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Ott CM, Constable S, Nguyen TM, White K, Lee WCA, Lippincott-Schwartz J, Mukhopadhyay S. Permanent deconstruction of intracellular primary cilia in differentiating granule cell neurons. J Cell Biol 2024; 223:e202404038. [PMID: 39137043 DOI: 10.1083/jcb.202404038] [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: 04/09/2024] [Revised: 06/03/2024] [Accepted: 06/26/2024] [Indexed: 08/15/2024] Open
Abstract
Primary cilia on granule cell neuron progenitors in the developing cerebellum detect sonic hedgehog to facilitate proliferation. Following differentiation, cerebellar granule cells become the most abundant neuronal cell type in the brain. While granule cell cilia are essential during early developmental stages, they become infrequent upon maturation. Here, we provide nanoscopic resolution of cilia in situ using large-scale electron microscopy volumes and immunostaining of mouse cerebella. In many granule cells, we found intracellular cilia, concealed from the external environment. Cilia were disassembled in differentiating granule cell neurons-in a process we call cilia deconstruction-distinct from premitotic cilia resorption in proliferating progenitors. In differentiating granule cells, cilia deconstruction involved unique disassembly intermediates, and, as maturation progressed, mother centriolar docking at the plasma membrane. Unlike ciliated neurons in other brain regions, our results show the deconstruction of concealed cilia in differentiating granule cells, which might prevent mitogenic hedgehog responsiveness. Ciliary deconstruction could be paradigmatic of cilia removal during differentiation in other tissues.
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Affiliation(s)
- Carolyn M Ott
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Sandii Constable
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tri M Nguyen
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Kevin White
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Wei-Chung Allen Lee
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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2
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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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Kalot R, Sentell Z, Kitzler TM, Torban E. Primary cilia and actin regulatory pathways in renal ciliopathies. FRONTIERS IN NEPHROLOGY 2024; 3:1331847. [PMID: 38292052 PMCID: PMC10824913 DOI: 10.3389/fneph.2023.1331847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/20/2023] [Indexed: 02/01/2024]
Abstract
Ciliopathies are a group of rare genetic disorders caused by defects to the structure or function of the primary cilium. They often affect multiple organs, leading to brain malformations, congenital heart defects, and anomalies of the retina or skeletal system. Kidney abnormalities are among the most frequent ciliopathic phenotypes manifesting as smaller, dysplastic, and cystic kidneys that are often accompanied by renal fibrosis. Many renal ciliopathies cause chronic kidney disease and often progress to end-stage renal disease, necessitating replacing therapies. There are more than 35 known ciliopathies; each is a rare hereditary condition, yet collectively they account for a significant proportion of chronic kidney disease worldwide. The primary cilium is a tiny microtubule-based organelle at the apex of almost all vertebrate cells. It serves as a "cellular antenna" surveying environment outside the cell and transducing this information inside the cell to trigger multiple signaling responses crucial for tissue morphogenesis and homeostasis. Hundreds of proteins and unique cellular mechanisms are involved in cilia formation. Recent evidence suggests that actin remodeling and regulation at the base of the primary cilium strongly impacts ciliogenesis. In this review, we provide an overview of the structure and function of the primary cilium, focusing on the role of actin cytoskeleton and its regulators in ciliogenesis. We then describe the key clinical, genetic, and molecular aspects of renal ciliopathies. We highlight what is known about actin regulation in the pathogenesis of these diseases with the aim to consider these recent molecular findings as potential therapeutic targets for renal ciliopathies.
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Affiliation(s)
- Rita Kalot
- Department of Medicine and Department of Physiology, McGill University, Montreal, QC, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Zachary Sentell
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Thomas M. Kitzler
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- McGill University Health Center, Montreal, QC, Canada
| | - Elena Torban
- Department of Medicine and Department of Physiology, McGill University, Montreal, QC, Canada
- The Research Institute of the McGill University Health Center, Montreal, QC, Canada
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Ott CM, Constable S, Nguyen TM, White K, Lee WCA, Lippincott-Schwartz J, Mukhopadhyay S. Permanent deconstruction of intracellular primary cilia in differentiating granule cell neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.07.565988. [PMID: 38106104 PMCID: PMC10723395 DOI: 10.1101/2023.12.07.565988] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Primary cilia on granule cell neuron progenitors in the developing cerebellum detect sonic hedgehog to facilitate proliferation. Following differentiation, cerebellar granule cells become the most abundant neuronal cell type in the brain. While essential during early developmental stages, the fate of granule cell cilia is unknown. Here, we provide nanoscopic resolution of ciliary dynamics in situ by studying developmental changes in granule cell cilia using large-scale electron microscopy volumes and immunostaining of mouse cerebella. We found that many granule cell primary cilia were intracellular and concealed from the external environment. Cilia were disassembed in differentiating granule cell neurons in a process we call cilia deconstruction that was distinct from pre-mitotic cilia resorption in proliferating progenitors. In differentiating granule cells, ciliary loss involved unique disassembly intermediates, and, as maturation progressed, mother centriolar docking at the plasma membrane. Cilia did not reform from the docked centrioles, rather, in adult mice granule cell neurons remained unciliated. Many neurons in other brain regions require cilia to regulate function and connectivity. In contrast, our results show that granule cell progenitors had concealed cilia that underwent deconstruction potentially to prevent mitogenic hedgehog responsiveness. The ciliary deconstruction mechanism we describe could be paradigmatic of cilia removal during differentiation in other tissues.
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Affiliation(s)
- Carolyn M. Ott
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Sandii Constable
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tri M. Nguyen
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Current affiliation, Zetta AI LLC, USA
| | - Kevin White
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Wei-Chung Allen Lee
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Saikat Mukhopadhyay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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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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Murillo-Pineda M, Coto-Cid JM, Romero M, Zorrilla JG, Chinchilla N, Medina-Calzada Z, Varela RM, Juárez-Soto Á, Macías FA, Reales E. Effects of Sesquiterpene Lactones on Primary Cilia Formation (Ciliogenesis). Toxins (Basel) 2023; 15:632. [PMID: 37999495 PMCID: PMC10675014 DOI: 10.3390/toxins15110632] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/22/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023] Open
Abstract
Sesquiterpene lactones (SLs), plant-derived metabolites with broad spectra of biological effects, including anti-tumor and anti-inflammatory, hold promise for drug development. Primary cilia, organelles extending from cell surfaces, are crucial for sensing and transducing extracellular signals essential for cell differentiation and proliferation. Their life cycle is linked to the cell cycle, as cilia assemble in non-dividing cells of G0/G1 phases and disassemble before entering mitosis. Abnormalities in both primary cilia (non-motile cilia) and motile cilia structure or function are associated with developmental disorders (ciliopathies), heart disease, and cancer. However, the impact of SLs on primary cilia remains unknown. This study evaluated the effects of selected SLs (grosheimin, costunolide, and three cyclocostunolides) on primary cilia biogenesis and stability in human retinal pigment epithelial (RPE) cells. Confocal fluorescence microscopy was employed to analyze the effects on primary cilia formation (ciliogenesis), primary cilia length, and stability. The effects on cell proliferation were evaluated by flow cytometry. All SLs disrupted primary cilia formation in the early stages of ciliogenesis, irrespective of starvation conditions or cytochalasin-D treatment, with no effect on cilia length or cell cycle progression. Interestingly, grosheimin stabilized and promoted primary cilia formation under cilia homeostasis and elongation treatment conditions. Thus, SLs have potential as novel drugs for ciliopathies and tumor treatment.
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Affiliation(s)
- Marina Murillo-Pineda
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Juan M. Coto-Cid
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
- Department of Organic Chemistry, University of Seville, 41012 Seville, Spain
| | - María Romero
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Jesús G. Zorrilla
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126 Naples, Italy
| | - Nuria Chinchilla
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Zahara Medina-Calzada
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Rosa M. Varela
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Álvaro Juárez-Soto
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Francisco A. Macías
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Elena Reales
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
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Abstract
Primary cilia play a key role in the ability of cells to respond to extracellular stimuli, such as signaling molecules and environmental cues. These sensory organelles are crucial to the development of many organ systems, and defects in primary ciliogenesis lead to multisystemic genetic disorders, known as ciliopathies. Here, we review recent advances in the understanding of several key aspects of the regulation of ciliogenesis. Primary ciliogenesis is thought to take different pathways depending on cell type, and some recent studies shed new light on the cell-type-specific mechanisms regulating ciliogenesis at the apical surface in polarized epithelial cells, which are particularly relevant for many ciliopathies. Furthermore, recent findings have demonstrated the importance of actin cytoskeleton dynamics in positively and negatively regulating multiple stages of ciliogenesis, including the vesicular trafficking of ciliary components and the positioning and docking of the basal body. Finally, studies on the formation of motile cilia in multiciliated epithelial cells have revealed requirements for actin remodeling in this process too, as well as showing evidence of an additional alternative ciliogenesis pathway.
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Affiliation(s)
- Huxley K Hoffman
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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8
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Insights into the Regulation of Ciliary Disassembly. Cells 2021; 10:cells10112977. [PMID: 34831200 PMCID: PMC8616418 DOI: 10.3390/cells10112977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 12/15/2022] Open
Abstract
The primary cilium, an antenna-like structure that protrudes out from the cell surface, is present in most cell types. It is a microtubule-based organelle that serves as a mega-signaling center and is important for sensing biochemical and mechanical signals to carry out various cellular processes such as proliferation, migration, differentiation, and many others. At any given time, cilia length is determined by a dynamic balance of cilia assembly and disassembly processes. Abnormally short or long cilia can cause a plethora of human diseases commonly referred to as ciliopathies, including, but not limited to, skeletal malformations, obesity, autosomal dominant polycystic kidney disease, retinal degeneration, and bardet-biedl syndrome. While the process of cilia assembly is studied extensively, the process of cilia disassembly and its biological role(s) are less well understood. This review discusses current knowledge on ciliary disassembly and how different cellular processes and molecular signals converge to carry out this process. This information will help us understand how the process of ciliary disassembly is regulated, identify the key steps that need further investigation, and possibly design therapeutic targets for a subset of ciliopathies that are causally linked to defective ciliary disassembly.
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