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Chandrasekaran A, Graham K, Stachowiak JC, Rangamani P. Kinetic trapping organizes actin filaments within liquid-like protein droplets. Nat Commun 2024; 15:3139. [PMID: 38605007 PMCID: PMC11009352 DOI: 10.1038/s41467-024-46726-6] [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: 06/05/2023] [Accepted: 03/07/2024] [Indexed: 04/13/2024] Open
Abstract
Several actin-binding proteins (ABPs) phase separate to form condensates capable of curating the actin network shapes. Here, we use computational modeling to understand the principles of actin network organization within VASP condensate droplets. Our simulations reveal that the different actin shapes, namely shells, rings, and mixture states are highly dependent on the kinetics of VASP-actin interactions, suggesting that they arise from kinetic trapping. Specifically, we show that reducing the residence time of VASP on actin filaments reduces degree of bundling, thereby promoting assembly of shells rather than rings. We validate the model predictions experimentally using a VASP-mutant with decreased bundling capability. Finally, we investigate the ring opening within deformed droplets and found that the sphere-to-ellipsoid transition is favored under a wide range of filament lengths while the ellipsoid-to-rod transition is only permitted when filaments have a specific range of lengths. Our findings highlight key mechanisms of actin organization within phase-separated ABPs.
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Affiliation(s)
- Aravind Chandrasekaran
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093-0411, USA
| | - Kristin Graham
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78712, USA
| | - Jeanne C Stachowiak
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
- Department of Chemical Engineering, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, 92093-0411, USA.
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2
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Graham K, Chandrasekaran A, Wang L, Ladak A, Lafer EM, Rangamani P, Stachowiak JC. Liquid-like VASP condensates drive actin polymerization and dynamic bundling. NATURE PHYSICS 2023; 19:574-585. [PMID: 38405682 PMCID: PMC10887402 DOI: 10.1038/s41567-022-01924-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 12/15/2022] [Indexed: 02/27/2024]
Abstract
The organization of actin filaments into bundles is required for cellular processes such as motility, morphogenesis, and cell division. Filament bundling is controlled by a network of actin-binding proteins. Recently, several proteins that comprise this network have been found to undergo liquid-liquid phase separation. How might liquid-like condensates contribute to filament bundling? Here, we show that the processive actin polymerase and bundling protein, VASP, forms liquid-like droplets under physiological conditions. As actin polymerizes within VASP droplets, elongating filaments partition to the edges of the droplet to minimize filament curvature, forming an actin-rich ring within the droplet. The rigidity of this ring is balanced by the droplet's surface tension, as predicted by a continuum-scale computational model. However, as actin polymerizes and the ring grows thicker, its rigidity increases and eventually overcomes the surface tension of the droplet, deforming into a linear bundle. The resulting bundles contain long, parallel actin filaments that grow from their tips. Significantly, the fluid nature of the droplets is critical for bundling, as more solid droplets resist deformation, preventing filaments from rearranging to form bundles. Once the parallel arrangement of filaments is created within a VASP droplet, it propagates through the addition of new actin monomers to achieve a length that is many times greater than the initial droplet. This droplet-based mechanism of bundling may be relevant to the assembly of cellular architectures rich in parallel actin filaments, such as filopodia, stress fibers, and focal adhesions.
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Affiliation(s)
- Kristin Graham
- University of Texas at Austin, Department of Biomedical Engineering
| | | | - Liping Wang
- University of Texas Health Science Center at San Antonio, Department of Biochemistry and Structural Biology
| | - Aly Ladak
- University of Texas at Austin, Department of Biomedical Engineering
| | - Eileen M Lafer
- University of Texas Health Science Center at San Antonio, Department of Biochemistry and Structural Biology
| | - Padmini Rangamani
- University of California San Diego, Department of Mechanical and Aerospace Engineering
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3
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Afanasyeva TAV, Schnellbach YT, Gibson TJ, Roepman R, Collin RWJ. OUP accepted manuscript. Hum Mol Genet 2022; 31:2560-2570. [PMID: 35253837 PMCID: PMC9396937 DOI: 10.1093/hmg/ddac057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/17/2022] [Accepted: 03/03/2022] [Indexed: 11/14/2022] Open
Abstract
Retinitis pigmentosa (RP) is a genetically heterogeneous form of inherited retinal disease that leads to progressive visual impairment. One genetic subtype of RP, RP54, has been linked to mutations in PCARE (photoreceptor cilium actin regulator). We have recently shown that PCARE recruits WASF3 to the tip of a primary cilium, and thereby activates an Arp2/3 complex which results in the remodeling of actin filaments that drives the expansion of the ciliary tip membrane. On the basis of these findings, and the lack of proper photoreceptor development in mice lacking Pcare, we postulated that PCARE plays an important role in photoreceptor outer segment disk formation. In this study, we aimed to decipher the relationship between predicted structural and function amino acid motifs within PCARE and its function. Our results show that PCARE contains a predicted helical coiled coil domain together with evolutionary conserved binding sites for photoreceptor kinase MAK (type RP62), as well as EVH1 domain-binding linear motifs. Upon deletion of the helical domain, PCARE failed to localize to the cilia. Furthermore, upon deletion of the EVH1 domain-binding motifs separately or together, co-expression of mutant protein with WASF3 resulted in smaller ciliary tip membrane expansions. Finally, inactivation of the lipid modification on the cysteine residue at amino acid position 3 also caused a moderate decrease in the sizes of ciliary tip expansions. Taken together, our data illustrate the importance of amino acid motifs and domains within PCARE in fulfilling its physiological function.
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Affiliation(s)
- Tess A V Afanasyeva
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, GA6525, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, GA6525, The Netherlands
| | - Yan-Ting Schnellbach
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, GA6525, The Netherlands
| | - Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Ronald Roepman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, GA6525, The Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, GA 6525, The Netherlands
| | - Rob W J Collin
- To whom correspondence should be addressed at: Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands. Tel: +31 243613750; Fax: +31 243668752;
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4
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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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Okolo F, Zhang G, Rhodes J, Gittes GK, Potoka DA. Intra-Amniotic Sildenafil Treatment Promotes Lung Growth and Attenuates Vascular Remodeling in an Experimental Model of Congenital Diaphragmatic Hernia. Fetal Diagn Ther 2020; 47:787-799. [PMID: 32663823 DOI: 10.1159/000508986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/26/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Defective lung development resulting in lung hypoplasia and an attenuated and hypermuscularized pulmonary vasculature contributes to significant postnatal mortality in congenital diaphragmatic hernia (CDH). We hypothesize that deficient embryonic pulmonary blood flow contributes to defective lung development in CDH, which may therefore be ameliorated via enhancement of embryonic pulmonary blood flow. METHODS The mouse nitrofen model of CDH was utilized to measure embryonic pulmonary blood flow by in utero intracardiac injection of FITC-labeled tomato lectin and color-flow Doppler ultrasound. The effect of prenatal intra-amniotic treatment with sildenafil on survival, lung growth, and vascular morphology in the nitrofen model was determined. RESULTS Nitrofen-treated embryos exhibited decreased blood flow in the lung periphery compared to controls, and intra-amniotic sildenafil significantly improved embryonic pulmonary blood flow. Similar to nitrofen alone, pups delivered after nitrofen treatment and intra-amniotic injection of dextrose control exhibited respiratory distress and never survived beyond 6 h. Intra-amniotic sildenafil ameliorated respiratory distress in nitrofen-treated pups and improved postnatal survival to 82%. Following intra-amniotic sildenafil treatment at embryonic day (E)10.5, nitrofen-treated P0 lungs were larger with increased left lobe weight, reduced small pulmonary arterial wall muscularization, and increased airway branching complexity compared to controls. Intra-amniotic sildenafil treatment later at E15.5 also resulted in improved survival, lung growth, and attenuation of vascular remodeling in nitrofen-treated embryos. CONCLUSIONS Defective embryonic pulmonary blood flow may contribute to lung maldevelopment in CDH. Enhancement of embryonic pulmonary blood flow via intra-amniotic sildenafil results in lung growth and attenuation of pulmonary vascular remodeling and may have therapeutic potential for CDH.
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Affiliation(s)
- Frances Okolo
- Department of Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - GuangFeng Zhang
- Department of Surgery, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA
| | - Julie Rhodes
- Department of Surgery, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA
| | - George K Gittes
- Department of Surgery, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA,
| | - Douglas A Potoka
- Department of Surgery, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pennsylvania, USA
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6
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Nucleoside analogue activators of cyclic AMP-independent protein kinase A of Trypanosoma. Nat Commun 2019; 10:1421. [PMID: 30926779 PMCID: PMC6440977 DOI: 10.1038/s41467-019-09338-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 03/07/2019] [Indexed: 02/08/2023] Open
Abstract
Protein kinase A (PKA), the main effector of cAMP in eukaryotes, is a paradigm for the mechanisms of ligand-dependent and allosteric regulation in signalling. Here we report the orthologous but cAMP-independent PKA of the protozoan Trypanosoma and identify 7-deaza-nucleosides as potent activators (EC50 ≥ 6.5 nM) and high affinity ligands (KD ≥ 8 nM). A co-crystal structure of trypanosome PKA with 7-cyano-7-deazainosine and molecular docking show how substitution of key amino acids in both CNB domains of the regulatory subunit and its unique C-terminal αD helix account for this ligand swap between trypanosome PKA and canonical cAMP-dependent PKAs. We propose nucleoside-related endogenous activators of Trypanosoma brucei PKA (TbPKA). The existence of eukaryotic CNB domains not associated with binding of cyclic nucleotides suggests that orphan CNB domains in other eukaryotes may bind undiscovered signalling molecules. Phosphoproteome analysis validates 7-cyano-7-deazainosine as powerful cell-permeable inducer to explore cAMP-independent PKA signalling in medically important neglected pathogens.
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Harker AJ, Katkar HH, Bidone TC, Aydin F, Voth GA, Applewhite DA, Kovar DR. Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin. Mol Biol Cell 2019; 30:851-862. [PMID: 30601697 PMCID: PMC6589784 DOI: 10.1091/mbc.e18-08-0500] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately threefold longer processive runs on trailing barbed ends of fascin-bundled F-actin. Here, we used single-molecule TIRFM (total internal reflection fluorescence microscopy) and developed a kinetic model to further dissect Ena/VASP’s processive mechanism on bundled filaments. We discovered that Ena’s enhanced processivity on trailing barbed ends is specific to fascin bundles, with no enhancement on fimbrin or α-actinin bundles. Notably, Ena/VASP’s processive run length increases with the number of both fascin-bundled filaments and Ena “arms,” revealing avidity facilitates enhanced processivity. Consistently, Ena tetramers form more filopodia than mutant dimer and trimers in Drosophila culture cells. Moreover, enhanced processivity on trailing barbed ends of fascin-bundled filaments is an evolutionarily conserved property of Ena/VASP homologues, including human VASP and Caenorhabditis elegans UNC-34. These results demonstrate that Ena tetramers are tailored for enhanced processivity on fascin bundles and that avidity of multiple arms associating with multiple filaments is critical for this process. Furthermore, we discovered a novel regulatory process whereby bundle size and bundling protein specificity control activities of a processive assembly factor.
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Affiliation(s)
- Alyssa J Harker
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| | - Harshwardhan H Katkar
- Department of Chemistry, cThe James Franck Institute, and dInstitute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637.,Department of Biology, Reed College, Portland, OR 97202
| | - Tamara C Bidone
- Department of Chemistry, cThe James Franck Institute, and dInstitute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637.,Department of Biology, Reed College, Portland, OR 97202
| | - Fikret Aydin
- Department of Chemistry, cThe James Franck Institute, and dInstitute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637.,Department of Biology, Reed College, Portland, OR 97202
| | - Gregory A Voth
- Department of Chemistry, cThe James Franck Institute, and dInstitute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637.,Department of Biology, Reed College, Portland, OR 97202
| | | | - David R Kovar
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637.,Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
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8
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Tan HT, Chung MCM. Label-Free Quantitative Phosphoproteomics Reveals Regulation of Vasodilator-Stimulated Phosphoprotein upon Stathmin-1 Silencing in a Pair of Isogenic Colorectal Cancer Cell Lines. Proteomics 2018; 18:e1700242. [PMID: 29460479 DOI: 10.1002/pmic.201700242] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 02/10/2018] [Indexed: 02/06/2023]
Abstract
In this communication, we present the phosphoproteome changes in an isogenic pair of colorectal cancer cell lines, viz., the poorly metastatic HCT-116 and the highly metastatic derivative E1, upon stathmin-1 (STMN1) knockdown. The aim was to better understand how the alterations of the phosphoproteins in these cells are involved in cancer metastasis. After the phosphopeptides were enriched using the TiO2 HAMMOC approach, comparative proteomics analysis was carried out using sequential window acquisition of all theoretical mass spectra-MS. Following bioinformatics analysis using MarkerView and OneOmics platforms, we identified a list of regulated phosphoproteins that may play a potential role in signaling, maintenance of cytoskeletal structure, and focal adhesion. Among these phosphoproteins, was the actin cytoskeleton regulator protein, vasodilator-stimulated phosphoprotein (VASP), where its change in phosphorylation status was found to be concomitant with STMN1-associated roles in metastasis. We further showed that silencing of stathmin-1 altered the expression, subcellular localization and phosphorylation status of VASP, which suggested that it might be associated with remodeling of the cell cytoskeleton in colorectal cancer metastasis.
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Affiliation(s)
- Hwee Tong Tan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Maxey Ching Ming Chung
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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9
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Abstract
Animal cell migration constitutes a complex process involving a multitude of forces generated and maintained by the actin cytoskeleton. Dynamic changes of the cell surface, for instance to effect cell edge protrusion, are at the core of initiating migratory processes, both in tissue culture models and whole animals. Here we sketch different aspects of imaging representative molecular constituents in such actin-driven processes, which power and regulate the polymerisation of actin filaments into bundles and networks, constituting the building blocks of such protrusions. The examples presented illustrate both the diversity of subcellular distributions of distinct molecular components, according to their function, and the complexity of dynamic changes in protrusion size, shape, and/or orientation in 3D. Considering these dynamics helps mechanistically connecting subcellular distributions of molecular machines driving protrusion and migration with their biochemical function.
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Affiliation(s)
- Anika Steffen
- Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Frieda Kage
- Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany. .,Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
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10
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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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11
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Yu-Kemp HC, Kemp JP, Brieher WM. CRMP-1 enhances EVL-mediated actin elongation to build lamellipodia and the actin cortex. J Cell Biol 2017. [PMID: 28630144 PMCID: PMC5551698 DOI: 10.1083/jcb.201606084] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
CRMP proteins regulate the cytoskeleton, but the underlying mechanisms are poorly understood. Yu-Kemp et al. show that CRMP-1 helps Ena/VASP proteins elongate actin filaments to assemble actin networks that are necessary for the integrity of epithelial sheets. Cells can control actin polymerization by nucleating new filaments or elongating existing ones. We recently identified CRMP-1 as a factor that stimulates the formation of Listeria monocytogenes actin comet tails, thereby implicating it in actin assembly. We now show that CRMP-1 is a major contributor to actin assembly in epithelial cells, where it works with the Ena/VASP family member EVL to assemble the actin cytoskeleton in the apical cortex and in protruding lamellipodia. CRMP-1 and EVL bind to one another and together accelerate actin filament barbed-end elongation. CRMP-1 also stimulates actin assembly in the presence of VASP and Mena in vitro, but CRMP-1–dependent actin assembly in MDCK cells is EVL specific. Our results identify CRMP-1 as a novel regulator of actin filament elongation and reveal a surprisingly important role for CRMP-1, EVL, and actin polymerization in maintaining the structural integrity of epithelial sheets.
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Affiliation(s)
- Hui-Chia Yu-Kemp
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - James P Kemp
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - William M Brieher
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
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12
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Shahin MH, Sá AC, Webb A, Gong Y, Langaee T, McDonough CW, Riva A, Beitleshees AL, Chapman AB, Gums JG, Turner ST, Boerwinkle E, Scherer SE, Sadee W, Cooper-DeHoff RM, Johnson JA. Genome-Wide Prioritization and Transcriptomics Reveal Novel Signatures Associated With Thiazide Diuretics Blood Pressure Response. ACTA ACUST UNITED AC 2017; 10:CIRCGENETICS.116.001404. [PMID: 28115488 DOI: 10.1161/circgenetics.116.001404] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 11/21/2016] [Indexed: 01/02/2023]
Abstract
BACKGROUND Thiazide diuretics are among the most commonly prescribed antihypertensives. However, <50% of thiazide-treated patients achieve blood pressure (BP) control. Herein, we used different omics (genomics and transcriptomics) to identify novel biomarkers of thiazide diuretics BP response. METHODS AND RESULTS Genome-wide analysis included 228 white hypertensives with BP determined at baseline and after 9 weeks of hydrochlorothiazide. Single-nucleotide polymorphisms with P <5×10-5 were prioritized according to their biological function, using RegulomeDB, haploreg, and Genome-Wide Annotation of Variants. The results from the prioritization approach revealed rs10995 as the most likely functional single-nucleotide polymorphism, among single-nucleotide polymorphisms tested, that has been associated with hydrochlorothiazide BP response. The rs10995 G-allele was associated with better BP response to hydrochlorothiazide versus noncarriers (Δ systolic BP/Δ diastolic BP: -12.3/-8.2 versus -6.8/-3.5 mm Hg, respectively, Δ systolic BP P=3×10-4, Δ diastolic BP P=5×10-5). This association was replicated in independent participants treated with chlorthalidone. In addition, rs10995 G-allele was associated with increased mRNA expression of VASP (vasodilator-stimulated phosphoprotein). Moreover, baseline expression of the VASP mRNA was significantly higher in 25 good responders to hydrochlorothiazide compared with 25 poor responders (P=0.01). This finding was replicated in independent participants treated with chlorthalidone (P=0.04). Last, allelic-specific expression analysis revealed a significant but modest imbalance with rs10995 and rs10156, a single-nucleotide polymorphism in high linkage disequilibrium (r2=0.7) with rs10995, which both could contribute to the observed genetic effects by affecting VASP mRNA expression. CONCLUSIONS This study highlights the strength of using different omics to identify novel biomarkers of drug response and suggests VASP as a potential determinant of thiazide diuretics BP response. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00246519 and NCT01203852.
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13
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Shen K, Johnson DW, Gobe GC. The role of cGMP and its signaling pathways in kidney disease. Am J Physiol Renal Physiol 2016; 311:F671-F681. [PMID: 27413196 DOI: 10.1152/ajprenal.00042.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/10/2016] [Indexed: 01/20/2023] Open
Abstract
Cyclic nucleotide signal transduction pathways are an emerging research field in kidney disease. Activated cell surface receptors transduce their signals via intracellular second messengers such as cAMP and cGMP. There is increasing evidence that regulation of the cGMP-cGMP-dependent protein kinase 1-phosphodiesterase (cGMP-cGK1-PDE) signaling pathway may be renoprotective. Selective PDE5 inhibitors have shown potential in treating kidney fibrosis in patients with chronic kidney disease (CKD), via their downstream signaling, and these inhibitors also have known activity as antithrombotic and anticancer agents. This review gives an outline of the cGMP-cGK1-PDE signaling pathways and details the downstream signaling and regulatory functions that are modulated by cGK1 and PDE inhibitors with regard to antifibrotic, antithrombotic, and antitumor activity. Current evidence that supports the renoprotective effects of regulating cGMP-cGK1-PDE signaling is also summarized. Finally, the effects of icariin, a natural plant extract with PDE5 inhibitory function, are discussed. We conclude that regulation of cGMP-cGK1-PDE signaling might provide novel, therapeutic strategies for the worsening global public health problem of CKD.
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Affiliation(s)
- Kunyu Shen
- Centre for Kidney Disease Research, School of Medicine, Translational Research Institute, The University of Queensland, Brisbane, Australia; Second School of Clinical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China; and
| | - David W Johnson
- Centre for Kidney Disease Research, School of Medicine, Translational Research Institute, The University of Queensland, Brisbane, Australia; Department of Nephrology, Princess Alexandra Hospital, Brisbane, Australia
| | - Glenda C Gobe
- Centre for Kidney Disease Research, School of Medicine, Translational Research Institute, The University of Queensland, Brisbane, Australia;
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14
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Tariq N, Basharat Z, Butt S, Baig DN. Distribution analysis of profilin isoforms at transcript resolution with mRNA-seq and secondary structure in various organs of Rattus norvegicus. Gene 2016; 589:49-55. [PMID: 27185630 DOI: 10.1016/j.gene.2016.05.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 11/15/2022]
Abstract
Profilin (Pfn) is an actin binding protein, ubiquitously found in mammals and is essential for the actin polymerization in cells. In brain, it plays a pivotal role in neurogenesis and synapse formation by interacting with various proteins. Four Pfn isoforms have been identified in mammals. This study presents the identification and transcriptional expression of various Pfn isoforms (Pfn1, Pfn2, Pfn3 and Pfn4) in brain, heart, kidney, liver, and muscle and testis of Rattus norvegicus. Organs have been classified into groups based on some similarities. Group I includes brain and testis, Group II includes skeletal muscle and heart, while Group III includes kidney and liver. Pfn1 has been identified in all groups, Pfn2 and Pfn3 have been identified in group I, group III and in one organ (skeletal muscle) of group II. To the best of the authors knowledge, no report of Pfn1 and Pfn2 presence in testis, Pfn3 in brain, liver and skeletal muscle, Pfn4 in kidney and skeletal muscle exists to date. Transcriptional expression showed variations among expression level of different Pfn isoforms in various organs with respect to the control gene GADPH. We hypothesize that this could be attributed to profilin isoform specific mRNA structure and corresponding motifs, which generally contribute to similar or varied decay rates, cellular localization, post transcriptional regulation pattern and ligand binding.
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Affiliation(s)
- Naila Tariq
- Department of Biological sciences, Forman Christian College (A Chartered University), 54600 Lahore, Pakistan
| | - Zarrin Basharat
- Department of Environmental Sciences, Fatima Jinnah Women University, 46000 Rawalpindi, Pakistan
| | - Saba Butt
- Department of Biological sciences, Forman Christian College (A Chartered University), 54600 Lahore, Pakistan
| | - Deeba Noreen Baig
- Department of Biological sciences, Forman Christian College (A Chartered University), 54600 Lahore, Pakistan
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15
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Namba T, Funahashi Y, Nakamuta S, Xu C, Takano T, Kaibuchi K. Extracellular and Intracellular Signaling for Neuronal Polarity. Physiol Rev 2015; 95:995-1024. [PMID: 26133936 DOI: 10.1152/physrev.00025.2014] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Neurons are one of the highly polarized cells in the body. One of the fundamental issues in neuroscience is how neurons establish their polarity; therefore, this issue fascinates many scientists. Cultured neurons are useful tools for analyzing the mechanisms of neuronal polarization, and indeed, most of the molecules important in their polarization were identified using culture systems. However, we now know that the process of neuronal polarization in vivo differs in some respects from that in cultured neurons. One of the major differences is their surrounding microenvironment; neurons in vivo can be influenced by extrinsic factors from the microenvironment. Therefore, a major question remains: How are neurons polarized in vivo? Here, we begin by reviewing the process of neuronal polarization in culture conditions and in vivo. We also survey the molecular mechanisms underlying neuronal polarization. Finally, we introduce the theoretical basis of neuronal polarization and the possible involvement of neuronal polarity in disease and traumatic brain injury.
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Affiliation(s)
- Takashi Namba
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yasuhiro Funahashi
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shinichi Nakamuta
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Chundi Xu
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tetsuya Takano
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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16
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Wu Y, Gunst SJ. Vasodilator-stimulated phosphoprotein (VASP) regulates actin polymerization and contraction in airway smooth muscle by a vinculin-dependent mechanism. J Biol Chem 2015; 290:11403-16. [PMID: 25759389 DOI: 10.1074/jbc.m115.645788] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Indexed: 11/06/2022] Open
Abstract
Vasodilator-stimulated phosphoprotein (VASP) can catalyze actin polymerization by elongating actin filaments. The elongation mechanism involves VASP oligomerization and its binding to profilin, a G-actin chaperone. Actin polymerization is required for tension generation during the contraction of airway smooth muscle (ASM); however, the role of VASP in regulating actin dynamics in ASM is not known. We stimulated ASM cells and tissues with the contractile agonist acetylcholine (ACh) or the adenylyl cyclase activator, forskolin (FSK), a dilatory agent. ACh and FSK stimulated VASP Ser(157) phosphorylation by different kinases. Inhibition of VASP Ser(157) phosphorylation by expression of the mutant VASP S157A in ASM tissues suppressed VASP phosphorylation and membrane localization in response to ACh, and also inhibited contraction and actin polymerization. ACh but not FSK triggered the formation of VASP-VASP complexes as well as VASP-vinculin and VASP-profilin complexes at membrane sites. VASP-VASP complex formation and the interaction of VASP with vinculin and profilin were inhibited by expression of the inactive vinculin mutant, vinculin Y1065F, but VASP phosphorylation and membrane localization were unaffected. We conclude that VASP phosphorylation at Ser(157) mediates its localization at the membrane, but that VASP Ser(157) phosphorylation and membrane localization are not sufficient to activate its actin catalytic activity. The interaction of VASP with activated vinculin at membrane adhesion sites is a necessary prerequisite for VASP-mediated molecular processes necessary for actin polymerization. Our results show that VASP is a critical regulator of actin dynamics and tension generation during the contractile activation of ASM.
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Affiliation(s)
- Yidi Wu
- From the Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
| | - Susan J Gunst
- From the Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana 46202-5120
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17
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Greenwood AI, Kwon J, Nicholson LK. Isomerase-catalyzed binding of interleukin-1 receptor-associated kinase 1 to the EVH1 domain of vasodilator-stimulated phosphoprotein. Biochemistry 2014; 53:3593-607. [PMID: 24857403 DOI: 10.1021/bi500031e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Interleukin-1 receptor-associated kinase 1 (IRAK1) is a crucial signaling kinase in the immune system, involved in Toll-like receptor signaling. Vasodilator-stimulated phosphoprotein (VASP) is a central player in cell migration that regulates actin polymerization and connects signaling events to cytoskeletal remodeling. A VASP–IRAK1 interaction is thought to be important in controlling macrophage migration in response to protein kinase C-ε activation. We show that the monomeric VASP EVH1 domain directly binds to the 168WPPPP172 motif in the IRAK1 undefined domain (IRAK1-UD) with moderate affinity (KDApp = 203 ± 3 μM). We further show that this motif adopts distinct cis and trans isomers for the Trp168–Pro169 peptide bond with nearly equal populations, and that binding to the VASP EVH1 domain is specific for the trans isomer, coupling binding to isomerization. Nuclear magnetic resonance line shape analysis and tryptophan fluorescence experiments reveal the complete kinetics and thermodynamics of the binding reaction, showing diffusion-limited binding to the trans isomer followed by slow, isomerization-dependent binding. We further demonstrate that the peptidyl-prolyl isomerase cyclophilin A (CypA) catalyzes isomerization of the Trp168–Pro169 peptide bond and accelerates binding of the IRAK1-UD to the VASP EVH1 domain. We propose that binding of IRAK1 to tetrameric VASP is regulated by avidity through the assembly of IRAK1 onto receptor-anchored signaling complexes and that an isomerase such as CypA may modulate IRAK1 signaling in vivo. These studies demonstrate a direct interaction between IRAK1 and VASP and suggest a potential mechanism for how this interaction might be regulated by both assembly of IRAK1 onto an activated signaling complex and PPIase enzymes.
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Affiliation(s)
- Alexander I Greenwood
- Department of Molecular Biology and Genetics, Cornell University , Ithaca, New York 14853, United States
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18
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Carlier MF, Pernier J, Avvaru BS. Control of actin filament dynamics at barbed ends by WH2 domains: From capping to permissive and processive assembly. Cytoskeleton (Hoboken) 2013; 70:540-9. [DOI: 10.1002/cm.21124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/27/2013] [Accepted: 07/01/2013] [Indexed: 01/01/2023]
Affiliation(s)
| | - Julien Pernier
- Cytoskeleton Dynamics and Motility Team; LEBS; CNRS; Gif-Sur-Yvette France
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19
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MULLER SYLVAINE, WEI LEI, LIU YUNGMING, LI KE, WANG XIONG, WANG BAOHA, OUYANG JINGPING, STOLTZ JEANFRANÇOIS. EXPRESSION AND LOCATION OF VASP IN HUMAN ENDOTHELIAL CELLS: EFFECT OF A LAMINAR SHEAR STRESS. J MECH MED BIOL 2011. [DOI: 10.1142/s0219519403000600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Recent elucidation of the primary VASP (vasodilator-simulated phosphoprotein) and identity of VASP binding proteins suggests that VASP is an important component of focal contacts which links signal transduction pathways and elements controlling cell motility. The aim of our study was to evaluate shear-stress-induced changes of VASP expression and localization in ECs. We showed, by western blotting measurements, that the shear stress involve some modifications on the expression of phosphorilated (50 kD) and non phosphorilated (46kD) VASP. Moreover, a fluorescence double-labeling shows the location of VASP on the actin fibers. At rest, ECs showed an array of microfilament bundles of the actin fibers and VASP were along their entire length. After exposure to shear stress, the stress fibers appeared and were oriented along with the flow. There were a thicker expression of VASP than in control, targeted to the ends of stress fibres. This seems to be an adjustment of the cells towards the mechanical stresses. These results suggest that VASP is a potential important component which participates in the regulation of cell actin remodelling induced by shear flow. VASP were involved in the mechano-transduction pathways.
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Affiliation(s)
- SYLVAINE MULLER
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
| | - LEI WEI
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
- Departement of pathophysiology, Medical College of Wuhan University, Wuhan, China
| | - YUNGMING LIU
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
- Departement of pathophysiology, Medical College of Wuhan University, Wuhan, China
| | - KE LI
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
- Departement of pathophysiology, Medical College of Wuhan University, Wuhan, China
| | - XIONG WANG
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
| | - BAOHA WANG
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
- Departement of pathophysiology, Medical College of Wuhan University, Wuhan, China
| | - JINGPING OUYANG
- Departement of pathophysiology, Medical College of Wuhan University, Wuhan, China
| | - JEAN-FRANÇOIS STOLTZ
- Mécanique et Ingénierie Cellulaire et Tissulaire, LEMTA UMR 7563 CNRS, Faculté de médecine, 54505 Vandoeuvre-les-Nancy, France
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20
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Phosphorylation of VASP by AMPK alters actin binding and occurs at a novel site. Biochem Biophys Res Commun 2011; 414:215-9. [DOI: 10.1016/j.bbrc.2011.09.059] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 09/13/2011] [Indexed: 10/17/2022]
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21
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Profirovic J, Han J, Andreeva AV, Neamu RF, Pavlovic S, Vogel SM, Walter U, Voyno-Yasenetskaya TA. Vasodilator-stimulated phosphoprotein deficiency potentiates PAR-1-induced increase in endothelial permeability in mouse lungs. J Cell Physiol 2011; 226:1255-64. [PMID: 20945373 DOI: 10.1002/jcp.22453] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is implicated in the protection of the endothelial barrier in vitro and in vivo. The function of VASP in thrombin signaling in the endothelial cells (ECs) is not known. For the first time we studied the effects of VASP deficiency on EC permeability and pulmonary vascular permeability in response to thrombin receptor stimulation. We provided the evidence that VASP deficiency potentiates the increase in endothelial permeability induced by activation of thrombin receptor in cultured human umbilical vein endothelial cells (HUVECs) and isolated mouse lungs. Using transendothelial resistance measurement, we showed that siRNA-mediated VASP downregulation in HUVECs leads to a potentiation of thrombin- and protease-activated receptor 1 (PAR-1) agonist-induced increase in endothelial permeability. Compared to control cells, VASP-deficient HUVECs had delayed endothelial junctional reassembly and abrogated VE-cadherin cytoskeletal anchoring in the recovery phase after thrombin stimulation, as demonstrated by immunofluorescence studies and cell fractionation analysis, respectively. Measurement of the capillary filtration coefficient in isolated mouse lungs demonstrated that VASP(-/-) mice have increased microvascular permeability in response to infusion with PAR-1 agonist compared to wild type mice. Lack of VASP led to decreased Rac1 activation both in VASP-deficient HUVECs after thrombin stimulation and VASP(-/-) mouse lungs after PAR-1 agonist infusion, indicating that VASP effects on thrombin signaling may be correlated with changes in Rac1 activity. This study demonstrates that VASP may play critical and complex role in the regulation of thrombin-dependent disruption of the endothelial barrier function.
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Affiliation(s)
- Jasmina Profirovic
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA.
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22
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Routray C, Liu C, Yaqoob U, Billadeau DD, Bloch KD, Kaibuchi K, Shah VH, Kang N. Protein kinase G signaling disrupts Rac1-dependent focal adhesion assembly in liver specific pericytes. Am J Physiol Cell Physiol 2011; 301:C66-74. [PMID: 21451103 DOI: 10.1152/ajpcell.00038.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Nitric oxide (NO) regulates the function of perivascular cells (pericytes), including hepatic stellate cells (HSC), mainly by activating cGMP and cGMP-dependent kinase (PKG) via NO/cGMP paracrine signaling. Although PKG is implicated in integrin-mediated cell adhesion to extracellular matrix, whether or how PKG signaling regulates the assembly of focal adhesion complexes (FA) and migration of HSC is not known. With the help of complementary molecular and cell biological approaches, we demonstrate here that activation of PKG signaling in HSC inhibits vascular tubulogenesis, migration/chemotaxis, and assembly of mature FA plaques, as assessed by vascular tubulogenesis assays and immunofluorescence localization of FA markers such as vinculin and vasodilator-stimulated phosphoprotein (VASP). To determine whether PKG inhibits FA assembly by phosphorylation of VASP at Ser-157, Ser-239, and Thr-278, we mutated these putative phosphorylation sites to alanine (VASP3A, phosphoresistant mutant) or aspartic acid (VASP3D, phosphomimetic), respectively. Data generated from these two mutants suggest that the effect of PKG on FA is independent of these three phosphorylation sites. In contrast, activation of PKG inhibits the activity of small GTPase Rac1 and its association with the effector protein IQGAP1. Moreover, PKG activation inhibits the formation of a trimeric protein complex containing Rac1, IQGAP1, and VASP. Finally, we found that expression of a constitutively active Rac1 mutant abolishes the inhibitory effects of PKG on FA formation. In summary, our data suggest that activation of PKG signaling in pericytes inhibits FA formation by inhibiting Rac1.
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Affiliation(s)
- Chittaranjan Routray
- GI Research Unit and Cancer Cell Biology Program, Mayo Clinic, Rochester, Minnesota 55905, USA
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23
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Tuduce IL, Schuh K, Bundschu K. Spred2 expression during mouse development. Dev Dyn 2010; 239:3072-85. [DOI: 10.1002/dvdy.22432] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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24
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Kang N, Yaqoob U, Geng Z, Bloch K, Liu C, Gomez T, Billadeau D, Shah V. Focal adhesion assembly in myofibroblasts fosters a microenvironment that promotes tumor growth. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:1888-900. [PMID: 20802179 DOI: 10.2353/ajpath.2010.100187] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cells within the tumor microenvironment influence tumor growth through multiple mechanisms. Pericytes such as hepatic stellate cells are an important cell within the tumor microenvironment; their transformation into highly motile myofibroblasts leads to angiogenesis, stromal cell recruitment, matrix deposition, and ensuing tumor growth. Thus, a better understanding of mechanisms that regulate motility of pericytes is required. Focal adhesions (FAs) form a physical link between the extracellular environment and the actin cytoskeleton, a requisite step for cell motility. FAs contain a collection of proteins including the Ena/VASP family member, vasodilator-stimulated phosphoprotein (VASP); however, a role for VASP in FA development has been elusive. Using a comprehensive siRNA knockdown approach and a variety of VASP mutants coupled with complementary cell imaging methodologies, we demonstrate a requirement of VASP for optimal development of FAs and cell spreading in LX2 liver myofibroblasts, which express high levels of endogenous VASP. Rac1, a binding partner of VASP, acts in tandem with VASP to regulate FAs. In vivo, perturbation of Ena/VASP function in tumor myofibroblast precursor cells significantly reduces pericyte recruitment to tumor vasculature, myofibroblastic transformation, tumor angiogenesis, and tumor growth, providing in vivo pathobiologic relevance to these findings. Taken together, our results identify Ena/VASP as a significant modifier of tumor growth through regulation of FA dynamics and ensuing pericyte/myofibroblast function within the tumor microenvironment.
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25
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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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26
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Vimentin expression influences flow dependent VASP phosphorylation and regulates cell migration and proliferation. Biochem Biophys Res Commun 2010; 395:401-6. [DOI: 10.1016/j.bbrc.2010.04.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 04/05/2010] [Indexed: 12/21/2022]
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27
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Chesarone MA, Goode BL. Actin nucleation and elongation factors: mechanisms and interplay. Curr Opin Cell Biol 2009; 21:28-37. [PMID: 19168341 DOI: 10.1016/j.ceb.2008.12.001] [Citation(s) in RCA: 213] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 12/09/2008] [Accepted: 12/19/2008] [Indexed: 11/18/2022]
Abstract
Cells require actin nucleators to catalyze the de novo assembly of filaments and actin elongation factors to control the rate and extent of polymerization. Nucleation and elongation factors identified to date include Arp2/3 complex, formins, Ena/VASP, and newcomers Spire, Cobl, and Lmod. Here, we discuss recent advances in understanding their activities and mechanisms and new evidence for their cooperation and interaction in vivo. Earlier models had suggested that different nucleators function independently to assemble distinct actin arrays. However, more recent observations indicate that the construction of most cellular actin networks depends on the activities of multiple actin assembly-promoting factors working in concert.
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Affiliation(s)
- Melissa A Chesarone
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
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28
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Schlegel N, Waschke J. VASP is involved in cAMP-mediated Rac 1 activation in microvascular endothelial cells. Am J Physiol Cell Physiol 2008; 296:C453-62. [PMID: 19118163 DOI: 10.1152/ajpcell.00360.2008] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulating evidence points to a significant role of vasodilator-stimulated phosphoprotein (VASP) in the maintenance of endothelial barrier functions. We have recently shown that impaired barrier functions in VASP-deficient microvascular myocardial endothelial cells (MyEnd VASP(-/-)) correlated with decreased Rac 1 activity. To further test the hypothesis that VASP is involved in regulation of Rac 1 activity, we studied cAMP-dependent Rac 1 activation. Both inhibition of Rac 1 activation by NSC-23766 and inhibition of PKA by PKI completely blunted the efficacy of forskolin/rolipram (F/R)-mediated cAMP increase to stabilize barrier functions as revealed by measurements of transendothelial resistance (TER). Because these results indicate that PKA/Rac 1 activation is important for barrier stabilization, we tested this signaling pathway in VASP(-/-) cells. We found that F/R and isoproterenol reduced permeability measured as FITC-dextran flux across VASP(-/-) monolayers, but not below baseline levels of wild-type cells (WT). Moreover, cAMP-mediated Rac 1 activation was reduced to approximately 50% of WT levels, and both PKA inhibition by PKI and PKA anchoring via A kinase anchoring peptides (AKAPs) by HT31 almost completely abolished Rac 1 activation in VASP(-/-) and WT endothelium. Accordingly, HT31 significantly reduced F/R-mediated TER increase in WT cells and completely blocked the protective effect of cAMP on endothelial barrier properties. Together, our data underline the significant role of cAMP-mediated Rac 1 activation for endothelial barrier stabilization and demonstrate that both AKAP-mediated PKA anchoring and VASP are required for this process.
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Affiliation(s)
- Nicolas Schlegel
- Institute of Anatomy and Cell Biology, Julius-Maximilians-Univ., Koellikerstr. 6, 97070 Würzburg, Germany
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29
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Knauer O, Binai NA, Carra G, Beckhaus T, Hanschmann KM, Renné T, Backert S, Karas M, Wessler S. Differential phosphoproteome profiling reveals a functional role for VASP in Helicobacter pylori-induced cytoskeleton turnover in gastric epithelial cells. Cell Microbiol 2008; 10:2285-96. [PMID: 18637808 DOI: 10.1111/j.1462-5822.2008.01207.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Infection with Helicobacter pylori induces various gastric diseases, including ulceration, gastritis and neoplasia. As H. pylori-induced cellular mechanisms leading to these disease states are widely unclear, we analysed the phosphoproteome of H. pylori-infected gastric epithelial cells. Phosphoproteins from infected cells were enriched using affinity columns and analysed by two-dimensional gel electrophoresis and mass spectrometry. Eleven novel phosphoproteins that showed differentially regulated phosphorylation levels during H. pylori infection were identified. Interestingly, the identified proteins were actin-binding, transport and folding, RNA/DNA-binding or cancer-associated proteins. We analysed functions of one identified H. pylori-regulated candidate, the vasodilator-stimulated phosphoprotein (VASP). H. pylori induced VASP phosphorylation at residues Ser157, Ser239 and Thr278, which was enhanced by the bacterial oncogene cytotoxin-associated gene A. Overexpression of a phosphorylation-resistant VASP mutant efficiently blocked host cell elongation. We identified cGMP-dependent protein kinase G-mediated Ser239 and Thr278 phosphorylation of VASP as a crucial event in H. pylori-dependent host cell elongation. These results suggest that phosphorylated VASP could be a novel target candidate for therapeutic intervention in H. pylori-related gastric diseases.
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Affiliation(s)
- Olivia Knauer
- Junior Research Group, Paul-Ehrlich Institute, Paul-Ehrlich Str. 51-59, D-63225 Langen, Germany
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30
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Dickinson RB. Models for actin polymerization motors. J Math Biol 2008; 58:81-103. [PMID: 18612640 DOI: 10.1007/s00285-008-0200-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 06/06/2008] [Indexed: 01/06/2023]
Abstract
Actin polymerization drives cell membrane protrusions and the propulsion of intracellular pathogens. The molecular mechanisms driving actin polymerization are not yet fully understood. Various mathematical models have been proposed to explain how cells convert chemical energy released upon actin polymerization into a pushing force on a surface. These models have attempted to explain puzzling properties of actin-based motility, including persistent attachment of the network to the membrane during propulsion and the interesting trajectories of propelled particles. These models fall generally into two classes: those requiring filament (+)-ends to fluctuate freely from the membrane to add subunits, and those where filaments elongate with their (+)-ends persistently associated with surface through filament end-tracking proteins ("actoclampin" models). This review compares and contrasts the key predictions of these two classes of models with regard to force-velocity profiles, and evaluates them with respect to experiments with biomimetic particles, and the experimental evidence on the role of end-tracking proteins such as formins and nucleation-promoting factors in actin-based motility.
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Affiliation(s)
- Richard B Dickinson
- Departments of Chemical Engineering and Biomedical Engineering, University of Florida, Gainesville, FL, 32611, USA.
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31
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Kursula P, Kursula I, Massimi M, Song YH, Downer J, Stanley WA, Witke W, Wilmanns M. High-resolution Structural Analysis of Mammalian Profilin 2a Complex Formation with Two Physiological Ligands: The Formin Homology 1 Domain of mDia1 and the Proline-rich Domain of VASP. J Mol Biol 2008; 375:270-90. [DOI: 10.1016/j.jmb.2007.10.050] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 10/15/2007] [Accepted: 10/17/2007] [Indexed: 12/28/2022]
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Holtzman JH, Woronowicz K, Golemi-Kotra D, Schepartz A. Miniature protein ligands for EVH1 domains: interplay between affinity, specificity, and cell motility. Biochemistry 2007; 46:13541-53. [PMID: 17973491 PMCID: PMC2659575 DOI: 10.1021/bi700975f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dynamic rearrangements of the actin cytoskeleton power cell motility in contexts ranging from intracellular microbial pathogenesis to axon guidance. The Ena/VASP family proteins-Mena, VASP, and Evl-are believed to control cell motility by serving as a direct link between signaling events and the actin cytoskeleton. It has previously been reported that a novel miniature protein, pGolemi, binds with high affinity to the EVH1 domain of Mena (Mena1-112) but not to those of VASP (VASP1-115) or Evl (Evl1-115) and also causes an unusual defect in actin-driven Listeria monocytogenes motility. Here, scanning mutagenesis was used to examine the effects of single amino acid changes within pGolemi on EVH1 domain affinity and specificity, miniature protein secondary structure, and L. monocytogenes motility. The data suggest that pGolemi contains the expected aPP-like fold and binds Mena1-112 in a manner highly analogous to the proline-rich repeat region of L. monocytogenes ActA protein. Residues throughout pGolemi contribute to both EVH1 domain affinity and paralog specificity. Moreover, the affinities of pGolemi variants for Mena1-112 correlate with selectivity against the EVH1 domains of VASP and Evl. In L. monocytogenes motility assays, speed and speed variability correlate strongly with EVH1 paralog specificity, suggesting that the Ena/VASP paralogs do not play equivalent roles in the process of L. monocytogenes actin tail maturation.
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Furman C, Sieminski AL, Kwiatkowski AV, Rubinson DA, Vasile E, Bronson RT, Fässler R, Gertler FB. Ena/VASP is required for endothelial barrier function in vivo. ACTA ACUST UNITED AC 2007; 179:761-75. [PMID: 17998398 PMCID: PMC2080895 DOI: 10.1083/jcb.200705002] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) proteins are key actin regulators that localize at regions of dynamic actin remodeling, including cellular protrusions and cell–cell and cell–matrix junctions. Several studies have suggested that Ena/VASP proteins are involved in the formation and function of cellular junctions. Here, we establish the importance of Ena/VASP in endothelial junctions in vivo by analysis of Ena/VASP-deficient animals. In the absence of Ena/VASP, the vasculature exhibits patterning defects and lacks structural integrity, leading to edema, hemorrhaging, and late stage embryonic lethality. In endothelial cells, we find that Ena/VASP activity is required for normal F-actin content, actomyosin contractility, and proper response to shear stress. These findings demonstrate that Ena/VASP is critical for actin cytoskeleton remodeling events involved in the maintenance of functional endothelia.
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Affiliation(s)
- Craig Furman
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Scholten A, van Veen TAB, Vos MA, Heck AJR. Diversity of cAMP-Dependent Protein Kinase Isoforms and Their Anchoring Proteins in Mouse Ventricular Tissue. J Proteome Res 2007; 6:1705-17. [PMID: 17432891 DOI: 10.1021/pr060601a] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using a chemical proteomics approach, we efficiently enriched for the generally low abundant cAMP signaling proteins, and their interactors, directly from mouse ventricular tissue. The presence of undesired contaminating (noncyclic) nucleotide-binding proteins was diminished using a tailored sequential elution protocol. Through further optimization of this affinity purification and elution protocol, we were able to detect all known protein kinase A regulatory isoforms (PKA-R). Furthermore, 11 different A-kinase anchoring proteins (AKAPs) were detected. A proposed fusion protein of paralemmin 2 and AKAP2 could be decisively established as a novel AKAP at the protein level in ventricular tissue. When comparing this dataset of cAMP-affinity purified proteins with earlier data obtained with immobilized cGMP from rat ventricular tissue, we observe a large overlap in the retained proteins but also some clear differences. Furthermore, implementation of an in-depth analysis of in vivo phosphorylation sites on PKA-R revealed the presence of several differentially phosphorylated PKA-R isoforms. This illustrates yet another layer of functional regulation in cyclic nucleotide signaling. In general, our improved chemical proteomics screen offers a broad, but detailed, view on nature's complex diversity in cyclic nucleotide signaling mechanisms. Possibly different AKAP-isoforms may direct differentially phosphorylated PKA-R isoforms to different cellular compartments, providing a multifaceted platform for just this kinase.
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Affiliation(s)
- Arjen Scholten
- Department of Biomolecular Mass Spectrometry, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands
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Diakonova M, Helfer E, Seveau S, Swanson JA, Kocks C, Rui L, Carlier MF, Carter-Su C. Adapter protein SH2-Bbeta stimulates actin-based motility of Listeria monocytogenes in a vasodilator-stimulated phosphoprotein (VASP)-dependent fashion. Infect Immun 2007; 75:3581-93. [PMID: 17452473 PMCID: PMC1932951 DOI: 10.1128/iai.00214-07] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
SH2-Bbeta (Src homology 2 Bbeta) is an adapter protein that is required for maximal growth hormone-dependent actin reorganization in membrane ruffling and cell motility. Here we show that SH2-Bbeta is also required for maximal actin-based motility of Listeria monocytogenes. SH2-Bbeta localizes to Listeria-induced actin tails and increases the rate of bacterial propulsion in infected cells and in cell extracts. Furthermore, Listeria motility is decreased in mouse embryo fibroblasts from SH2-B(-/-) mice. Both recruitment of SH2-Bbeta to Listeria and SH2-Bbeta stimulation of actin-based propulsion require the vasodilator-stimulated phosphoprotein (VASP), which binds ActA at the surfaces of Listeria cells and enhances bacterial actin-based motility. SH2-Bbeta enhances actin-based movement of ActA-coated beads in a biomimetic actin-based motility assay, provided that VASP is present. In vitro binding assays show that SH2-Bbeta binds ActA but not VASP; however, binding to ActA is greater in the presence of VASP. Because VASP also plays an essential regulatory role in actin-based processes in eukaryotic cells, the present results provide mechanistic insight into the functions of both SH2-Bbeta and VASP in motility and also increase our understanding of the fundamental mechanism by which Listeria spreads.
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Affiliation(s)
- Maria Diakonova
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA.
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Rosenberger P, Khoury J, Kong T, Weissmüller T, Robinson AM, Colgan SP. Identification of vasodilator-stimulated phosphoprotein (VASP) as an HIF-regulated tissue permeability factor during hypoxia. FASEB J 2007; 21:2613-21. [PMID: 17412998 PMCID: PMC4049288 DOI: 10.1096/fj.06-8004com] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Increased tissue permeability is commonly associated with hypoxia of many origins. Since hypoxia-inducible factor (HIF) represents a predominant hypoxia signaling mechanism, we compared hypoxia-elicited changes in tissue barrier function in mice conditionally lacking intestinal epithelial hypoxia-inducible factor-1alpha (hif1a). Somewhat surprisingly, these studies revealed that mutant hif1a mice were protected from hypoxia-induced increases in intestinal permeability in vivo. Guided by microarray analysis of tissues derived from these mutant hif1a mice, we identified HIF-1-dependent repression of vasodilator-stimulated phosphoprotein (VASP), a molecule known to be important in the control of cytoskeletal dynamics, including barrier function. Studies at the mRNA and protein level confirmed hypoxia-elicited repression of VASP in murine tissue, cultured epithelia and endothelia, as well as human saphenous vein ex vivo. Targeted repression of VASP by siRNA recapitulated our findings with hypoxia and directed overexpression of VASP abolished hypoxia-induced barrier dysfunction. Studies in the cloned human VASP promoter revealed hypoxia-dependent transcriptional repression, and functional studies by chromatin immunoprecipitation (ChIP) and site-directed mutagenesis revealed hypoxia-dependent binding of HIF-1alpha to the human VASP promoter. These studies identify HIF-1-dependent repression of VASP as a control point for hypoxia-regulated barrier dysfunction.
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Affiliation(s)
- Peter Rosenberger
- Department of Anesthesiology and Intensive Care Medicine, Tübingen University Hospital, Tubingen, Germany
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37
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van Werkum JW, van der Stelt CAK, Seesing TH, ten Berg JM, Hackeng CM. The flow cytometric VASP assay can be used to determine the effectiveness of clopidogrel in patients treated with abciximab. J Thromb Haemost 2007; 5:881-3. [PMID: 17263784 DOI: 10.1111/j.1538-7836.2007.02421.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cook ALM, Haynes JM. Phosphorylation of the PKG substrate, vasodilator-stimulated phosphoprotein (VASP), in human cultured prostatic stromal cells. Nitric Oxide 2007; 16:10-7. [PMID: 17049286 DOI: 10.1016/j.niox.2006.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 08/06/2006] [Accepted: 09/05/2006] [Indexed: 11/29/2022]
Abstract
Nitric oxide (NO) is known to regulate contractility and proliferation of cells within the prostate, however, the mechanism by which this occurs is unknown. The cGMP-dependent protein kinase (PKG) signalling pathway may be involved, and recent work has shown that activation of this pathway can be assessed by analysis of phosphorylation of vasodilator-stimulated phosphoprotein (VASP). The aim of the current study is to characterise the expression of VASP in the human prostate and human cultured prostatic stromal cells (HCPSCs), and to investigate whether NO activates PKG in these cells. Our studies revealed that VASP is expressed, and that incubation of HCPSCs with PKG-activating cGMP-analogues or the NO-donor, SNP, caused a significant PKG-dependent increase in VASP serine-239 phosphorylation. In addition, SNP elicited a reduction in intracellular K(+) in a time frame consistent with the phosphorylation of VASP and activation of PKG. These data demonstrate that VASP can be used to assess the NO/cGMP/PKG signalling pathway in HCPSCs. In addition, we demonstrate for the first time that SNP, probably via NO release, leads to phosphorylation of VASP in a manner consistent with PKG activation.
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Affiliation(s)
- Anna-Louise M Cook
- School of Biomedical Sciences, Curtin University of Technology, Bentley, WA, USA
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Tao Y, Chen YC, Wang Y, Zhang ZJ, Xu WR. Phosphorylated vasodilator-stimulated phosphoprotein is localized on mitotic spindles of the gastric cancer cell line SGC-7901. World J Gastroenterol 2006; 12:7478-81. [PMID: 17167837 PMCID: PMC4087594 DOI: 10.3748/wjg.v12.i46.7478] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To elucidate the localization of vasodilator stimulated phosphoprotein (VASP), a cytoskeletal organizing protein and a substrate of protein kinases A and G in mitotic gastric cancer cells.
METHODS: Immunofluorescence microscopy was used to observe the localization of α-tubulin, VASP and Ser157 phosphorylated VASP (p-VASP) in interphase of mitotic gastric cancer of the cell line SGC-7901.
RESULTS: Immunofluorescence staining showed that p-VASP but not VASP was co-localized with α-tubulin on spindle poles and fibers in prophase, metaphase and anaphase of the mitotic process of the gastric cancer cell line SGC-7901. H89, an inhibitor of protein kinases A and G, had no effect on the localization of p-VASP on the spindles.
CONCLUSION: VASP may play a role in assembling and stabilizing the mitotic spindle of cells, and phosphorylation of the protein is the precondition for it to exert this function.
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Affiliation(s)
- Yan Tao
- School of Medicine, Jiangsu University, No. 2 Dongwu Road, Zhenjiang 212001, Jiangsu Province, China
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40
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Abstract
Sprouty-related proteins with an EVH1 domain (Spreds) belong to a new protein family harboring a conserved N-terminal EVH1 domain, which is related to the VASP (vasodilator-stimulated phosphoprotein) EVH1 domain (Enabled/VASP homology 1 domain) and a C-terminal Sprouty-related domain, typical for Sprouty proteins. Spreds were, like Sproutys, initially discovered as inhibitors of the Ras/MAPK pathway, and the SPR (Sprouty-related) domains of both protein families seem to be very important for many protein interactions and cellular processes. VASP was initially characterized as a proline-rich substrate of protein kinases A and G in human platelets and later shown to be a scaffold protein, regulating both signal transduction pathways and the actin filament system. The VASP-EVH1 domain is known to bind specifically to a FP(4) binding motif, which is, for example, present in the focal adhesion proteins vinculin and zyxin. In this review we give a structural and functional overview on these three protein families and ask whether nature plays a modular protein domain puzzle with stable exchangeable elements or if these closely related domains have various functions when pasted in a different protein context.
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Affiliation(s)
- Karin Bundschu
- Abteilung Biochemie und Molekulare Biologie, Universität Ulm, 89081 Ulm, Germany.
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41
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Bournier O, Kroviarski Y, Rotter B, Nicolas G, Lecomte MC, Dhermy D. Spectrin interacts with EVL (Enabled/vasodilator-stimulated phosphoprotein-like protein), a protein involved in actin polymerization. Biol Cell 2006; 98:279-93. [PMID: 16336193 DOI: 10.1042/bc20050024] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND INFORMATION The alpha- and beta-spectrin chains constitute the filaments of the spectrin-based skeleton, which was first identified in erythrocytes. The discovery of analogous structures at plasma membranes of eukaryotic cells has led to investigations of the role of this spectrin skeleton in many cellular processes. The alphaII-spectrin chain expressed in nucleated cells harbours in its central region several functional motifs, including an SH3 (Src homology 3) domain. RESULTS Using yeast two-hybrid screening, we have identified EVL [Enabled/VASP (vasodilator-stimulated phosphoprotein)-like protein] as a new potential partner of the alphaII-spectrin SH3 domain. In the present study, we investigated the interaction of the alphaII-spectrin SH3 domain with EVL and compared this with other proteins related to EVL [Mena (mammalian Enabled) and VASP]. We confirmed the in vitro interaction between EVL and the alphaII-spectrin SH3 domain by GST (glutathione S-transferase) pull-down assays, and showed that the co-expression of EVL with the alphaII-spectrin SH3 domain in COS-7 cells resulted in the partial delocalization of the SH3 domain from cytoplasm to filopodia and lamellipodia, where it was co-localized with EVL. In kidney epithelial and COS-7 cells, we demonstrated the co-immunoprecipitation of the alphaII-spectrin chain with over-expressed EVL. Immunofluorescence studies showed that the over-expression of EVL in COS-7 cells promoted the formation of filopodia and lamellipodia, and the expressed EVL was detected in filopodial tips and the leading edge of lamellipodia. In these cells over-expressing EVL, the alphaII-spectrin membrane labelling lagged behind EVL staining in lamellipodia and filopodia, with co-localization of these two stains in the contact area. In kidney epithelial cell lines, focused co-localization of spectrin with expressed EVL was observed in the membrane of the lateral domain, where the cell-cell contacts are reinforced. CONCLUSIONS The possible link between the spectrin-based skeleton and actin via the EVL protein suggests a new way of integrating the spectrin-based skeleton in areas of dynamic actin reorganization.
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Wentworth J, Pula G, Poole A. Vasodilator-stimulated phosphoprotein (VASP) is phosphorylated on Ser157 by protein kinase C-dependent and -independent mechanisms in thrombin-stimulated human platelets. Biochem J 2006; 393:555-64. [PMID: 16197368 PMCID: PMC1360706 DOI: 10.1042/bj20050796] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
VASP (vasodilator-stimulated phosphoprotein) is an actin- and profilin-binding protein that is expressed in platelets at high levels and plays a major role in negatively regulating secretory and adhesive events in these cells. VASP is a major substrate for cAMP- and cGMP-regulated protein kinases and it has been shown to be directly phosphorylated on Ser157 by PKC (protein kinase C). In the present paper, we show that, in human platelets, VASP is phosphorylated by PKC on Ser157, but not Ser239, in response to phorbol ester stimulation, in a manner blocked by the PKC inhibitor BIM I (bisindolylmaleimide I). In response to thrombin, VASP was also phosphorylated on Ser157, but this response was only partially inhibited by BIM I, indicating PKC-dependent and -independent pathways to VASP phosphorylation by thrombin. Using inhibitors, we have ruled out the possibility that the PKC-independent pathway acts through guanylate cyclase generation of cGMP, or through a phosphoinositide 3-kinase-dependent kinase. Inhibition of Rho kinase, however, substantially reduced Ser157 VASP phosphorylation, and its effects were additive with BIM I. This implicates Rho kinase and PKC as the major kinases that phosphorylate VASP Ser157 in response to thrombin in platelets.
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Affiliation(s)
- James K. T. Wentworth
- Department of Pharmacology, School of Medical Sciences, University Walk, Bristol BS8 1TD, U.K
| | - Giordano Pula
- Department of Pharmacology, School of Medical Sciences, University Walk, Bristol BS8 1TD, U.K
| | - Alastair W. Poole
- Department of Pharmacology, School of Medical Sciences, University Walk, Bristol BS8 1TD, U.K
- To whom correspondence should be addressed (email )
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43
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Bausen M, Fuhrmann JC, Betz H, O'sullivan GA. The state of the actin cytoskeleton determines its association with gephyrin: Role of ena/VASP family members. Mol Cell Neurosci 2006; 31:376-86. [PMID: 16376568 DOI: 10.1016/j.mcn.2005.11.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 10/26/2005] [Accepted: 11/07/2005] [Indexed: 11/16/2022] Open
Abstract
The role the cytoskeleton plays in generating and/or maintaining gephyrin-dependent receptor clusters at inhibitory synapses is poorly understood. Here, the effects of actin cytoskeleton disruption were investigated in eGFP-gephyrin-transfected cells and hippocampal neurons. While gephyrin was not associated with microfilaments in transfected cells, it colocalized with G-actin and cytochalasin-D-induced F-actin patches. The linker region between the MoeA and MogA homology domains of gephyrin was required for colocalization with F-actin patches and for the binding of gephyrin to ena/VASP, an actin anti-capping factor that, in vitro, caused gephyrin binding to polymerized actin. In hippocampal neurons, treatment with cytochalasin D resulted in the redistribution of the neuronal ena/VASP homologue Mena into actin patches and, at early stages of development, a reduction in the number of gephyrin clusters. Our data suggest that Mena binding to F-actin allows for gephyrin recruitment to the leading edge of uncapped actin filaments.
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Affiliation(s)
- Melanie Bausen
- Department of Neurochemistry, Max-Planck Institute for Brain Research, 60528 Frankfurt, Germany
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Shakir MA, Gill JS, Lundquist EA. Interactions of UNC-34 Enabled with Rac GTPases and the NIK kinase MIG-15 in Caenorhabditis elegans axon pathfinding and neuronal migration. Genetics 2006; 172:893-913. [PMID: 16204220 PMCID: PMC1456253 DOI: 10.1534/genetics.105.046359] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Accepted: 09/21/2005] [Indexed: 01/20/2023] Open
Abstract
Many genes that affect axon pathfinding and cell migration have been identified. Mechanisms by which these genes and the molecules they encode interact with one another in pathways and networks to control developmental events are unclear. Rac GTPases, the cytoskeletal signaling molecule Enabled, and NIK kinase have all been implicated in regulating axon pathfinding and cell migration. Here we present evidence that, in Caenorhabditis elegans, three Rac GTPases, CED-10, RAC-2, and MIG-2, define three redundant pathways that each control axon pathfinding, and that the NIK kinase MIG-15 acts in each Rac pathway. Furthermore, we show that the Enabled molecule UNC-34 defines a fourth partially redundant pathway that acts in parallel to Rac/MIG-15 signaling in axon pathfinding. Enabled and the three Racs also act redundantly to mediate AQR and PQR neuronal cell migration. The Racs and UNC-34 Ena might all control the formation of actin-based protrusive structures (lamellipodia and filopodia) that mediate growth cone outgrowth and cell migration. MIG-15 does not act with the three Racs in execution of cell migration. Rather, MIG-15 affects direction of PQR neuronal migration, similar to UNC-40 and DPY-19, which control initial Q cell polarity, and Wnt signaling, which acts later to control Q cell-directed migration. MIG-2 Rac, which acts with CED-10 Rac, RAC-2 Rac, and UNC-34 Ena in axon pathfinding and cell migration, also acts with MIG-15 in PQR directional migration.
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Affiliation(s)
- M Afaq Shakir
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
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45
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Profirovic J, Gorovoy M, Niu J, Pavlovic S, Voyno-Yasenetskaya T. A Novel Mechanism of G Protein-dependent Phosphorylation of Vasodilator-stimulated Phosphoprotein. J Biol Chem 2005; 280:32866-76. [PMID: 16046415 DOI: 10.1074/jbc.m501361200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is a major substrate of protein kinase A (PKA). Here we described the novel mechanism of VASP phosphorylation via cAMP-independent PKA activation. We showed that in human umbilical vein endothelial cells (HUVECs) alpha-thrombin induced phosphorylation of VASP. Specific inhibition of Galpha13 protein by the RGS domain of a guanine nucleotide exchange factor, p115RhoGEF, inhibited thrombin-dependent phosphorylation of VASP. More importantly, Galpha13-induced VASP phosphorylation was dependent on activation of RhoA and mitogen-activated protein kinase kinase kinase, MEKK1, leading to the stimulation of the NF-kappaB signaling pathway. alpha-Thrombin-dependent VASP phosphorylation was inhibited by small interfering RNA-mediated knockdown of RhoA, whereas Galpha13-dependent VASP phosphorylation was inhibited by a specific RhoA inhibitor botulinum toxin C3 and by a dominant negative mutant of MEKK1. We determined that Galpha13-dependent VASP phosphorylation was also inhibited by specific PKA inhibitors, PKI and H-89. In addition, the expression of phosphorylation-deficient IkappaB and pretreatment with the proteasome inhibitor MG-132 abolished Galpha13- and alpha-thrombin-induced VASP phosphorylation. In summary, we have described a novel pathway of Galpha13-induced VASP phosphorylation that involves activation of RhoA and MEKK1, phosphorylation and degradation of IkappaB, release of PKA catalytic subunit from the complex with IkappaB and NF-kappaB, and subsequent phosphorylation of VASP.
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Affiliation(s)
- Jasmina Profirovic
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA
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46
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Ball LJ, Kühne R, Schneider-Mergener J, Oschkinat H. Recognition of Proline-Rich Motifs by Protein-Protein-Interaction Domains. Angew Chem Int Ed Engl 2005; 44:2852-69. [PMID: 15880548 DOI: 10.1002/anie.200400618] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Protein-protein interactions are essential in every aspect of cellular activity. Multiprotein complexes form and dissociate constantly in a specifically tuned manner, often by conserved mechanisms. Protein domains that bind proline-rich motifs (PRMs) are frequently involved in signaling events. The unique properties of proline provide a mechanism for highly discriminatory recognition without requiring high affinities. We present herein a detailed, quantitative assessment of the structural features that define the interfaces between PRM-binding domains and their target PRMs, and investigate the specificity of PRM recognition. Together with the analysis of peptide-library screens, this approach has allowed the identification of several highly conserved key interactions found in all complexes of PRM-binding domains. The inhibition of protein-protein interactions by using small-molecule agents is very challenging. Therefore, it is important to first pinpoint the critical interactions that must be considered in the design of inhibitors of PRM-binding domains.
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Affiliation(s)
- Linda J Ball
- Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
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47
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Ball LJ, Kühne R, Schneider-Mergener J, Oschkinat H. Erkennung Prolin-reicher Motive (PRMs) durch Protein-Protein-Wechselwirkungsdomänen. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200400618] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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48
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Mruk DD, Cheng CY. Sertoli-Sertoli and Sertoli-germ cell interactions and their significance in germ cell movement in the seminiferous epithelium during spermatogenesis. Endocr Rev 2004; 25:747-806. [PMID: 15466940 DOI: 10.1210/er.2003-0022] [Citation(s) in RCA: 596] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Spermatogenesis is the process by which a single spermatogonium develops into 256 spermatozoa, one of which will fertilize the ovum. Since the 1950s when the stages of the epithelial cycle were first described, reproductive biologists have been in pursuit of one question: How can a spermatogonium traverse the epithelium, while at the same time differentiating into elongate spermatids that remain attached to the Sertoli cell throughout their development? Although it was generally agreed upon that junction restructuring was involved, at that time the types of junctions present in the testis were not even discerned. Today, it is known that tight, anchoring, and gap junctions are found in the testis. The testis also has two unique anchoring junction types, the ectoplasmic specialization and tubulobulbar complex. However, attention has recently shifted on identifying the regulatory molecules that "open" and "close" junctions, because this information will be useful in elucidating the mechanism of germ cell movement. For instance, cytokines have been shown to induce Sertoli cell tight junction disassembly by shutting down the production of tight junction proteins. Other factors such as proteases, protease inhibitors, GTPases, kinases, and phosphatases also come into play. In this review, we focus on this cellular phenomenon, recapping recent developments in the field.
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Affiliation(s)
- Dolores D Mruk
- Population Council, Center for Biomedical Research, New York, New York 10021, USA.
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49
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Golemi-Kotra D, Mahaffy R, Footer MJ, Holtzman JH, Pollard TD, Theriot JA, Schepartz A. High affinity, paralog-specific recognition of the Mena EVH1 domain by a miniature protein. J Am Chem Soc 2004; 126:4-5. [PMID: 14709031 DOI: 10.1021/ja037954k] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many protein domains involved in cell signaling contain or interact with proline-rich sequences, and the design of molecules that perturb signaling pathways represents a foremost goal of chemical biology. Previously we described a protein design strategy in which the well-folded alpha-helix in avian pancreatic polypeptide (aPP) presents short alpha-helical recognition epitopes. The miniature proteins designed in this way recognize even shallow protein clefts with high affinity and specificity. Here we show that the well-folded type-II polyproline helix in aPP can present the short PPII-helical recognition epitope within the ActA protein of Listeria monocytogenes. Like miniature proteins that use an alpha-helix for protein recognition, the miniature protein designed in this way displays high affinity for a natural ActA target, the EVH1 domain Mena1-112, and achieves the elusive goal of paralog specificity, discriminating well between EVH1 domains Mena1-112, VASP1-115, and Evl1-112. Most importantly, the miniature protein competed with ActA in Xenopus laevis egg cytoplasmic extracts, decreasing actin-dependent motility of L. monocytogenes and causing extreme speed variations and discontinuous tail formation. Our results suggest that miniature proteins based on aPP may represent an excellent framework for the design of ligands that differentiate the roles of EVH1 domains in vitro and in vivo.
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Affiliation(s)
- Dasantila Golemi-Kotra
- Departments of Chemistry and Molecular, Cellular, Yale University, New Haven, Connecticut 06511, USA
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50
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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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