1
|
Serre JM, Lucas B, Martin SCT, Heier JA, Shao X, Hardin J. C. elegans srGAP is an α-catenin M domain-binding protein that strengthens cadherin-dependent adhesion during morphogenesis. Development 2022; 149:dev200775. [PMID: 36125129 PMCID: PMC10655919 DOI: 10.1242/dev.200775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 08/23/2022] [Indexed: 11/20/2022]
Abstract
The cadherin-catenin complex (CCC) is central to embryonic development and tissue repair, yet how CCC binding partners function alongside core CCC components remains poorly understood. Here, we establish a previously unappreciated role for an evolutionarily conserved protein, the slit-robo GTPase-activating protein SRGP-1/srGAP, in cadherin-dependent morphogenetic processes in the Caenorhabditis elegans embryo. SRGP-1 binds to the M domain of the core CCC component, HMP-1/α-catenin, via its C terminus. The SRGP-1 C terminus is sufficient to target it to adherens junctions, but only during later embryonic morphogenesis, when junctional tension is known to increase. Surprisingly, mutations that disrupt stabilizing salt bridges in the M domain block this recruitment. Loss of SRGP-1 leads to an increase in mobility and decrease of junctional HMP-1. In sensitized genetic backgrounds with weakened adherens junctions, loss of SRGP-1 leads to late embryonic failure. Rescue of these phenotypes requires the C terminus of SRGP-1 but also other domains of the protein. Taken together, these data establish a role for an srGAP in stabilizing and organizing the CCC during epithelial morphogenesis by binding to a partially closed conformation of α-catenin at junctions.
Collapse
Affiliation(s)
- Joel M. Serre
- Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Bethany Lucas
- Department of Biology, Regis University, 3333 Regis Blvd., Denver, CO 80221, USA
| | - Sterling C. T. Martin
- Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jonathon A. Heier
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Xiangqiang Shao
- Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jeff Hardin
- Program in Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA
- Biophysics Graduate Program, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| |
Collapse
|
2
|
Lopez Rioja A, Faulkner A, Mellor H. srGAP2 deactivates RhoA to control the duration of thrombin-mediated endothelial permeability. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2022; 4:K1-K10. [PMID: 35441126 PMCID: PMC9012936 DOI: 10.1530/vb-21-0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 02/28/2022] [Indexed: 11/08/2022]
Abstract
The endothelial barrier is a tightly regulated gateway in the transport of material between circulation and the tissues. Inflammatory mediators such as thrombin are able to open paracellular spaces in the endothelial monolayer to allow the extravasation of plasma proteins and leukocytes. Here we show that the protein SLIT-ROBO Rho GTPase-activating protein 2 (srGAP2) plays a critical role in regulating the extent of thrombin-mediated opening. We show that srGAP2 is not required for normal barrier function in resting endothelial cells, but that depletion of srGAP2 significantly increases the magnitude and duration of junctional opening in response to thrombin. We show that srGAP2 acts to switch off RhoA signaling after the contraction phase of thrombin-induced permeability, allowing respreading of cells and reformation of the barrier. srGAP2 is also required for effective restoration of the barrier after treatment with two other vasoactive agents that active RhoA - TNFα and angiotensin II. Taken together, we show that srGAP2 has a general function in controlling RhoA signaling in endothelial permeability, acting to limit the degree and duration of opening, by triggering the switch from endothelial cell contraction to respreading.
Collapse
Affiliation(s)
- Alba Lopez Rioja
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
| | - Ashton Faulkner
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
| | - Harry Mellor
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
| |
Collapse
|
3
|
Fixing the GAP: the role of RhoGAPs in cancer. Eur J Cell Biol 2022; 101:151209. [DOI: 10.1016/j.ejcb.2022.151209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/29/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022] Open
|
4
|
Courtland JL, Bradshaw TWA, Waitt G, Soderblom EJ, Ho T, Rajab A, Vancini R, Kim IH, Soderling SH. Genetic disruption of WASHC4 drives endo-lysosomal dysfunction and cognitive-movement impairments in mice and humans. eLife 2021; 10:e61590. [PMID: 33749590 PMCID: PMC7984842 DOI: 10.7554/elife.61590] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 02/09/2021] [Indexed: 12/12/2022] Open
Abstract
Mutation of the Wiskott-Aldrich syndrome protein and SCAR homology (WASH) complex subunit, SWIP, is implicated in human intellectual disability, but the cellular etiology of this association is unknown. We identify the neuronal WASH complex proteome, revealing a network of endosomal proteins. To uncover how dysfunction of endosomal SWIP leads to disease, we generate a mouse model of the human WASHC4c.3056C>G mutation. Quantitative spatial proteomics analysis of SWIPP1019R mouse brain reveals that this mutation destabilizes the WASH complex and uncovers significant perturbations in both endosomal and lysosomal pathways. Cellular and histological analyses confirm that SWIPP1019R results in endo-lysosomal disruption and uncover indicators of neurodegeneration. We find that SWIPP1019R not only impacts cognition, but also causes significant progressive motor deficits in mice. A retrospective analysis of SWIPP1019R patients reveals similar movement deficits in humans. Combined, these findings support the model that WASH complex destabilization, resulting from SWIPP1019R, drives cognitive and motor impairments via endo-lysosomal dysfunction in the brain.
Collapse
Affiliation(s)
- Jamie L Courtland
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Tyler WA Bradshaw
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Greg Waitt
- Proteomics and Metabolomics Shared Resource, Duke University School of MedicineDurhamUnited States
| | - Erik J Soderblom
- Proteomics and Metabolomics Shared Resource, Duke University School of MedicineDurhamUnited States
- Department of Cell Biology, Duke University School of MedicineDurhamUnited States
| | - Tricia Ho
- Proteomics and Metabolomics Shared Resource, Duke University School of MedicineDurhamUnited States
| | - Anna Rajab
- Burjeel Hospital, VPS HealthcareMuscatOman
| | - Ricardo Vancini
- Department of Pathology, Duke University School of MedicineDurhamUnited States
| | - Il Hwan Kim
- Department of Cell Biology, Duke University School of MedicineDurhamUnited States
- Department of Anatomy and Neurobiology, University of Tennessee Heath Science CenterMemphisUnited States
| | - Scott H Soderling
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
- Department of Cell Biology, Duke University School of MedicineDurhamUnited States
| |
Collapse
|
5
|
Ho NTT, Rahane CS, Pramanik S, Kim PS, Kutzner A, Heese K. FAM72, Glioblastoma Multiforme (GBM) and Beyond. Cancers (Basel) 2021; 13:cancers13051025. [PMID: 33804473 PMCID: PMC7957592 DOI: 10.3390/cancers13051025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
Simple Summary Glioblastoma multiforme (GBM) is a serious and aggressive cancer disease that has not allowed scientists to rest for decades. In this review, we consider the new gene pair |-SRGAP2–FAM72-| and discuss its role in the cell cycle and the possibility of defining new therapeutic approaches for the treatment of GBM and other cancers via this gene pair |-SRGAP2–FAM72-|. Abstract Neural stem cells (NSCs) offer great potential for regenerative medicine due to their excellent ability to differentiate into various specialized cell types of the brain. In the central nervous system (CNS), NSC renewal and differentiation are under strict control by the regulation of the pivotal SLIT-ROBO Rho GTPase activating protein 2 (SRGAP2)—Family with sequence similarity 72 (FAM72) master gene (i.e., |-SRGAP2–FAM72-|) via a divergent gene transcription activation mechanism. If the gene transcription control unit (i.e., the intergenic region of the two sub-gene units, SRGAP2 and FAM72) gets out of control, NSCs may transform into cancer stem cells and generate brain tumor cells responsible for brain cancer such as glioblastoma multiforme (GBM). Here, we discuss the surveillance of this |-SRGAP2–FAM72-| master gene and its role in GBM, and also in light of FAM72 for diagnosing various types of cancers outside of the CNS.
Collapse
Affiliation(s)
- Nguyen Thi Thanh Ho
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Chinmay Satish Rahane
- Maharashtra Institute of Medical Education and Research, Talegaon Dabhade, Maharashtra 410507, India;
| | - Subrata Pramanik
- Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany;
| | - Pok-Son Kim
- Department of Mathematics, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea;
| | - Arne Kutzner
- Department of Information Systems, College of Computer Science, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791, Korea;
- Correspondence:
| |
Collapse
|
6
|
Bhosle VK, Mukherjee T, Huang YW, Patel S, Pang BWF, Liu GY, Glogauer M, Wu JY, Philpott DJ, Grinstein S, Robinson LA. SLIT2/ROBO1-signaling inhibits macropinocytosis by opposing cortical cytoskeletal remodeling. Nat Commun 2020; 11:4112. [PMID: 32807784 PMCID: PMC7431850 DOI: 10.1038/s41467-020-17651-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 07/08/2020] [Indexed: 01/06/2023] Open
Abstract
Macropinocytosis is essential for myeloid cells to survey their environment and for growth of RAS-transformed cancer cells. Several growth factors and inflammatory stimuli are known to induce macropinocytosis, but its endogenous inhibitors have remained elusive. Stimulation of Roundabout receptors by Slit ligands inhibits directional migration of many cell types, including immune cells and cancer cells. We report that SLIT2 inhibits macropinocytosis in vitro and in vivo by inducing cytoskeletal changes in macrophages. In mice, SLIT2 attenuates the uptake of muramyl dipeptide, thereby preventing NOD2-dependent activation of NF-κB and consequent secretion of pro-inflammatory chemokine, CXCL1. Conversely, blocking the action of endogenous SLIT2 enhances CXCL1 secretion. SLIT2 also inhibits macropinocytosis in RAS-transformed cancer cells, thereby decreasing their survival in nutrient-deficient conditions which resemble tumor microenvironment. Our results identify SLIT2 as a physiological inhibitor of macropinocytosis and challenge the conventional notion that signals that enhance macropinocytosis negatively regulate cell migration, and vice versa.
Collapse
Affiliation(s)
- Vikrant K Bhosle
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - Tapas Mukherjee
- Department of Immunology, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
| | - Yi-Wei Huang
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - Sajedabanu Patel
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - Bo Wen Frank Pang
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
- Institute of Medical Science, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
- BenchSci, Suite 201, 559 College Street, Toronto, ON, M6G 1A9, Canada
| | - Guang-Ying Liu
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
| | - Michael Glogauer
- Faculty of Dentistry, University of Toronto, 101 Elm Street, Toronto, ON, M5G 2L3, Canada
- Department of Dental Oncology and Maxillofacial Prosthetics, University Health Network, Princess Margaret Cancer Centre, 610 University Avenue, Toronto, ON, M5G 2C1, Canada
- Centre for Advanced Dental Research and Care, Mount Sinai Hospital, 600 University Avenue, Toronto, ON, M5G 1X5, Canada
| | - Jane Y Wu
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
- Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Dana J Philpott
- Department of Immunology, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
| | - Sergio Grinstein
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
- Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, 290 Victoria Street, Toronto, ON, M5C 1N8, Canada
| | - Lisa A Robinson
- Program in Cell Biology, The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON, M5G 0A4, Canada.
- Institute of Medical Science, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
- Division of Nephrology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
- Department of Paediatrics, Faculty of Medicine, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
| |
Collapse
|
7
|
Chen PW, Billington N, Maron BY, Sload JA, Chinthalapudi K, Heissler SM. The BAR domain of the Arf GTPase-activating protein ASAP1 directly binds actin filaments. J Biol Chem 2020; 295:11303-11315. [PMID: 32444496 DOI: 10.1074/jbc.ra119.009903] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 05/13/2020] [Indexed: 12/11/2022] Open
Abstract
The Arf GTPase-activating protein (Arf GAP) with SH3 domain, ankyrin repeat and PH domain 1 (ASAP1) establishes a connection between the cell membrane and the cortical actin cytoskeleton. The formation, maintenance, and turnover of actin filaments and bundles in the actin cortex are important for cell adhesion, invasion, and migration. Here, using actin cosedimentation, polymerization, and depolymerization assays, along with total internal reflection fluorescence (TIRF), confocal, and EM analyses, we show that the N-terminal N-BAR domain of ASAP1 directly binds to F-actin. We found that ASAP1 homodimerization aligns F-actin in predominantly unipolar bundles and stabilizes them against depolymerization. Furthermore, the ASAP1 N-BAR domain moderately reduced the spontaneous polymerization of G-actin. The overexpression of the ASAP1 BAR-PH tandem domain in fibroblasts induced the formation of actin-filled projections more effectively than did full-length ASAP1. An ASAP1 construct that lacked the N-BAR domain failed to induce cellular projections. Our results suggest that ASAP1 regulates the dynamics and the formation of higher-order actin structures, possibly through direct binding to F-actin via its N-BAR domain. We propose that ASAP1 is a hub protein for dynamic protein-protein interactions in mechanosensitive structures, such as focal adhesions, invadopodia, and podosomes, that are directly implicated in oncogenic events. The effect of ASAP1 on actin dynamics puts a spotlight on its function as a central signaling molecule that regulates the dynamics of the actin cytoskeleton by transmitting signals from the plasma membrane.
Collapse
Affiliation(s)
- Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, Massachusetts, USA
| | - Neil Billington
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA
| | - Ben Y Maron
- Department of Biology, Williams College, Williamstown, Massachusetts, USA
| | - Jeffrey A Sload
- Department of Biology, Williams College, Williamstown, Massachusetts, USA
| | - Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| | - Sarah M Heissler
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
| |
Collapse
|
8
|
Humphries BA, Wang Z, Yang C. MicroRNA Regulation of the Small Rho GTPase Regulators-Complexities and Opportunities in Targeting Cancer Metastasis. Cancers (Basel) 2020; 12:E1092. [PMID: 32353968 PMCID: PMC7281527 DOI: 10.3390/cancers12051092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 02/07/2023] Open
Abstract
The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.
Collapse
Affiliation(s)
- Brock A. Humphries
- Center for Molecular Imaging, Department of Radiology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Zhishan Wang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| | - Chengfeng Yang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| |
Collapse
|
9
|
Shin B, Kupferman J, Schmidt E, Polleux F, Delany AM, Lee SK. Rac1 Inhibition Via Srgap2 Restrains Inflammatory Osteoclastogenesis and Limits the Clastokine, SLIT3. J Bone Miner Res 2020; 35:789-800. [PMID: 31880824 PMCID: PMC7690287 DOI: 10.1002/jbmr.3945] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 12/04/2019] [Accepted: 12/07/2019] [Indexed: 01/26/2023]
Abstract
The Rac1-specific guanosine triphosphatase (GTPase)-activating protein Slit-Robo GAP2 (Srgap2) is dramatically upregulated during RANKL-induced osteoclastogenesis. Srgap2 interacts with the cell membrane to locally inhibit activity of Rac1. In this study, we determined the role of Srgap2 in the myeloid lineage on bone homeostasis and the osteoclastic response to TNFα treatment. The bone phenotype of mice specifically lacking Srgap2 in the myeloid lineage (Srgap2 f/f :LysM-Cre; Srgap2 conditional knockout [cKO]) was investigated using histomorphometric analysis, in vitro cultures and Western blot analysis. Similar methods were used to determine the impact of TNFα challenge on osteoclast formation in Srgap2 cKO mice. Bone parameters in male Srgap2 cKO mice were unaffected. However, female cKO mice displayed higher trabecular bone volume due to increased osteoblast surface and bone formation rate, whereas osteoclastic parameters were unaltered. In vitro, cells from Srgap2 cKO had strongly enhanced Rac1 activation, but RANKL-induced osteoclast formation was unaffected. In contrast, conditioned medium from Srgap2 cKO osteoclasts promoted osteoblast differentiation and had increased levels of the bone anabolic clastokine SLIT3, providing a possible mechanism for increased bone formation in vivo. Rac1 is rapidly activated by the inflammatory cytokine TNFα. Supracalvarial injection of TNFα caused an augmented osteoclastic response in Srgap2 cKO mice. In vitro, cells from Srgap2 cKO mice displayed increased osteoclast formation in response to TNFα. We conclude that Srgap2 plays a prominent role in limiting osteoclastogenesis during inflammation through Rac1, and restricts expression of the paracrine clastokine SLIT3, a positive regulator of bone formation. © 2019 American Society for Bone and Mineral Research.
Collapse
Affiliation(s)
- Bongjin Shin
- Center on Aging, UConn Health, Farmington, CT, USA
| | | | - Ewoud Schmidt
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Franck Polleux
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Anne M Delany
- Center for Molecular Oncology, UConn Health, Farmington, CT, USA
| | | |
Collapse
|
10
|
Garabedian MV, Stanishneva-Konovalova T, Lou C, Rands TJ, Pollard LW, Sokolova OS, Goode BL. Integrated control of formin-mediated actin assembly by a stationary inhibitor and a mobile activator. J Cell Biol 2018; 217:3512-3530. [PMID: 30076201 PMCID: PMC6168263 DOI: 10.1083/jcb.201803164] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/20/2018] [Accepted: 07/17/2018] [Indexed: 12/15/2022] Open
Abstract
This study shows that in vivo actin nucleation by the yeast formin Bnr1 is controlled through the coordinated effects of two distinct regulators, a stationary inhibitor (the F-BAR protein Hof1) and a mobile activator (Bud6), establishing a positive feedback loop for precise spatial and temporal control of actin assembly. Formins are essential actin assembly factors whose activities are controlled by a diverse array of binding partners. Until now, most formin ligands have been studied on an individual basis, leaving open the question of how multiple inputs are integrated to regulate formins in vivo. Here, we show that the F-BAR domain of Saccharomyces cerevisiae Hof1 interacts with the FH2 domain of the formin Bnr1 and blocks actin nucleation. Electron microscopy of the Hof1–Bnr1 complex reveals a novel dumbbell-shaped structure, with the tips of the F-BAR holding two FH2 dimers apart. Deletion of Hof1’s F-BAR domain in vivo results in disorganized actin cables and secretory defects. The formin-binding protein Bud6 strongly alleviates Hof1 inhibition in vitro, and bud6Δ suppresses hof1Δ defects in vivo. Whereas Hof1 stably resides at the bud neck, we show that Bud6 is delivered to the neck on secretory vesicles. We propose that Hof1 and Bud6 functions are intertwined as a stationary inhibitor and a mobile activator, respectively.
Collapse
Affiliation(s)
- Mikael V Garabedian
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA
| | | | - Chenyu Lou
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA
| | - Thomas J Rands
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA
| | - Luther W Pollard
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA
| | - Olga S Sokolova
- Bioengineering Department, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Bruce L Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA
| |
Collapse
|
11
|
SRGAP1, a crucial target of miR-340 and miR-124, functions as a potential oncogene in gastric tumorigenesis. Oncogene 2017; 37:1159-1174. [PMID: 29234151 PMCID: PMC5861093 DOI: 10.1038/s41388-017-0029-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 09/04/2017] [Accepted: 09/05/2017] [Indexed: 02/06/2023]
Abstract
Slit-Robo GTPase-activating protein 1 (SRGAP1) functions as a GAP for Rho-family GTPases and downstream of Slit-Robo signaling. We aim to investigate the biological function of SRGAP1 and reveal its regulation by deregulated microRNAs (miRNAs) in gastric cancer (GC). mRNA and protein expression of SRGAP1 were examined by quantitative reverse transcription PCR (qRT-PCR) and western blot. The biological role of SRGAP1 was demonstrated through siRNA-mediated knockdown experiments. The regulation of SRGAP1 by miR-340 and miR-124 was confirmed by western blot, dual luciferase activity assays and rescue experiments. SRGAP1 is overexpressed in 9 out of 12 (75.0%) GC cell lines. In primary GC samples from TCGA cohort, SRGAP1 shows gene amplification in 5/258 (1.9%) of cases and its mRNA expression demonstrates a positive correlation with copy number gain. Knockdown of SRGAP1 in GC cells suppressed cell proliferation, reduced colony formation, and significantly inhibited cell invasion and migration. Luciferase reporter assays revealed that SRGAP1 knockdown significantly inhibited Wnt/β-catenin pathway. In addition, SRGAP1 was found to be a direct target of two tumor-suppressive miRNAs, miR-340 and miR-124. Concordantly, these two miRNAs were downregulated in primary gastric tumors and these decreasing levels w5ere associated with poor outcomes. Expression of miR-340 and SRGAP1 displayed a reverse relationship in primary samples and re-expressed SRGAP1, rescued the anti-cancer effects of miR-340. Taken together, these data strongly suggest that, apart from gene amplification and mutation, the activation of SRGAP1 in GC is partly due to the downregulation of tumor-suppressive miRNAs, miR-340 and miR-124. Thus SRGAP1 is overexpressed in gastric carcinogenesis and plays an oncogenic role through activating Wnt/β-catenin pathway.
Collapse
|
12
|
López-Ortega O, Santos-Argumedo L. Myosin 1g Contributes to CD44 Adhesion Protein and Lipid Rafts Recycling and Controls CD44 Capping and Cell Migration in B Lymphocytes. Front Immunol 2017; 8:1731. [PMID: 29321775 PMCID: PMC5732150 DOI: 10.3389/fimmu.2017.01731] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/23/2017] [Indexed: 12/30/2022] Open
Abstract
Cell migration and adhesion are critical for immune system function and involve many proteins, which must be continuously transported and recycled in the cell. Recycling of adhesion molecules requires the participation of several proteins, including actin, tubulin, and GTPases, and of membrane components such as sphingolipids and cholesterol. However, roles of actin motor proteins in adhesion molecule recycling are poorly understood. In this study, we identified myosin 1g as one of the important motor proteins that drives recycling of the adhesion protein CD44 in B lymphocytes. We demonstrate that the lack of Myo1g decreases the cell-surface levels of CD44 and of the lipid raft surrogate GM1. In cells depleted of Myo1g, the recycling of CD44 was delayed, the delay seems to be caused at the level of formation of recycling complex and entry into recycling endosomes. Moreover, a defective lipid raft recycling in Myo1g-deficient cells had an impact both on the capping of CD44 and on cell migration. Both processes required the transportation of lipid rafts to the cell surface to deliver signaling components. Furthermore, the extramembrane was essential for cell expansion and remodeling of the plasma membrane topology. Therefore, Myo1g is important during the recycling of lipid rafts to the membrane and to the accompanied proteins that regulate plasma membrane plasticity. Thus, Myosin 1g contributes to cell adhesion and cell migration through CD44 recycling in B lymphocytes.
Collapse
Affiliation(s)
- Orestes López-Ortega
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México
| | - Leopoldo Santos-Argumedo
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, México
| |
Collapse
|
13
|
Abstract
The Slit-Robo GTPase-activating proteins (srGAPs) were first identified as potential Slit-Robo effectors that influence growth cone guidance. Given their N-terminal F-BAR, central GAP and C-terminal SH3 domains, srGAPs have the potential to affect membrane dynamics, Rho family GTPase activity and other binding partners. Recent research has clarified how srGAP family members act in distinct ways at the cell membrane, and has expanded our understanding of the roles of srGAPs in neuronal and non-neuronal cells. Gene duplication of the human-specific paralog of srGAP2 has resulted in srGAP2 family proteins that may have increased the density of dendritic spines and promoted neoteny of the human brain during crucial periods of human evolution, underscoring the importance of srGAPs in the unique sculpting of the human brain. Importantly, srGAPs also play roles outside of the nervous system, including during contact inhibition of cell movement and in establishing and maintaining cell adhesions in epithelia. Changes in srGAP expression may contribute to neurodevelopmental disorders, cancer metastasis and inflammation. As discussed in this Review, much remains to be discovered about how this interesting family of proteins functions in a diverse set of processes in metazoans and the functional roles srGAPs play in human disease.
Collapse
Affiliation(s)
- Bethany Lucas
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
| | - Jeff Hardin
- Program in Genetics, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
- Department of Integrative Biology, University of Wisconsin-Madison, 1117 W. Johnson St., Madison, WI 53706, USA
| |
Collapse
|
14
|
Luo W, Janoštiak R, Tolde O, Ryzhova LM, Koudelková L, Dibus M, Brábek J, Hanks SK, Rosel D. ARHGAP42 is activated by Src-mediated tyrosine phosphorylation to promote cell motility. J Cell Sci 2017; 130:2382-2393. [PMID: 28584191 PMCID: PMC5536916 DOI: 10.1242/jcs.197434] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 05/26/2017] [Indexed: 01/08/2023] Open
Abstract
The tyrosine kinase Src acts as a key regulator of cell motility by phosphorylating multiple protein substrates that control cytoskeletal and adhesion dynamics. In an earlier phosphotyrosine proteomics study, we identified a novel Rho-GTPase activating protein, now known as ARHGAP42, as a likely biologically relevant Src substrate. ARHGAP42 is a member of a family of RhoGAPs distinguished by tandem BAR-PH domains lying N-terminal to the GAP domain. Like other family members, ARHGAP42 acts preferentially as a GAP for RhoA. We show that Src principally phosphorylates ARHGAP42 on tyrosine 376 (Tyr-376) in the short linker between the BAR-PH and GAP domains. The expression of ARHGAP42 variants in mammalian cells was used to elucidate its regulation. We found that the BAR domain is inhibitory toward the GAP activity of ARHGAP42, such that BAR domain deletion resulted in decreased active GTP-bound RhoA and increased cell motility. With the BAR domain intact, ARHGAP42 GAP activity could be activated by phosphorylation of Tyr-376 to promote motile cell behavior. Thus, phosphorylation of ARHGAP42 Tyr-376 is revealed as a novel regulatory event by which Src can affect actin dynamics through RhoA inhibition.
Collapse
Affiliation(s)
- Weifeng Luo
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
| | - Radoslav Janoštiak
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
| | - Ondřej Tolde
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
- Department of Cell Biology, Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (BIOCEV), Průmyslová 595, Vestec u Prahy 25242, Czech Republic
| | - Larisa M Ryzhova
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Lenka Koudelková
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
- Department of Cell Biology, Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (BIOCEV), Průmyslová 595, Vestec u Prahy 25242, Czech Republic
| | - Michal Dibus
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
- Department of Cell Biology, Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (BIOCEV), Průmyslová 595, Vestec u Prahy 25242, Czech Republic
| | - Jan Brábek
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
- Department of Cell Biology, Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (BIOCEV), Průmyslová 595, Vestec u Prahy 25242, Czech Republic
| | - Steven K Hanks
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Daniel Rosel
- Department of Cell Biology, Charles University in Prague, Viničná 7, Prague, 12843, Czech Republic
- Department of Cell Biology, Biotechnology and Biomedicine Centre of the Academy of Sciences and Charles University (BIOCEV), Průmyslová 595, Vestec u Prahy 25242, Czech Republic
| |
Collapse
|
15
|
Graziano BR, Gong D, Anderson KE, Pipathsouk A, Goldberg AR, Weiner OD. A module for Rac temporal signal integration revealed with optogenetics. J Cell Biol 2017; 216:2515-2531. [PMID: 28687663 PMCID: PMC5551696 DOI: 10.1083/jcb.201604113] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 11/23/2016] [Accepted: 05/18/2017] [Indexed: 01/07/2023] Open
Abstract
Dissecting the logic of individual signaling modules in complex networks can be challenging for cascades that exhibit feedback and redundancy. In this study, Graziano et al. take an optogenetics-based approach to identify and dissect a module that converts sustained PIP3 production to transient Rac activation in the neutrophil chemotaxis signaling network. Sensory systems use adaptation to measure changes in signaling inputs rather than absolute levels of signaling inputs. Adaptation enables eukaryotic cells to directionally migrate over a large dynamic range of chemoattractant. Because of complex feedback interactions and redundancy, it has been difficult to define the portion or portions of eukaryotic chemotactic signaling networks that generate adaptation and identify the regulators of this process. In this study, we use a combination of optogenetic intracellular inputs, CRISPR-based knockouts, and pharmacological perturbations to probe the basis of neutrophil adaptation. We find that persistent, optogenetically driven phosphatidylinositol (3,4,5)-trisphosphate (PIP3) production results in only transient activation of Rac, a hallmark feature of adaptive circuits. We further identify the guanine nucleotide exchange factor P-Rex1 as the primary PIP3-stimulated Rac activator, whereas actin polymerization and the GTPase-activating protein ArhGAP15 are essential for proper Rac turnoff. This circuit is masked by feedback and redundancy when chemoattractant is used as the input, highlighting the value of probing signaling networks at intermediate nodes to deconvolve complex signaling cascades.
Collapse
Affiliation(s)
- Brian R Graziano
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - Delquin Gong
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | | | - 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
| | - Anna R Goldberg
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA
| | - 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
| |
Collapse
|
16
|
Marko TA, Shamsan GA, Edwards EN, Hazelton PE, Rathe SK, Cornax I, Overn PR, Varshney J, Diessner BJ, Moriarity BS, O'Sullivan MG, Odde DJ, Largaespada DA. Slit-Robo GTPase-Activating Protein 2 as a metastasis suppressor in osteosarcoma. Sci Rep 2016; 6:39059. [PMID: 27966608 PMCID: PMC5155223 DOI: 10.1038/srep39059] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/16/2016] [Indexed: 11/15/2022] Open
Abstract
Osteosarcoma is the most common primary bone tumor, with metastatic disease responsible for most treatment failure and patient death. A forward genetic screen utilizing Sleeping Beauty mutagenesis in mice previously identified potential genetic drivers of osteosarcoma metastasis, including Slit-Robo GTPase-Activating Protein 2 (Srgap2). This study evaluates the potential role of SRGAP2 in metastases-associated properties of osteosarcoma cell lines through Srgap2 knockout via the CRISPR/Cas9 nuclease system and conditional overexpression in the murine osteosarcoma cell lines K12 and K7M2. Proliferation, migration, and anchorage independent growth were evaluated. RNA sequencing and immunohistochemistry of human osteosarcoma tissue samples were used to further evaluate the potential role of the Slit-Robo pathway in osteosarcoma. The effects of Srgap2 expression modulation in the murine OS cell lines support the hypothesis that SRGAP2 may have a role as a suppressor of metastases in osteosarcoma. Additionally, SRGAP2 and other genes in the Slit-Robo pathway have altered transcript levels in a subset of mouse and human osteosarcoma, and SRGAP2 protein expression is reduced or absent in a subset of primary tumor samples. SRGAP2 and other axon guidance proteins likely play a role in osteosarcoma metastasis, with loss of SRGAP2 potentially contributing to a more aggressive phenotype.
Collapse
Affiliation(s)
- Tracy A Marko
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA
| | - Ghaidan A Shamsan
- Department of Biomedical Engineering University of Minnesota, Minneapolis, MN, USA
| | | | - Paige E Hazelton
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA
| | - Susan K Rathe
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA
| | - Ingrid Cornax
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA.,Comparative Pathology Shared Resource, University of Minnesota, Minneapolis, MN, USA
| | - Paula R Overn
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA.,Comparative Pathology Shared Resource, University of Minnesota, Minneapolis, MN, USA
| | - Jyotika Varshney
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA
| | | | - Branden S Moriarity
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA.,Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA
| | - M Gerard O'Sullivan
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA.,Comparative Pathology Shared Resource, University of Minnesota, Minneapolis, MN, USA.,College of Veterinary Medicine, Department of Veterinary Population Medicine, University of Minnesota, Minneapolis, MN, USA
| | - David J Odde
- Department of Biomedical Engineering University of Minnesota, Minneapolis, MN, USA
| | - David A Largaespada
- University of Minnesota, Masonic Cancer Center Minneapolis, MN, USA.,Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA
| |
Collapse
|
17
|
Dupré L, Houmadi R, Tang C, Rey-Barroso J. T Lymphocyte Migration: An Action Movie Starring the Actin and Associated Actors. Front Immunol 2015; 6:586. [PMID: 26635800 PMCID: PMC4649030 DOI: 10.3389/fimmu.2015.00586] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/02/2015] [Indexed: 12/14/2022] Open
Abstract
The actin cytoskeleton is composed of a dynamic filament meshwork that builds the architecture of the cell to sustain its fundamental properties. This physical structure is characterized by a continuous remodeling, which allows cells to accomplish complex motility steps such as directed migration, crossing of biological barriers, and interaction with other cells. T lymphocytes excel in these motility steps to ensure their immune surveillance duties. In particular, actin cytoskeleton remodeling is a key to facilitate the journey of T lymphocytes through distinct tissue environments and to tune their stop and go behavior during the scanning of antigen-presenting cells. The molecular mechanisms controlling actin cytoskeleton remodeling during T lymphocyte motility have been only partially unraveled, since the function of many actin regulators has not yet been assessed in these cells. Our review aims to integrate the current knowledge into a comprehensive picture of how the actin cytoskeleton drives T lymphocyte migration. We will present the molecular actors that control actin cytoskeleton remodeling, as well as their role in the different T lymphocyte motile steps. We will also highlight which challenges remain to be addressed experimentally and which approaches appear promising to tackle them.
Collapse
Affiliation(s)
- Loïc Dupré
- INSERM, UMR 1043, Centre de Physiopathologie de Toulouse Purpan , Toulouse , France ; Université Toulouse III Paul-Sabatier , Toulouse , France ; CNRS, UMR 5282 , Toulouse , France
| | - Raïssa Houmadi
- INSERM, UMR 1043, Centre de Physiopathologie de Toulouse Purpan , Toulouse , France ; Université Toulouse III Paul-Sabatier , Toulouse , France ; CNRS, UMR 5282 , Toulouse , France
| | - Catherine Tang
- INSERM, UMR 1043, Centre de Physiopathologie de Toulouse Purpan , Toulouse , France ; Université Toulouse III Paul-Sabatier , Toulouse , France ; CNRS, UMR 5282 , Toulouse , France ; Master BIOTIN, Université Montpellier I , Montpellier , France
| | - Javier Rey-Barroso
- INSERM, UMR 1043, Centre de Physiopathologie de Toulouse Purpan , Toulouse , France ; Université Toulouse III Paul-Sabatier , Toulouse , France ; CNRS, UMR 5282 , Toulouse , France
| |
Collapse
|
18
|
The Neuronal Migration Factor srGAP2 Achieves Specificity in Ligand Binding through a Two-Component Molecular Mechanism. Structure 2015; 23:1989-2000. [DOI: 10.1016/j.str.2015.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 08/16/2015] [Accepted: 08/17/2015] [Indexed: 01/26/2023]
|
19
|
Bezanilla M, Gladfelter AS, Kovar DR, Lee WL. Cytoskeletal dynamics: a view from the membrane. ACTA ACUST UNITED AC 2015; 209:329-37. [PMID: 25963816 PMCID: PMC4427793 DOI: 10.1083/jcb.201502062] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Many aspects of cytoskeletal assembly and dynamics can be recapitulated in vitro; yet, how the cytoskeleton integrates signals in vivo across cellular membranes is far less understood. Recent work has demonstrated that the membrane alone, or through membrane-associated proteins, can effect dynamic changes to the cytoskeleton, thereby impacting cell physiology. Having identified mechanistic links between membranes and the actin, microtubule, and septin cytoskeletons, these studies highlight the membrane’s central role in coordinating these cytoskeletal systems to carry out essential processes, such as endocytosis, spindle positioning, and cellular compartmentalization.
Collapse
Affiliation(s)
- Magdalena Bezanilla
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637 Department of Molecular Genetics and Cell Biology and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Wei-Lih Lee
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003
| |
Collapse
|
20
|
The structure of FMNL2-Cdc42 yields insights into the mechanism of lamellipodia and filopodia formation. Nat Commun 2015; 6:7088. [PMID: 25963737 PMCID: PMC4432619 DOI: 10.1038/ncomms8088] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/31/2015] [Indexed: 11/08/2022] Open
Abstract
Formins are actin polymerization factors that elongate unbranched actin filaments at the barbed end. Rho family GTPases activate Diaphanous-related formins through the relief of an autoregulatory interaction. The crystal structures of the N-terminal domains of human FMNL1 and FMNL2 in complex with active Cdc42 show that Cdc42 mediates contacts with all five armadillo repeats of the formin with specific interactions formed by the Rho-GTPase insert helix. Mutation of three residues within Rac1 results in a gain-of-function mutation for FMNL2 binding and reconstitution of the Cdc42 phenotype in vivo. Dimerization of FMNL1 through a parallel coiled coil segment leads to formation of an umbrella-shaped structure that—together with Cdc42—spans more than 15 nm in diameter. The two interacting FMNL–Cdc42 heterodimers expose six membrane interaction motifs on a convex protein surface, the assembly of which may facilitate actin filament elongation at the leading edge of lamellipodia and filopodia. FMNL formins polymerize actin filaments to generate cellular protrusions such as lamellipodia and filopodia at the leading edge of a cell. Here the authors provide detailed mechanistic insights into the formation of actin-based protrusions through GTPase dependent activation and membrane localization of FMNL1 and FMNL2.
Collapse
|
21
|
Ebrahimi S, Okabe S. Structural dynamics of dendritic spines: Molecular composition, geometry and functional regulation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2391-8. [DOI: 10.1016/j.bbamem.2014.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 05/18/2014] [Accepted: 06/02/2014] [Indexed: 12/16/2022]
|
22
|
Evaluation of genome-wide expression profiles of blood and sputum neutrophils in cystic fibrosis patients before and after antibiotic therapy. PLoS One 2014; 9:e104080. [PMID: 25084273 PMCID: PMC4118979 DOI: 10.1371/journal.pone.0104080] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 07/06/2014] [Indexed: 02/05/2023] Open
Abstract
In seeking more specific biomarkers of the cystic fibrosis (CF) lung inflammatory disease that would be sensitive to antibiotic therapy, we sought to evaluate the gene expression profiles of neutrophils in CF patients before treatment in comparison with non-CF healthy individuals and after antibiotic treatment. Genes involved in neutrophil-mediated inflammation, i.e. chemotaxis, respiratory burst, apoptosis, and granule exocytosis, were the targets of this study. Microarray analysis was carried out in blood and airway neutrophils from CF patients and in control subjects. A fold change (log) threshold of 1.4 and a cut-off of p<0.05 were utilized to identify significant genes. Community networks and principal component analysis were used to distinguish the groups of controls, pre- and post-therapy patients. Control subjects and CF patients before therapy were readily separated, whereas a clear distinction between patients before and after antibiotic therapy was not possible. Blood neutrophils before therapy presented 269 genes down-regulated and 56 up-regulated as compared with control subjects. Comparison between the same patients before and after therapy showed instead 44 genes down-regulated and 72 up-regulated. Three genes appeared to be sensitive to therapy and returned to "healthy" condition: phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), hydrogen voltage-gated channel 1 (HVCN1), and β-arrestin 1 (ARRB1). The up-regulation of these genes after therapy were confirmed by real time PCR. In airway neutrophils, 1029 genes were differentially expressed post- vs pre-therapy. Of these, 30 genes were up-regulated and 75 down-regulated following antibiotic treatment. However, biological plausibility determined that only down-regulated genes belonged to the gene classes studied for blood neutrophils. Finally, it was observed that commonly expressed genes showed a greater variability in airway neutrophils than that found in blood neutrophils, both before and after therapy. These results indicate more specific targets for future interventions in CF patients involving respiratory burst, apoptosis, and granule exocytosis.
Collapse
|
23
|
Abstract
Formin proteins were recognized as effectors of Rho GTPases some 15 years ago. They contribute to different cellular actin cytoskeleton structures by their ability to polymerize straight actin filaments at the barbed end. While not all formins necessarily interact with Rho GTPases, a subgroup of mammalian formins, termed Diaphanous-related formins or DRFs, were shown to be activated by small GTPases of the Rho superfamily. DRFs are autoinhibited in the resting state by an N- to C-terminal interaction that renders the central actin polymerization domain inactive. Upon the interaction with a GTP-bound Rho, Rac, or Cdc42 GTPase, the C-terminal autoregulation domain is displaced from its N-terminal recognition site and the formin becomes active to polymerize actin filaments. In this review we discuss the current knowledge on the structure, activation, and function of formin-GTPase interactions for the mammalian formin families Dia, Daam, FMNL, and FHOD. We describe both direct and indirect interactions of formins with GTPases, which lead to formin activation and cytoskeletal rearrangements. The multifaceted function of formins as effector proteins of Rho GTPases thus reflects the diversity of the actin cytoskeleton in cells.
Collapse
Affiliation(s)
- Sonja Kühn
- Center of Advanced European Studies and Research (caesar); Group Physical Biochemistry; Bonn, Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research (caesar); Group Physical Biochemistry; Bonn, Germany
| |
Collapse
|
24
|
Graziano BR, Yu HYE, Alioto SL, Eskin JA, Ydenberg CA, Waterman DP, Garabedian M, Goode BL. The F-BAR protein Hof1 tunes formin activity to sculpt actin cables during polarized growth. Mol Biol Cell 2014; 25:1730-43. [PMID: 24719456 PMCID: PMC4038500 DOI: 10.1091/mbc.e14-03-0850] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 11/23/2022] Open
Abstract
Asymmetric cell growth and division rely on polarized actin cytoskeleton remodeling events, the regulation of which is poorly understood. In budding yeast, formins stimulate the assembly of an organized network of actin cables that direct polarized secretion. Here we show that the Fer/Cip4 homology-Bin amphiphysin Rvs protein Hof1, which has known roles in cytokinesis, also functions during polarized growth by directly controlling the activities of the formin Bnr1. A mutant lacking the C-terminal half of Hof1 displays misoriented and architecturally altered cables, along with impaired secretory vesicle traffic. In vitro, Hof1 inhibits the actin nucleation and elongation activities of Bnr1 without displacing the formin from filament ends. These effects depend on the Src homology 3 domain of Hof1, the formin homology 1 (FH1) domain of Bnr1, and Hof1 dimerization, suggesting a mechanism by which Hof1 "restrains" the otherwise flexible FH1-FH2 apparatus. In vivo, loss of inhibition does not alter actin levels in cables but, instead, cable shape and functionality. Thus Hof1 tunes formins to sculpt the actin cable network.
Collapse
Affiliation(s)
- Brian R Graziano
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Hoi-Ying E Yu
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Salvatore L Alioto
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Julian A Eskin
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Casey A Ydenberg
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - David P Waterman
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Mikael Garabedian
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| | - Bruce L Goode
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454
| |
Collapse
|
25
|
Fu Y, Duan X, Tang C, Li X, Voegele RT, Wang X, Wei G, Kang Z. TaADF7, an actin-depolymerizing factor, contributes to wheat resistance against Puccinia striiformis f. sp. tritici. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:16-30. [PMID: 24635700 DOI: 10.1111/tpj.12457] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 12/10/2013] [Accepted: 01/09/2014] [Indexed: 05/21/2023]
Abstract
The actin cytoskeleton is involved in plant defense responses; however, the role of the actin-depolymerizing factor (ADF) family, which regulates actin cytoskeletal dynamics, in plant disease resistance, is largely unknown. Here, we characterized a wheat (Triticum aestivum) ADF gene, TaADF7, with three copies located on chromosomes 1A, 1B, and 1D, respectively. All three copies encoded the same protein, although there were variations in 19 nucleotide positions in the open reading frame. Transcriptional expression of the three TaADF7 copies were all sharply elevated in response to avirulent Puccinia striiformis f. sp. tritici (Pst) infection, with similar expression patterns. TaADF7 regulated the actin cytoskeletal dynamics by targeting the actin cytoskeleton to execute actin binding/severing activities. When the TaADF7 copies were all silenced by virus-induced gene silencing, the growth of Pst hypha increased and sporadic urediniospores were observed, as compared with control plants, upon inoculation with avirulent Pst. In addition, the accumulation of reactive oxygen species (ROS) and the hypersensitive response (HR) were greatly weakened, whereas cytochalasin B partially rescued the HR in TaADF7 knock-down plants. Together, these findings suggest that TaADF7 is likely to contribute to wheat resistance against Pst infection by modulating the actin cytoskeletal dynamics to influence ROS accumulation and the HR.
Collapse
Affiliation(s)
- Yanping Fu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Franceschetti T, Kessler CB, Lee SK, Delany AM. miR-29 promotes murine osteoclastogenesis by regulating osteoclast commitment and migration. J Biol Chem 2013; 288:33347-60. [PMID: 24085298 DOI: 10.1074/jbc.m113.484568] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Osteoclast differentiation is regulated by transcriptional, post-transcriptional, and post-translational mechanisms. MicroRNAs are fundamental post-transcriptional regulators of gene expression. The function of the miR-29 (a/b/c) family in cells of the osteoclast lineage is not well understood. In primary cultures of mouse bone marrow-derived macrophages, inhibition of miR-29a, -29b, or -29c diminished formation of TRAP (tartrate-resistant acid phosphatase-positive) multinucleated osteoclasts, and the osteoclasts were smaller. Quantitative RT-PCR showed that all miR-29 family members increased during osteoclast differentiation, in concert with mRNAs for the osteoclast markers Trap (Acp5) and cathepsin K. Similar regulation was observed in the monocytic cell line RAW264.7. In stably transduced RAW264.7 cell lines expressing an inducible miR-29 competitive inhibitor (sponge construct), miR-29 knockdown impaired osteoclastic commitment and migration of pre-osteoclasts. However, miR-29 knockdown did not affect cell viability, actin ring formation, or apoptosis in mature osteoclasts. To better understand how miR-29 regulates osteoclast function, we validated miR-29 target genes using Luciferase 3'-UTR reporter assays and specific miR-29 inhibitors. We demonstrated that miR-29 negatively regulates RNAs critical for cytoskeletal organization, including Cdc42 (cell division control protein 42) and Srgap2 (SLIT-ROBO Rho GTPase-activating protein 2). Moreover, miR-29 targets RNAs associated with the macrophage lineage: Gpr85 (G protein-coupled receptor 85), Nfia (nuclear factor I/A), and Cd93. In addition, Calcr (calcitonin receptor), which regulates osteoclast survival and resorption, is a novel miR-29 target. Thus, miR-29 is a positive regulator of osteoclast formation and targets RNAs important for cytoskeletal organization, commitment, and osteoclast function. We hypothesize that miR-29 controls the tempo and amplitude of osteoclast differentiation.
Collapse
|
27
|
Affiliation(s)
- Dennis Breitsprecher
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | | |
Collapse
|
28
|
Yamazaki D, Itoh T, Miki H, Takenawa T. srGAP1 regulates lamellipodial dynamics and cell migratory behavior by modulating Rac1 activity. Mol Biol Cell 2013; 24:3393-405. [PMID: 24006490 PMCID: PMC3814155 DOI: 10.1091/mbc.e13-04-0178] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
srGAP1 limits Rac1 activity at lamellipodia in a negative feedback manner, allowing concomitant activation of Rac1 and RhoA at lamellipodia. Rho signaling causes membrane ruffling through actomyosin contractility and removes the protrusive structures. Such coordination of Rac and Rho determines migratory behavior through lamellipodial dynamics. The distinct levels of Rac activity differentially regulate the pattern of intrinsic cell migration. However, it remains unknown how Rac activity is modulated and how the level of Rac activity controls cell migratory behavior. Here we show that Slit-Robo GAP 1 (srGAP1) is a modulator of Rac activity in locomotive cells. srGAP1 possesses a GAP activity specific to Rac1 and is recruited to lamellipodia in a Rac1-dependent manner. srGAP1 limits Rac1 activity and allows concomitant activation of Rac1 and RhoA, which are mutually inhibitory. When both GTPases are activated, the protrusive structures caused by Rac1-dependent actin reorganization are spatially restricted and periodically destabilized, causing ruffling by RhoA-induced actomyosin contractility. Depletion of srGAP1 overactivates Rac1 and inactivates RhoA, resulting in continuous spatiotemporal spreading of lamellipodia and a modal shift of intrinsic cell motility from random to directionally persistent. Thus srGAP1 is a key determinant of lamellipodial dynamics and cell migratory behavior.
Collapse
Affiliation(s)
- Daisuke Yamazaki
- Division of Membrane Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan Department of Cellular Regulation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan Laboratory of Lipid Biochemistry, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
| | | | | | | |
Collapse
|
29
|
Favaro P, Traina F, Machado-Neto JA, Lazarini M, Lopes MR, Pereira JKN, Costa FF, Infante E, Ridley AJ, Saad STO. FMNL1 promotes proliferation and migration of leukemia cells. J Leukoc Biol 2013; 94:503-12. [PMID: 23801653 DOI: 10.1189/jlb.0113057] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The human FMNL1 is expressed predominantly in hematopoietic cells and has been described previously as overexpressed in hematopoietic malignancies. However, it is not known whether FMNL1 contributes to leukemogenesis. Here, we investigate the FMNL1 function using two different human leukemia models: Namalwa and K562 cell lines. FMNL1 depletion reduced cell proliferation and colony formation in both leukemic cell types, as well as a decrease in the tumor growth of FMNL1-depleted Namalwa cell xenografts. In addition, there was a decrease in migration and in TEM in FMNL1-depleted Namalwa cells. FMNL1 endogenously associates with Rac1, and FMNL1 silencing resulted in an increased Rac1 activity. The reduced migration observed in FMNL1-depleted cells was restored by inhibiting Rac activity. Our results indicate that FMNL1 stimulates leukemia cell proliferation as well as migration. This suggests that FMNL1 contributes to leukemogenesis and could act in part through Rac1 regulation.
Collapse
Affiliation(s)
- Patricia Favaro
- Department of Biological Sciences, Federal University of São Paulo, Diadema, São Paulo, Brazil.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Ma Y, Mi YJ, Dai YK, Fu HL, Cui DX, Jin WL. The inverse F-BAR domain protein srGAP2 acts through srGAP3 to modulate neuronal differentiation and neurite outgrowth of mouse neuroblastoma cells. PLoS One 2013; 8:e57865. [PMID: 23505444 PMCID: PMC3591447 DOI: 10.1371/journal.pone.0057865] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/27/2013] [Indexed: 11/18/2022] Open
Abstract
The inverse F-BAR (IF-BAR) domain proteins srGAP1, srGAP2 and srGAP3 are implicated in neuronal development and may be linked to mental retardation, schizophrenia and seizure. A partially overlapping expression pattern and highly similar protein structures indicate a functional redundancy of srGAPs in neuronal development. Our previous study suggests that srGAP3 negatively regulates neuronal differentiation in a Rac1-dependent manner in mouse Neuro2a cells. Here we show that exogenously expressed srGAP1 and srGAP2 are sufficient to inhibit valporic acid (VPA)-induced neurite initiation and growth in the mouse Neuro2a cells. While ectopic- or over-expression of RhoGAP-defective mutants, srGAP1R542A and srGAP2R527A exert a visible inhibitory effect on neuronal differentiation. Unexpectedly, knockdown of endogenous srGAP2 fails to facilitate the neuronal differentiation induced by VPA, but promotes neurite outgrowth of differentiated cells. All three IF-BAR domains from srGAP1-3 can induce filopodia formation in Neuro2a, but the isolated IF-BAR domain from srGAP2, not from srGAP1 and srGAP3, can promote VPA-induced neurite initiation and neuronal differentiation. We identify biochemical and functional interactions of the three srGAPs family members. We propose that srGAP3-Rac1 signaling may be required for the effect of srGAP1 and srGAP2 on attenuating neuronal differentiation. Furthermore, inhibition of Slit-Robo interaction can phenocopy a loss-of-function of srGAP3, indicating that srGAP3 may be dedicated to the Slit-Robo pathway. Our results demonstrate the interplay between srGAP1, srGAP2 and srGAP3 regulates neuronal differentiation and neurite outgrowth. These findings may provide us new insights into the possible roles of srGAPs in neuronal development and a potential mechanism for neurodevelopmental diseases.
Collapse
Affiliation(s)
- Yue Ma
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Department of Bio-Nano-Science and Engineering, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Ya-Jing Mi
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Lab of Cell Biology & Translational Medicine, Xi'an Medical University, Xi'an, People's Republic of China
| | - Yun-Kai Dai
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Hua-Lin Fu
- Department of Bio-Nano-Science and Engineering, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Da-Xiang Cui
- Department of Bio-Nano-Science and Engineering, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Wei-Lin Jin
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- Department of Bio-Nano-Science and Engineering, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
- * E-mail:
| |
Collapse
|
31
|
The formins FMNL1 and mDia1 regulate coiling phagocytosis of Borrelia burgdorferi by primary human macrophages. Infect Immun 2013; 81:1683-95. [PMID: 23460512 DOI: 10.1128/iai.01411-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Spirochetes of the Borrelia burgdorferi sensu lato complex are the causative agent of Lyme borreliosis, a tick-borne infectious disease primarily affecting the skin, nervous system, and joints. During infection, macrophages and dendritic cells are the first immune cells to encounter invading borreliae. Phagocytosis and intracellular processing of Borrelia by these cells is thus decisive for the eventual outcome of infection. Phagocytic uptake of Borrelia by macrophages proceeds preferentially through coiling phagocytosis, which is characterized by actin-rich unilateral pseudopods that capture and enwrap spirochetes. Actin-dependent growth of these pseudopods necessitates de novo nucleation of actin filaments, which is regulated by actin-nucleating factors such as Arp2/3 complex. Here, we demonstrate that, in addition, also actin-regulatory proteins of the formin family are important for uptake of borreliae by primary human macrophages. Using immunofluorescence, live-cell imaging, and ratiometric analysis, we find specific enrichment of the formins FMNL1 and mDia1 at macrophage pseudopods that are in contact with borreliae. Consistently, small interfering RNA (siRNA)-mediated knockdown of FMNL1 or mDia1 leads to decreased formation of Borrelia-induced pseudopods and to decreased internalization of borreliae by macrophages. Our results suggest that macrophage coiling phagocytosis is a complex process involving several actin nucleation/regulatory factors. They also point specifically to the formins mDia1 and FMNL1 as novel regulators of spirochete uptake by human immune cells.
Collapse
|
32
|
Han Y, Yu G, Sarioglu H, Caballero-Martinez A, Schlott F, Ueffing M, Haase H, Peschel C, Krackhardt AM. Proteomic investigation of the interactome of FMNL1 in hematopoietic cells unveils a role in calcium-dependent membrane plasticity. J Proteomics 2012. [PMID: 23182705 DOI: 10.1016/j.jprot.2012.11.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Formin-like 1 (FMNL1) is a formin-related protein highly expressed in hematopoietic cells and overexpressed in leukemias as well as diverse transformed cell lines. It has been described to play a role in diverse functions of hematopoietic cells such as phagocytosis of macrophages as well as polarization and cytotoxicity of T cells. However, the specific role of FMNL1 in these processes has not been clarified yet and regulation by interaction partners in primary hematopoietic cells has never been investigated. We performed a proteomic screen for investigation of the interactome of FMNL1 in primary hematopoietic cells resulting in the identification of a number of interaction partners. Bioinformatic analysis considering semantic similarity suggested the giant protein AHNAK1 to be an essential interaction partner of FMNL1. We confirmed AHNAK1 as a general binding partner for FMNL1 in diverse hematopoietic cells and demonstrate that the N-terminal part of FMNL1 binds to the C-terminus of AHNAK1. Moreover, we show that the constitutively activated form of FMNL1 (FMNL1γ) induces localization of AHNAK1 to the cell membrane. Finally, we provide evidence that overexpression or knock down of FMNL1 has an impact on the capacitative calcium influx after ionomycin-mediated activation of diverse cell lines and primary cells.
Collapse
Affiliation(s)
- Yanan Han
- Medizinische Klinik III, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 Munich, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Modified SH2 domain to phototrap and identify phosphotyrosine proteins from subcellular sites within cells. Proc Natl Acad Sci U S A 2012; 109:E2929-38. [PMID: 23027962 DOI: 10.1073/pnas.1207358109] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Spatial regulation of tyrosine phosphorylation is important for many aspects of cell biology. However, phosphotyrosine accounts for less than 1% of all phosphorylated substrates, and it is typically a very transient event in vivo. These factors complicate the identification of key tyrosine kinase substrates, especially in the context of their extraordinary spatial organization. Here, we describe an approach to identify tyrosine kinase substrates based on their subcellular distribution from within cells. This method uses an unnatural amino acid-modified Src homology 2 (SH2) domain that is expressed within cells and can covalently trap phosphotyrosine proteins on exposure to light. This SH2 domain-based photoprobe was targeted to cellular structures, such as the actin cytoskeleton, mitochondria, and cellular membranes, to capture tyrosine kinase substrates unique to each cellular region. We demonstrate that RhoA, one of the proteins associated with actin, can be phosphorylated on two tyrosine residues within the switch regions, suggesting that phosphorylation of these residues might modulate RhoA signaling to the actin cytoskeleton. We conclude that expression of SH2 domains within cellular compartments that are capable of covalent phototrapping can reveal the spatial organization of tyrosine kinase substrates that are likely to be important for the regulation of subcellular structures.
Collapse
|
34
|
Okada H, Uezu A, Soderblom EJ, Moseley MA, Gertler FB, Soderling SH. Peptide array X-linking (PAX): a new peptide-protein identification approach. PLoS One 2012; 7:e37035. [PMID: 22606326 PMCID: PMC3351392 DOI: 10.1371/journal.pone.0037035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 04/12/2012] [Indexed: 12/19/2022] Open
Abstract
Many protein interaction domains bind short peptides based on canonical sequence consensus motifs. Here we report the development of a peptide array-based proteomics tool to identify proteins directly interacting with ligand peptides from cell lysates. Array-formatted bait peptides containing an amino acid-derived cross-linker are photo-induced to crosslink with interacting proteins from lysates of interest. Indirect associations are removed by high stringency washes under denaturing conditions. Covalently trapped proteins are subsequently identified by LC-MS/MS and screened by cluster analysis and domain scanning. We apply this methodology to peptides with different proline-containing consensus sequences and show successful identifications from brain lysates of known and novel proteins containing polyproline motif-binding domains such as EH, EVH1, SH3, WW domains. These results suggest the capacity of arrayed peptide ligands to capture and subsequently identify proteins by mass spectrometry is relatively broad and robust. Additionally, the approach is rapid and applicable to cell or tissue fractions from any source, making the approach a flexible tool for initial protein-protein interaction discovery.
Collapse
Affiliation(s)
- Hirokazu Okada
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
| | - Akiyoshi Uezu
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
| | - Erik J. Soderblom
- Institute for Genome Science & Policy Proteomics Core Facility, Duke University Medical School, Durham, North Carolina, United States of America
| | - M. Arthur Moseley
- Institute for Genome Science & Policy Proteomics Core Facility, Duke University Medical School, Durham, North Carolina, United States of America
| | - Frank B. Gertler
- Koch Institute for Integrative Cancer Research at MIT, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Scott H. Soderling
- Department of Cell Biology, Duke University Medical School, Durham, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
35
|
Rohn JL, Sims D, Liu T, Fedorova M, Schöck F, Dopie J, Vartiainen MK, Kiger AA, Perrimon N, Baum B. Comparative RNAi screening identifies a conserved core metazoan actinome by phenotype. ACTA ACUST UNITED AC 2012; 194:789-805. [PMID: 21893601 PMCID: PMC3171124 DOI: 10.1083/jcb.201103168] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RNAi screens in Drosophila and human cells for novel actin
regulators revealed conserved roles for proteins involved in nuclear actin
export, RNA splicing, and ubiquitination. Although a large number of actin-binding proteins and their regulators have been
identified through classical approaches, gaps in our knowledge remain. Here, we
used genome-wide RNA interference as a systematic method to define metazoan
actin regulators based on visual phenotype. Using comparative screens in
cultured Drosophila and human cells, we generated phenotypic
profiles for annotated actin regulators together with proteins bearing predicted
actin-binding domains. These phenotypic clusters for the known metazoan
“actinome” were used to identify putative new core actin
regulators, together with a number of genes with conserved but poorly studied
roles in the regulation of the actin cytoskeleton, several of which we studied
in detail. This work suggests that although our search for new components of the
core actin machinery is nearing saturation, regulation at the level of nuclear
actin export, RNA splicing, ubiquitination, and other upstream processes remains
an important but unexplored frontier of actin biology.
Collapse
Affiliation(s)
- Jennifer L Rohn
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Okada H, Uezu A, Mason FM, Soderblom EJ, Moseley MA, Soderling SH. SH3 domain-based phototrapping in living cells reveals Rho family GAP signaling complexes. Sci Signal 2011; 4:rs13. [PMID: 22126966 DOI: 10.1126/scisignal.2002189] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rho family GAPs [guanosine triphosphatase (GTPase) activating proteins] negatively regulate Rho family GTPase activity and therefore modulate signaling events that control cytoskeletal dynamics. The spatial distribution of these GAPs and their specificity toward individual GTPases are controlled by their interactions with various proteins within signaling complexes. These interactions are likely mediated through the Src homology 3 (SH3) domain, which is abundant in the Rho family GAP proteome and exhibits a micromolar binding affinity, enabling the Rho family GAPs to participate in transient interactions with multiple binding partners. To capture these elusive GAP signaling complexes in situ, we developed a domain-based proteomics approach, starting with in vivo phototrapping of SH3 domain-binding proteins and the mass spectrometry identification of associated proteins for nine representative Rho family GAPs. After the selection of candidate binding proteins by cluster analysis, we performed peptide array-based high-throughput in vitro binding assays to confirm the direct interactions and map the SH3 domain-binding sequences. We thereby identified 54 SH3-mediated binding interactions (including 51 previously unidentified ones) for nine Rho family GAPs. We constructed Rho family GAP interactomes that provided insight into the functions of these GAPs. We further characterized one of the predicted functions for the Rac-specific GAP WRP and identified a role for WRP in mediating clustering of the postsynaptic scaffolding protein gephyrin and the GABA(A) (γ-aminobutyric acid type A) receptor at inhibitory synapses.
Collapse
Affiliation(s)
- Hirokazu Okada
- Department of Cell Biology, Duke University Medical School, Durham, NC 27710, USA
| | | | | | | | | | | |
Collapse
|