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Chaudhari K, Gorla M, Chang C, Kania A, Bashaw GJ. Robo recruitment of the Wave regulatory complex plays an essential and conserved role in midline repulsion. eLife 2021; 10:e64474. [PMID: 33843588 PMCID: PMC8096436 DOI: 10.7554/elife.64474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/06/2021] [Indexed: 12/23/2022] Open
Abstract
The Roundabout (Robo) guidance receptor family induces axon repulsion in response to its ligand Slit by inducing local cytoskeletal changes; however, the link to the cytoskeleton and the nature of these cytoskeletal changes are poorly understood. Here, we show that the heteropentameric Scar/Wave Regulatory Complex (WRC), which drives Arp2/3-induced branched actin polymerization, is a direct effector of Robo signaling. Biochemical evidence shows that Slit triggers WRC recruitment to the Robo receptor's WRC-interacting receptor sequence (WIRS) motif. In Drosophila embryos, mutants of the WRC enhance Robo1-dependent midline crossing defects. Additionally, mutating Robo1's WIRS motif significantly reduces receptor activity in rescue assays in vivo, and CRISPR-Cas9 mutagenesis shows that the WIRS motif is essential for endogenous Robo1 function. Finally, axon guidance assays in mouse dorsal spinal commissural axons and gain-of-function experiments in chick embryos demonstrate that the WIRS motif is also required for Robo1 repulsion in mammals. Together, our data support an essential conserved role for the WIRS-WRC interaction in Robo1-mediated axon repulsion.
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Affiliation(s)
- Karina Chaudhari
- Department of Neuroscience, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Madhavi Gorla
- Department of Neuroscience, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Chao Chang
- Institut de recherches cliniques de Montréal (IRCM)MontréalCanada
- Department of Anatomy and Cell Biology and Division of Experimental Medicine, McGill UniversityMontréalCanada
| | - Artur Kania
- Institut de recherches cliniques de Montréal (IRCM)MontréalCanada
- Department of Anatomy and Cell Biology and Division of Experimental Medicine, McGill UniversityMontréalCanada
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
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Singh V, Davidson AC, Hume PJ, Koronakis V. Arf6 Can Trigger Wave Regulatory Complex-Dependent Actin Assembly Independent of Arno. Int J Mol Sci 2020; 21:ijms21072457. [PMID: 32252226 PMCID: PMC7177560 DOI: 10.3390/ijms21072457] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 12/17/2022] Open
Abstract
The small GTPase ADP-ribosylation factor 6 (Arf6) anchors at the plasma membrane to orchestrate key functions, such as membrane trafficking and regulating cortical actin cytoskeleton rearrangement. A number of studies have identified key players that interact with Arf6 to regulate actin dynamics in diverse cell processes, yet it is still unknown whether Arf6 can directly signal to the wave regulatory complex to mediate actin assembly. By reconstituting actin dynamics on supported lipid bilayers, we found that Arf6 in co-ordination with Rac1(Ras-related C3 botulinum toxin substrate 1) can directly trigger actin polymerization by recruiting wave regulatory complex components. Interestingly, we demonstrated that Arf6 triggers actin assembly at the membrane directly without recruiting the Arf guanine nucleotide exchange factor (GEF) ARNO (ARF nucleotide-binding site opener), which is able to activate Arf1 to enable WRC-dependent actin assembly. Furthermore, using labelled E. coli, we demonstrated that actin assembly by Arf6 also contributes towards efficient phagocytosis in THP-1 macrophages. Taken together, this study reveals a mechanism for Arf6-driven actin polymerization.
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Singh V, Davidson AC, Hume PJ, Humphreys D, Koronakis V. Arf GTPase interplay with Rho GTPases in regulation of the actin cytoskeleton. Small GTPases 2019; 10:411-418. [PMID: 28524754 PMCID: PMC6748364 DOI: 10.1080/21541248.2017.1329691] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/08/2017] [Accepted: 05/09/2017] [Indexed: 01/04/2023] Open
Abstract
The Arf and Rho subfamilies of small GTPases are nucleotide-dependent molecular switches that act as master regulators of vesicular trafficking and the actin cytoskeleton organization. Small GTPases control cell processes with high fidelity by acting through distinct repertoires of binding partners called effectors. While we understand a great deal about how these GTPases act individually, relatively little is known about how they cooperate, especially in the control of effectors. This review highlights how Arf GTPases collaborate with Rac1 to regulate actin cytoskeleton dynamics at the membrane via recruiting and activating the Wave Regulatory Complex (WRC), a Rho effector that underpins lamellipodia formation and macropinocytosis. This provides insight into Arf regulation of the actin cytoskeleton, while putting the spotlight on small GTPase cooperation with emerging evidence of its importance in fundamental cell biology and interactions with pathogenic bacteria.
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Affiliation(s)
- Vikash Singh
- Department of Pathology, University of Cambridge, Cambridge, UK
| | | | - Peter J. Hume
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Daniel Humphreys
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
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Basquin C, Trichet M, Vihinen H, Malardé V, Lagache T, Ripoll L, Jokitalo E, Olivo-Marin JC, Gautreau A, Sauvonnet N. Membrane protrusion powers clathrin-independent endocytosis of interleukin-2 receptor. EMBO J 2015; 34:2147-61. [PMID: 26124312 PMCID: PMC4557667 DOI: 10.15252/embj.201490788] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 05/27/2015] [Accepted: 05/27/2015] [Indexed: 11/09/2022] Open
Abstract
Endocytosis controls many functions including nutrient uptake, cell division, migration and signal transduction. A clathrin- and caveolin-independent endocytosis pathway is used by important physiological cargos, including interleukin-2 receptors (IL-2R). However, this process lacks morphological and dynamic data. Our electron microscopy (EM) and tomography studies reveal that IL-2R-pits and vesicles are initiated at the base of protrusions. We identify the WAVE complex as a specific endocytic actor. The WAVE complex interacts with IL-2R, via a WAVE-interacting receptor sequence (WIRS) present in the receptor polypeptide, and allows for receptor clustering close to membrane protrusions. In addition, using total internal reflection fluorescent microscopy (TIRF) and automated analysis we demonstrate that two timely distinct bursts of actin polymerization are required during IL-2R uptake, promoted first by the WAVE complex and then by N-WASP. Finally, our data reveal that dynamin acts as a transition controller for the recruitment of Arp2/3 activators required for IL-2R endocytosis. Altogether, our work identifies the spatio-temporal specific role of factors initiating clathrin-independent endocytosis by a unique mechanism that does not depend on the deformation of a flat membrane, but rather on that of membrane protrusions.
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Affiliation(s)
- Cyril Basquin
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, Paris, France CNRS UMR3691, Paris, France
| | - Michaël Trichet
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institut de Biologie Paris-Seine (IBPS), FR3631, Electron Microscopy Facility, Paris, France
| | - Helena Vihinen
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Valérie Malardé
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, Paris, France CNRS UMR3691, Paris, France
| | - Thibault Lagache
- CNRS UMR3691, Paris, France Unité d'Analyse d'Images Biologiques, Institut Pasteur, Paris, France
| | - Léa Ripoll
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, Paris, France CNRS UMR3691, Paris, France
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | | - Alexis Gautreau
- Laboratoire de Biochimie, Unité Mixte de Recherche 7654 Ecole Polytechnique Centre, National de la Recherche Scientifique, Palaiseau, France
| | - Nathalie Sauvonnet
- Unité de Biologie des Interactions Cellulaires, Institut Pasteur, Paris, France CNRS UMR3691, Paris, France
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