity. In the context of these new frameworks we describe here an atlas of natural plasticity of cell identity in C. elegans, including our current understanding of the cellular and molecular mechanisms at play. The worm further provides interesting cases at the borderlines of cellular plasticity that highlight the conceptual challenges still ahead. We then discuss a set of future questions and perspectives arising from the studies of natural plasticity in the worm that are shared with other reprogramming and plasticity events across phyla.
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Affiliation(s)
- Julien Lambert
- IGBMC, Development and Stem Cells Department, CNRS UMR7104, INSERM U1258, Université de Strasbourg, Strasbourg, France
| | - Carla Lloret-Fernández
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Lucie Laplane
- CNRS UMR 8590, University Paris I Panthéon-Sorbonne, IHPST, Paris, France
| | - Richard J Poole
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.
| | - Sophie Jarriault
- IGBMC, Development and Stem Cells Department, CNRS UMR7104, INSERM U1258, Université de Strasbourg, Strasbourg, France.
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12
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Akella JS, Barr MM. The tubulin code specializes neuronal cilia for extracellular vesicle release. Dev Neurobiol 2021; 81:231-252. [PMID: 33068333 PMCID: PMC8052387 DOI: 10.1002/dneu.22787] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 09/07/2020] [Accepted: 09/23/2020] [Indexed: 12/17/2022]
Abstract
Cilia are microtubule-based organelles that display diversity in morphology, ultrastructure, protein composition, and function. The ciliary microtubules of C. elegans sensory neurons exemplify this diversity and provide a paradigm to understand mechanisms driving ciliary specialization. Only a subset of ciliated neurons in C. elegans are specialized to make and release bioactive extracellular vesicles (EVs) into the environment. The cilia of extracellular vesicle releasing neurons have distinct axonemal features and specialized intraflagellar transport that are important for releasing EVs. In this review, we discuss the role of the tubulin code in the specialization of microtubules in cilia of EV releasing neurons.
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Affiliation(s)
- Jyothi S Akella
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
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13
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Role of DZIP1-CBY-FAM92 transition zone complex in the basal body to membrane attachment and ciliary budding. Biochem Soc Trans 2021; 48:1067-1075. [PMID: 32491167 DOI: 10.1042/bst20191007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/20/2020] [Accepted: 05/07/2020] [Indexed: 02/07/2023]
Abstract
Cilia play important signaling or motile functions in various organisms. In Human, cilia dysfunctions are responsible for a wide range of diseases, called ciliopathies. Cilia assembly is a tightly controlled process, which starts with the conversion of the centriole into a basal body, leading to the formation of the ciliary bud that protrudes inside a ciliary vesicle and/or ultimately at the cell surface. Ciliary bud formation is associated with the assembly of the transition zone (TZ), a complex architecture of proteins of the ciliary base which plays critical functions in gating proteins in and out of the ciliary compartment. Many proteins are involved in the assembly of the TZ, which shows structural and functional variations in different cell types or organisms. In this review, we discuss how a particular complex, composed of members of the DZIP1, CBY and FAM92 families of proteins, is required for the initial stages of cilia assembly leading to ciliary bud formation and how their functional hierarchy contributes to TZ assembly. Moreover, we summarize how evidences in Drosophila reveal functional differences of the DZIP1-CBY-FAM92 complex in the different ciliated tissues of this organism. Whereas it is essential for proper TZ assembly in the two types of ciliated tissues, it is involved in stable anchoring of basal bodies to the plasma membrane in male germ cells. Overall, the DZIP1-CBY-FAM92 complex reveals a molecular assembly pathway required for the initial stages of ciliary bud formation and that is conserved from Drosophila to Human.
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Van De Weghe JC, Giordano JL, Mathijssen IB, Mojarrad M, Lugtenberg D, Miller CV, Dempsey JC, Mohajeri MSA, van Leeuwen E, Pajkrt E, Klaver CC, Houlden H, Eslahi A, Waters AM, Bamshad MJ, Nickerson DA, Aggarwal VS, de Vries BB, Maroofian R, Doherty D. TMEM218 dysfunction causes ciliopathies, including Joubert and Meckel syndromes. HGG ADVANCES 2021; 2:100016. [PMID: 33791682 PMCID: PMC8009330 DOI: 10.1016/j.xhgg.2020.100016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/16/2020] [Indexed: 11/24/2022] Open
Abstract
The Joubert-Meckel syndrome spectrum is a continuum of recessive ciliopathy conditions caused by primary cilium dysfunction. The primary cilium is a microtubule-based, antenna-like organelle that projects from the surface of most human cell types, allowing them to respond to extracellular signals. The cilium is partitioned from the cell body by the transition zone, a known hotspot for ciliopathy-related proteins. Despite years of Joubert syndrome (JBTS) gene discovery, the genetic cause cannot be identified in up to 30% of individuals with JBTS, depending on the cohort, sequencing method, and criteria for pathogenic variants. Using exome and targeted sequencing of 655 families with JBTS, we identified three individuals from two families harboring biallelic, rare, predicted-deleterious missense TMEM218 variants. Via MatchMaker Exchange, we identified biallelic TMEM218 variants in four additional families with ciliopathy phenotypes. Of note, four of the six families carry missense variants affecting the same highly conserved amino acid position 115. Clinical features included the molar tooth sign (N = 2), occipital encephalocele (N = 5, all fetuses), retinal dystrophy (N = 4, all living individuals), polycystic kidneys (N = 2), and polydactyly (N = 2), without liver involvement. Combined with existing functional data linking TMEM218 to ciliary transition zone function, our human genetic data make a strong case for TMEM218 dysfunction as a cause of ciliopathy phenotypes including JBTS with retinal dystrophy and Meckel syndrome. Identifying all genetic causes of the Joubert-Meckel spectrum enables diagnostic testing, prognostic and recurrence risk counseling, and medical monitoring, as well as work to delineate the underlying biological mechanisms and identify targets for future therapies.
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Affiliation(s)
| | - Jessica L. Giordano
- Department of OB/GYN, Columbia University Vagelos College of Physicians and Surgeons, New York, NY 10032, USA
| | - Inge B. Mathijssen
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Majid Mojarrad
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Genetic Research Center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Genetic Center of Khorasan Razavi, Mashhad, Iran
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Caitlin V. Miller
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | | | - Mahsa Sadat Asl Mohajeri
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elizabeth van Leeuwen
- Department of Obstetrics and Gynecology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Eva Pajkrt
- Department of Obstetrics and Gynecology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Caroline C.W. Klaver
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Henry Houlden
- Department of Neuromuscular Disorders, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Atieh Eslahi
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Student Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Aoife M. Waters
- Great Ormond Street Hospital NHS Foundation Trust, London WC1N 1LE, UK
| | | | - Michael J. Bamshad
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
- University of Washington Center for Mendelian Genomics, Seattle, WA 98195, USA
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Deborah A. Nickerson
- University of Washington Center for Mendelian Genomics, Seattle, WA 98195, USA
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Vimla S. Aggarwal
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032 USA
| | - Bert B.A. de Vries
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Reza Maroofian
- Department of Neuromuscular Disorders, University College London Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Dan Doherty
- Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101 USA
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Cook SJ, Crouse CM, Yemini E, Hall DH, Emmons SW, Hobert O. The connectome of the Caenorhabditis elegans pharynx. J Comp Neurol 2020; 528:2767-2784. [PMID: 32352566 PMCID: PMC7601127 DOI: 10.1002/cne.24932] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/06/2020] [Accepted: 04/17/2020] [Indexed: 12/31/2022]
Abstract
Detailed anatomical maps of individual organs and entire animals have served as invaluable entry points for ensuing dissection of their evolution, development, and function. The pharynx of the nematode Caenorhabditis elegans is a simple neuromuscular organ with a self-contained, autonomously acting nervous system, composed of 20 neurons that fall into 14 anatomically distinct types. Using serial electron micrograph (EM) reconstruction, we re-evaluate here the connectome of the pharyngeal nervous system, providing a novel and more detailed view of its structure and predicted function. Contrasting the previous classification of pharyngeal neurons into distinct inter- and motor neuron classes, we provide evidence that most pharyngeal neurons are also likely sensory neurons and most, if not all, pharyngeal neurons also classify as motor neurons. Together with the extensive cross-connectivity among pharyngeal neurons, which is more widespread than previously realized, the sensory-motor characteristics of most neurons define a shallow network architecture of the pharyngeal connectome. Network analysis reveals that the patterns of neuronal connections are organized into putative computational modules that reflect the known functional domains of the pharynx. Compared with the somatic nervous system, pharyngeal neurons both physically associate with a larger fraction of their neighbors and create synapses with a greater proportion of their neighbors. We speculate that the overall architecture of the pharyngeal nervous system may be reminiscent of the architecture of ancestral, primitive nervous systems.
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Affiliation(s)
- Steven J. Cook
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - Charles M. Crouse
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Eviatar Yemini
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
| | - David H. Hall
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Scott W. Emmons
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Oliver Hobert
- Department of Biological Sciences, Columbia University, Howard Hughes Medical Institute, New York, NY 10027
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Walsh JD, Boivin O, Barr MM. What about the males? the C. elegans sexually dimorphic nervous system and a CRISPR-based tool to study males in a hermaphroditic species. J Neurogenet 2020; 34:323-334. [PMID: 32648491 PMCID: PMC7796903 DOI: 10.1080/01677063.2020.1789978] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/26/2020] [Indexed: 12/26/2022]
Abstract
Sexual dimorphism is a device that supports genetic diversity while providing selective pressure against speciation. This phenomenon is at the core of sexually reproducing organisms. Caenorhabditis elegans provides a unique experimental system where males exist in a primarily hermaphroditic species. Early works of John Sulston, Robert Horvitz, and John White provided a complete map of the hermaphrodite nervous system, and recently the male nervous system was added. This addition completely realized the vision of C. elegans pioneer Sydney Brenner: a model organism with an entirely mapped nervous system. With this 'connectome' of information available, great strides have been made toward understanding concepts such as how a sex-shared nervous system (in hermaphrodites and males) can give rise to sex-specific functions, how neural plasticity plays a role in developing a dimorphic nervous system, and how a shared nervous system receives and processes external cues in a sexually-dimorphic manner to generate sex-specific behaviors. In C. elegans, the intricacies of male-mating behavior have been crucial for studying the function and circuitry of the male-specific nervous system and used as a model for studying human autosomal dominant polycystic kidney disease (ADPKD). With the emergence of CRISPR, a seemingly limitless tool for generating genomic mutations with pinpoint precision, the C. elegans model system will continue to be a useful instrument for pioneering research in the fields of behavior, reproductive biology, and neurogenetics.
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Affiliation(s)
- Jonathon D Walsh
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Olivier Boivin
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
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17
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Akella JS, Carter SP, Nguyen K, Tsiropoulou S, Moran AL, Silva M, Rizvi F, Kennedy BN, Hall DH, Barr MM, Blacque OE. Ciliary Rab28 and the BBSome negatively regulate extracellular vesicle shedding. eLife 2020; 9:e50580. [PMID: 32101165 PMCID: PMC7043889 DOI: 10.7554/elife.50580] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 02/02/2020] [Indexed: 12/15/2022] Open
Abstract
Cilia both receive and send information, the latter in the form of extracellular vesicles (EVs). EVs are nano-communication devices that influence cell, tissue, and organism behavior. Mechanisms driving ciliary EV biogenesis are almost entirely unknown. Here, we show that the ciliary G-protein Rab28, associated with human autosomal recessive cone-rod dystrophy, negatively regulates EV levels in the sensory organs of Caenorhabditis elegans in a cilia specific manner. Sequential targeting of lipidated Rab28 to periciliary and ciliary membranes is highly dependent on the BBSome and the prenyl-binding protein phosphodiesterase 6 subunit delta (PDE6D), respectively, and BBSome loss causes excessive and ectopic EV production. We also find that EV defective mutants display abnormalities in sensory compartment morphogenesis. Together, these findings reveal that Rab28 and the BBSome are key in vivo regulators of EV production at the periciliary membrane and suggest that EVs may mediate signaling between cilia and glia to shape sensory organ compartments. Our data also suggest that defects in the biogenesis of cilia-related EVs may contribute to human ciliopathies.
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Affiliation(s)
- Jyothi S Akella
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers UniversityPiscatawayUnited States
| | - Stephen P Carter
- School of Biomolecular and Biomedical Science, Conway Institute, University College DublinDublinIreland
| | - Ken Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of MedicineBronxUnited States
| | - Sofia Tsiropoulou
- School of Biomolecular and Biomedical Science, Conway Institute, University College DublinDublinIreland
| | - Ailis L Moran
- School of Biomolecular and Biomedical Science, Conway Institute, University College DublinDublinIreland
| | - Malan Silva
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers UniversityPiscatawayUnited States
- Department of Biology, University of UtahSalt Lake CityUnited States
| | - Fatima Rizvi
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers UniversityPiscatawayUnited States
| | - Breandan N Kennedy
- School of Biomolecular and Biomedical Science, Conway Institute, University College DublinDublinIreland
| | - David H Hall
- Center for C. elegans Anatomy, Albert Einstein College of MedicineBronxUnited States
| | - Maureen M Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers UniversityPiscatawayUnited States
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, Conway Institute, University College DublinDublinIreland
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18
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Affiliation(s)
- Wei Li
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Guangshuo Ou
- China Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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