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Gruenheit N, Baldwin A, Stewart B, Jaques S, Keller T, Parkinson K, Salvidge W, Baines R, Brimson C, Wolf JB, Chisholm R, Harwood AJ, Thompson CRL. Mutant resources for functional genomics in Dictyostelium discoideum using REMI-seq technology. BMC Biol 2021; 19:172. [PMID: 34429112 PMCID: PMC8386026 DOI: 10.1186/s12915-021-01108-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 07/22/2021] [Indexed: 01/26/2023] Open
Abstract
Background Genomes can be sequenced with relative ease, but ascribing gene function remains a major challenge. Genetically tractable model systems are crucial to meet this challenge. One powerful model is the social amoeba Dictyostelium discoideum, a eukaryotic microbe widely used to study diverse questions in the cell, developmental and evolutionary biology. Results We describe REMI-seq, an adaptation of Tn-seq, which allows high throughput, en masse, and quantitative identification of the genomic site of insertion of a drug resistance marker after restriction enzyme-mediated integration. We use REMI-seq to develop tools which greatly enhance the efficiency with which the sequence, transcriptome or proteome variation can be linked to phenotype in D. discoideum. These comprise (1) a near genome-wide resource of individual mutants and (2) a defined pool of ‘barcoded’ mutants to allow large-scale parallel phenotypic analyses. These resources are freely available and easily accessible through the REMI-seq website that also provides comprehensive guidance and pipelines for data analysis. We demonstrate that integrating these resources allows novel regulators of cell migration, phagocytosis and macropinocytosis to be rapidly identified. Conclusions We present methods and resources, generated using REMI-seq, for high throughput gene function analysis in a key model system. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01108-y.
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Affiliation(s)
- Nicole Gruenheit
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Amy Baldwin
- Cardiff School of Biosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Balint Stewart
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Sarah Jaques
- Cardiff School of Biosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Thomas Keller
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Katie Parkinson
- Division of Developmental Biology and Medicine, Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - William Salvidge
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Robert Baines
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Chris Brimson
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK
| | - Jason B Wolf
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Rex Chisholm
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, 60611, USA
| | - Adrian J Harwood
- Cardiff School of Biosciences, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Christopher R L Thompson
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK.
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Buckley CM, Pots H, Gueho A, Vines JH, Munn CJ, Phillips BA, Gilsbach B, Traynor D, Nikolaev A, Soldati T, Parnell AJ, Kortholt A, King JS. Coordinated Ras and Rac Activity Shapes Macropinocytic Cups and Enables Phagocytosis of Geometrically Diverse Bacteria. Curr Biol 2020; 30:2912-2926.e5. [PMID: 32531280 PMCID: PMC7416115 DOI: 10.1016/j.cub.2020.05.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/20/2020] [Accepted: 05/14/2020] [Indexed: 12/15/2022]
Abstract
Engulfment of extracellular material by phagocytosis or macropinocytosis depends on the ability of cells to generate specialized cup-shaped protrusions. To effectively capture and internalize their targets, these cups are organized into a ring or ruffle of actin-driven protrusion encircling a non-protrusive interior domain. These functional domains depend on the combined activities of multiple Ras and Rho family small GTPases, but how their activities are integrated and differentially regulated over space and time is unknown. Here, we show that the amoeba Dictyostelium discoideum coordinates Ras and Rac activity using the multidomain protein RGBARG (RCC1, RhoGEF, BAR, and RasGAP-containing protein). We find RGBARG uses a tripartite mechanism of Ras, Rac, and phospholipid interactions to localize at the protruding edge and interface with the interior of both macropinocytic and phagocytic cups. There, we propose RGBARG shapes the protrusion by expanding Rac activation at the rim while suppressing expansion of the active Ras interior domain. Consequently, cells lacking RGBARG form enlarged, flat interior domains unable to generate large macropinosomes. During phagocytosis, we find that disruption of RGBARG causes a geometry-specific defect in engulfing rod-shaped bacteria and ellipsoidal beads. This demonstrates the importance of coordinating small GTPase activities during engulfment of more complex shapes and thus the full physiological range of microbes, and how this is achieved in a model professional phagocyte. We identify a new regulator that shapes macropinocytic and phagocytic cups Shaping protrusions into cups requires differential regulation of Ras and Rac Cups are organized by integrating interactions with phospholipids and multiple GTPases Defective cup formation causes a target shape-specific defect in phagocytosis
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Affiliation(s)
- Catherine M Buckley
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Henderikus Pots
- Department of Cell Biochemistry, University of Groningen, Groningen 9747 AG, Netherlands
| | - Aurelie Gueho
- Department of Biochemistry, Faculty of Sciences, Sciences II, University of Geneva, CH-1211-Geneva-4, Switzerland
| | - James H Vines
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Christopher J Munn
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Ben A Phillips
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Bernd Gilsbach
- German Centre for Neurodegenerative Diseases, Tübingen 72076, Germany
| | - David Traynor
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Anton Nikolaev
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Sciences, Sciences II, University of Geneva, CH-1211-Geneva-4, Switzerland
| | - Andrew J Parnell
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen 9747 AG, Netherlands
| | - Jason S King
- Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TT, UK.
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Williams TD, Paschke PI, Kay RR. Function of small GTPases in Dictyostelium macropinocytosis. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180150. [PMID: 30967009 PMCID: PMC6304742 DOI: 10.1098/rstb.2018.0150] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2018] [Indexed: 12/17/2022] Open
Abstract
Macropinocytosis-the large-scale, non-specific uptake of fluid by cells-is used by Dictyostelium discoideum amoebae to obtain nutrients. These cells form circular ruffles around regions of membrane defined by a patch of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and the activated forms of the small G-proteins Ras and Rac. When this ruffle closes, a vesicle of the medium is delivered to the cell interior for further processing. It is accepted that PIP3 is required for efficient macropinocytosis. Here, we assess the roles of Ras and Rac in Dictyostelium macropinocytosis. Gain-of-function experiments show that macropinocytosis is stimulated by persistent Ras activation and genetic analysis suggests that RasG and RasS are the key Ras proteins involved. Among the activating guanine exchange factors (GEFs), GefF is implicated in macropinocytosis by an insertional mutant. The individual roles of Rho family proteins are little understood but activation of at least some may be independent of PIP3. This article is part of the Theo Murphy meeting issue 'Macropinocytosis'.
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Affiliation(s)
| | | | - Robert R. Kay
- MRC-Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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Williams TD, Peak-Chew SY, Paschke P, Kay RR. Akt and SGK protein kinases are required for efficient feeding by macropinocytosis. J Cell Sci 2019; 132:jcs.224998. [PMID: 30617109 DOI: 10.1242/jcs.224998] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Macropinocytosis is an actin-driven process of large-scale and non-specific fluid uptake used for feeding by some cancer cells and the macropinocytosis model organism Dictyostelium discoideum In Dictyostelium, macropinocytic cups are organized by 'macropinocytic patches' in the plasma membrane. These contain activated Ras, Rac and phospholipid PIP3, and direct actin polymerization to their periphery. We show that a Dictyostelium Akt (PkbA) and an SGK (PkbR1) protein kinase act downstream of PIP3 and, together, are nearly essential for fluid uptake. This pathway enables the formation of larger macropinocytic patches and macropinosomes, thereby dramatically increasing fluid uptake. Through phosphoproteomics, we identify a RhoGAP, GacG, as a PkbA and PkbR1 target, and show that it is required for efficient macropinocytosis and expansion of macropinocytic patches. The function of Akt and SGK in cell feeding through control of macropinosome size has implications for cancer cell biology.
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Affiliation(s)
| | | | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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