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Aydin F, Katkar HH, Morganthaler A, Harker AJ, Kovar DR, Voth GA. Prediction of the essential intermolecular contacts for side-binding of VASP on F-actin. Cytoskeleton (Hoboken) 2024. [PMID: 38647032 DOI: 10.1002/cm.21864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/08/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) family proteins play a crucial role in mediating the actin network architecture in the cytoskeleton. The Ena/VASP homology 2 (EVH2) domain in each of the four identical arms of the tetrameric VASP consists of a loading poly-Pro region, a G-actin-binding domain (GAB), and an F-actin-binding domain (FAB). Together, the poly-Pro, GAB, and FAB domains allow VASP to bind to sides of actin filaments in a bundle, and recruit profilin-G-actin to processively elongate the filaments. The atomic resolution structure of the ternary complex, consisting of the loading poly-Pro region and GAB domain of VASP with profilin-actin, has been solved over a decade ago; however, a detailed structure of the FAB-F-actin complex has not been resolved to date. Experimental insights, based on homology of the FAB domain with the C region of WASP, have been used to hypothesize that the FAB domain binds to the cleft between subdomains 1 and 3 of F-actin. Here, in order to develop our understanding of the VASP-actin complex, we first augment known structural information about the GAB domain binding to actin with the missing FAB domain-actin structure, which we predict using homology modeling and docking simulations. In earlier work, we used mutagenesis and kinetic modeling to study the role of domain-level binding-unbinding kinetics of Ena/VASP on actin filaments in a bundle, specifically on the side of actin filaments. We further look at the nature of the side-binding of the FAB domain of VASP at the atomistic level using our predicted structure, and tabulate effective mutation sites on the FAB domain that would disrupt the VASP-actin complex. We test the binding affinity of Ena with mutated FAB domain using total internal reflection fluorescence microscopy experiments. The binding affinity of VASP is affected significantly for the mutant, providing additional support for our predicted structure.
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Affiliation(s)
- Fikret Aydin
- Department of Chemistry, The James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA
| | - Harshwardhan H Katkar
- Department of Chemistry, The James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA
| | - Alisha Morganthaler
- Department of Biochemistry and Molecular Biology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA
| | - Alyssa J Harker
- Department of Biochemistry and Molecular Biology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA
| | - David R Kovar
- Department of Biochemistry and Molecular Biology and Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA
| | - Gregory A Voth
- Department of Chemistry, The James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA
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2
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Gui J, Zhou H, Wan H, Yang D, Liu Q, Zhu L, Mi Y. The Role of Vasodilator-stimulated Phosphoproteins in the Development of Malignant Tumors. Curr Cancer Drug Targets 2024; 24:477-489. [PMID: 37962042 PMCID: PMC11092557 DOI: 10.2174/0115680096262439231023110106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/06/2023] [Accepted: 09/06/2023] [Indexed: 11/15/2023]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is an actin-binding protein that includes three structural domains: Enabled/VASP homolog1 (EVH1), EVH2, and proline-rich (PRR). VASP plays an important role in various cellular behaviors related to cytoskeletal regulation. More importantly, VASP plays a key role in the progression of several malignant tumors and is associated with malignant cell proliferation, invasion, and metastasis. Here, we have summarized current studies on the impact of VASP on the development of several malignant tumors and their mechanisms. This study provides a new theoretical basis for clinical molecular diagnosis and molecular targeted therapy.
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Affiliation(s)
- Jiandong Gui
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Hangsheng Zhou
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Hongyuan Wan
- Wuxi School of Medicine, Jiangnan University, 1800 Lihudadao, Wuxi, 214122, Jiangsu Province, China
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Dongjie Yang
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Qing Liu
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
- Huadong Sanatorium, 67 Dajishan, Wuxi 214122, Jiangsu Province, China
| | - Lijie Zhu
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
| | - Yuanyuan Mi
- Department of Urology, Affiliated Hospital of Jiangnan University, 1000 Hefeng Road, Wuxi, 214122, Jiangsu Province, China
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3
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Benz PM, Frömel T, Laban H, Zink J, Ulrich L, Groneberg D, Boon RA, Poley P, Renne T, de Wit C, Fleming I. Cardiovascular Functions of Ena/VASP Proteins: Past, Present and Beyond. Cells 2023; 12:1740. [PMID: 37443774 PMCID: PMC10340426 DOI: 10.3390/cells12131740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/18/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Actin binding proteins are of crucial importance for the spatiotemporal regulation of actin cytoskeletal dynamics, thereby mediating a tremendous range of cellular processes. Since their initial discovery more than 30 years ago, the enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family has evolved as one of the most fascinating and versatile family of actin regulating proteins. The proteins directly enhance actin filament assembly, but they also organize higher order actin networks and link kinase signaling pathways to actin filament assembly. Thereby, Ena/VASP proteins regulate dynamic cellular processes ranging from membrane protrusions and trafficking, and cell-cell and cell-matrix adhesions, to the generation of mechanical tension and contractile force. Important insights have been gained into the physiological functions of Ena/VASP proteins in platelets, leukocytes, endothelial cells, smooth muscle cells and cardiomyocytes. In this review, we summarize the unique and redundant functions of Ena/VASP proteins in cardiovascular cells and discuss the underlying molecular mechanisms.
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Affiliation(s)
- Peter M. Benz
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
- German Centre of Cardiovascular Research (DZHK), Partner Site Rhein-Main, 60596 Frankfurt am Main, Germany
| | - Timo Frömel
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
| | - Hebatullah Laban
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
| | - Joana Zink
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
| | - Lea Ulrich
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
| | - Dieter Groneberg
- Institute of Physiology I, University of Würzburg, 97070 Würzburg, Germany
| | - Reinier A. Boon
- German Centre of Cardiovascular Research (DZHK), Partner Site Rhein-Main, 60596 Frankfurt am Main, Germany
- Cardiopulmonary Institute, 60596 Frankfurt am Main, Germany
- Centre of Molecular Medicine, Institute of Cardiovascular Regeneration, Goethe-University, 60596 Frankfurt am Main, Germany
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Centre, 1081 HZ Amsterdam, The Netherlands
| | - Philip Poley
- Institut für Physiologie, Universität zu Lübeck, 23562 Lübeck, Germany
- German Centre of Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, 23562 Lübeck, Germany
| | - Thomas Renne
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- Center for Thrombosis and Hemostasis (CTH), Johannes Gutenberg University Medical Center, 55131 Mainz, Germany
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, D02 VN51 Dublin, Ireland
| | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, 23562 Lübeck, Germany
- German Centre of Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, 23562 Lübeck, Germany
| | - Ingrid Fleming
- Institute for Vascular Signalling, Centre for Molecular Medicine, Goethe University, 60596 Frankfurt am Main, Germany
- German Centre of Cardiovascular Research (DZHK), Partner Site Rhein-Main, 60596 Frankfurt am Main, Germany
- Cardiopulmonary Institute, 60596 Frankfurt am Main, Germany
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4
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Ecovoiu AA, Ratiu AC, Micheu MM, Chifiriuc MC. Inter-Species Rescue of Mutant Phenotype—The Standard for Genetic Analysis of Human Genetic Disorders in Drosophila melanogaster Model. Int J Mol Sci 2022; 23:ijms23052613. [PMID: 35269756 PMCID: PMC8909942 DOI: 10.3390/ijms23052613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 11/16/2022] Open
Abstract
Drosophila melanogaster (the fruit fly) is arguably a superstar of genetics, an astonishing versatile experimental model which fueled no less than six Nobel prizes in medicine. Nowadays, an evolving research endeavor is to simulate and investigate human genetic diseases in the powerful D. melanogaster platform. Such a translational experimental strategy is expected to allow scientists not only to understand the molecular mechanisms of the respective disorders but also to alleviate or even cure them. In this regard, functional gene orthology should be initially confirmed in vivo by transferring human or vertebrate orthologous transgenes in specific mutant backgrounds of D. melanogaster. If such a transgene rescues, at least partially, the mutant phenotype, then it qualifies as a strong candidate for modeling the respective genetic disorder in the fruit fly. Herein, we review various examples of inter-species rescue of relevant mutant phenotypes of the fruit fly and discuss how these results recommend several human genes as candidates to study and validate genetic variants associated with human diseases. We also consider that a wider implementation of this evolutionist exploratory approach as a standard for the medicine of genetic disorders would allow this particular field of human health to advance at a faster pace.
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Affiliation(s)
- Alexandru Al. Ecovoiu
- Department of Genetics, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania;
| | - Attila Cristian Ratiu
- Department of Genetics, Faculty of Biology, University of Bucharest, 060101 Bucharest, Romania;
- Correspondence: ; Tel.: +40-722250366
| | - Miruna Mihaela Micheu
- Department of Cardiology, Clinical Emergency Hospital of Bucharest, 014461 Bucharest, Romania;
| | - Mariana Carmen Chifiriuc
- The Research Institute of the University of Bucharest and Faculty of Biology, University of Bucharest, 050095 Bucharest, Romania;
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5
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Augustin V, Kins S. Fe65: A Scaffolding Protein of Actin Regulators. Cells 2021; 10:cells10071599. [PMID: 34202290 PMCID: PMC8304848 DOI: 10.3390/cells10071599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 01/19/2023] Open
Abstract
The scaffolding protein family Fe65, composed of Fe65, Fe65L1, and Fe65L2, was identified as an interaction partner of the amyloid precursor protein (APP), which plays a key function in Alzheimer’s disease. All three Fe65 family members possess three highly conserved interaction domains, forming complexes with diverse binding partners that can be assigned to different cellular functions, such as transactivation of genes in the nucleus, modulation of calcium homeostasis and lipid metabolism, and regulation of the actin cytoskeleton. In this article, we rule out putative new intracellular signaling mechanisms of the APP-interacting protein Fe65 in the regulation of actin cytoskeleton dynamics in the context of various neuronal functions, such as cell migration, neurite outgrowth, and synaptic plasticity.
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Yaniv SP, Meltzer H, Alyagor I, Schuldiner O. Developmental axon regrowth and primary neuron sprouting utilize distinct actin elongation factors. J Cell Biol 2021; 219:151569. [PMID: 32191286 PMCID: PMC7199854 DOI: 10.1083/jcb.201903181] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 11/06/2019] [Accepted: 02/14/2020] [Indexed: 01/23/2023] Open
Abstract
Intrinsic neurite growth potential is a key determinant of neuronal regeneration efficiency following injury. The stereotypical remodeling of Drosophila γ-neurons includes developmental regrowth of pruned axons to form adult specific connections, thereby offering a unique system to uncover growth potential regulators. Motivated by the dynamic expression in remodeling γ-neurons, we focus here on the role of actin elongation factors as potential regulators of developmental axon regrowth. We found that regrowth in vivo requires the actin elongation factors Ena and profilin, but not the formins that are expressed in γ-neurons. In contrast, primary γ-neuron sprouting in vitro requires profilin and the formin DAAM, but not Ena. Furthermore, we demonstrate that DAAM can compensate for the loss of Ena in vivo. Similarly, DAAM mutants express invariably high levels of Ena in vitro. Thus, we show that different linear actin elongation factors function in distinct contexts even within the same cell type and that they can partially compensate for each other.
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Affiliation(s)
- Shiri P Yaniv
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Hagar Meltzer
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Idan Alyagor
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
| | - Oren Schuldiner
- Department of Molecular Cell Biology, Weizmann Institute of Sciences, Rehovot, Israel
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7
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Zink J, Frye M, Frömel T, Carlantoni C, John D, Schreier D, Weigert A, Laban H, Salinas G, Stingl H, Günther L, Popp R, Hu J, Vanhollebeke B, Schmidt H, Acker-Palmer A, Renné T, Fleming I, Benz PM. EVL regulates VEGF receptor-2 internalization and signaling in developmental angiogenesis. EMBO Rep 2021; 22:e48961. [PMID: 33512764 PMCID: PMC7857432 DOI: 10.15252/embr.201948961] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 12/03/2020] [Accepted: 12/09/2020] [Indexed: 12/11/2022] Open
Abstract
Endothelial tip cells are essential for VEGF‐induced angiogenesis, but underlying mechanisms are elusive. The Ena/VASP protein family, consisting of EVL, VASP, and Mena, plays a pivotal role in axon guidance. Given that axonal growth cones and endothelial tip cells share many common features, from the morphological to the molecular level, we investigated the role of Ena/VASP proteins in angiogenesis. EVL and VASP, but not Mena, are expressed in endothelial cells of the postnatal mouse retina. Global deletion of EVL (but not VASP) compromises the radial sprouting of the vascular plexus in mice. Similarly, endothelial‐specific EVL deletion compromises the radial sprouting of the vascular plexus and reduces the endothelial tip cell density and filopodia formation. Gene sets involved in blood vessel development and angiogenesis are down‐regulated in EVL‐deficient P5‐retinal endothelial cells. Consistently, EVL deletion impairs VEGF‐induced endothelial cell proliferation and sprouting, and reduces the internalization and phosphorylation of VEGF receptor 2 and its downstream signaling via the MAPK/ERK pathway. Together, we show that endothelial EVL regulates sprouting angiogenesis via VEGF receptor‐2 internalization and signaling.
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Affiliation(s)
- Joana Zink
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Maike Frye
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Timo Frömel
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Claudia Carlantoni
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - David John
- German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany.,Insitute for Cardiovascular Regeneration, Goethe University, Frankfurt am Main, Germany
| | - Danny Schreier
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Weigert
- Institute of Biochemistry I-Pathobiochemistry, Faculty of Medicine, Goethe-University, Frankfurt am Main, Germany
| | - Hebatullah Laban
- Department of Cardiovascular Physiology, Institute of Physiology and Pathophysiology, Heidelberg University, Heidelberg, Germany
| | - Gabriela Salinas
- NGS-Integrative Genomics Core Unit (NIG), Institute of Human Genetics, University Medical Center Göttingen (UMG), Göttingen, Germany
| | - Heike Stingl
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Lea Günther
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Rüdiger Popp
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Jiong Hu
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Benoit Vanhollebeke
- Laboratory of Neurovascular Signaling, ULB Neuroscience Institute Department of Molecular Biology, University of Brussels, Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Brussels, Belgium
| | - Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Amparo Acker-Palmer
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt am Main, Germany
| | - Thomas Renné
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ingrid Fleming
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
| | - Peter M Benz
- Centre for Molecular Medicine, Institute for Vascular Signalling, Goethe University, Frankfurt am Main, Germany.,German Centre of Cardiovascular Research (DZHK), Partner site Rhein-Main, Frankfurt am Main, Germany
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McNeill EM, Thompson C, Berke B, Chou VT, Rusch J, Duckworth A, DeProto J, Taylor A, Gates J, Gertler F, Keshishian H, Van Vactor D. Drosophila enabled promotes synapse morphogenesis and regulates active zone form and function. Neural Dev 2020; 15:4. [PMID: 32183907 PMCID: PMC7076993 DOI: 10.1186/s13064-020-00141-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 02/25/2020] [Indexed: 11/10/2022] Open
Abstract
Background Recent studies of synapse form and function highlight the importance of the actin cytoskeleton in regulating multiple aspects of morphogenesis, neurotransmission, and neural plasticity. The conserved actin-associated protein Enabled (Ena) is known to regulate development of the Drosophila larval neuromuscular junction through a postsynaptic mechanism. However, the functions and regulation of Ena within the presynaptic terminal has not been determined. Methods Here, we use a conditional genetic approach to address a presynaptic role for Ena on presynaptic morphology and ultrastructure, and also examine the pathway in which Ena functions through epistasis experiments. Results We find that Ena is required to promote the morphogenesis of presynaptic boutons and branches, in contrast to its inhibitory role in muscle. Moreover, while postsynaptic Ena is regulated by microRNA-mediated mechanisms, presynaptic Ena relays the output of the highly conserved receptor protein tyrosine phosphatase Dlar and associated proteins including the heparan sulfate proteoglycan Syndecan, and the non-receptor Abelson tyrosine kinase to regulate addition of presynaptic varicosities. Interestingly, Ena also influences active zones, where it restricts active zone size, regulates the recruitment of synaptic vesicles, and controls the amplitude and frequency of spontaneous glutamate release. Conclusion We thus show that Ena, under control of the Dlar pathway, is required for presynaptic terminal morphogenesis and bouton addition and that Ena has active zone and neurotransmission phenotypes. Notably, in contrast to Dlar, Ena appears to integrate multiple pathways that regulate synapse form and function.
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Affiliation(s)
- Elizabeth M McNeill
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA.
| | - Cheryl Thompson
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Brett Berke
- Department of Biology, Yale University, New Haven, CT, USA
| | - Vivian T Chou
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| | - Jannette Rusch
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - April Duckworth
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jamin DeProto
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Alicia Taylor
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, USA.,Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Julie Gates
- Department of Biology, Bucknell University, Lewisburg, PA, USA
| | - Frank Gertler
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, England
| | | | - David Van Vactor
- Department of Cell Biology and Program in Neuroscience, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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9
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Pharmaco-Genetic Screen To Uncover Actin Regulators Targeted by Prostaglandins During Drosophila Oogenesis. G3-GENES GENOMES GENETICS 2019; 9:3555-3565. [PMID: 31506320 PMCID: PMC6829128 DOI: 10.1534/g3.119.400704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Prostaglandins (PGs) are lipid signaling molecules with numerous physiologic functions, including pain/inflammation, fertility, and cancer. PGs are produced downstream of cyclooxygenase (COX) enzymes, the targets of non-steroidal anti-inflammatory drugs (NSAIDs). In numerous systems, PGs regulate actin cytoskeletal remodeling, however, their mechanisms of action remain largely unknown. To address this deficiency, we undertook a pharmaco-genetic interaction screen during late-stage Drosophila oogenesis. Drosophila oogenesis is as an established model for studying both actin dynamics and PGs. Indeed, during Stage 10B, cage-like arrays of actin bundles surround each nurse cell nucleus, and during Stage 11, the cortical actin contracts, squeezing the cytoplasmic contents into the oocyte. Both of these cytoskeletal properties are required for follicle development and fertility, and are regulated by PGs. Here we describe a pharmaco-genetic interaction screen that takes advantage of the fact that Stage 10B follicles will mature in culture and COX inhibitors, such as aspirin, block this in vitro follicle maturation. In the screen, aspirin was used at a concentration that blocks 50% of the wild-type follicles from maturing in culture. By combining this aspirin treatment with heterozygosity for mutations in actin regulators, we quantitatively identified enhancers and suppressors of COX inhibition. Here we present the screen results and initial follow-up studies on three strong enhancers – Enabled, Capping protein, and non-muscle Myosin II Regulatory Light Chain. Overall, these studies provide new insight into how PGs regulate both actin bundle formation and cellular contraction, properties that are not only essential for development, but are misregulated in disease.
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10
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Myat MM, Louis D, Mavrommatis A, Collins L, Mattis J, Ledru M, Verghese S, Su TT. Regulators of cell movement during development and regeneration in Drosophila. Open Biol 2019; 9:180245. [PMID: 31039676 PMCID: PMC6544984 DOI: 10.1098/rsob.180245] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 04/05/2019] [Indexed: 11/16/2022] Open
Abstract
Cell migration is a fundamental cell biological process essential both for normal development and for tissue regeneration after damage. Cells can migrate individually or as a collective. To better understand the genetic requirements for collective migration, we expressed RNA interference (RNAi) against 30 genes in the Drosophila embryonic salivary gland cells that are known to migrate collectively. The genes were selected based on their effect on cell and membrane morphology, cytoskeleton and cell adhesion in cell culture-based screens or in Drosophila tissues other than salivary glands. Of these, eight disrupted salivary gland migration, targeting: Rac2, Rab35 and Rab40 GTPases, MAP kinase-activated kinase-2 (MAPk-AK2), RdgA diacylglycerol kinase, Cdk9, the PDSW subunit of NADH dehydrogenase (ND-PDSW) and actin regulator Enabled (Ena). The same RNAi lines were used to determine their effect during regeneration of X-ray-damaged larval wing discs. Cells translocate during this process, but it remained unknown whether they do so by directed cell divisions, by cell migration or both. We found that RNAi targeting Rac2, MAPk-AK2 and RdgA disrupted cell translocation during wing disc regeneration, but RNAi against Ena and ND-PDSW had little effect. We conclude that, in Drosophila, cell movements in development and regeneration have common as well as distinct genetic requirements.
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Affiliation(s)
- Monn Monn Myat
- Department of Biology, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Dheveline Louis
- Department of Biology, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Andreas Mavrommatis
- Department of Biology, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Latoya Collins
- Department of Biology, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Jamal Mattis
- Department of Biology, Medgar Evers College, City University of New York, Brooklyn, NY 11225, USA
| | - Michelle Ledru
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Shilpi Verghese
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
| | - Tin Tin Su
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
- University of Colorado Comprehensive Cancer Center, Anschutz Medical Campus, 13001 East 17th Place, Aurora, CO 80045, USA
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11
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Acevedo LA, Greenwood AI, Nicholson LK. A Noncanonical Binding Site in the EVH1 Domain of Vasodilator-Stimulated Phosphoprotein Regulates Its Interactions with the Proline Rich Region of Zyxin. Biochemistry 2017; 56:4626-4636. [PMID: 28783324 DOI: 10.1021/acs.biochem.7b00618] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is a processive actin polymerase with roles in the control of cell shape and cell migration. Through interaction with the cytoskeletal adaptor protein Zyxin, VASP can localize to damaged stress fibers where it serves to repair and reinforce these structures. VASP localization is mediated by its N-terminal Ena/VASP homology (EVH1) domain, which binds to the (W/F)PxφP motif (most commonly occurring as FPPPP) found in cytoskeletal proteins such as vinculin, lamellipodin, and Zyxin. Sequentially close clusters of four or five of these motifs frequently occur, as in the proline rich region of Zyxin with four such motifs. This suggests that tetrameric VASP might bind very tightly to Zyxin through avidity, with all four EVH1 domains binding to a single Zyxin molecule. Here, quantitative nuclear magnetic resonance titration analysis reveals a dominant bivalent 1:1 (Zyxin:EVH1) interaction between the Zyxin proline rich region and the VASP EVH1 domain that utilizes the EVH1 canonical binding site and a novel secondary binding site on the opposite face of the EVH1 domain. We further show that binding to the secondary binding site is specifically inhibited by mutation of VASP EVH1 domain residue Y39 to E, which mimics Abl-induced phosphorylation of Y39. On the basis of these findings, we propose a model in which phosphorylation of Y39 acts as a stoichiometry switch that governs binding partner selection by the constitutive VASP tetramer. These results have broader implications for other multivalent VASP EVH1 domain binding partners and for furthering our understanding of the role of Y39 phosphorylation in regulating VASP localization and cellular function.
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Affiliation(s)
- Lucila Andrea Acevedo
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
| | - Alexander I Greenwood
- Department of Applied Science, College of William and Mary , Williamsburg, Virginia 23185, United States
| | - Linda K Nicholson
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
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12
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Tomatis VM, Josh P, Papadopulos A, Gormal RS, Lanoue V, Martin S, Meunier FA. ENA/VASP proteins regulate exocytosis by mediating myosin VI-dependent recruitment of secretory granules to the cortical actin network. Mol Cell Neurosci 2017; 84:100-111. [PMID: 28784263 DOI: 10.1016/j.mcn.2017.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/17/2017] [Accepted: 07/27/2017] [Indexed: 10/24/2022] Open
Abstract
In neurosecretory cells, myosin VI associated with secretory granules (SGs) mediates their activity-dependent recruitment to the cortical actin network and is necessary to sustain exocytosis. The mechanism by which myosin VI interacts with SGs is unknown. Using a myosin VI pull-down assay and mass spectrometry we identified Mena, a member of the ENA/VASP family, as a myosin VI binding partner in PC12 cells, and confirmed that Mena colocalized with myosin VI on SGs. Using a knock-sideways approach to inactivate the ENA/VASP family members by mitochondrial relocation, we revealed a concomitant redistribution of myosin VI. This was ensued by a reduction in the association of myosin VI with SGs, a decreased SG mobility and density in proximity to the plasma membrane as well as decreased evoked exocytosis. These data demonstrate that ENA/VASP proteins regulate SG exocytosis through modulating the activity of myosin VI.
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Affiliation(s)
- Vanesa M Tomatis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Peter Josh
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Vanessa Lanoue
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Sally Martin
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Queensland 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
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13
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Vaughen J, Igaki T. Slit-Robo Repulsive Signaling Extrudes Tumorigenic Cells from Epithelia. Dev Cell 2017; 39:683-695. [PMID: 27997825 DOI: 10.1016/j.devcel.2016.11.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 10/04/2016] [Accepted: 11/19/2016] [Indexed: 02/08/2023]
Abstract
Cells dynamically interact throughout animal development to coordinate growth and deter disease. For example, cell-cell competition weeds out aberrant cells to enforce homeostasis. In Drosophila, tumorigenic cells mutant for the cell polarity gene scribble (scrib) are actively eliminated from epithelia when surrounded by wild-type cells. While scrib cell elimination depends critically on JNK signaling, JNK-dependent cell death cannot sufficiently explain scrib cell extirpation. Thus, how JNK executed cell elimination remained elusive. Here, we show that repulsive Slit-Robo2-Ena signaling exerts an extrusive force downstream of JNK to eliminate scrib cells from epithelia by disrupting E-cadherin. While loss of Slit-Robo2-Ena in scrib cells potentiates scrib tumor formation within the epithelium, Robo2-Ena hyperactivation surprisingly triggers luminal scrib tumor growth following excess extrusion. This extrusive signaling is amplified by a positive feedback loop between Slit-Robo2-Ena and JNK. Our observations provide a potential causal mechanism for Slit-Robo dysregulation in numerous human cancers.
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Affiliation(s)
- John Vaughen
- Laboratory of Genetics, Graduate School of Biostudies, Kyoto University, Yoshida-Konoecho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tatsushi Igaki
- Laboratory of Genetics, Graduate School of Biostudies, Kyoto University, Yoshida-Konoecho, Sakyo-ku, Kyoto 606-8501, Japan.
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14
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Actin stress fiber organization promotes cell stiffening and proliferation of pre-invasive breast cancer cells. Nat Commun 2017; 8:15237. [PMID: 28508872 PMCID: PMC5440822 DOI: 10.1038/ncomms15237] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 03/10/2017] [Indexed: 12/25/2022] Open
Abstract
Studies of the role of actin in tumour progression have highlighted its key contribution in cell softening associated with cell invasion. Here, using a human breast cell line with conditional Src induction, we demonstrate that cells undergo a stiffening state prior to acquiring malignant features. This state is characterized by the transient accumulation of stress fibres and upregulation of Ena/VASP-like (EVL). EVL, in turn, organizes stress fibres leading to transient cell stiffening, ERK-dependent cell proliferation, as well as enhancement of Src activation and progression towards a fully transformed state. Accordingly, EVL accumulates predominantly in premalignant breast lesions and is required for Src-induced epithelial overgrowth in Drosophila. While cell softening allows for cancer cell invasion, our work reveals that stress fibre-mediated cell stiffening could drive tumour growth during premalignant stages. A careful consideration of the mechanical properties of tumour cells could therefore offer new avenues of exploration when designing cancer-targeting therapies. When cells acquire a malignant phenotype they become less stiff and this helps migration and invasion favouring metastasis. Here the authors show that Src-driven cell transformation and transition to a less stiff state follows an event of membrane stiffening due to stress fibres accumulation.
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15
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Qu Y, Hahn I, Webb SED, Pearce SP, Prokop A. Periodic actin structures in neuronal axons are required to maintain microtubules. Mol Biol Cell 2016; 28:296-308. [PMID: 27881663 PMCID: PMC5231898 DOI: 10.1091/mbc.e16-10-0727] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 12/31/2022] Open
Abstract
Drosophila genetics is combined with high-resolution microscopy and a number of functional readouts to demonstrate key factors required for the presence of regularly spaced rings of cortical actin in axons. The data suggest important roles for the actin rings in microtubule regulation, most likely by sustaining their polymerization. Axons are cable-like neuronal processes wiring the nervous system. They contain parallel bundles of microtubules as structural backbones, surrounded by regularly spaced actin rings termed the periodic membrane skeleton (PMS). Despite being an evolutionarily conserved, ubiquitous, highly ordered feature of axons, the function of PMS is unknown. Here we studied PMS abundance, organization, and function, combining versatile Drosophila genetics with superresolution microscopy and various functional readouts. Analyses with 11 actin regulators and three actin-targeting drugs suggest that PMS contains short actin filaments that are depolymerization resistant and sensitive to spectrin, adducin, and nucleator deficiency, consistent with microscopy-derived models proposing PMS as specialized cortical actin. Upon actin removal, we observed gaps in microtubule bundles, reduced microtubule polymerization, and reduced axon numbers, suggesting a role of PMS in microtubule organization. These effects become strongly enhanced when carried out in neurons lacking the microtubule-stabilizing protein Short stop (Shot). Combining the aforementioned actin manipulations with Shot deficiency revealed a close correlation between PMS abundance and microtubule regulation, consistent with a model in which PMS-dependent microtubule polymerization contributes to their maintenance in axons. We discuss potential implications of this novel PMS function along axon shafts for axon maintenance and regeneration.
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Affiliation(s)
- Yue Qu
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Ines Hahn
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Stephen E D Webb
- Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
| | - Simon P Pearce
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom.,School of Mathematics, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Andreas Prokop
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
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16
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Abstract
Ena/VASP tetramer composition was analysed and mixed oligomerization of Mena with EVL was found to be unfavourable, while other paralogue combinations formed without apparent bias. The tetramerization domain of Ena/VASP proteins is responsible for their selective tetramer formation. The members of the actin regulatory family of Ena/VASP proteins form stable tetramers. The vertebrate members of the Ena/VASP family, VASP, Mena and EVL, have many overlapping properties and expression patterns, but functional and regulatory differences between paralogues have been observed. The formation of mixed oligomers may serve a regulatory role to refine Ena/VASP activity. While it has been assumed that family members can form mixed oligomers, this possibility has not been investigated systematically. Using cells expressing controlled combinations of VASP, Mena and EVL, we evaluated the composition of Ena/VASP oligomers and found that VASP forms oligomers without apparent bias with itself, Mena or EVL. However, Mena and EVL showed only weak hetero-oligomerization, suggesting specificity in the association of Ena/VASP family members. Co-expression of VASP increased the ability of Mena and EVL to form mixed oligomers. Additionally, we found that the tetramerization domain (TD) at the C-termini of Ena/VASP proteins conferred the observed selectivity. Finally, we demonstrate that replacement of the TD with a synthetic tetramerizing coiled coil sequence supports homo-oligomerization and normal VASP subcellular localization.
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17
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Loya CM, McNeill EM, Bao H, Zhang B, Van Vactor D. miR-8 controls synapse structure by repression of the actin regulator enabled. Development 2014; 141:1864-74. [PMID: 24718988 PMCID: PMC3994775 DOI: 10.1242/dev.105791] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play important roles in nervous system development and physiology. However, our understanding of the strategies by which miRNAs control synapse development is limited. We find that the highly conserved miRNA miR-8 regulates the morphology of presynaptic arbors at the Drosophila neuromuscular junction (NMJ) through a postsynaptic mechanism. Developmental analysis shows that miR-8 is required for presynaptic expansion that occurs in response to larval growth of the postsynaptic muscle targets. With an in vivo sensor, we confirm our hypothesis that the founding member of the conserved Ena/VASP (Enabled/Vasodilator Activated Protein) family is regulated by miR-8 through a conserved site in the Ena 3′ untranslated region (UTR). Synaptic marker analysis and localization studies suggest that Ena functions within the subsynaptic reticulum (SSR) surrounding presynaptic terminals. Transgenic lines that express forms of a conserved mammalian Ena ortholog further suggest that this localization and function of postsynaptic Ena/VASP family protein is dependent on conserved C-terminal domains known to mediate actin binding and assembly while antagonizing actin-capping proteins. Ultrastructural analysis demonstrates that miR-8 is required for SSR morphogenesis. As predicted by our model, we find that Ena is both sufficient and necessary to account for miR-8-mediated regulation of SSR architecture, consistent with its localization in this compartment. Finally, electrophysiological analysis shows that miR-8 is important for spontaneous neurotransmitter release frequency and quantal content. However, unlike the structural phenotypes, increased expression of Ena fails to mimic the functional defects observed in miR-8-null animals. Together, these findings suggest that miR-8 limits the expansion of presynaptic terminals during larval synapse development through regulation of postsynaptic actin assembly that is independent of changes in synapse physiology.
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Affiliation(s)
- Carlos M Loya
- Department of Cell Biology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
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18
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Dickerman BK, McDonald JA, Sen GC. The Human dsRNA binding protein PACT is unable to functionally substitute for the Drosophila dsRNA binding protein R2D2. F1000Res 2014; 2:220. [PMID: 24715958 PMCID: PMC3962003 DOI: 10.12688/f1000research.2-220.v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/19/2014] [Indexed: 11/20/2022] Open
Abstract
The dsRNA binding protein (dsRBP) PACT was first described as an activator of the dsRNA dependent protein kinase PKR in response to stress signals. Additionally, it has been identified as a component of the small RNA processing pathway. A role for PACT in this pathway represents an important interplay between two modes of post-transcriptional gene regulation. The function of PACT in this context is poorly understood. Thus, additional approaches are required to clarify the mechanism by which PACT functions. In this study, the genetic utility of
Drosophila melanogaster was employed to identify dsRNA-binding proteins that are functionally orthologous to PACT. Transgenic
Drosophila expressing human PACT were generated to determine whether PACT is capable of functionally substituting for the
Drosophila dsRBP R2D2, which has a well-defined role in small RNA biogenesis. Results presented here indicate that PACT is unable to substitute for R2D2 at the whole organism level.
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Affiliation(s)
- Benjamin K Dickerman
- Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Jocelyn A McDonald
- Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Ganes C Sen
- Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
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19
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Benz PM, Merkel CJ, Offner K, Abeßer M, Ullrich M, Fischer T, Bayer B, Wagner H, Gambaryan S, Ursitti JA, Adham IM, Linke WA, Feller SM, Fleming I, Renné T, Frantz S, Unger A, Schuh K. Mena/VASP and αII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy. Cell Commun Signal 2013; 11:56. [PMID: 23937664 PMCID: PMC3751641 DOI: 10.1186/1478-811x-11-56] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 08/06/2013] [Indexed: 11/10/2022] Open
Abstract
Background In the heart, cytoplasmic actin networks are thought to have important roles in mechanical support, myofibrillogenesis, and ion channel function. However, subcellular localization of cytoplasmic actin isoforms and proteins involved in the modulation of the cytoplasmic actin networks are elusive. Mena and VASP are important regulators of actin dynamics. Due to the lethal phenotype of mice with combined deficiency in Mena and VASP, however, distinct cardiac roles of the proteins remain speculative. In the present study, we analyzed the physiological functions of Mena and VASP in the heart and also investigated the role of the proteins in the organization of cytoplasmic actin networks. Results We generated a mouse model, which simultaneously lacks Mena and VASP in the heart. Mena/VASP double-deficiency induced dilated cardiomyopathy and conduction abnormalities. In wild-type mice, Mena and VASP specifically interacted with a distinct αII-Spectrin splice variant (SH3i), which is in cardiomyocytes exclusively localized at Z- and intercalated discs. At Z- and intercalated discs, Mena and β-actin localized to the edges of the sarcomeres, where the thin filaments are anchored. In Mena/VASP double-deficient mice, β-actin networks were disrupted and the integrity of Z- and intercalated discs was markedly impaired. Conclusions Together, our data suggest that Mena, VASP, and αII-Spectrin assemble cardiac multi-protein complexes, which regulate cytoplasmic actin networks. Conversely, Mena/VASP deficiency results in disrupted β-actin assembly, Z- and intercalated disc malformation, and induces dilated cardiomyopathy and conduction abnormalities.
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Affiliation(s)
- Peter M Benz
- Institute of Physiology I, University of Würzburg, D-97070 Würzburg, Germany.
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20
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Sano H, Kunwar PS, Renault AD, Barbosa V, Clark IBN, Ishihara S, Sugimura K, Lehmann R. The Drosophila actin regulator ENABLED regulates cell shape and orientation during gonad morphogenesis. PLoS One 2012; 7:e52649. [PMID: 23300733 PMCID: PMC3530444 DOI: 10.1371/journal.pone.0052649] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/16/2012] [Indexed: 12/27/2022] Open
Abstract
Organs develop distinctive morphologies to fulfill their unique functions. We used Drosophila embryonic gonads as a model to study how two different cell lineages, primordial germ cells (PGCs) and somatic gonadal precursors (SGPs), combine to form one organ. We developed a membrane GFP marker to image SGP behaviors live. These studies show that a combination of SGP cell shape changes and inward movement of anterior and posterior SGPs leads to the compaction of the spherical gonad. This process is disrupted in mutants of the actin regulator, enabled (ena). We show that Ena coordinates these cell shape changes and the inward movement of the SGPs, and Ena affects the intracellular localization of DE-cadherin (DE-cad). Mathematical simulation based on these observations suggests that changes in DE-cad localization can generate the forces needed to compact an elongated structure into a sphere. We propose that Ena regulates force balance in the SGPs by sequestering DE-cad, leading to the morphogenetic movement required for gonad compaction.
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Affiliation(s)
- Hiroko Sano
- HHMI and Developmental Genetics Program, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University Medical Center, New York, New York, United States of America.
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21
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Abl-1-bridged tyrosine phosphorylation of VASP by Abelson kinase impairs association of VASP to focal adhesions and regulates leukaemic cell adhesion. Biochem J 2012; 441:889-99. [PMID: 22014333 DOI: 10.1042/bj20110951] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mena [mammalian Ena (Enabled)]/VASP (vasodilator-stimulated phosphoprotein) proteins are the homologues of Drosophila Ena. In Drosophila, Ena is a substrate of the tyrosine kinase DAbl (Drosophila Abl). However, the link between Abl and the Mena/VASP family is not fully understood in mammals. We previously reported that Abi-1 (Abl interactor 1) promotes phosphorylation of Mena and BCAP (B-cell adaptor for phosphoinositide 3-kinase) by bridging the interaction between c-Abl and the substrate. In the present study we have identified VASP, another member of the Mena/VASP family, as an Abi-1-bridged substrate of Abl. VASP is phosphorylated by Abl when Abi-1 is co-expressed. We also found that VASP interacted with Abi-1 both in vitro and in vivo. VASP was tyrosine-phosphorylated in Bcr-Abl-positive leukaemic cells in an Abi-1-dependent manner. Co-expression of c-Abl and Abi-1 or the phosphomimetic Y39D mutation in VASP resulted in less accumulation of VASP at focal adhesions. VASP Y39D had a reduced affinity to the proline-rich region of zyxin. Interestingly, overexpression of both phosphomimetic and unphosphorylated forms of VASP, but not wild-type VASP, impaired adhesion of K562 cells to fibronectin. These results suggest that the phosphorylation and dephosphorylation cycle of VASP by the Abi-1-bridged mechanism regulates association of VASP with focal adhesions, which may regulate adhesion of Bcr-Abl-transformed leukaemic cells.
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22
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Srinivasan S, Mahowald AP, Fuller MT. The receptor tyrosine phosphatase Lar regulates adhesion between Drosophila male germline stem cells and the niche. Development 2012; 139:1381-90. [PMID: 22378638 DOI: 10.1242/dev.070052] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The stem cell niche provides a supportive microenvironment to maintain adult stem cells in their undifferentiated state. Adhesion between adult stem cells and niche cells or the local basement membrane ensures retention of stem cells in the niche environment. Drosophila male germline stem cells (GSCs) attach to somatic hub cells, a component of their niche, through E-cadherin-mediated adherens junctions, and orient their centrosomes toward these localized junctional complexes to carry out asymmetric divisions. Here we show that the transmembrane receptor tyrosine phosphatase Leukocyte-antigen-related-like (Lar), which is best known for its function in axonal migration and synapse morphogenesis in the nervous system, helps maintain GSCs at the hub by promoting E-cadherin-based adhesion between hub cells and GSCs. Lar is expressed in GSCs and early spermatogonial cells and localizes to the hub-GSC interface. Loss of Lar function resulted in a reduced number of GSCs at the hub. Lar function was required cell-autonomously in germ cells for proper localization of Adenomatous polyposis coli 2 and E-cadherin at the hub-GSC interface and for the proper orientation of centrosomes in GSCs. Ultrastructural analysis revealed that in Lar mutants the adherens junctions between hub cells and GSCs lack the characteristic dense staining seen in wild-type controls. Thus, the Lar receptor tyrosine phosphatase appears to polarize and retain GSCs through maintenance of localized E-cadherin-based adherens junctions.
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Affiliation(s)
- Shrividhya Srinivasan
- Department of Developmental Biology, Stanford University, School of Medicine, Stanford, CA 94305, USA
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23
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Gonçalves-Pimentel C, Gombos R, Mihály J, Sánchez-Soriano N, Prokop A. Dissecting regulatory networks of filopodia formation in a Drosophila growth cone model. PLoS One 2011; 6:e18340. [PMID: 21464901 PMCID: PMC3065487 DOI: 10.1371/journal.pone.0018340] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 02/25/2011] [Indexed: 11/18/2022] Open
Abstract
F-actin networks are important structural determinants of cell shape and morphogenesis. They are regulated through a number of actin-binding proteins. The function of many of these proteins is well understood, but very little is known about how they cooperate and integrate their activities in cellular contexts. Here, we have focussed on the cellular roles of actin regulators in controlling filopodial dynamics. Filopodia are needle-shaped, actin-driven cell protrusions with characteristic features that are well conserved amongst vertebrates and invertebrates. However, existing models of filopodia formation are still incomplete and controversial, pieced together from a wide range of different organisms and cell types. Therefore, we used embryonic Drosophila primary neurons as one consistent cellular model to study filopodia regulation. Our data for loss-of-function of capping proteins, enabled, different Arp2/3 complex components, the formin DAAM and profilin reveal characteristic changes in filopodia number and length, providing a promising starting point to study their functional relationships in the cellular context. Furthermore, the results are consistent with effects reported for the respective vertebrate homologues, demonstrating the conserved nature of our Drosophila model system. Using combinatorial genetics, we demonstrate that different classes of nucleators cooperate in filopodia formation. In the absence of Arp2/3 or DAAM filopodia numbers are reduced, in their combined absence filopodia are eliminated, and in genetic assays they display strong functional interactions with regard to filopodia formation. The two nucleators also genetically interact with enabled, but not with profilin. In contrast, enabled shows strong genetic interaction with profilin, although loss of profilin alone does not affect filopodia numbers. Our genetic data support a model in which Arp2/3 and DAAM cooperate in a common mechanism of filopodia formation that essentially depends on enabled, and is regulated through profilin activity at different steps.
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Affiliation(s)
- Catarina Gonçalves-Pimentel
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
- Center for Neuroscience and Cell Biology,
University of Coimbra, Coimbra, Portugal
| | - Rita Gombos
- Biological Research Center, Hungarian Academy
of Sciences, Institute of Genetics, Szeged, Hungary
| | - József Mihály
- Biological Research Center, Hungarian Academy
of Sciences, Institute of Genetics, Szeged, Hungary
| | - Natalia Sánchez-Soriano
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
| | - Andreas Prokop
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
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24
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Gertler F, Condeelis J. Metastasis: tumor cells becoming MENAcing. Trends Cell Biol 2010; 21:81-90. [PMID: 21071226 DOI: 10.1016/j.tcb.2010.10.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 09/28/2010] [Accepted: 10/01/2010] [Indexed: 12/31/2022]
Abstract
During breast cancer metastasis cells emigrate from the primary tumor to the bloodstream, and this carries them to distant sites where they infiltrate and sometimes form metastases within target organs. These cells must penetrate the dense extracellular matrix comprising the basement membrane of the mammary duct/acinus and migrate toward blood and lymphatic vessels, processes that mammary tumor cells execute primarily using epidermal growth factor (EGF)-dependent protrusive and migratory activity. Here, we focus on how the actin regulatory protein Mena affects EGF-elicited movement, invasion and metastasis. Recent findings indicate that, in invasive migratory tumor cells, Mena isoforms that endow heightened sensitivity to EGF and increased protrusive and migratory abilities are upregulated, whereas other isoforms are selectively downregulated. This change in Mena isoform expression enables tumor cells to invade in response to otherwise benign EGF stimulus levels and could offer an opportunity to identify metastatic risk in patients.
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Affiliation(s)
- Frank Gertler
- Department of Biology and Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology (MIT), 77 Massachusetts Ave, Cambridge, MA 02138, USA.
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25
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Tucker PK, Evans IR, Wood W. Ena drives invasive macrophage migration in Drosophila embryos. Dis Model Mech 2010; 4:126-34. [PMID: 21045209 PMCID: PMC3008967 DOI: 10.1242/dmm.005694] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
It is seldom the primary tumour that proves fatal in cancer, with metastasis the fundamental pathological process for disease progression. Upregulation of Mena, a member of the evolutionarily conserved Ena/VASP family of actin cytoskeletal regulators, promotes metastasis and invasive motility of breast cancer cells in vivo. To complement in vitro studies of Ena/VASP function in fibroblasts, we manipulated levels of Ena, the Drosophila homologue of Mena, in migrating embryonic macrophages (haemocytes). Consistent with data from fibroblasts in vitro, Ena localises to regions of actin dynamics within migrating haemocytes, stimulates lamellipodial dynamics and positively regulates the number and length of filopodia. However, whereas Ena overexpression in fibroblasts reduces migration speeds, overexpressing Ena in haemocytes leads to a dramatic increase in migration speeds, more closely resembling the increased motility of breast cancer cells that overexpress Mena. We provide evidence that this key difference is due to spatial constraints imposed on cells within the three-dimensional environment of the embryo; this might explain how Mena can be used to promote aggressive migratory behaviour during cancer progression.
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Affiliation(s)
- Philippa K Tucker
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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Lin WH, Nebhan CA, Anderson BR, Webb DJ. Vasodilator-stimulated phosphoprotein (VASP) induces actin assembly in dendritic spines to promote their development and potentiate synaptic strength. J Biol Chem 2010; 285:36010-20. [PMID: 20826790 DOI: 10.1074/jbc.m110.129841] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dendritic spines are small actin-rich structures that receive the majority of excitatory synaptic input in the brain. The actin-based dynamics of spines are thought to mediate synaptic plasticity, which underlies cognitive processes, such as learning and memory. However, little is known about the molecular mechanisms that regulate actin dynamics in spines and synapses. In this study we show the multifunctional actin-binding protein vasodilator-stimulated phosphoprotein (VASP) regulates the density, size, and morphology of dendritic spines by inducing actin assembly in these structures. Knockdown of endogenous VASP by siRNA led to a significant decrease in the density of spines and synapses, whereas expression of siRNA-resistant VASP rescued this defect. The ability of VASP to modulate spine and synapse formation, maturation, and spine head enlargement is dependent on its actin binding Ena/VASP homology 2 (EVH2) domain and its EVH1 domain, which contributes to VASP localization to actin-rich structures. Moreover, VASP increases the amount of PSD-scaffolding proteins and the number of surface GluR1-containing α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) in spines. VASP knockdown results in a reduction in surface AMPAR density, suggesting a role for this protein in regulating synaptic strength. Consistent with this, VASP significantly enhances the retention of GluR1 in spines as determined by fluorescence recovery after photobleaching and increases AMPAR-mediated synaptic transmission. Collectively, our results suggest that actin polymerization and bundling by VASP are critical for spine formation, expansion, and modulating synaptic strength.
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Affiliation(s)
- Wan-Hsin Lin
- Department of Biological Sciences and Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37235, USA
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27
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Fleming T, Chien SC, Vanderzalm PJ, Dell M, Gavin MK, Forrester WC, Garriga G. The role of C. elegans Ena/VASP homolog UNC-34 in neuronal polarity and motility. Dev Biol 2010; 344:94-106. [PMID: 20452341 DOI: 10.1016/j.ydbio.2010.04.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 04/13/2010] [Accepted: 04/22/2010] [Indexed: 12/30/2022]
Abstract
Ena/VASP proteins mediate the effects of guidance cues on the actin cytoskeleton. The single C. elegans homolog of the Ena/VASP family of proteins, UNC-34, is required for the migrations of cells and growth cones. Here we show that unc-34 mutant alleles also interact genetically with Wnt mutants to reveal a role for unc-34 in the establishment of neuronal polarity along the C. elegans anterior-posterior axis. Our mutant analysis shows that eliminating UNC-34 function results in neuronal migration and polarity phenotypes that are enhanced at higher temperatures, revealing a heat-sensitive process that is normally masked by the presence of UNC-34. Finally, we show that the UNC-34 protein is expressed broadly and accumulates in axons and at the apical junctions of epithelial cells. While most mutants lacked detectable UNC-34, three unc-34 mutants that contained missense mutations in the EVH1 domain produced full-length UNC-34 that failed to localize to apical junctions and axons, supporting the role for the EVH1 domain in localizing Ena/VASP family members.
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Affiliation(s)
- Tinya Fleming
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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28
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Link NM, Hunke C, Mueller JW, Eichler J, Bayer P. The solution structure of pGolemi, a high affinity Mena EVH1 binding miniature protein, suggests explanations for paralog-specific binding to Ena/VASP homology (EVH) 1 domains. Biol Chem 2009; 390:417-26. [PMID: 19284291 DOI: 10.1515/bc.2009.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ena/VASP homology 1 (EVH1) domains are polyproline binding domains that are present in a wide range of adaptor proteins, among them Ena/VASP proteins involved in actin remodeling and axonal guidance. The interaction of ActA, a transmembrane protein from the food-borne pathogen Listeria monocytogenes, with EVH1 domains has been shown to be crucial for recruitment of the host's actin skeleton and, as a consequence, for the infectivity of this bacterium. We present the structure of a synthetic high-affinity Mena EVH1 ligand, pGolemi, capable of paralog-specific binding, solved by NMR spectroscopy. This peptide shares the common pancreatic peptide fold with its scaffold, avian pancreatic peptide, but shows pivotal differences in the amino-terminus. The interplay of spatial fixation and flexibility appears to be the reason for its high affinity towards Mena EVH1. Combined with earlier investigations, our structural data shed light on the specificity determinants of pGolemi and the importance of additional binding epitopes around the residues Thr74 and Phe32 on EVH1 domains regulating paralog specificity. Our results are expected to facilitate the design of other high-affinity, paralog-specific EVH1 domain ligands, and serve as a fundament for the investigation of the molecular mode of action of EVH1 domains.
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Affiliation(s)
- Nina M Link
- Medizinische und Strukturelle Biochemie, Zentrum für Medizinische Biotechnologie, Universität Duisburg-Essen, Universitätsstr. 2-5, D-45117 Essen, Germany.
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29
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Gates J, Nowotarski SH, Yin H, Mahaffey JP, Bridges T, Herrera C, Homem CCF, Janody F, Montell DJ, Peifer M. Enabled and Capping protein play important roles in shaping cell behavior during Drosophila oogenesis. Dev Biol 2009; 333:90-107. [PMID: 19576200 DOI: 10.1016/j.ydbio.2009.06.030] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 06/20/2009] [Accepted: 06/22/2009] [Indexed: 12/29/2022]
Abstract
During development, cells craft an impressive array of actin-based structures, mediating events as diverse as cytokinesis, apical constriction, and cell migration. One challenge is to determine how cells regulate actin assembly and disassembly to carry out these cell behaviors. During Drosophila oogenesis diverse cell behaviors are seen in the soma and germline. We used oogenesis to explore developmental roles of two important actin regulators: Enabled/VASP proteins and Capping protein. We found that Enabled plays an important role in cortical integrity of nurse cells, formation of robust bundled actin filaments in late nurse cells that facilitate nurse cell dumping, and migration of somatic border cells. During nurse cell dumping, Enabled localizes to barbed ends of the nurse cell actin filaments, suggesting its mechanism of action. We further pursued this mechanism using mutant Enabled proteins, each affecting one of its protein domains. These data suggest critical roles for the EVH2 domain and its tetramerization subdomain, while the EVH1 domain appears less critical. Enabled appears to be negatively regulated during oogenesis by Abelson kinase. We also explored the function of Capping protein. This revealed important roles in oocyte determination, nurse cell cortical integrity and nurse cell dumping, and support the idea that Capping protein and Enabled act antagonistically during dumping. Together these data reveal places that these actin regulators shape oogenesis.
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Affiliation(s)
- Julie Gates
- Lineberger Comprehensive Cancer Center and Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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30
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Lyulcheva E, Taylor E, Michael M, Vehlow A, Tan S, Fletcher A, Krause M, Bennett D. Drosophila pico and its mammalian ortholog lamellipodin activate serum response factor and promote cell proliferation. Dev Cell 2009; 15:680-90. [PMID: 19000833 PMCID: PMC2691947 DOI: 10.1016/j.devcel.2008.09.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 08/06/2008] [Accepted: 09/30/2008] [Indexed: 12/19/2022]
Abstract
MIG-10/RIAM/lamellipodin (MRL) proteins link activated Ras-GTPases with actin regulatory Ena/VASP proteins to induce local changes in cytoskeletal dynamics and cell motility. MRL proteins alter monomeric (G):filamentous (F) actin ratios, but the impact of these changes had not been fully appreciated. We report here that the Drosophila MRL ortholog, pico, is required for tissue and organismal growth. Reduction in pico levels resulted in reduced cell division rates, growth retardation, increased G:F actin ratios and lethality. Conversely, pico overexpression reduced G:F actin ratios and promoted tissue overgrowth in an epidermal growth factor (EGF) receptor (EGFR)-dependent manner. Consistently, in HeLa cells, lamellipodin was required for EGF-induced proliferation. We show that pico and lamellipodin share the ability to activate serum response factor (SRF), a transcription factor that responds to reduced G:F-actin ratios via its co-factor Mal. Genetics data indicate that mal/SRF levels are important for pico-mediated tissue growth. We propose that MRL proteins link EGFR activation to mitogenic SRF signaling via changes in actin dynamics.
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Affiliation(s)
- Ekaterina Lyulcheva
- Department of Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, UK
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31
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Peterson FC, Volkman BF. Diversity of polyproline recognition by EVH1 domains. Front Biosci (Landmark Ed) 2009; 14:833-46. [PMID: 19273103 DOI: 10.2741/3281] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Enabled/VASP Homology-1 (EVH1) domains function primarily as interaction modules that link signaling proteins by binding to proline-rich sequences. EVH1 domains are ~115 residues in length and adopt the pleckstrin homology (PH) fold. Four different protein families contain EVH1 domains: Ena/VASP, Homer, WASP and SPRED. Except for the SPRED domains, for which no binding partners are known, EVH1 domains use a conserved hydrophobic cleft to bind a four-residue motif containing 2-4 prolines. Conserved aromatic residues, including an invariant tryptophan, create a wedge-shaped groove on the EVH1 surface that matches the triangular profile of a polyproline type II helix. Hydrophobic residues adjacent to the polyproline motif dock into complementary sites on the EVH1 domain to enhance ligand binding specificity. Pseudosymmetry in the polyproline type II helix allows peptide ligands to bind in either of two N-to-C terminal orientations, depending on interactions between sequences flanking the prolines and the EVH1 domain. EVH1 domains also recognize non-proline motifs, as illustrated by the structure of an EVH1:LIM3 complex and the extended EVH1 ligands of the verprolin family.
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Affiliation(s)
- Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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32
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Gates J, Mahaffey JP, Rogers SL, Emerson M, Rogers EM, Sottile SL, Van Vactor D, Gertler FB, Peifer M. Enabled plays key roles in embryonic epithelial morphogenesis in Drosophila. Development 2008; 134:2027-39. [PMID: 17507404 DOI: 10.1242/dev.02849] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies in cultured cells and in vitro have identified many actin regulators and begun to define their mechanisms of action. Among these are Enabled (Ena)/VASP proteins, anti-Capping proteins that influence fibroblast migration, growth cone motility, and keratinocyte cell adhesion in vitro. However, partially redundant family members in mammals and maternal Ena contribution in Drosophila previously prevented assessment of the roles of Ena/VASP proteins in embryonic morphogenesis in flies or mammals. We used several approaches to remove maternal and zygotic Ena function, allowing us to address this question. We found that inactivating Ena does not disrupt cell adhesion or epithelial organization, suggesting its role in these processes is cell type-specific. However, Ena plays an important role in many morphogenetic events, including germband retraction, segmental groove retraction and head involution, whereas it is dispensable for other morphogenetic movements. We focused on dorsal closure, analyzing mechanisms by which Ena acts. Ena modulates filopodial number and length, thus influencing the speed of epithelial zippering and the ability of cells to match with correct neighbors. We also explored filopodial regulation in cultured Drosophila cells and embryos. These data provide new insights into developmental and mechanistic roles of this important actin regulator.
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Affiliation(s)
- Julie Gates
- Lineberger Comprehensive Cancer Center and Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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33
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Corrigall D, Walther RF, Rodriguez L, Fichelson P, Pichaud F. Hedgehog Signaling Is a Principal Inducer of Myosin-II-Driven Cell Ingression in Drosophila Epithelia. Dev Cell 2007; 13:730-742. [DOI: 10.1016/j.devcel.2007.09.015] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 07/17/2007] [Accepted: 09/25/2007] [Indexed: 11/29/2022]
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34
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Hearing development and spiral ganglion neurite growth in VASP deficient mice. Brain Res 2007; 1178:73-82. [PMID: 17920567 DOI: 10.1016/j.brainres.2007.06.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 04/27/2007] [Accepted: 06/07/2007] [Indexed: 10/23/2022]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) has been found to be involved in intracellular signalling pathways and to play an important role in the actin associated organization and formation of the cytoskeleton. Since differential VASP expression was noted in inner ear tissues, the present study was performed to investigate the hearing development in VASP deficient mice. Hearing development in VASP-/- mice and wild type animals was investigated by auditory brain stem (ABR) measurements. In addition, inner ear tissues of wild type animals were tested for VASP expression using PCR, Western blot analysis, in situ hybridisation, and immunohistochemistry. To compare spiral ganglion (SG) neurite growth, SG explants from VASP-/- and wild type mice were analyzed under cell culture conditions. The electroacoustical results of the present study indicate that VASP deficient mice present with a later onset of hearing during postnatal development compared to wild type animals. Transient VASP expression was detected in neonatal SG of wild type mice. Tissue culture experiments with SG explants from VASP-/- animals revealed significant alterations in SG neurite extension compared to wild types. The present findings suggest a role for VASP during neonatal development of the mammalian cochlea and allow speculation on a possible delayed innervation of cochlear hair cells due to changes in SG neurite growth in VASP-deficient mice. Temporary VASP deficits in the neonatal inner ear may be compensated by related proteins like MENA leading to a delayed but complete development of hearing function in VASP-/- animals.
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35
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Chan CB, Liu X, Tang X, Fu H, Ye K. Akt phosphorylation of zyxin mediates its interaction with acinus-S and prevents acinus-triggered chromatin condensation. Cell Death Differ 2007; 14:1688-99. [PMID: 17572661 DOI: 10.1038/sj.cdd.4402179] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Zyxin, a focal adhesion molecule, contains LIM domains and shuttles between the cytoplasm and the nucleus. Nuclear zyxin promotes cardiomyocyte survival, which is mediated by nuclear-activated Akt. However, the molecular mechanism of how zyxin antagonizes apoptosis remains elusive. Here, we report that zyxin binds to acinus-S, a nuclear speckle protein inducing apoptotic chromatin condensation after cleavage by caspases, and prevents its apoptotic action, which is regulated by Akt. Akt binds and phosphorylates zyxin on serine 142, leading to its association with acinus. Interestingly, 14-3-3gamma, but not zeta isoform selectively, triggers zyxin nuclear translocation, which is Akt phosphorylation dependent. Zyxin is also a substrate of caspases, but Akt phosphorylation is unable to prevent its apoptotic cleavage. Expression of zyxin S142D, a phosphorylation mimetic mutant, diminishes acinus proteolytic cleavage and chromatin condensation; by contrast, wild-type zyxin or unphosphorylated S142A mutant fails. Thus, Akt regulates zyxin/acinus complex formation in the nucleus, contributing to suppression of apoptosis.
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Affiliation(s)
- C-B Chan
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Room 145, Whitehead Building, 615 Michael Street, Atlanta, GA 30322, USA
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36
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Chereau D, Dominguez R. Understanding the role of the G-actin-binding domain of Ena/VASP in actin assembly. J Struct Biol 2006; 155:195-201. [PMID: 16684607 DOI: 10.1016/j.jsb.2006.01.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2005] [Accepted: 01/22/2006] [Indexed: 11/26/2022]
Abstract
The Ena/VASP and WASP family of proteins play distinct roles in actin cytoskeleton remodeling. Ena/VASP is linked to actin filament elongation, whereas WASP plays a role in filament nucleation and branching mediated by Arp2/3 complex. The molecular mechanisms controlling both processes are only emerging. Both Ena/VASP and WASP are multidomain proteins. They both present poly-Pro regions, which mediate the binding of profilin-actin, followed by G-actin-binding (GAB) domains of the WASP-homology 2 (WH2) type. However, the WH2 of Ena/VASP is somewhat different from that of WASP, and has been poorly characterized. Here we demonstrate that this WH2 binds profilin-actin with higher affinity than actin alone. The results are consistent with a model whereby allosteric modulation of affinity drives the transition of profilin-actin from the poly-Pro region to the WH2 and then to the barbed end of the filament during elongation. Therefore, the function of the WH2 in Ena/VASP appears to be to "process" profilin-actin for its incorporation at the barbed end of the growing filament. Conformational changes in the newly incorporated actin subunit, resulting either from nucleotide hydrolysis or from the G- to F-actin transition, may serve as a "sensor" for the processive stepping of Ena/VASP. Conserved domain architecture suggests that WASP may work similarly.
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Affiliation(s)
- David Chereau
- Boston Biomedical Research Institute, 64 Grove Street, Watertown, MA 02472, USA
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37
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Urbanelli L, Massini C, Emiliani C, Orlacchio A, Bernardi G, Orlacchio A. Characterization of human Enah gene. ACTA ACUST UNITED AC 2006; 1759:99-107. [PMID: 16494957 DOI: 10.1016/j.bbaexp.2006.01.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 01/05/2006] [Accepted: 01/06/2006] [Indexed: 11/28/2022]
Abstract
Enabled homolog (Enah) is a mammalian ortholog of Drosophila Enabled (Ena), which is genetically linked to the Drosophila Abl tyrosine phosphorylation signaling cascade and is required for normal neural development. Vertebrates have three Ena-related genes: Enah, VASP (vasodilator-stimulated phosphoprotein) and Ena/VASP like (EVL). These genes play an important role in linking signal transduction pathways to localized remodeling of the actin cytoskeleton. We isolated and sequenced a cDNA encoding human Enah. Comparison of the amino acid sequences of mouse (Mus musculus) and human (Homo sapiens) species shows 86.6% identity. The human protein appears longer than the mouse and additional amino acids are concentrated in a region containing repeats of the amino acid sequence LERER. The complete gene is about 157 kb and consists of 14 exons. Analysis of multiple tissue northern blot revealed a major transcript of about 4.8 kb in all tissue examined. Alternatively spliced isoforms were isolated by RT-PCR. The gene is differentially expressed and to gain insight factors affecting its expression we cloned and preliminarily characterized human Enah gene promoter.
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Affiliation(s)
- Lorena Urbanelli
- Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Sezione di Biochimica e Biologia Molecolare, Università degli Studi di Perugia, via del Giochetto, 06122 Perugia, Italy
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38
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Xanthos JB, Wanner SJ, Miller JR. Cloning and developmental expression of Xenopus Enabled (Xena). Dev Dyn 2005; 233:631-7. [PMID: 15778995 DOI: 10.1002/dvdy.20358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Regulation of actin dynamics, organization, and interaction with cell surface adhesion proteins is critical for tissue morphogenesis during development. The Ena/VASP family of actin-binding proteins function in several cellular processes that involve dynamic regulation of the actin cytoskeleton, including axon guidance, platelet aggregation, cell migration, and cell adhesion. The vertebrate Ena/VASP family is composed of three genes: Ena (Enabled), VASP (Vasodilator Stimulated Phosphoprotein), and Evl (Ena/VASP-Like). To better understand the role of Ena/VASP proteins during vertebrate development, we have cloned and characterized the developmental expression of Ena in Xenopus laevis. Analysis of the temporal expression of Xenopus Ena (Xena) demonstrates that multiple isoforms of Xena are detected throughout embryogenesis and that the presence of different isoforms is developmentally regulated. In situ hybridization analyses reveal that Xena is broadly expressed throughout development. During gastrulation and neurulation, Xena is detected in the neuroepithelium, notochord, and somites. In tadpoles, Xena expression is restricted to dorsal regions of the brain, whereas it is expressed at lower levels throughout the spinal cord. Xena expression is also detected in the notochord, myotome, heart, pronephros, and cranial placodes, including the olfactory and otic placodes. Analysis of the subcellular localization of Xena using a GFP fusion protein revealed that Xena localizes to adherens junctions and focal adhesions in Xenopus animal caps and NIH3T3 fibroblasts, respectively. These results define spatiotemporal windows in which Xena may function during early Xenopus development to modulate actin-dependent processes such as cell adhesion and migration.
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Affiliation(s)
- Jennifer B Xanthos
- Department of Genetics, Cell Biology and Development, and Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
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39
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Wanner SJ, Danos MC, Lohr JL, Miller JR. Molecular cloning and expression of Ena/Vasp-like (Evl) during Xenopus development. Gene Expr Patterns 2005; 5:423-8. [PMID: 15661649 DOI: 10.1016/j.modgep.2004.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 09/07/2004] [Indexed: 11/16/2022]
Abstract
Ena/VASP proteins are actin-binding proteins implicated in the regulation of axon guidance, platelet aggregation, cell motility, and cell adhesion. The vertebrate Ena/VASP family is comprised of three genes: Ena (Enabled), VASP (Vasodilator Stimulated Phosphoprotein), and Evl (Ena/VASP-Like). We have cloned and characterized cDNAs encoding three alternatively spliced isoforms of Xenopus laevis Evl, designated Xevl, Xevl-I and Xevl-H. Analysis of the temporal expression of Xevl, Xevl-I and Xevl-H demonstrates that transcripts for each isoform are first detectable at low levels at stage 18, show increased abundance by stage 23, and persist throughout the remainder of embryogenesis. In situ hybridization analyses using a probe that detects all three Xevl isoforms or a probe that specifically detects the Xevl-H isoform revealed expression in the cement gland, brain, neural tube, myotome, and neural placodes, including the otic, lateral line, and olfactory placodes. These results suggest roles for Xevl in regulating actin dynamics and cell adhesion in neural and mesodermal tissues during later stages of Xenopus development.
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Affiliation(s)
- Sarah J Wanner
- Department of Genetics, Cell Biology and Development, Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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40
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Martin M, Ahern-Djamali SM, Hoffmann FM, Saxton WM. Abl tyrosine kinase and its substrate Ena/VASP have functional interactions with kinesin-1. Mol Biol Cell 2005; 16:4225-30. [PMID: 15975902 PMCID: PMC1196332 DOI: 10.1091/mbc.e05-02-0116] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Relatively little is known about how microtubule motors are controlled or about how the functions of different cytoskeletal systems are integrated. A yeast two-hybrid screen for proteins that bind to Drosophila Enabled (Ena), an actin polymerization factor that is negatively regulated by Abl tyrosine kinase, identified kinesin heavy chain (Khc), a member of the kinesin-1 subfamily of microtubule motors. Coimmunoprecipitation from Drosophila cytosol confirmed a physical interaction between Khc and Ena. Kinesin-1 motors can carry organelles and other macromolecular cargoes from neuronal cell bodies toward terminals in fast-axonal-transport. Ena distribution in larval axons was not affected by mutations in the Khc gene, suggesting that Ena is not itself a fast transport cargo of Drosophila kinesin-1. Genetic interaction tests showed that in a background sensitized by reduced Khc gene dosage, a reduction in Abl gene dosage caused distal paralysis and axonal swellings. A concomitant reduction in ena dosage rescued those defects. These results suggest that Ena/VASP, when not inhibited by the Abl pathway, can bind Khc and reduce its transport activity in axons.
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Affiliation(s)
- MaryAnn Martin
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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41
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Badour K, Zhang J, Siminovitch KA. Involvement of the Wiskott-Aldrich syndrome protein and other actin regulatory adaptors in T cell activation. Semin Immunol 2005; 16:395-407. [PMID: 15541654 DOI: 10.1016/j.smim.2004.08.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The actin cytoskeleton is a dynamic structure recognized for many years as integral to the coupling of external stimuli to cell activation and ensuing changes in morphology and movement. It is only recently, however, that a molecular understanding of actin involvement in these activities has emerged coincident with the identification of cytosolic signaling effectors that couple extracellular stimuli to induction of actin nucleation. Notable among these actin regulatory effectors are members of the Wiskott-Aldrich syndrome protein (WASp) family, a group of cytoskeletal adaptors imbued with the capacity to connect various signal transduction pathways to the Arp 2/3 complex and Arp 2/3-mediated actin polymerization. In T cells, the functional characterization of WASp and other actin-modulatory adaptors has proved instrumental in delineating the molecular interactions evoking actin cytoskeletal reorganization downstream of antigen receptor engagement and in clarifying the influence of actin-based processes on T cell activation. In this review, the structural and functional properties of the major actin regulatory cytoskeletal adaptors in T cells are described with an emphasis on the roles of these proteins in fostering the TCR actin cytoskeletal interplay required for induction of T cell activation and expression of dynamic effector responses.
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Affiliation(s)
- Karen Badour
- Department of Medicine, McLaughlin Centre of Molecular Medicine, University of Toronto, Mount Sinai Hospital, Samuel Lunenfeld and Toronto General Hospital Research Institutes, 600 University Avenue, #656A, Toronto, Ont., Canada M5G 1X5.
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42
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Withee J, Galligan B, Hawkins N, Garriga G. Caenorhabditis elegans WASP and Ena/VASP proteins play compensatory roles in morphogenesis and neuronal cell migration. Genetics 2005; 167:1165-76. [PMID: 15280232 PMCID: PMC1470955 DOI: 10.1534/genetics.103.025676] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We report here that WASP and Ena/VASP family proteins play overlapping roles in C. elegans morphogenesis and neuronal cell migration. Specifically, these studies demonstrate that UNC-34/Ena plays a role in morphogenesis that is revealed only in the absence of WSP-1 function and that WSP-1 has a role in neuronal cell migration that is revealed only in the absence of UNC-34/Ena activity. To identify additional genes that act in parallel to unc-34/ena during morphogenesis, we performed a screen for synthetic lethals in an unc-34 null mutant background utilizing an RNAi feeding approach. To our knowledge, this is the first reported RNAi-based screen for genetic interactors. As a result of this screen, we identified a second C. elegans WASP family protein, wve-1, that is most homologous to SCAR/WAVE proteins. Animals with impaired wve-1 function display defects in gastrulation, fail to undergo proper morphogenesis, and exhibit defects in neuronal cell migrations and axon outgrowth. Reducing wve-1 levels in either unc-34/ena or wsp-1 mutant backgrounds also leads to a significant enhancement of the gastrulation and morphogenesis defects. Thus, unc-34/ena, wsp-1, and wve-1 play overlapping roles during embryogenesis and unc-34/ena and wsp-1 play overlapping roles in neuronal cell migration. These observations show that WASP and Ena/VASP proteins can compensate for each other in vivo and provide the first demonstration of a role for Ena/VASP proteins in gastrulation and morphogenesis. In addition, our results provide the first example of an in vivo role for WASP family proteins in neuronal cell migrations and cytokinesis in metazoans.
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Affiliation(s)
- Jim Withee
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
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Ng J, Luo L. Rho GTPases regulate axon growth through convergent and divergent signaling pathways. Neuron 2005; 44:779-93. [PMID: 15572110 DOI: 10.1016/j.neuron.2004.11.014] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 08/20/2004] [Accepted: 10/15/2004] [Indexed: 11/16/2022]
Abstract
Rho GTPases are essential regulators of cytoskeletal reorganization, but how they do so during neuronal morphogenesis in vivo is poorly understood. Here we show that the actin depolymerization factor cofilin is essential for axon growth in Drosophila neurons. Cofilin function in axon growth is inhibited by LIM kinase and activated by Slingshot phosphatase. Dephosphorylating cofilin appears to be the major function of Slingshot in regulating axon growth in vivo. Genetic data provide evidence that Rho or Rac/Cdc42, via effector kinases Rok or Pak, respectively, activate LIM kinase to inhibit axon growth. Importantly, Rac also activates a Pak-independent pathway that promotes axon growth, and different RacGEFs regulate these distinct pathways. These genetic analyses reveal convergent and divergent pathways from Rho GTPases to the cytoskeleton during axon growth in vivo and suggest that different developmental outcomes could be achieved by biases in pathway selection.
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Affiliation(s)
- Julian Ng
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
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Pavy N, Laroche J, Bousquet J, Mackay J. Large-scale statistical analysis of secondary xylem ESTs in pine. PLANT MOLECULAR BIOLOGY 2005; 57:203-24. [PMID: 15821878 DOI: 10.1007/s11103-004-6969-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2004] [Accepted: 11/30/2004] [Indexed: 05/18/2023]
Abstract
A computational analysis of pine transcripts was conducted to contribute to the functional annotation of conifer sequences. A statistical analysis of expressed sequential tags(ESTs) belonging the 7732 contigs in the TIGR Pinus Gene Index (PGI1.0) identified 260 differentially represented gene sequences across six cDNA libraries from loblolly pine secondary xylem. Cluster analysis of this subset of contigs resulted in five groups representing genes preferentially represented in one of the xylem samples (compression wood, plannings, root xylem, latewood) and one group containing mostly genes simultaneously present in compression and side wood libraries. To complement the sequence annotation, 27 cDNA clones representing selected transcripts were completely sequenced. Several genes were identified that could represent putative markers for xylem from different organs, at different stages of development. Several sequences encoding regulatory proteins were over-represented in root xylem as opposed to the other xylem samples. Some of them belonged to known families of plant transcription factors, but two genes were previously uncharacterized in plants. One transcript was homologous to the gene encoding the Smad4 interacting factor, a key co-activator in TGFbeta (transforming growth factor) signalling in animals. Thus, the digital analysis of pine ESTs highlighted a putative gene function of potentially broad interest but that has yet to be investigated in plants. More generally, this study showed that the application of numerical approaches to EST databases should be helpful in establishing priorities among genes to consider for targeted functional studies. Thus, we illustrated the potential of extracting information from conifer sequences already accessible through well-structured public databases.
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Affiliation(s)
- Nathalie Pavy
- ARBOREA and Centre de Recherche en Biologie Forestiére, Universitè Laval, Pavillon Charles-Eugéne-Marchand, Sainte-Foy, Que., G1K 7P4, Canada.
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Otey CA, Rachlin A, Moza M, Arneman D, Carpen O. The palladin/myotilin/myopalladin family of actin-associated scaffolds. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 246:31-58. [PMID: 16164966 DOI: 10.1016/s0074-7696(05)46002-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The dynamic remodeling of the actin cytoskeleton plays a critical role in cellular morphogenesis and cell motility. Actin-associated scaffolds are key to this process, as they recruit cohorts of actin-binding proteins and associated signaling complexes to subcellular sites where remodeling is required. This review is focused on a recently discovered family of three proteins, myotilin, palladin, and myopalladin, all of which function as scaffolds that regulate actin organization. While myotilin and myopalladin are most abundant in skeletal and cardiac muscle, palladin is ubiquitously expressed in the organs of developing vertebrates. Palladin's function has been investigated primarily in the central nervous system and in tissue culture, where it appears to play a key role in cellular morphogenesis. The three family members each interact with specific molecular partners: all three bind to alpha-actinin; in addition, palladin also binds to vasodilator-stimulated phosphoprotein (VASP) and ezrin, myotilin binds to filamin and actin, and myopalladin also binds to nebulin and cardiac ankyrin repeat protein (CARP). Since mutations in myotilin result in two forms of muscle disease, an essential role for this family member in organizing the skeletal muscle sarcomere is implied.
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Affiliation(s)
- Carol A Otey
- Department of Cell and Molecular Physiology and the Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Boukhelifa M, Parast MM, Bear JE, Gertler FB, Otey CA. Palladin is a novel binding partner for Ena/VASP family members. ACTA ACUST UNITED AC 2004; 58:17-29. [PMID: 14983521 DOI: 10.1002/cm.10173] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Palladin is an actin-associated protein that contains proline-rich motifs within its amino-terminal sequence that are similar to motifs found in zyxin, vinculin, and the Listeria protein ActA. These motifs are known to be potential binding sites for the Vasodilator-Stimulated Phosphoprotein (VASP). Here, we demonstrate that palladin is an additional direct binding partner for VASP, by using co-immunoprecipitation and blot overlay techniques with both endogenous palladin and recombinant myc-tagged palladin. These results show that VASP binds to full-length palladin and also to the amino-terminal half of palladin, where the polyproline motifs are located. Using a synthetic peptide array, two discrete binding sites for VASP were identified within palladin's proline-rich amino-terminal domain. Using double-label immunofluorescence staining of fully-spread and actively-spreading fibroblasts, the extent of co-localization of palladin and VASP was explored. These proteins were found to strongly co-localize along stress fibers, and partially co-localize in focal adhesions, lamellipodia, and focal complexes. These results suggest that the recently described actin-associated protein palladin may play an important role in recruiting VASP to sites of actin filament growth, anchorage, and crosslinking.
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Affiliation(s)
- Malika Boukhelifa
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, 27599-7545, USA
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Schick B, Praetorius M, Eigenthaler M, Jung V, Müller M, Walter U, Knipper M. Increased noise sensitivity and altered inner ear MENA distribution in VASP-/- mice. Cell Tissue Res 2004; 318:493-502. [PMID: 15578270 DOI: 10.1007/s00441-004-0964-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2004] [Accepted: 06/26/2004] [Indexed: 11/25/2022]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) and mammalian-enabled protein (MENA) share similar cellular localisation and functions (signal transduction pathways, regulation of actin cytoskeleton dynamics). Functional substitution and compensation among Ena/VASP proteins have been proposed as the reason for the absence of major morphological and functional deficits in VASP-/- mice. The aim of this study was to investigate VASP expression in the mouse cochlea, to analyse cochlear function in VASP-/- mice compared with wildtype mice, and to analyse cochlear MENA distribution taking into account that MENA protein might compensate VASP loss in the cochlea of VASP-/- mice. We confirmed specific VASP expression in the pillar cells of the mice organ of Corti as previously reported for rat cochlea. By analysing the hearing function in VASP-/- mice, we found no differences in auditory brainstem responses and distortion product otoacoustic emissions from those of wildtype mice but evidence for an increased noise sensitivity at lower frequencies. When MENA protein levels in cochlea tissue were tested in mutant and wildtype mice by Western blot analysis, no significant differences were found, as was also seen with regard to MENA mRNA levels in laser-microdissected single pillar cells. Most surprisingly, however, MENA protein was absent in pillar cells of VASP-/- mice, whereas it was detected in other cochlear cells. The finding of a cell-specific, and not organ-specific, redundancy of MENA protein expression noted for the first time in VASP-/- mice is proposed as the reason for the observed distinct cochlear phenotype.
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Affiliation(s)
- Bernhard Schick
- Department of Otolaryngology, University Erlangen-Nürnberg, Waldstrasse 1, 91054, Erlangen, Germany.
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Krause M, Dent EW, Bear JE, Loureiro JJ, Gertler FB. Ena/VASP proteins: regulators of the actin cytoskeleton and cell migration. Annu Rev Cell Dev Biol 2004; 19:541-64. [PMID: 14570581 DOI: 10.1146/annurev.cellbio.19.050103.103356] [Citation(s) in RCA: 508] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ena/VASP proteins are a conserved family of actin regulatory proteins made up of EVH1, EVH2 domains, and a proline-rich central region. They have been implicated in actin-based processes such as fibroblast migration, axon guidance, and T cell polarization and are important for the actin-based motility of the intracellular pathogen Listeria monocytogenes. Mechanistically, these proteins associate with barbed ends of actin filaments and antagonize filament capping by capping protein (CapZ). In addition, they reduce the density of Arp2/3-dependent actin filament branches and bind Profilin at sites of actin polymerization. Vertebrate Ena/VASP proteins are substrates for PKA/PKG serine/threonine kinases. Phosphorylation by these kinases appears to modulate Ena/VASP function within cells, although the mechanism underlying this regulation remains to be determined.
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Affiliation(s)
- Matthias Krause
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Ally S, Sauer NJ, Loureiro JJ, Snapper SB, Gertler FB, Goldberg MB. Shigella interactions with the actin cytoskeleton in the absence of Ena/VASP family proteins. Cell Microbiol 2004; 6:355-66. [PMID: 15009027 DOI: 10.1046/j.1462-5822.2003.00359.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Shigella move through the cytosol of infected cells by assembly of a propulsive actin tail at one end of the bacterium. Vasodilator-stimulated phosphoprotein (VASP), a member of the Ena/VASP family of proteins, is important in cellular actin dynamics and is present on intracellular Shigella. VASP binds both profilin, an actin monomer-binding protein, and vinculin, a component of intercellular contacts that also binds the Shigella actin assembly protein IcsA. It has been postulated that VASP might serve as a linker between vinculin and profilin on intracellular Shigella, thereby delivering profilin to the Shigella actin assembly machinery. We show that Shigella actin-based motility is unaltered in cells that are deficient for the Ena/VASP family of proteins. In these cells, Shigella form normal-appearing actin tails and move at rates that are comparable to the rates of bacterial movement in Ena/VASP-deficient cells complemented with the Ena/VASP family member Mena. Finally, whereas vinculin can bind the Arp2/3 complex, we show that Arp2/3 recruitment to Shigella is not correlated with vinculin recruitment, indicating that the role of vinculin in Shigella motility is not recruitment of Arp2/3. Thus, although VASP is recruited to the surface of intracellular Shigella, it is not essential for Shigella actin-based motility.
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Affiliation(s)
- Shabeen Ally
- Infectious Disease Division, Massachusetts General Hospital, Cambridge, MA 02139, USA
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50
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Massberg S, Grüner S, Konrad I, Garcia Arguinzonis MI, Eigenthaler M, Hemler K, Kersting J, Schulz C, Muller I, Besta F, Nieswandt B, Heinzmann U, Walter U, Gawaz M. Enhanced in vivo platelet adhesion in vasodilator-stimulated phosphoprotein (VASP)-deficient mice. Blood 2004; 103:136-42. [PMID: 12933589 DOI: 10.1182/blood-2002-11-3417] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Platelet adhesion and activation at the vascular wall are the initial steps leading to arterial thrombosis and vascular occlusion. Prostacyclin and nitric oxide inhibit platelet adhesion, acting via cyclic adenosine monophosphate (cAMP)- and cyclic guanosine monophosphate (cGMP)-dependent protein kinases. A major downstream target for both cAMP- and cGMP-dependent protein kinases is the vasodilator-stimulated phosphoprotein (VASP). To test the significance of VASP for the regulation of platelet adhesion in vivo, we studied platelet-vessel wall interactions using VASP-deficient (VASP-/-) mice. Under physiologic conditions, platelet adhesion to endothelial cells was significantly enhanced in VASP null mutants when compared with wild-type mice (P <.05). Platelet recruitment in VASP null mice involved P-selectin and the fibrinogen receptor glycoprotein IIb-IIIa (GPIIb-IIIa). Under pathophysiologic conditions, the loss of VASP increased platelet adhesion to the postischemic intestinal microvasculature, to the atherosclerotic endothelium of ApoE-deficient mice, and to the subendothelial matrix following endothelial denudation (P <.05 vs wild type). Importantly, platelet adhesion in VASP null mutants was unresponsive to nitric oxide. These data show for the first time in vivo that VASP is involved in down-regulation of platelet adhesion to the vascular wall under both physiologic and pathophysiologic conditions.
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Affiliation(s)
- Steffen Massberg
- Deutsches Herzzentrum und 1, Medizinische Klinik, Klinikum rechts der Isar, Technische Universität München, München, Germany.
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