1
|
Basu B, Lake AVR, China B, Szymanska K, Wheway G, Bell S, Morrison E, Bond J, Johnson CA. Racgap1 knockdown results in cells with multiple cilia due to cytokinesis failure. Ann Hum Genet 2024; 88:45-57. [PMID: 37771269 PMCID: PMC10952936 DOI: 10.1111/ahg.12529] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/16/2023] [Accepted: 09/07/2023] [Indexed: 09/30/2023]
Abstract
Most mammalian cells have a single primary cilium that acts as a signalling hub in mediating cellular functions. However, little is known about the mechanisms that result in aberrant supernumerary primary cilia per cell. In this study, we re-analysed a previously published whole-genome siRNA-based reverse genetic screen for genes mediating ciliogenesis to identify knockdowns that permit multi-ciliation. We identified siRNA knockdowns that caused significant formation of supernumerary cilia, validated candidate hits in different cell-lines and confirmed that RACGAP1, a component of the centralspindlin complex, was the strongest candidate hit at the whole-genome level. Following loss of RACGAP1, mother centrioles were specified correctly prior to ciliogenesis and the cilia appeared normal. Live cell imaging revealed that increased cilia incidence was caused by cytokinesis failure which led to the formation of multinucleate cells with supernumerary cilia. This suggests that the signalling mechanisms for ciliogenesis are unable to identify supernumerary centrosomes and therefore allow ciliation of duplicated centrosomes as if they were in a new diploid daughter cell. These results, demonstrating that aberrant ciliogenesis is de-coupled from cell cycle regulation, have functional implications in diseases marked by centrosomal amplification.
Collapse
Affiliation(s)
- Basudha Basu
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Alice V. R. Lake
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Becky China
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Katarzyna Szymanska
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Gabrielle Wheway
- University Hospital Southampton NHS Foundation TrustSouthamptonUK
- Faculty of Medicine, Human Development and HealthUniversity of SouthamptonSouthamptonUK
| | - Sandra Bell
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Ewan Morrison
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Jacquelyn Bond
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Colin A. Johnson
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| |
Collapse
|
2
|
Smith CEL, Lake AVR, Johnson CA. Primary Cilia, Ciliogenesis and the Actin Cytoskeleton: A Little Less Resorption, A Little More Actin Please. Front Cell Dev Biol 2020; 8:622822. [PMID: 33392209 PMCID: PMC7773788 DOI: 10.3389/fcell.2020.622822] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 11/24/2020] [Indexed: 12/13/2022] Open
Abstract
Primary cilia are microtubule-based organelles that extend from the apical surface of most mammalian cells, forming when the basal body (derived from the mother centriole) docks at the apical cell membrane. They act as universal cellular “antennae” in vertebrates that receive and integrate mechanical and chemical signals from the extracellular environment, serving diverse roles in chemo-, mechano- and photo-sensation that control developmental signaling, cell polarity and cell proliferation. Mutations in ciliary genes cause a major group of inherited developmental disorders called ciliopathies. There are very few preventative treatments or new therapeutic interventions that modify disease progression or the long-term outlook of patients with these conditions. Recent work has identified at least four distinct but interrelated cellular processes that regulate cilia formation and maintenance, comprising the cell cycle, cellular proteostasis, signaling pathways and structural influences of the actin cytoskeleton. The actin cytoskeleton is composed of microfilaments that are formed from filamentous (F) polymers of globular G-actin subunits. Actin filaments are organized into bundles and networks, and are attached to the cell membrane, by diverse cross-linking proteins. During cell migration, actin filament bundles form either radially at the leading edge or as axial stress fibers. Early studies demonstrated that loss-of-function mutations in ciliopathy genes increased stress fiber formation and impaired ciliogenesis whereas pharmacological inhibition of actin polymerization promoted ciliogenesis. These studies suggest that polymerization of the actin cytoskeleton, F-actin branching and the formation of stress fibers all inhibit primary cilium formation, whereas depolymerization or depletion of actin enhance ciliogenesis. Here, we review the mechanistic basis for these effects on ciliogenesis, which comprise several cellular processes acting in concert at different timescales. Actin polymerization is both a physical barrier to both cilia-targeted vesicle transport and to the membrane remodeling required for ciliogenesis. In contrast, actin may cause cilia loss by localizing disassembly factors at the ciliary base, and F-actin branching may itself activate the YAP/TAZ pathway to promote cilia disassembly. The fundamental role of actin polymerization in the control of ciliogenesis may present potential new targets for disease-modifying therapeutic approaches in treating ciliopathies.
Collapse
Affiliation(s)
- Claire E L Smith
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - Alice V R Lake
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - Colin A Johnson
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| |
Collapse
|
3
|
Logan CV, Cossins J, Rodríguez Cruz PM, Parry DA, Maxwell S, Martínez-Martínez P, Riepsaame J, Abdelhamed ZA, Lake AVR, Moran M, Robb S, Chow G, Sewry C, Hopkins PM, Sheridan E, Jayawant S, Palace J, Johnson CA, Beeson D. Congenital Myasthenic Syndrome Type 19 Is Caused by Mutations in COL13A1, Encoding the Atypical Non-fibrillar Collagen Type XIII α1 Chain. Am J Hum Genet 2015; 97:878-85. [PMID: 26626625 PMCID: PMC4678414 DOI: 10.1016/j.ajhg.2015.10.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/28/2015] [Indexed: 12/30/2022] Open
Abstract
The neuromuscular junction (NMJ) consists of a tripartite synapse with a presynaptic nerve terminal, Schwann cells that ensheathe the terminal bouton, and a highly specialized postsynaptic membrane. Synaptic structural integrity is crucial for efficient signal transmission. Congenital myasthenic syndromes (CMSs) are a heterogeneous group of inherited disorders that result from impaired neuromuscular transmission, caused by mutations in genes encoding proteins that are involved in synaptic transmission and in forming and maintaining the structural integrity of NMJs. To identify further causes of CMSs, we performed whole-exome sequencing (WES) in families without an identified mutation in known CMS-associated genes. In two families affected by a previously undefined CMS, we identified homozygous loss-of-function mutations in COL13A1, which encodes the alpha chain of an atypical non-fibrillar collagen with a single transmembrane domain. COL13A1 localized to the human muscle motor endplate. Using CRISPR-Cas9 genome editing, modeling of the COL13A1 c.1171delG (p.Leu392Sfs∗71) frameshift mutation in the C2C12 cell line reduced acetylcholine receptor (AChR) clustering during myotube differentiation. This highlights the crucial role of collagen XIII in the formation and maintenance of the NMJ. Our results therefore delineate a myasthenic disorder that is caused by loss-of-function mutations in COL13A1, encoding a protein involved in organization of the NMJ, and emphasize the importance of appropriate symptomatic treatment for these individuals.
Collapse
Affiliation(s)
- Clare V Logan
- Section of Ophthalmology & Neurosciences, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Judith Cossins
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Pedro M Rodríguez Cruz
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - David A Parry
- Section of Genetics, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Susan Maxwell
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Pilar Martínez-Martínez
- Neuroimmunology Group, Division of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, PO box 616, 6200 MD Maastricht, the Netherlands
| | - Joey Riepsaame
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Zakia A Abdelhamed
- Section of Ophthalmology & Neurosciences, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Alice V R Lake
- Section of Ophthalmology & Neurosciences, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Maria Moran
- Department of Paediatric Neurology, Nottingham City Hospital, Nottingham University Hospitals NHS Trust, Hucknall Road, Nottingham NG5 1PB, UK
| | - Stephanie Robb
- Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital, 30 Guilford Street, London WC1N 1EH, UK
| | - Gabriel Chow
- Department of Paediatric Neurology, Nottingham City Hospital, Nottingham University Hospitals NHS Trust, Hucknall Road, Nottingham NG5 1PB, UK
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, Institute of Child Health and Great Ormond Street Hospital, 30 Guilford Street, London WC1N 1EH, UK
| | - Philip M Hopkins
- Section of Translational Anaesthesia and Surgical Sciences, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Eamonn Sheridan
- Section of Genetics, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK
| | - Sandeep Jayawant
- Department of Paediatric Neurology, John Radcliffe Hospital, Oxford Radcliffe Hospitals NHS Trust, Oxford OX3 9DU, UK
| | - Jacqueline Palace
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK; Department of Clinical Neurology, John Radcliffe Hospital, Oxford Radcliffe Hospitals NHS Trust, Oxford OX3 9DU, UK
| | - Colin A Johnson
- Section of Ophthalmology & Neurosciences, Leeds Institute of Biomedical and Clinical Sciences, University of Leeds, Leeds LS9 7TF, UK.
| | - David Beeson
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK.
| |
Collapse
|