1
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Buracco S, Döring H, Engelbart S, Singh SP, Paschke P, Whitelaw J, Thomason PA, Paul NR, Tweedy L, Lilla S, McGarry L, Corbyn R, Claydon S, Mietkowska M, Machesky LM, Rottner K, Insall RH. Scar/WAVE drives actin protrusions independently of its VCA domain using proline-rich domains. Curr Biol 2024; 34:4436-4451.e9. [PMID: 39332399 DOI: 10.1016/j.cub.2024.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 04/04/2024] [Accepted: 08/13/2024] [Indexed: 09/29/2024]
Abstract
Cell migration requires the constant modification of cellular shape by reorganization of the actin cytoskeleton. Fine-tuning of this process is critical to ensure new actin filaments are formed only at specific times and in defined regions of the cell. The Scar/WAVE complex is the main catalyst of pseudopod and lamellipodium formation during cell migration. It is a pentameric complex highly conserved through eukaryotic evolution and composed of Scar/WAVE, Abi, Nap1/NCKAP1, Pir121/CYFIP, and HSPC300/Brk1. Its function is usually attributed to activation of the Arp2/3 complex through Scar/WAVE's VCA domain, while other parts of the complex are expected to mediate spatial-temporal regulation and have no direct role in actin polymerization. Here, we show in both B16-F1 mouse melanoma and Dictyostelium discoideum cells that Scar/WAVE without its VCA domain still induces the formation of morphologically normal, actin-rich protrusions, extending at comparable speeds despite a drastic reduction of Arp2/3 recruitment. However, the proline-rich regions in Scar/WAVE and Abi subunits are essential, though either is sufficient for the generation of actin protrusions in B16-F1 cells. We further demonstrate that N-WASP can compensate for the absence of Scar/WAVE's VCA domain and induce lamellipodia formation, but it still requires an intact WAVE complex, even if without its VCA domain. We conclude that the Scar/WAVE complex does more than directly activating Arp2/3, with proline-rich domains playing a central role in promoting actin protrusions. This implies a broader function for the Scar/WAVE complex, concentrating and simultaneously activating many actin-regulating proteins as a lamellipodium-producing core.
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Affiliation(s)
- Simona Buracco
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK.
| | - Hermann Döring
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Stefanie Engelbart
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | | | - Peggy Paschke
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Jamie Whitelaw
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Peter A Thomason
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Nikki R Paul
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Luke Tweedy
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Sergio Lilla
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Lynn McGarry
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Ryan Corbyn
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK
| | - Sophie Claydon
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Magdalena Mietkowska
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Laura M Machesky
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany; Braunschweig Integrated Centre of Systems Biology (BRICS), 38106 Braunschweig, Germany
| | - Robert H Insall
- Cancer Research UK Scotland Institute, Switchback Road, Glasgow G61 1BD, UK; School of Cancer Sciences, University of Glasgow, Switchback Road, Glasgow G61 1QH, UK.
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2
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Li D, Yang Y, Lv C, Wang Y, Chao X, Huang J, Singh SP, Yuan Y, Zhang C, Lou J, Gao P, Huang S, Li B, Cai H. GxcM-Fbp17/RacC-WASP signaling regulates polarized cortex assembly in migrating cells via Arp2/3. J Cell Biol 2023; 222:e202208151. [PMID: 37010470 PMCID: PMC10072221 DOI: 10.1083/jcb.202208151] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 02/02/2023] [Accepted: 03/17/2023] [Indexed: 04/04/2023] Open
Abstract
The actin-rich cortex plays a fundamental role in many cellular processes. Its architecture and molecular composition vary across cell types and physiological states. The full complement of actin assembly factors driving cortex formation and how their activities are spatiotemporally regulated remain to be fully elucidated. Using Dictyostelium as a model for polarized and rapidly migrating cells, we show that GxcM, a RhoGEF localized specifically in the rear of migrating cells, functions together with F-BAR protein Fbp17, a small GTPase RacC, and the actin nucleation-promoting factor WASP to coordinately promote Arp2/3 complex-mediated cortical actin assembly. Overactivation of this signaling cascade leads to excessive actin polymerization in the rear cortex, whereas its disruption causes defects in cortical integrity and function. Therefore, apart from its well-defined role in the formation of the protrusions at the cell front, the Arp2/3 complex-based actin carries out a previously unappreciated function in building the rear cortical subcompartment in rapidly migrating cells.
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Affiliation(s)
- Dong Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yihong Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Chenglin Lv
- Department of Engineering Mechanics, Applied Mechanics Laboratory, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China
| | - Yingjie Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xiaoting Chao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jiafeng Huang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | | | - Ye Yuan
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chengyu Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jizhong Lou
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Pu Gao
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Bo Li
- Department of Engineering Mechanics, Applied Mechanics Laboratory, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, China
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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3
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Singh SP, Paschke P, Tweedy L, Insall RH. AKT and SGK kinases regulate cell migration by altering Scar/WAVE complex activation and Arp2/3 complex recruitment. Front Mol Biosci 2022; 9:965921. [PMID: 36106016 PMCID: PMC9466652 DOI: 10.3389/fmolb.2022.965921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/28/2022] [Indexed: 11/23/2022] Open
Abstract
Cell polarity and cell migration both depend on pseudopodia and lamellipodia formation. These are regulated by coordinated signaling acting through G-protein coupled receptors and kinases such as PKB/AKT and SGK, as well as the actin cytoskeletal machinery. Here we show that both Dictyostelium PKB and SGK kinases (encoded by pkbA and pkgB) are dispensable for chemotaxis towards folate. However, both are involved in the regulation of pseudopod formation and thus cell motility. Cells lacking pkbA and pkgB showed a substantial drop in cell speed. Actin polymerization is perturbed in pkbA- and reduced in pkgB- and pkbA-/pkgB- mutants. The Scar/WAVE complex, key catalyst of pseudopod formation, is recruited normally to the fronts of all mutant cells (pkbA-, pkgB- and pkbA-/pkgB-), but is unexpectedly unable to recruit the Arp2/3 complex in cells lacking SGK. Consequently, loss of SGK causes a near-complete loss of normal actin pseudopodia, though this can be rescued by overexpression of PKB. Hence both PKB and SGK are required for correct assembly of F-actin and recruitment of the Arp2/3 complex by the Scar/WAVE complex during pseudopodia formation.
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Affiliation(s)
- Shashi Prakash Singh
- CRUK Beatson Institute, Glasgow, United Kingdom
- School of Infection and Immunity, University of Glasgow, Glasgow, United Kingdom
- *Correspondence: Shashi Prakash Singh,
| | | | - Luke Tweedy
- CRUK Beatson Institute, Glasgow, United Kingdom
| | - Robert H. Insall
- CRUK Beatson Institute, Glasgow, United Kingdom
- School of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
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4
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Kage F, Döring H, Mietkowska M, Schaks M, Grüner F, Stahnke S, Steffen A, Müsken M, Stradal TEB, Rottner K. Lamellipodia-like actin networks in cells lacking WAVE regulatory complex. J Cell Sci 2022; 135:276259. [PMID: 35971979 PMCID: PMC9511706 DOI: 10.1242/jcs.260364] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 12/25/2022] Open
Abstract
Cell migration frequently involves the formation of lamellipodia induced by Rac GTPases activating WAVE regulatory complex (WRC) to drive Arp2/3 complex-dependent actin assembly. Previous genome editing studies in B16-F1 melanoma cells solidified the view of an essential, linear pathway employing the aforementioned components. Here, disruption of the WRC subunit Nap1 (encoded by Nckap1) and its paralog Hem1 (encoded by Nckap1l) followed by serum and growth factor stimulation, or active GTPase expression, revealed a pathway to formation of Arp2/3 complex-dependent lamellipodia-like structures (LLS) that requires both Rac and Cdc42 GTPases, but not WRC. These phenotypes were independent of the WRC subunit eliminated and coincided with the lack of recruitment of Ena/VASP family actin polymerases. Moreover, aside from Ena/VASP proteins, LLS contained all lamellipodial regulators tested, including cortactin (also known as CTTN), the Ena/VASP ligand lamellipodin (also known as RAPH1) and FMNL subfamily formins. Rac-dependent but WRC-independent actin remodeling could also be triggered in NIH 3T3 fibroblasts by growth factor (HGF) treatment or by gram-positive Listeria monocytogenes usurping HGF receptor signaling for host cell invasion. Taken together, our studies thus establish the existence of a signaling axis to Arp2/3 complex-dependent actin remodeling at the cell periphery that operates without WRC and Ena/VASP. Summary: Rac-dependent actin remodeling can occur in the absence of WAVE regulatory complex, triggered by active Cdc42. WAVE regulatory complex-independent actin structures harbor Arp2/3 complex but not VASP.
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Affiliation(s)
- Frieda Kage
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Hermann Döring
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Magdalena Mietkowska
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Matthias Schaks
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Franziska Grüner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Stephanie Stahnke
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Anika Steffen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Mathias Müsken
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.,Central Facility for Microscopy, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany
| | - Theresia E B Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), 38106 Braunschweig, Germany
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5
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Mijanović L, Weber I. Adhesion of Dictyostelium Amoebae to Surfaces: A Brief History of Attachments. Front Cell Dev Biol 2022; 10:910736. [PMID: 35721508 PMCID: PMC9197732 DOI: 10.3389/fcell.2022.910736] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/13/2022] [Indexed: 12/23/2022] Open
Abstract
Dictyostelium amoebae adhere to extracellular material using similar mechanisms to metazoan cells. Notably, the cellular anchorage loci in Amoebozoa and Metazoa are both arranged in the form of discrete spots and incorporate a similar repertoire of intracellular proteins assembled into multicomponent complexes located on the inner side of the plasma membrane. Surprisingly, however, Dictyostelium lacks integrins, the canonical transmembrane heterodimeric receptors that dominantly mediate adhesion of cells to the extracellular matrix in multicellular animals. In this review article, we summarize the current knowledge about the cell-substratum adhesion in Dictyostelium, present an inventory of the involved proteins, and draw parallels with the situation in animal cells. The emerging picture indicates that, while retaining the basic molecular architecture common to their animal relatives, the adhesion complexes in free-living amoeboid cells have evolved to enable less specific interactions with diverse materials encountered in their natural habitat in the deciduous forest soil. Dissection of molecular mechanisms that underlay short lifetime of the cell-substratum attachments and high turnover rate of the adhesion complexes in Dictyostelium should provide insight into a similarly modified adhesion phenotype that accompanies the mesenchymal-amoeboid transition in tumor metastasis.
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Affiliation(s)
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
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6
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Jung G, Pan M, Alexander C, Jin T, Hammer JA. Dual regulation of the actin cytoskeleton by CARMIL-GAP. J Cell Sci 2022; 135:275754. [PMID: 35583107 PMCID: PMC9270954 DOI: 10.1242/jcs.258704] [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: 03/27/2021] [Accepted: 05/09/2022] [Indexed: 11/29/2022] Open
Abstract
Capping protein Arp2/3 myosin I linker (CARMIL) proteins are multi-domain scaffold proteins that regulate actin dynamics by regulating the activity of capping protein (CP). Here, we characterize CARMIL-GAP (GAP for GTPase-activating protein), a Dictyostelium CARMIL isoform that contains a ∼130 residue insert that, by homology, confers GTPase-activating properties for Rho-related GTPases. Consistent with this idea, this GAP domain binds Dictyostelium Rac1a and accelerates its rate of GTP hydrolysis. CARMIL-GAP concentrates with F-actin in phagocytic cups and at the leading edge of chemotaxing cells, and CARMIL-GAP-null cells exhibit pronounced defects in phagocytosis and chemotactic streaming. Importantly, these defects are fully rescued by expressing GFP-tagged CARMIL-GAP in CARMIL-GAP-null cells. Finally, rescue with versions of CARMIL-GAP that lack either GAP activity or the ability to regulate CP show that, although both activities contribute significantly to CARMIL-GAP function, the GAP activity plays the bigger role. Together, our results add to the growing evidence that CARMIL proteins influence actin dynamics by regulating signaling molecules as well as CP, and that the continuous cycling of the nucleotide state of Rho GTPases is often required to drive Rho-dependent biological processes. Summary:Dictyostelium CARMIL-GAP supports phagocytosis and chemotaxis by regulating both capping protein and Rac1.
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Affiliation(s)
- Goeh Jung
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
| | - Miao Pan
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, USA
| | - Chris Alexander
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
| | - Tian Jin
- Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Disease, National Institutes of Health, USA
| | - John A Hammer
- Cell and Developmental Biology Center, National Heart lung and Blood Institute, National Institutes of Health, USA
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7
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Delgado MG, Rivera CA, Lennon-Duménil AM. Macropinocytosis and Cell Migration: Don't Drink and Drive…. Subcell Biochem 2022; 98:85-102. [PMID: 35378704 DOI: 10.1007/978-3-030-94004-1_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Macropinocytosis is a nonspecific mechanism by which cells compulsively "drink" the surrounding extracellular fluids in order to feed themselves or sample the molecules therein, hence gaining information about their environment. This process is cell-intrinsically incompatible with the migration of many cells, implying that the two functions are antagonistic. The migrating cell uses a molecular switch to stop and explore its surrounding fluid by macropinocytosis, after which it employs the same molecular machinery to start migrating again to examine another location. This cycle of migration/macropinocytosis allows cells to explore tissues, and it is key to a range of physiological processes. Evidence of this evolutionarily conserved antagonism between the two processes can be found in several cell types-immune cells, for example, being particularly adept-and ancient organisms (e.g., the social amoeba Dictyostelium discoideum). How macropinocytosis and migration are negatively coupled is the subject of this chapter.
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8
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Umarao P, Rath PP, Gourinath S. Cdc42/Rac Interactive Binding Containing Effector Proteins in Unicellular Protozoans With Reference to Human Host: Locks of the Rho Signaling. Front Genet 2022; 13:781885. [PMID: 35186026 PMCID: PMC8847673 DOI: 10.3389/fgene.2022.781885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 01/14/2022] [Indexed: 11/23/2022] Open
Abstract
Small GTPases are the key to actin cytoskeleton signaling, which opens the lock of effector proteins to forward the signal downstream in several cellular pathways. Actin cytoskeleton assembly is associated with cell polarity, adhesion, movement and other functions in eukaryotic cells. Rho proteins, specifically Cdc42 and Rac, are the primary regulators of actin cytoskeleton dynamics in higher and lower eukaryotes. Effector proteins, present in an inactive state gets activated after binding to the GTP bound Cdc42/Rac to relay a signal downstream. Cdc42/Rac interactive binding (CRIB) motif is an essential conserved sequence found in effector proteins to interact with Cdc42 or Rac. A diverse range of Cdc42/Rac and their effector proteins have evolved from lower to higher eukaryotes. The present study has identified and further classified CRIB containing effector proteins in lower eukaryotes, focusing on parasitic protozoans causing neglected tropical diseases and taking human proteins as a reference point to the highest evolved organism in the evolutionary trait. Lower eukaryotes’ CRIB containing proteins fall into conventional effector molecules, PAKs (p21 activated kinase), Wiskoit-Aldrich Syndrome proteins family, and some have unique domain combinations unlike any known proteins. We also highlight the correlation between the effector protein isoforms and their selective specificity for Cdc42 or Rac proteins during evolution. Here, we report CRIB containing effector proteins; ten in Dictyostelium and Entamoeba, fourteen in Acanthamoeba, one in Trypanosoma and Giardia. CRIB containing effector proteins that have been studied so far in humans are potential candidates for drug targets in cancer, neurological disorders, and others. Conventional CRIB containing proteins from protozoan parasites remain largely elusive and our data provides their identification and classification for further in-depth functional validations. The tropical diseases caused by protozoan parasites lack combinatorial drug targets as effective paradigms. Targeting signaling mechanisms operative in these pathogens can provide greater molecules in combatting their infections.
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Affiliation(s)
- Preeti Umarao
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Pragyan Parimita Rath
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Samudrala Gourinath
- Structural Biology Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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9
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Brunetti RM, Kockelkoren G, Raghavan P, Bell GR, Britain D, Puri N, Collins SR, Leonetti MD, Stamou D, Weiner OD. WASP integrates substrate topology and cell polarity to guide neutrophil migration. J Cell Biol 2022; 221:e202104046. [PMID: 34964841 PMCID: PMC8719638 DOI: 10.1083/jcb.202104046] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 10/19/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
To control their movement, cells need to coordinate actin assembly with the geometric features of their substrate. Here, we uncover a role for the actin regulator WASP in the 3D migration of neutrophils. We show that WASP responds to substrate topology by enriching to sites of inward, substrate-induced membrane deformation. Superresolution imaging reveals that WASP preferentially enriches to the necks of these substrate-induced invaginations, a distribution that could support substrate pinching. WASP facilitates recruitment of the Arp2/3 complex to these sites, stimulating local actin assembly that couples substrate features with the cytoskeleton. Surprisingly, WASP only enriches to membrane deformations in the front half of the cell, within a permissive zone set by WASP's front-biased regulator Cdc42. While WASP KO cells exhibit relatively normal migration on flat substrates, they are defective at topology-directed migration. Our data suggest that WASP integrates substrate topology with cell polarity by selectively polymerizing actin around substrate-induced membrane deformations in the front half of the cell.
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Affiliation(s)
- Rachel M. Brunetti
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
- Center for Geometrically Engineered Cellular Membranes, University of California, San Francisco, San Francisco, CA
| | - Gabriele Kockelkoren
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
- Center for Geometrically Engineered Cellular Membranes, University of Copenhagen, Copenhagen, Denmark
| | - Preethi Raghavan
- University of California, Berkeley–University of California, San Francisco Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA
- Chan Zuckerberg Biohub, San Francisco, CA
| | - George R.R. Bell
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA
| | - Derek Britain
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
- Center for Geometrically Engineered Cellular Membranes, University of California, San Francisco, San Francisco, CA
| | - Natasha Puri
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Sean R. Collins
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, CA
| | | | - Dimitrios Stamou
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
- Center for Geometrically Engineered Cellular Membranes, University of Copenhagen, Copenhagen, Denmark
| | - Orion D. Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
- Center for Geometrically Engineered Cellular Membranes, University of California, San Francisco, San Francisco, CA
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10
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Gaertner F, Reis-Rodrigues P, de Vries I, Hons M, Aguilera J, Riedl M, Leithner A, Tasciyan S, Kopf A, Merrin J, Zheden V, Kaufmann WA, Hauschild R, Sixt M. WASp triggers mechanosensitive actin patches to facilitate immune cell migration in dense tissues. Dev Cell 2022; 57:47-62.e9. [PMID: 34919802 PMCID: PMC8751638 DOI: 10.1016/j.devcel.2021.11.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 09/06/2021] [Accepted: 11/24/2021] [Indexed: 12/26/2022]
Abstract
When crawling through the body, leukocytes often traverse tissues that are densely packed with extracellular matrix and other cells, and this raises the question: How do leukocytes overcome compressive mechanical loads? Here, we show that the actin cortex of leukocytes is mechanoresponsive and that this responsiveness requires neither force sensing via the nucleus nor adhesive interactions with a substrate. Upon global compression of the cell body as well as local indentation of the plasma membrane, Wiskott-Aldrich syndrome protein (WASp) assembles into dot-like structures, providing activation platforms for Arp2/3 nucleated actin patches. These patches locally push against the external load, which can be obstructing collagen fibers or other cells, and thereby create space to facilitate forward locomotion. We show in vitro and in vivo that this WASp function is rate limiting for ameboid leukocyte migration in dense but not in loose environments and is required for trafficking through diverse tissues such as skin and lymph nodes.
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Affiliation(s)
- Florian Gaertner
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
| | | | - Ingrid de Vries
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Miroslav Hons
- BIOCEV, First Faculty of Medicine, Charles University, Vestec, Czech Republic
| | - Juan Aguilera
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Michael Riedl
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Alexander Leithner
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Saren Tasciyan
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Aglaja Kopf
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Jack Merrin
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Vanessa Zheden
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | | | - Robert Hauschild
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria
| | - Michael Sixt
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
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11
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Kay RR, Lutton J, Coker H, Paschke P, King JS, Bretschneider T. The Amoebal Model for Macropinocytosis. Subcell Biochem 2022; 98:41-59. [PMID: 35378702 DOI: 10.1007/978-3-030-94004-1_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Macropinocytosis is a relatively unexplored form of large-scale endocytosis driven by the actin cytoskeleton. Dictyostelium amoebae form macropinosomes from cups extended from the plasma membrane, then digest their contents and absorb the nutrients in the endo-lysosomal system. They use macropinocytosis for feeding, maintaining a high rate of fluid uptake that makes assay and experimentation easy. Mutants collected over the years identify cytoskeletal and signalling proteins required for macropinocytosis. Cups are organized around plasma membrane domains of intense PIP3, Ras and Rac signalling, proper formation of which also depends on the RasGAPs NF1 and RGBARG, PTEN, the PIP3-regulated protein kinases Akt and SGK and their activators PDK1 and TORC2, Rho proteins, plus other components yet to be identified. This PIP3 domain directs dendritic actin polymerization to the extending lip of macropinocytic cups by recruiting a ring of the SCAR/WAVE complex around itself and thus activating the Arp2/3 complex. The dynamics of PIP3 domains are proposed to shape macropinocytic cups from start to finish. The role of the Ras-PI3-kinase module in organizing feeding structures in unicellular organisms most likely predates its adoption into growth factor signalling, suggesting an evolutionary origin for growth factor signalling.
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Affiliation(s)
- Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Josiah Lutton
- Department of Computer Science, University of Warwick, Coventry, UK
| | - Helena Coker
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Peggy Paschke
- MRC Laboratory of Molecular Biology, Cambridge, UK.,Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, UK
| | - Jason S King
- School of Biomedical Sciences, University of Sheffield, Sheffield, UK
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12
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Extracellular Signalling Modulates Scar/WAVE Complex Activity through Abi Phosphorylation. Cells 2021; 10:cells10123485. [PMID: 34943993 PMCID: PMC8700165 DOI: 10.3390/cells10123485] [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: 10/13/2021] [Revised: 12/01/2021] [Accepted: 12/05/2021] [Indexed: 01/01/2023] Open
Abstract
The lamellipodia and pseudopodia of migrating cells are produced and maintained by the Scar/WAVE complex. Thus, actin-based cell migration is largely controlled through regulation of Scar/WAVE. Here, we report that the Abi subunit-but not Scar-is phosphorylated in response to extracellular signalling in Dictyostelium cells. Like Scar, Abi is phosphorylated after the complex has been activated, implying that Abi phosphorylation modulates pseudopodia, rather than causing new ones to be made. Consistent with this, Scar complex mutants that cannot bind Rac are also not phosphorylated. Several environmental cues also affect Abi phosphorylation-cell-substrate adhesion promotes it and increased extracellular osmolarity diminishes it. Both unphosphorylatable and phosphomimetic Abi efficiently rescue the chemotaxis of Abi KO cells and pseudopodia formation, confirming that Abi phosphorylation is not required for activation or inactivation of the Scar/WAVE complex. However, pseudopodia and Scar patches in the cells with unphosphorylatable Abi protrude for longer, altering pseudopod dynamics and cell speed. Dictyostelium, in which Scar and Abi are both unphosphorylatable, can still form pseudopods, but migrate substantially faster. We conclude that extracellular signals and environmental responses modulate cell migration by tuning the behaviour of the Scar/WAVE complex after it has been activated.
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13
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Pipathsouk A, Brunetti RM, Town JP, Graziano BR, Breuer A, Pellett PA, Marchuk K, Tran NHT, Krummel MF, Stamou D, Weiner OD. The WAVE complex associates with sites of saddle membrane curvature. J Cell Biol 2021; 220:e202003086. [PMID: 34096975 PMCID: PMC8185649 DOI: 10.1083/jcb.202003086] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/13/2021] [Accepted: 05/18/2021] [Indexed: 12/30/2022] Open
Abstract
How local interactions of actin regulators yield large-scale organization of cell shape and movement is not well understood. Here we investigate how the WAVE complex organizes sheet-like lamellipodia. Using super-resolution microscopy, we find that the WAVE complex forms actin-independent 230-nm-wide rings that localize to regions of saddle membrane curvature. This pattern of enrichment could explain several emergent cell behaviors, such as expanding and self-straightening lamellipodia and the ability of endothelial cells to recognize and seal transcellular holes. The WAVE complex recruits IRSp53 to sites of saddle curvature but does not depend on IRSp53 for its own localization. Although the WAVE complex stimulates actin nucleation via the Arp2/3 complex, sheet-like protrusions are still observed in ARP2-null, but not WAVE complex-null, cells. Therefore, the WAVE complex has additional roles in cell morphogenesis beyond Arp2/3 complex activation. Our work defines organizing principles of the WAVE complex lamellipodial template and suggests how feedback between cell shape and actin regulators instructs cell morphogenesis.
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Affiliation(s)
- Anne Pipathsouk
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Rachel M. Brunetti
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Jason P. Town
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Brian R. Graziano
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
| | - Artù Breuer
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | | | - Kyle Marchuk
- Department of Pathology and Biological Imaging Development CoLab, University of California, San Francisco, San Francisco, CA
| | - Ngoc-Han T. Tran
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Matthew F. Krummel
- Department of Pathology and Biological Imaging Development CoLab, University of California, San Francisco, San Francisco, CA
| | - Dimitrios Stamou
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Orion D. Weiner
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
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14
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Filić V, Mijanović L, Putar D, Talajić A, Ćetković H, Weber I. Regulation of the Actin Cytoskeleton via Rho GTPase Signalling in Dictyostelium and Mammalian Cells: A Parallel Slalom. Cells 2021; 10:1592. [PMID: 34202767 PMCID: PMC8305917 DOI: 10.3390/cells10071592] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/15/2023] Open
Abstract
Both Dictyostelium amoebae and mammalian cells are endowed with an elaborate actin cytoskeleton that enables them to perform a multitude of tasks essential for survival. Although these organisms diverged more than a billion years ago, their cells share the capability of chemotactic migration, large-scale endocytosis, binary division effected by actomyosin contraction, and various types of adhesions to other cells and to the extracellular environment. The composition and dynamics of the transient actin-based structures that are engaged in these processes are also astonishingly similar in these evolutionary distant organisms. The question arises whether this remarkable resemblance in the cellular motility hardware is accompanied by a similar correspondence in matching software, the signalling networks that govern the assembly of the actin cytoskeleton. Small GTPases from the Rho family play pivotal roles in the control of the actin cytoskeleton dynamics. Indicatively, Dictyostelium matches mammals in the number of these proteins. We give an overview of the Rho signalling pathways that regulate the actin dynamics in Dictyostelium and compare them with similar signalling networks in mammals. We also provide a phylogeny of Rho GTPases in Amoebozoa, which shows a variability of the Rho inventories across different clades found also in Metazoa.
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Affiliation(s)
- Vedrana Filić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
| | | | | | | | | | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (L.M.); (D.P.); (A.T.); (H.Ć.)
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15
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Yelland T, Le AH, Nikolaou S, Insall R, Machesky L, Ismail S. Structural Basis of CYRI-B Direct Competition with Scar/WAVE Complex for Rac1. Structure 2021; 29:226-237.e4. [PMID: 33217330 PMCID: PMC7955166 DOI: 10.1016/j.str.2020.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/07/2020] [Accepted: 11/02/2020] [Indexed: 01/16/2023]
Abstract
Rac1 is a major regulator of actin dynamics, with GTP-bound Rac1 promoting actin assembly via the Scar/WAVE complex. CYRI competes with Scar/WAVE for interaction with Rac1 in a feedback loop regulating actin dynamics. Here, we reveal the nature of the CYRI-Rac1 interaction, through crystal structures of CYRI-B lacking the N-terminal helix (CYRI-BΔN) and the CYRI-BΔN:Rac1Q61L complex, providing the molecular basis for CYRI-B regulation of the Scar/WAVE complex. We reveal CYRI-B as having two subdomains - an N-terminal Rac1 binding subdomain with a unique Rac1-effector interface and a C-terminal Ratchet subdomain that undergoes conformational changes induced by Rac1 binding. Finally, we show that the CYRI protein family, CYRI-A and CYRI-B can produce an autoinhibited hetero- or homodimers, adding an additional layer of regulation to Rac1 signaling.
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Affiliation(s)
| | | | | | - Robert Insall
- CRUK- Beatson Institute, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1BD, UK
| | - Laura Machesky
- CRUK- Beatson Institute, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1BD, UK.
| | - Shehab Ismail
- CRUK- Beatson Institute, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1BD, UK; Department of Chemistry, KU Leuven, Celestijnenlaan 200G, 3001 Heverlee, Belgium.
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16
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Abstract
The Scar/WAVE complex catalyzes the protrusion of pseudopods and lamellipods, and is therefore a principal regulator of cell migration. However, it is unclear how its activity is regulated, beyond a dependence on Rac. Phosphorylation of the proline-rich region, by kinases such as Erk2, has been suggested as an upstream activator. We have recently reported that phosphorylation is not required for complex activation. Rather, it occurs after Scar/WAVE has been activated, and acts as a modulator. Neither chemoattractant signaling nor Erk2 affects the amount of phosphorylation, though in Dictyostelium it is promoted by cell-substrate adhesion. We now report that cell-substrate adhesion also promotes Scar/WAVE2 phosphorylation in mammalian cells, suggesting that the process is evolutionarily conserved.
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Affiliation(s)
| | - Robert H Insall
- Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
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17
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Papalazarou V, Swaminathan K, Jaber-Hijazi F, Spence H, Lahmann I, Nixon C, Salmeron-Sanchez M, Arnold HH, Rottner K, Machesky LM. The Arp2/3 complex is crucial for colonisation of the mouse skin by melanoblasts. Development 2020; 147:dev194555. [PMID: 33028610 PMCID: PMC7687863 DOI: 10.1242/dev.194555] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/22/2020] [Indexed: 01/10/2023]
Abstract
The Arp2/3 complex is essential for the assembly of branched filamentous actin, but its role in physiology and development is surprisingly little understood. Melanoblasts deriving from the neural crest migrate along the developing embryo and traverse the dermis to reach the epidermis, colonising the skin and eventually homing within the hair follicles. We have previously established that Rac1 and Cdc42 direct melanoblast migration in vivo We hypothesised that the Arp2/3 complex might be the main downstream effector of these small GTPases. Arp3 depletion in the melanocyte lineage results in severe pigmentation defects in dorsal and ventral regions of the mouse skin. Arp3 null melanoblasts demonstrate proliferation and migration defects and fail to elongate as their wild-type counterparts. Conditional deletion of Arp3 in primary melanocytes causes improper proliferation, spreading, migration and adhesion to extracellular matrix. Collectively, our results suggest that the Arp2/3 complex is absolutely indispensable in the melanocyte lineage in mouse development, and indicate a significant role in developmental processes that require tight regulation of actin-mediated motility.
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Affiliation(s)
- Vassilis Papalazarou
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Campus, Switchback Road, Bearsden, Glasgow G61 1QH, UK
- Centre for the Cellular Microenvironment, University of Glasgow, Glasgow G12 8LT, UK
| | - Karthic Swaminathan
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Farah Jaber-Hijazi
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Heather Spence
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Ines Lahmann
- Cell and Molecular Biology, Institute of Biochemistry and Biotechnology, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Colin Nixon
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | | | - Hans-Henning Arnold
- Cell and Molecular Biology, Institute of Biochemistry and Biotechnology, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Laura M Machesky
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Campus, Switchback Road, Bearsden, Glasgow G61 1QH, UK
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18
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Nicolai L, Schiefelbein K, Lipsky S, Leunig A, Hoffknecht M, Pekayvaz K, Raude B, Marx C, Ehrlich A, Pircher J, Zhang Z, Saleh I, Marel AK, Löf A, Petzold T, Lorenz M, Stark K, Pick R, Rosenberger G, Weckbach L, Uhl B, Xia S, Reichel CA, Walzog B, Schulz C, Zheden V, Bender M, Li R, Massberg S, Gaertner F. Vascular surveillance by haptotactic blood platelets in inflammation and infection. Nat Commun 2020; 11:5778. [PMID: 33188196 PMCID: PMC7666582 DOI: 10.1038/s41467-020-19515-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 10/14/2020] [Indexed: 12/21/2022] Open
Abstract
Breakdown of vascular barriers is a major complication of inflammatory diseases. Anucleate platelets form blood-clots during thrombosis, but also play a crucial role in inflammation. While spatio-temporal dynamics of clot formation are well characterized, the cell-biological mechanisms of platelet recruitment to inflammatory micro-environments remain incompletely understood. Here we identify Arp2/3-dependent lamellipodia formation as a prominent morphological feature of immune-responsive platelets. Platelets use lamellipodia to scan for fibrin(ogen) deposited on the inflamed vasculature and to directionally spread, to polarize and to govern haptotactic migration along gradients of the adhesive ligand. Platelet-specific abrogation of Arp2/3 interferes with haptotactic repositioning of platelets to microlesions, thus impairing vascular sealing and provoking inflammatory microbleeding. During infection, haptotaxis promotes capture of bacteria and prevents hematogenic dissemination, rendering platelets gate-keepers of the inflamed microvasculature. Consequently, these findings identify haptotaxis as a key effector function of immune-responsive platelets. Breakdown of vascular barriers is a major complication of inflammatory diseases. However, the mechanisms underlying platelet recruitment to inflammatory micro-environments remains unclear. Here, the authors identify haptotaxis as a key effector function of immune-responsive platelets
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Affiliation(s)
- Leo Nicolai
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany
| | - Karin Schiefelbein
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Silvia Lipsky
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Alexander Leunig
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Marie Hoffknecht
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Kami Pekayvaz
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Ben Raude
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Charlotte Marx
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Andreas Ehrlich
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Joachim Pircher
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Zhe Zhang
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Inas Saleh
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | | | - Achim Löf
- Ludwig-Maximilians-Universität, 80799, Munich, Germany
| | - Tobias Petzold
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Michael Lorenz
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Konstantin Stark
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Robert Pick
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, München, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, Planegg-Martinsried, Munich, Germany
| | - Gerhild Rosenberger
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Ludwig Weckbach
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany
| | - Bernd Uhl
- Department of Otorhinolarynology, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Sheng Xia
- Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, MD, 21205, USA
| | | | - Barbara Walzog
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, München, Germany.,Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, Planegg-Martinsried, Munich, Germany
| | - Christian Schulz
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany
| | - Vanessa Zheden
- Institute of Science and Technology (IST) Austria, 3400, Klosterneuburg, Austria
| | - Markus Bender
- Institute of Experimental Biomedicine I, University Hospital and Rudolf Virchow Center, Würzburg, Germany
| | - Rong Li
- Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, MD, 21205, USA
| | - Steffen Massberg
- Medizinische Klinik und Poliklinik I, Klinikum der Ludwig-Maximilians-Universität, 81377, Munich, Germany. .,DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany.
| | - Florian Gaertner
- DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 80802, Munich, Germany. .,Institute of Science and Technology (IST) Austria, 3400, Klosterneuburg, Austria.
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19
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Velle KB, Fritz-Laylin LK. Conserved actin machinery drives microtubule-independent motility and phagocytosis in Naegleria. J Cell Biol 2020; 219:e202007158. [PMID: 32960946 PMCID: PMC7594500 DOI: 10.1083/jcb.202007158] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/11/2020] [Accepted: 08/14/2020] [Indexed: 12/11/2022] Open
Abstract
Much of our understanding of actin-driven phenotypes in eukaryotes has come from the "yeast-to-human" opisthokont lineage and the related amoebozoa. Outside of these groups lies the genus Naegleria, which shared a common ancestor with humans >1 billion years ago and includes the "brain-eating amoeba." Unlike nearly all other known eukaryotic cells, Naegleria amoebae lack interphase microtubules; this suggests that actin alone drives phenotypes like cell crawling and phagocytosis. Naegleria therefore represents a powerful system to probe actin-driven functions in the absence of microtubules, yet surprisingly little is known about its actin cytoskeleton. Using genomic analysis, microscopy, and molecular perturbations, we show that Naegleria encodes conserved actin nucleators and builds Arp2/3-dependent lamellar protrusions. These protrusions correlate with the capacity to migrate and eat bacteria. Because human cells also use Arp2/3-dependent lamellar protrusions for motility and phagocytosis, this work supports an evolutionarily ancient origin for these processes and establishes Naegleria as a natural model system for studying microtubule-independent cytoskeletal phenotypes.
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20
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Singh SP, Thomason PA, Lilla S, Schaks M, Tang Q, Goode BL, Machesky LM, Rottner K, Insall RH. Cell-substrate adhesion drives Scar/WAVE activation and phosphorylation by a Ste20-family kinase, which controls pseudopod lifetime. PLoS Biol 2020; 18:e3000774. [PMID: 32745097 PMCID: PMC7425996 DOI: 10.1371/journal.pbio.3000774] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/13/2020] [Accepted: 07/13/2020] [Indexed: 01/22/2023] Open
Abstract
The Scar/WAVE complex is the principal catalyst of pseudopod and lamellipod formation. Here we show that Scar/WAVE's proline-rich domain is polyphosphorylated after the complex is activated. Blocking Scar/WAVE activation stops phosphorylation in both Dictyostelium and mammalian cells, implying that phosphorylation modulates pseudopods after they have been formed, rather than controlling whether they are initiated. Unexpectedly, phosphorylation is not promoted by chemotactic signaling but is greatly stimulated by cell:substrate adhesion and diminished when cells deadhere. Phosphorylation-deficient or phosphomimetic Scar/WAVE mutants are both normally functional and rescue the phenotype of knockout cells, demonstrating that phosphorylation is dispensable for activation and actin regulation. However, pseudopods and patches of phosphorylation-deficient Scar/WAVE last substantially longer in mutants, altering the dynamics and size of pseudopods and lamellipods and thus changing migration speed. Scar/WAVE phosphorylation does not require ERK2 in Dictyostelium or mammalian cells. However, the MAPKKK homologue SepA contributes substantially-sepA mutants have less steady-state phosphorylation, which does not increase in response to adhesion. The mutants also behave similarly to cells expressing phosphorylation-deficient Scar, with longer-lived pseudopods and patches of Scar recruitment. We conclude that pseudopod engagement with substratum is more important than extracellular signals at regulating Scar/WAVE's activity and that phosphorylation acts as a pseudopod timer by promoting Scar/WAVE turnover.
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Affiliation(s)
| | | | | | - Matthias Schaks
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany & Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Qing Tang
- Brandeis University, Waltham, Massachusetts, United States of America
| | - Bruce L. Goode
- Brandeis University, Waltham, Massachusetts, United States of America
| | | | - Klemens Rottner
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany & Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Robert H. Insall
- CRUK Beatson Institute, Glasgow, United Kingdom
- Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
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21
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Whitelaw JA, Swaminathan K, Kage F, Machesky LM. The WAVE Regulatory Complex Is Required to Balance Protrusion and Adhesion in Migration. Cells 2020; 9:E1635. [PMID: 32646006 PMCID: PMC7407199 DOI: 10.3390/cells9071635] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 12/15/2022] Open
Abstract
Cells migrating over 2D substrates are required to polymerise actin at the leading edge to form lamellipodia protrusions and nascent adhesions to anchor the protrusion to the substrate. The major actin nucleator in lamellipodia formation is the Arp2/3 complex, which is activated by the WAVE regulatory complex (WRC). Using inducible Nckap1 floxed mouse embryonic fibroblasts (MEFs), we confirm that the WRC is required for lamellipodia formation, and importantly, for generating the retrograde flow of actin from the leading cell edge. The loss of NCKAP1 also affects cell spreading and focal adhesion dynamics. In the absence of lamellipodium, cells can become elongated and move with a single thin pseudopod, which appears devoid of N-WASP. This phenotype was more prevalent on collagen than fibronectin, where we observed an increase in migratory speed. Thus, 2D cell migration on collagen is less dependent on branched actin.
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Affiliation(s)
| | - Karthic Swaminathan
- CRUK Beatson Institute, Glasgow G61 1BD, UK; (K.S.); (L.M.M.)
- School of Chemistry and Bioscience, University of Bradford, Bradford BD7 1PD, UK
| | - Frieda Kage
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755-3844, USA;
- Zoological Institute, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - Laura M. Machesky
- CRUK Beatson Institute, Glasgow G61 1BD, UK; (K.S.); (L.M.M.)
- Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK
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22
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Jeon P, Jeon TJ. WasC, a WASP family protein, is involved in cell adhesion and migration through regulation of F-actin polymerization in Dictyostelium. J Microbiol 2020; 58:696-702. [PMID: 32524343 DOI: 10.1007/s12275-020-0138-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/29/2020] [Accepted: 05/18/2020] [Indexed: 11/24/2022]
Abstract
The actin cytoskeleton is involved in the regulation of cell morphology and migration. Wiskott-Aldrich Syndrome proteins (WASPs) play an important role in controlling actin polymerization by activating the Arp2/3 complex. The present study investigated the roles of WasC, one of the 3 WASPs in Dictyostelium, in cellular processes. Cells lacking WasC displayed strong cell adhesion and approximately 1.5-fold increase in F-actin levels as compared to the wild-type cells. Loss of wasC caused defects in phagocytosis and decreased the migration speed in chemoattractant-mediated cell migration but did not affect directionality. WasC was localized to the protruding region in migrating cells and, transiently and rapidly translocated to the cell cortex in response to chemoattractant stimulation, in an F-actin dependent manner. Our results suggest that WasC is involved in cell adhesion and migration by regulating F-actin polymerization at the leading edge of migrating cells, probably as a negative regulator. The increased strength of adhesion in wasC null cells is likely to decrease the migration speed but not the directionality.
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Affiliation(s)
- Pyeonghwa Jeon
- Department of Biology & BK21- Plus Research Team for Bioactive Control Technology, College of Natural Sciences, Chosun University, Gwangju, 61452, Republic of Korea
| | - Taeck Joong Jeon
- Department of Biology & BK21- Plus Research Team for Bioactive Control Technology, College of Natural Sciences, Chosun University, Gwangju, 61452, Republic of Korea.
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23
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Cheng Y, Felix B, Othmer HG. The Roles of Signaling in Cytoskeletal Changes, Random Movement, Direction-Sensing and Polarization of Eukaryotic Cells. Cells 2020; 9:E1437. [PMID: 32531876 PMCID: PMC7348768 DOI: 10.3390/cells9061437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 12/21/2022] Open
Abstract
Movement of cells and tissues is essential at various stages during the lifetime of an organism, including morphogenesis in early development, in the immune response to pathogens, and during wound-healing and tissue regeneration. Individual cells are able to move in a variety of microenvironments (MEs) (A glossary of the acronyms used herein is given at the end) by suitably adapting both their shape and how they transmit force to the ME, but how cells translate environmental signals into the forces that shape them and enable them to move is poorly understood. While many of the networks involved in signal detection, transduction and movement have been characterized, how intracellular signals control re-building of the cyctoskeleton to enable movement is not understood. In this review we discuss recent advances in our understanding of signal transduction networks related to direction-sensing and movement, and some of the problems that remain to be solved.
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Affiliation(s)
- Yougan Cheng
- Bristol Myers Squibb, Route 206 & Province Line Road, Princeton, NJ 08543, USA;
| | - Bryan Felix
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
| | - Hans G. Othmer
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
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24
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Nikolaou S, Machesky LM. The stressful tumour environment drives plasticity of cell migration programmes, contributing to metastasis. J Pathol 2020; 250:612-623. [PMID: 32057095 PMCID: PMC7216910 DOI: 10.1002/path.5395] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/21/2020] [Accepted: 02/10/2020] [Indexed: 12/19/2022]
Abstract
Tumours evolve to cope with environmental stresses or challenges such as nutrient starvation, depletion of survival factors, and unbalanced mechanical forces. The uncontrolled growth and aberrant deregulation of core cell homeostatic pathways induced by genetic mutations create an environment of stress. Here, we explore how the adaptations of tumours to the changing environment can drive changes in the motility machinery of cells, affecting migration, invasion, and metastasis. Tumour cells can invade individually or collectively, or they can be extruded out of the surrounding epithelium. These mechanisms are thought to be modifications of normal processes occurring during development or tissue repair. Therefore, tumours may activate these pathways in response to environmental stresses, enabling them to survive in hostile environments and spread to distant sites. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Savvas Nikolaou
- Division of Cancer Metastasis and RecurrenceCRUK Beatson InstituteGlasgowUK
| | - Laura M Machesky
- Division of Cancer Metastasis and RecurrenceCRUK Beatson InstituteGlasgowUK
- Institute of Cancer SciencesUniversity of GlasgowGlasgowUK
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25
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Amato C, Thomason PA, Davidson AJ, Swaminathan K, Ismail S, Machesky LM, Insall RH. WASP Restricts Active Rac to Maintain Cells' Front-Rear Polarization. Curr Biol 2019; 29:4169-4182.e4. [PMID: 31786060 PMCID: PMC6926487 DOI: 10.1016/j.cub.2019.10.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 10/01/2019] [Accepted: 10/18/2019] [Indexed: 12/20/2022]
Abstract
Efficient motility requires polarized cells, with pseudopods at the front and a retracting rear. Polarization is maintained by restricting the pseudopod catalyst, active Rac, to the front. Here, we show that the actin nucleation-promoting factor Wiskott-Aldrich syndrome protein (WASP) contributes to maintenance of front-rear polarity by controlling localization and cellular levels of active Rac. Dictyostelium cells lacking WASP inappropriately activate Rac at the rear, which affects their polarity and speed. WASP's Cdc42 and Rac interacting binding ("CRIB") motif has been thought to be essential for its activation. However, we show that the CRIB motif's biological role is unexpectedly complex. WASP CRIB mutants are no longer able to restrict Rac activity to the front, and cannot generate new pseudopods when SCAR/WAVE is absent. Overall levels of Rac activity also increase when WASP is unable to bind to Rac. However, WASP without a functional CRIB domain localizes normally at clathrin pits during endocytosis, and activates Arp2/3 complex. Similarly, chemical inhibition of Rac does not affect WASP localization or activation at sites of endocytosis. Thus, the interaction between small GTPases and WASP is more complex than previously thought-Rac regulates a subset of WASP functions, but WASP reciprocally restricts active Rac through its CRIB motif.
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Affiliation(s)
- Clelia Amato
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK.
| | - Peter A Thomason
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Andrew J Davidson
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Karthic Swaminathan
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Shehab Ismail
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Laura M Machesky
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
| | - Robert H Insall
- CRUK Beatson Institute, Switchback Road, Bearsden G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
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26
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Abstract
Actin polymerization is essential for cells to migrate, as well as for various cell biological processes such as cytokinesis and vesicle traffic. This brief review describes the mechanisms underlying its different roles and recent advances in our understanding. Actin usually requires "nuclei"-preformed actin filaments-to start polymerizing, but, once initiated, polymerization continues constitutively. The field therefore has a strong focus on nucleators, in particular the Arp2/3 complex and formins. These have different functions, are controlled by contrasting mechanisms, and generate alternate geometries of actin networks. The Arp2/3 complex functions only when activated by nucleation-promoting factors such as WASP, Scar/WAVE, WASH, and WHAMM and when binding to a pre-existing filament. Formins can be individually active but are usually autoinhibited. Each is controlled by different mechanisms and is involved in different biological roles. We also describe the processes leading to actin disassembly and their regulation and conclude with four questions whose answers are important for understanding actin dynamics but are currently unanswered.
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Affiliation(s)
- Simona Buracco
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Sophie Claydon
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
| | - Robert Insall
- Institute of Cancer Sciences, University of Glasgow, Bearsden, G61 1BD, UK
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27
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Graziano BR, Town JP, Sitarska E, Nagy TL, Fošnarič M, Penič S, Iglič A, Kralj-Iglič V, Gov NS, Diz-Muñoz A, Weiner OD. Cell confinement reveals a branched-actin independent circuit for neutrophil polarity. PLoS Biol 2019; 17:e3000457. [PMID: 31600188 PMCID: PMC6805013 DOI: 10.1371/journal.pbio.3000457] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 10/22/2019] [Accepted: 09/16/2019] [Indexed: 12/30/2022] Open
Abstract
Migratory cells use distinct motility modes to navigate different microenvironments, but it is unclear whether these modes rely on the same core set of polarity components. To investigate this, we disrupted actin-related protein 2/3 (Arp2/3) and the WASP-family verprolin homologous protein (WAVE) complex, which assemble branched actin networks that are essential for neutrophil polarity and motility in standard adherent conditions. Surprisingly, confinement rescues polarity and movement of neutrophils lacking these components, revealing a processive bleb-based protrusion program that is mechanistically distinct from the branched actin-based protrusion program but shares some of the same core components and underlying molecular logic. We further find that the restriction of protrusion growth to one site does not always respond to membrane tension directly, as previously thought, but may rely on closely linked properties such as local membrane curvature. Our work reveals a hidden circuit for neutrophil polarity and indicates that cells have distinct molecular mechanisms for polarization that dominate in different microenvironments. Cells display a high degree of plasticity in migration, but how polarity is organized in different microenvironments has remained unclear. This study uses mechanical perturbations to reveal that migration using actin-rich or bleb-based protrusions are both organized around Rac GTPase.
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Affiliation(s)
- Brian R. Graziano
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
| | - Jason P. Town
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
| | - Ewa Sitarska
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Tamas L. Nagy
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
| | - Miha Fošnarič
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Samo Penič
- Department of Theoretical Electrotechnics, Mathematics and Physics, Faculty of Electrical Engineering, University of Ljubljana, Slovenia
| | - Aleš Iglič
- Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, Slovenia
- Department of Theoretical Electrotechnics, Mathematics and Physics, Faculty of Electrical Engineering, University of Ljubljana, Slovenia
| | | | - Nir S. Gov
- Department of Chemical and Biological Physics, Weizmann Institute, Rehovot, Israel
| | - Alba Diz-Muñoz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Orion D. Weiner
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- * E-mail:
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28
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Marinović M, Xiong H, Rivero F, Weber I. Assaying Rho GTPase-Dependent Processes in Dictyostelium discoideum. Methods Mol Biol 2019; 1821:371-392. [PMID: 30062425 DOI: 10.1007/978-1-4939-8612-5_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The model organism D. discoideum is well suited to investigate basic questions of molecular and cell biology, particularly those related to the structure, regulation, and dynamics of the cytoskeleton, signal transduction, cell-cell adhesion, and development. D. discoideum cells make use of Rho-regulated signaling pathways to reorganize the actin cytoskeleton during chemotaxis, endocytosis, and cytokinesis. In this organism the Rho family encompasses 20 members, several belonging to the Rac subfamily, but there are no representatives of the Cdc42 and Rho subfamilies. Here we present protocols suitable for monitoring the actin polymerization response and the activation of Rac upon stimulation of aggregation-competent cells with the chemoattractant cAMP, and for monitoring the localization and dynamics of Rac activity in live cells.
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Affiliation(s)
- Maja Marinović
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Huajiang Xiong
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Francisco Rivero
- Centre for Atherothrombosis and Metabolic Disease, Hull York Medical School, Faculty of Health Sciences, University of Hull, Hull, UK.
| | - Igor Weber
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia.
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29
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Rijal R, Consalvo KM, Lindsey CK, Gomer RH. An endogenous chemorepellent directs cell movement by inhibiting pseudopods at one side of cells. Mol Biol Cell 2018; 30:242-255. [PMID: 30462573 PMCID: PMC6589559 DOI: 10.1091/mbc.e18-09-0562] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic chemoattraction signal transduction pathways, such as those used by Dictyostelium discoideum to move toward cAMP, use a G protein-coupled receptor to activate multiple conserved pathways such as PI3 kinase/Akt/PKB to induce actin polymerization and pseudopod formation at the front of a cell, and PTEN to localize myosin II to the rear of a cell. Relatively little is known about chemorepulsion. We previously found that AprA is a chemorepellent protein secreted by Dictyostelium cells. Here we used 29 cell lines with disruptions of cAMP and/or AprA signal transduction pathway components, and delineated the AprA chemorepulsion pathway. We find that AprA uses a subset of chemoattraction signal transduction pathways including Ras, protein kinase A, target of rapamycin (TOR), phospholipase A, and ERK1, but does not require the PI3 kinase/Akt/PKB and guanylyl cyclase pathways to induce chemorepulsion. Possibly as a result of not using the PI3 kinase/Akt/PKB pathway and guanylyl cyclases, AprA does not induce actin polymerization or increase the pseudopod formation rate, but rather appears to inhibit pseudopod formation at the side of cells closest to the source of AprA.
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Affiliation(s)
- Ramesh Rijal
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | - Kristen M Consalvo
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
| | | | - Richard H Gomer
- Department of Biology, Texas A&M University, College Station, TX 77843-3474
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30
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Schaks M, Singh SP, Kage F, Thomason P, Klünemann T, Steffen A, Blankenfeldt W, Stradal TE, Insall RH, Rottner K. Distinct Interaction Sites of Rac GTPase with WAVE Regulatory Complex Have Non-redundant Functions in Vivo. Curr Biol 2018; 28:3674-3684.e6. [PMID: 30393033 PMCID: PMC6264382 DOI: 10.1016/j.cub.2018.10.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 08/30/2018] [Accepted: 10/01/2018] [Indexed: 12/31/2022]
Abstract
Cell migration often involves the formation of sheet-like lamellipodia generated by branched actin filaments. The branches are initiated when Arp2/3 complex [1] is activated by WAVE regulatory complex (WRC) downstream of small GTPases of the Rac family [2]. Recent structural studies defined two independent Rac binding sites on WRC within the Sra-1/PIR121 subunit of the pentameric WRC [3, 4], but the functions of these sites in vivo have remained unknown. Here we dissect the mechanism of WRC activation and the in vivo relevance of distinct Rac binding sites on Sra-1, using CRISPR/Cas9-mediated gene disruption of Sra-1 and its paralog PIR121 in murine B16-F1 cells combined with Sra-1 mutant rescue. We show that the A site, positioned adjacent to the binding region of WAVE-WCA mediating actin and Arp2/3 complex binding, is the main site for allosteric activation of WRC. In contrast, the D site toward the C terminus is dispensable for WRC activation but required for optimal lamellipodium morphology and function. These results were confirmed in evolutionarily distant Dictyostelium cells. Moreover, the phenotype seen in D site mutants was recapitulated in Rac1 E31 and F37 mutants; we conclude these residues are important for Rac-D site interaction. Finally, constitutively activated WRC was able to induce lamellipodia even after both Rac interaction sites were lost, showing that Rac interaction is not essential for membrane recruitment. Our data establish that physical interaction with Rac is required for WRC activation, in particular through the A site, but is not mandatory for WRC accumulation in the lamellipodium.
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Affiliation(s)
- Matthias Schaks
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Shashi P Singh
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK
| | - Frieda Kage
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Peter Thomason
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK
| | - Thomas Klünemann
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Anika Steffen
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Wulf Blankenfeldt
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Theresia E Stradal
- Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Robert H Insall
- CRUK Beatson Institute, Switchback Road, Glasgow G61 1BD, UK; University of Glasgow Institute of Cancer Sciences, Switchback Road, Glasgow G61 1BD, UK.
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany; Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany.
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31
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Fort L, Batista JM, Thomason PA, Spence HJ, Whitelaw JA, Tweedy L, Greaves J, Martin KJ, Anderson KI, Brown P, Lilla S, Neilson MP, Tafelmeyer P, Zanivan S, Ismail S, Bryant DM, Tomkinson NCO, Chamberlain LH, Mastick GS, Insall RH, Machesky LM. Fam49/CYRI interacts with Rac1 and locally suppresses protrusions. Nat Cell Biol 2018; 20:1159-1171. [PMID: 30250061 PMCID: PMC6863750 DOI: 10.1038/s41556-018-0198-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/20/2018] [Indexed: 11/09/2022]
Abstract
Actin-based protrusions are reinforced through positive feedback, but it is unclear what restricts their size, or limits positive signals when they retract or split. We identify an evolutionarily conserved regulator of actin-based protrusion: CYRI (CYFIP-related Rac interactor) also known as Fam49 (family of unknown function 49). CYRI binds activated Rac1 via a domain of unknown function (DUF1394) shared with CYFIP, defining DUF1394 as a Rac1-binding module. CYRI-depleted cells have broad lamellipodia enriched in Scar/WAVE, but reduced protrusion-retraction dynamics. Pseudopods induced by optogenetic Rac1 activation in CYRI-depleted cells are larger and longer lived. Conversely, CYRI overexpression suppresses recruitment of active Scar/WAVE to the cell edge, resulting in short-lived, unproductive protrusions. CYRI thus focuses protrusion signals and regulates pseudopod complexity by inhibiting Scar/WAVE-induced actin polymerization. It thus behaves like a 'local inhibitor' as predicted in widely accepted mathematical models, but not previously identified in cells. CYRI therefore regulates chemotaxis, cell migration and epithelial polarization by controlling the polarity and plasticity of protrusions.
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Affiliation(s)
- Loic Fort
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - José Miguel Batista
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | | | | | | | | | - Jennifer Greaves
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Kurt I Anderson
- CRUK Beatson Institute, Glasgow, UK
- Francis Crick Institute, London, UK
| | | | | | | | | | | | - Shehab Ismail
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - David M Bryant
- CRUK Beatson Institute, Glasgow, UK
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK
| | - Nicholas C O Tomkinson
- WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK
| | - Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | | | - Robert H Insall
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
| | - Laura M Machesky
- CRUK Beatson Institute, Glasgow, UK.
- University of Glasgow Institute of Cancer Sciences, Glasgow, UK.
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32
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Davidson AJ, Amato C, Thomason PA, Insall RH. WASP family proteins and formins compete in pseudopod- and bleb-based migration. J Cell Biol 2018; 217:701-714. [PMID: 29191847 PMCID: PMC5800805 DOI: 10.1083/jcb.201705160] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 10/03/2017] [Accepted: 11/06/2017] [Indexed: 11/24/2022] Open
Abstract
Actin pseudopods induced by SCAR/WAVE drive normal migration and chemotaxis in eukaryotic cells. Cells can also migrate using blebs, in which the edge is driven forward by hydrostatic pressure instead of actin. In Dictyostelium discoideum, loss of SCAR is compensated by WASP moving to the leading edge to generate morphologically normal pseudopods. Here we use an inducible double knockout to show that cells lacking both SCAR and WASP are unable to grow, make pseudopods or, unexpectedly, migrate using blebs. Remarkably, amounts and dynamics of actin polymerization are normal. Pseudopods are replaced in double SCAR/WASP mutants by aberrant filopods, induced by the formin dDia2. Further disruption of the gene for dDia2 restores cells' ability to initiate blebs and thus migrate, though pseudopods are still lost. Triple knockout cells still contain near-normal F-actin levels. This work shows that SCAR, WASP, and dDia2 compete for actin. Loss of SCAR and WASP causes excessive dDia2 activity, maintaining F-actin levels but blocking pseudopod and bleb formation and migration.
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Affiliation(s)
| | - Clelia Amato
- Cancer Research UK Beatson Institute, Glasgow, Scotland, UK
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33
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Differential functions of WAVE regulatory complex subunits in the regulation of actin-driven processes. Eur J Cell Biol 2017; 96:715-727. [PMID: 28889942 DOI: 10.1016/j.ejcb.2017.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/23/2017] [Accepted: 08/25/2017] [Indexed: 11/22/2022] Open
Abstract
The WAVE regulatory complex (WRC) links upstream Rho-family GTPase signaling to the activation of the ARP2/3 complex in different organisms. WRC-induced and ARP2/3 complex-mediated actin nucleation beneath the plasma membrane is critical for actin assembly in the leading edge to drive efficient cell migration. The WRC is a stable heteropentamer composed of SCAR/WAVE, Abi, Nap, Pir and the small polypeptide Brk1/Hspc300. Functional interference with individual subunits of the complex frequently results in diminished amounts of the remaining polypeptides of the WRC complex, implying the complex to act as molecular entity. However, Abi was also found to associate with mammalian N-WASP, formins, Eps8/SOS1 or VASP, indicating additional functions of individual WRC subunits in eukaryotic cells. To address this issue systematically, we inactivated all WRC subunits, either alone or in combination with VASP in Dictyostelium cells and quantified the protein content of the remaining subunits in respective WRC knockouts. The individual mutants displayed highly differential phenotypes concerning various parameters, including cell morphology, motility, cytokinesis or multicellular development, corroborating the view of additional roles for individual subunits, beyond their established function in WRC-mediated Arp2/3 complex activation. Finally, our data uncover the interaction of the actin polymerase VASP with WRC-embedded Abi to mediate VASP accumulation in cell protrusions, driving efficient cell migration.
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Shear force-based genetic screen reveals negative regulators of cell adhesion and protrusive activity. Proc Natl Acad Sci U S A 2017; 114:E7727-E7736. [PMID: 28847951 DOI: 10.1073/pnas.1616600114] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The model organism Dictyostelium discoideum has greatly facilitated our understanding of the signal transduction and cytoskeletal pathways that govern cell motility. Cell-substrate adhesion is downstream of many migratory and chemotaxis signaling events. Dictyostelium cells lacking the tumor suppressor PTEN show strongly impaired migratory activity and adhere strongly to their substrates. We reasoned that other regulators of migration could be obtained through a screen for overly adhesive mutants. A screen of restriction enzyme-mediated integration mutagenized cells yielded numerous mutants with the desired phenotypes, and the insertion sites in 18 of the strains were mapped. These regulators of adhesion and motility mutants have increased adhesion and decreased motility. Characterization of seven strains demonstrated decreased directed migration, flatness, increased filamentous actin-based protrusions, and increased signal transduction network activity. Many of the genes share homology to human genes and demonstrate the diverse array of cellular networks that function in adhesion and migration.
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Molinie N, Gautreau A. WASP and WAVE Team Up at the Leading Edge. Dev Cell 2017; 39:135-136. [PMID: 27780037 DOI: 10.1016/j.devcel.2016.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Arp2/3-dependent branched actin networks drive membrane protrusions, with WAVE being recognized as the critical Arp2/3 activator in this process. In this issue of Developmental Cell, Zhu et al. (2016) demonstrate that WASP, an Arp2/3 activator mostly involved in endocytosis, collaborates with WAVE to promote migration of neuroblasts in Caenorhabditis elegans.
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Affiliation(s)
- Nicolas Molinie
- Ecole Polytechnique, Université Paris-Saclay, CNRS UMR7654, 91120 Palaiseau, France
| | - Alexis Gautreau
- Ecole Polytechnique, Université Paris-Saclay, CNRS UMR7654, 91120 Palaiseau, France.
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Zhu Z, Chai Y, Jiang Y, Li W, Hu H, Li W, Wu JW, Wang ZX, Huang S, Ou G. Functional Coordination of WAVE and WASP in C. elegans Neuroblast Migration. Dev Cell 2017; 39:224-238. [PMID: 27780040 DOI: 10.1016/j.devcel.2016.09.029] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/08/2016] [Accepted: 09/02/2016] [Indexed: 11/29/2022]
Abstract
Directional cell migration is critical for metazoan development. We define two molecular pathways that activate the Arp2/3 complex during neuroblast migration in Caenorhabditis elegans. The transmembrane protein MIG-13/Lrp12 is linked to the Arp2/3 nucleation-promoting factors WAVE or WASP through direct interactions with ABL-1 or SEM-5/Grb2, respectively. WAVE mutations partially impaired F-actin organization and decelerated cell migration, and WASP mutations did not inhibit cell migration but enhanced migration defects in WAVE-deficient cells. Purified SEM-5 and MIG-2 synergistically stimulated the F-actin branching activity of WASP-Arp2/3 in vitro. In GFP knockin animals, WAVE and WASP were largely organized into separate clusters at the leading edge, and the amount of WASP was less than WAVE but could be elevated by WAVE mutations. Our results indicate that the MIG-13-WAVE pathway provides the major force for directional cell motility, whereas MIG-13-WASP partially compensates for its loss, underscoring their coordinated activities in facilitating robust cell migration.
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Affiliation(s)
- Zhiwen Zhu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Yongping Chai
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Yuxiang Jiang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Wenjing Li
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Huifang Hu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Wei Li
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Jia-Wei Wu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Zhi-Xin Wang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China.
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Titus MA, Goodson HV. An evolutionary perspective on cell migration: Digging for the roots of amoeboid motility. J Cell Biol 2017; 216:1509-1511. [PMID: 28539388 PMCID: PMC5461037 DOI: 10.1083/jcb.201704112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Titus and Goodson preview work from the Mullins group analyzing the determinants of amoeboid motility with an evolutionary approach. Fritz-Laylin et al. (2017. J. Cell Biol.https://doi.org/10.1083/jcb.201701074) take advantage of the deep knowledge of mechanisms of actin-based motility and a growing number of sequenced genomes across the tree of life to gain insight into the machinery needed for pseudopod-based amoeboid motility and how it evolved.
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Affiliation(s)
- Margaret A Titus
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN
| | - Holly V Goodson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN
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Fritz-Laylin LK, Lord SJ, Mullins RD. WASP and SCAR are evolutionarily conserved in actin-filled pseudopod-based motility. J Cell Biol 2017; 216:1673-1688. [PMID: 28473602 PMCID: PMC5461030 DOI: 10.1083/jcb.201701074] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/12/2017] [Accepted: 03/31/2017] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic cells use diverse cellular mechanisms to crawl through complex environments. Fritz-Laylin et al. define α-motility as a mode of migration associated with dynamic, actin-filled pseudopods and show that WASP and SCAR constitute an evolutionarily conserved genetic signature of α-motility. Diverse eukaryotic cells crawl through complex environments using distinct modes of migration. To understand the underlying mechanisms and their evolutionary relationships, we must define each mode and identify its phenotypic and molecular markers. In this study, we focus on a widely dispersed migration mode characterized by dynamic actin-filled pseudopods that we call “α-motility.” Mining genomic data reveals a clear trend: only organisms with both WASP and SCAR/WAVE—activators of branched actin assembly—make actin-filled pseudopods. Although SCAR has been shown to drive pseudopod formation, WASP’s role in this process is controversial. We hypothesize that these genes collectively represent a genetic signature of α-motility because both are used for pseudopod formation. WASP depletion from human neutrophils confirms that both proteins are involved in explosive actin polymerization, pseudopod formation, and cell migration. WASP and WAVE also colocalize to dynamic signaling structures. Moreover, retention of WASP together with SCAR correctly predicts α-motility in disease-causing chytrid fungi, which we show crawl at >30 µm/min with actin-filled pseudopods. By focusing on one migration mode in many eukaryotes, we identify a genetic marker of pseudopod formation, the morphological feature of α-motility, providing evidence for a widely distributed mode of cell crawling with a single evolutionary origin.
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Affiliation(s)
- Lillian K Fritz-Laylin
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143
| | - Samuel J Lord
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143
| | - R Dyche Mullins
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143
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Veltman DM, Williams TD, Bloomfield G, Chen BC, Betzig E, Insall RH, Kay RR. A plasma membrane template for macropinocytic cups. eLife 2016; 5:e20085. [PMID: 27960076 PMCID: PMC5154761 DOI: 10.7554/elife.20085] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 11/14/2016] [Indexed: 12/18/2022] Open
Abstract
Macropinocytosis is a fundamental mechanism that allows cells to take up extracellular liquid into large vesicles. It critically depends on the formation of a ring of protrusive actin beneath the plasma membrane, which develops into the macropinocytic cup. We show that macropinocytic cups in Dictyostelium are organised around coincident intense patches of PIP3, active Ras and active Rac. These signalling patches are invariably associated with a ring of active SCAR/WAVE at their periphery, as are all examined structures based on PIP3 patches, including phagocytic cups and basal waves. Patch formation does not depend on the enclosing F-actin ring, and patches become enlarged when the RasGAP NF1 is mutated, showing that Ras plays an instructive role. New macropinocytic cups predominantly form by splitting from existing ones. We propose that cup-shaped plasma membrane structures form from self-organizing patches of active Ras/PIP3, which recruit a ring of actin nucleators to their periphery.
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Affiliation(s)
- Douwe M Veltman
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | | | | | - Bi-Chang Chen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Robert H Insall
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
| | - Robert R Kay
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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Skoge M, Wong E, Hamza B, Bae A, Martel J, Kataria R, Keizer-Gunnink I, Kortholt A, Van Haastert PJM, Charras G, Janetopoulos C, Irimia D. A Worldwide Competition to Compare the Speed and Chemotactic Accuracy of Neutrophil-Like Cells. PLoS One 2016; 11:e0154491. [PMID: 27332963 PMCID: PMC4917115 DOI: 10.1371/journal.pone.0154491] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 04/14/2016] [Indexed: 12/21/2022] Open
Abstract
Chemotaxis is the ability to migrate towards the source of chemical gradients. It underlies the ability of neutrophils and other immune cells to hone in on their targets and defend against invading pathogens. Given the importance of neutrophil migration to health and disease, it is crucial to understand the basic mechanisms controlling chemotaxis so that strategies can be developed to modulate cell migration in clinical settings. Because of the complexity of human genetics, Dictyostelium and HL60 cells have long served as models system for studying chemotaxis. Since many of our current insights into chemotaxis have been gained from these two model systems, we decided to compare them side by side in a set of winner-take-all races, the Dicty World Races. These worldwide competitions challenge researchers to genetically engineer and pharmacologically enhance the model systems to compete in microfluidic racecourses. These races bring together technological innovations in genetic engineering and precision measurement of cell motility. Fourteen teams participated in the inaugural Dicty World Race 2014 and contributed cell lines, which they tuned for enhanced speed and chemotactic accuracy. The race enabled large-scale analyses of chemotaxis in complex environments and revealed an intriguing balance of speed and accuracy of the model cell lines. The successes of the first race validated the concept of using fun-spirited competition to gain insights into the complex mechanisms controlling chemotaxis, while the challenges of the first race will guide further technological development and planning of future events.
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Affiliation(s)
- Monica Skoge
- Joseph Henry Laboratories of Physics and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Elisabeth Wong
- BioMEMS Resource Center, Massachusetts General Hospital, Shriners Burns Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Bashar Hamza
- BioMEMS Resource Center, Massachusetts General Hospital, Shriners Burns Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Albert Bae
- Max Planck Institute for Dynamics and Self Organization, Göttingen, Germany
| | - Joseph Martel
- BioMEMS Resource Center, Massachusetts General Hospital, Shriners Burns Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Biomedical Engineering, Wentworth Institute of Technology, Boston, Massachusetts, United States of America
| | - Rama Kataria
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | - Ineke Keizer-Gunnink
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | - Arjan Kortholt
- Department of Cell Biochemistry, University of Groningen, Groningen, Netherlands
| | | | - Guillaume Charras
- London Centre for Nanotechnology and Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | | | - Daniel Irimia
- BioMEMS Resource Center, Massachusetts General Hospital, Shriners Burns Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Diz-Muñoz A, Thurley K, Chintamen S, Altschuler SJ, Wu LF, Fletcher DA, Weiner OD. Membrane Tension Acts Through PLD2 and mTORC2 to Limit Actin Network Assembly During Neutrophil Migration. PLoS Biol 2016; 14:e1002474. [PMID: 27280401 PMCID: PMC4900667 DOI: 10.1371/journal.pbio.1002474] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/04/2016] [Indexed: 11/18/2022] Open
Abstract
For efficient polarity and migration, cells need to regulate the magnitude and spatial distribution of actin assembly. This process is coordinated by reciprocal interactions between the actin cytoskeleton and mechanical forces. Actin polymerization-based protrusion increases tension in the plasma membrane, which in turn acts as a long-range inhibitor of actin assembly. These interactions form a negative feedback circuit that limits the magnitude of membrane tension in neutrophils and prevents expansion of the existing front and the formation of secondary fronts. It has been suggested that the plasma membrane directly inhibits actin assembly by serving as a physical barrier that opposes protrusion. Here we show that efficient control of actin polymerization-based protrusion requires an additional mechanosensory feedback cascade that indirectly links membrane tension with actin assembly. Specifically, elevated membrane tension acts through phospholipase D2 (PLD2) and the mammalian target of rapamycin complex 2 (mTORC2) to limit actin nucleation. In the absence of this pathway, neutrophils exhibit larger leading edges, higher membrane tension, and profoundly defective chemotaxis. Mathematical modeling suggests roles for both the direct (mechanical) and indirect (biochemical via PLD2 and mTORC2) feedback loops in organizing cell polarity and motility—the indirect loop is better suited to enable competition between fronts, whereas the direct loop helps spatially organize actin nucleation for efficient leading edge formation and cell movement. This circuit is essential for polarity, motility, and the control of membrane tension. A mechanosensory biochemical cascade involving phospholipase D2 and mTORC2 coordinates physical forces and cytoskeletal rearrangements to allow efficient polarization and migration of neutrophils. How cells regulate the size and number of their protrusions for efficient polarity and motility is a fundamental question in cell biology. We recently found that immune cells known as neutrophils use physical forces to regulate this process. Actin polymerization-based protrusion stretches the plasma membrane, and this increased membrane tension acts as a long-range inhibitor of actin-based protrusions elsewhere in the cell. Here we investigate how membrane tension limits protrusion. We demonstrate that the magnitude of actin network assembly in neutrophils is determined by a mechanosensory biochemical cascade that converts increases in membrane tension into decreases in protrusion. Specifically, we show that increasing plasma membrane tension acts through a pathway containing the phospholipase D2 (PLD2) and the mammalian target of rapamycin complex 2 (mTORC2) to limit actin network assembly. Without this negative feedback pathway, neutrophils exhibit larger leading edges, higher membrane tension, and profoundly defective chemotaxis. Mathematical modeling indicates that this feedback circuit is a favorable topology to enable competition between protrusions during neutrophil polarization. Our work shows how biochemical signals, physical forces, and the cytoskeleton can collaborate to generate large-scale cellular organization.
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Affiliation(s)
- Alba Diz-Muñoz
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
- Bioengineering Department and Biophysics Program, University of California Berkeley, Berkeley, California, United States of America
| | - Kevin Thurley
- Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Sana Chintamen
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - Steven J. Altschuler
- Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Lani F. Wu
- Dept. of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Daniel A. Fletcher
- Bioengineering Department and Biophysics Program, University of California Berkeley, Berkeley, California, United States of America
- * E-mail: (DAF); (ODW)
| | - Orion D. Weiner
- Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
- * E-mail: (DAF); (ODW)
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Marinović M, Šoštar M, Filić V, Antolović V, Weber I. Quantitative imaging of Rac1 activity in Dictyostelium cells with a fluorescently labelled GTPase-binding domain from DPAKa kinase. Histochem Cell Biol 2016; 146:267-79. [DOI: 10.1007/s00418-016-1440-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2016] [Indexed: 02/06/2023]
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Miskolci V, Wu B, Moshfegh Y, Cox D, Hodgson L. Optical Tools To Study the Isoform-Specific Roles of Small GTPases in Immune Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:3479-93. [PMID: 26951800 PMCID: PMC4821714 DOI: 10.4049/jimmunol.1501655] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 02/17/2016] [Indexed: 12/20/2022]
Abstract
Despite the 92% homology of the hematopoietic cell-specific Rac2 to the canonical isoform Rac1, these isoforms have been shown to play nonredundant roles in immune cells. To study isoform-specific dynamics of Rac in live cells, we developed a genetically encoded, single-chain FRET-based biosensor for Rac2. We also made significant improvements to our existing single-chain Rac1 biosensor. We optimized the biosensor constructs for facile expression in hematopoietic cells and performed functional validations in murine macrophage sublines of RAW264.7 cells. Rac2, Rac1, and Cdc42 have been implicated in the formation of actin-rich protrusions by macrophages, but their individual activation dynamics have not been previously characterized. We found that both Rac1 and Rac2 had similar activation kinetics, yet they had distinct spatial distributions in response to the exogenous stimulus, fMLF. Active Rac1 was mainly localized to the cell periphery, whereas active Rac2 was distributed throughout the cell, with an apparent higher concentration in the perinuclear region. We also performed an extensive morphodynamic analysis of Rac1, Rac2, and Cdc42 activities during the extension of random protrusions. We found that Rac2 appears to play a leading role in the generation of random protrusions, as we observed an initial strong activation of Rac2 in regions distal from the leading edge, followed by the activation of Rac1, a second burst of Rac2 and then Cdc42 immediately behind the leading edge. Overall, isoform-specific biosensors that have been optimized for expression should be valuable for interrogating the coordination of Rho family GTPase activities in living cells.
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Affiliation(s)
- Veronika Miskolci
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Bin Wu
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Yasmin Moshfegh
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Dianne Cox
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Louis Hodgson
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461; Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461
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Senoo H, Cai H, Wang Y, Sesaki H, Iijima M. The novel RacE-binding protein GflB sharpens Ras activity at the leading edge of migrating cells. Mol Biol Cell 2016; 27:1596-605. [PMID: 27009206 PMCID: PMC4865317 DOI: 10.1091/mbc.e15-11-0796] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/18/2016] [Indexed: 12/25/2022] Open
Abstract
A novel protein, GflB, is found to control both Ras and Rho to optimize the reorganization of actin cytoskeletons for directed cell migration. GflB is subjected to feedback regulation from actin cytoskeletons, allowing cells to detect and control the size of actin-rich pseudopods and navigate their movements with extremely high precision. Directional sensing, a process in which cells convert an external chemical gradient into internal signaling events, is essential in chemotaxis. We previously showed that a Rho GTPase, RacE, regulates gradient sensing in Dictyostelium cells. Here, using affinity purification and mass spectrometry, we identify a novel RacE-binding protein, GflB, which contains a Ras GEF domain and a Rho GAP domain. Using biochemical and gene knockout approaches, we show that GflB balances the activation of Ras and Rho GTPases, which enables cells to precisely orient signaling events toward higher concentrations of chemoattractants. Furthermore, we find that GflB is located at the leading edge of migrating cells, and this localization is regulated by the actin cytoskeleton and phosphatidylserine. Our findings provide a new molecular mechanism that connects directional sensing and morphological polarization.
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Affiliation(s)
- Hiroshi Senoo
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Huaqing Cai
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu Wang
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Hiromi Sesaki
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Miho Iijima
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Gβ Regulates Coupling between Actin Oscillators for Cell Polarity and Directional Migration. PLoS Biol 2016; 14:e1002381. [PMID: 26890004 PMCID: PMC4758609 DOI: 10.1371/journal.pbio.1002381] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/15/2016] [Indexed: 02/03/2023] Open
Abstract
For directional movement, eukaryotic cells depend on the proper organization of their actin cytoskeleton. This engine of motility is made up of highly dynamic nonequilibrium actin structures such as flashes, oscillations, and traveling waves. In Dictyostelium, oscillatory actin foci interact with signals such as Ras and phosphatidylinositol 3,4,5-trisphosphate (PIP3) to form protrusions. However, how signaling cues tame actin dynamics to produce a pseudopod and guide cellular motility is a critical open question in eukaryotic chemotaxis. Here, we demonstrate that the strength of coupling between individual actin oscillators controls cell polarization and directional movement. We implement an inducible sequestration system to inactivate the heterotrimeric G protein subunit Gβ and find that this acute perturbation triggers persistent, high-amplitude cortical oscillations of F-actin. Actin oscillators that are normally weakly coupled to one another in wild-type cells become strongly synchronized following acute inactivation of Gβ. This global coupling impairs sensing of internal cues during spontaneous polarization and sensing of external cues during directional motility. A simple mathematical model of coupled actin oscillators reveals the importance of appropriate coupling strength for chemotaxis: moderate coupling can increase sensitivity to noisy inputs. Taken together, our data suggest that Gβ regulates the strength of coupling between actin oscillators for efficient polarity and directional migration. As these observations are only possible following acute inhibition of Gβ and are masked by slow compensation in genetic knockouts, our work also shows that acute loss-of-function approaches can complement and extend the reach of classical genetics in Dictyostelium and likely other systems as well. Coupling of individual oscillators regulates biological functions ranging from crickets chirping in unison to the coordination of pacemaker cells of the heart. This study finds that a similar concept—coupling between actin oscillators—is at work within single slime mold cells to establish polarity and guide their direction of migration. The actin cytoskeleton of motile cells is comprised of highly dynamic structures. Recently, small oscillating actin foci have been discovered around the periphery of Dictyostelium cells. These oscillators are thought to enable pseudopod formation, but how their dynamics are regulated for this is unknown. Here, we demonstrate that the strength of coupling between individual actin oscillators controls cell polarization and directional movement. Actin oscillators are weakly coupled to one another in wild-type cells, but they become strongly synchronized after acute inactivation of the signaling protein Gβ. This global coupling impairs sensing of internal cues during spontaneous polarization and sensing of external cues during directional motility. Supported by a mathematical model, our data suggest that wild-type cells are tuned to an optimal coupling strength for patterning by upstream cues. These observations are only possible following acute inhibition of Gβ, which highlights the value of revisiting classical mutants with acute loss-of-function perturbations.
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Rho Signaling in Dictyostelium discoideum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:61-181. [DOI: 10.1016/bs.ircmb.2015.10.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ridley AJ. Rho GTPase signalling in cell migration. Curr Opin Cell Biol 2015; 36:103-12. [PMID: 26363959 PMCID: PMC4728192 DOI: 10.1016/j.ceb.2015.08.005] [Citation(s) in RCA: 549] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/18/2015] [Accepted: 08/23/2015] [Indexed: 01/15/2023]
Abstract
Cells migrate in multiple different ways depending on their environment, which includes the extracellular matrix composition, interactions with other cells, and chemical stimuli. For all types of cell migration, Rho GTPases play a central role, although the relative contribution of each Rho GTPase depends on the environment and cell type. Here, I review recent advances in our understanding of how Rho GTPases contribute to different types of migration, comparing lamellipodium-driven versus bleb-driven migration modes. I also describe how cells migrate across the endothelium. In addition to Rho, Rac and Cdc42, which are well known to regulate migration, I discuss the roles of other less-well characterized members of the Rho family.
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Affiliation(s)
- Anne J Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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Nichols JME, Veltman D, Kay RR. Chemotaxis of a model organism: progress with Dictyostelium. Curr Opin Cell Biol 2015; 36:7-12. [DOI: 10.1016/j.ceb.2015.06.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 05/22/2015] [Accepted: 06/27/2015] [Indexed: 11/25/2022]
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Abstract
The cytoskeleton is utilized for a variety of cellular processes, including migration, endocytosis and adhesion. The required molecular components are often shared between different processes, but it is not well understood how the cells balance their use. We find that macropinocytosis and cell migration are negatively correlated. Heavy drinkers move only slowly and vice versa, fast cells do not take big gulps. Both processes are balanced by the lipid phosphatidylinositol 3,4,5-trisphosphate (PIP3). Elevated PIP3 signalling causes a shift towards macropinocytosis and inhibits motility by redirecting the SCAR/WAVE complex, a major nucleator of actin filaments. High resolution microscopy shows that patches with high levels of PIP3 recruit SCAR/WAVE on their periphery, resulting in circular ruffle formation and engulfment. Results shed new light on the role of PIP3, which is commonly thought to promote cell motility.
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Abstract
Cells migrate in multiple different ways depending on their environment, which includes the extracellular matrix composition, interactions with other cells, and chemical stimuli. For all types of cell migration, Rho GTPases play a central role, although the relative contribution of each Rho GTPase depends on the environment and cell type. Here, I review recent advances in our understanding of how Rho GTPases contribute to different types of migration, comparing lamellipodium-driven versus bleb-driven migration modes. I also describe how cells migrate across the endothelium. In addition to Rho, Rac and Cdc42, which are well known to regulate migration, I discuss the roles of other less-well characterized members of the Rho family.
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Affiliation(s)
- Anne J Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK.
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