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Tsuji-Tamura K, Sato M, Tamura M. Pharmacological control of angiogenesis by regulating phosphorylation of myosin light chain 2. Cell Signal 2024; 120:111223. [PMID: 38729320 DOI: 10.1016/j.cellsig.2024.111223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 04/25/2024] [Accepted: 05/07/2024] [Indexed: 05/12/2024]
Abstract
BACKGROUND Control of angiogenesis is widely considered a therapeutic strategy, but reliable control methods are still under development. Phosphorylation of myosin light chain 2 (MLC2), which regulates actin-myosin interaction, is critical to the behavior of vascular endothelial cells (ECs) during angiogenesis. MLC2 is phosphorylated by MLC kinase (MLCK) and dephosphorylated by MLC phosphatase (MLCP) containing a catalytic subunit PP1. We investigated the potential role of MLC2 in the pharmacological control of angiogenesis. METHODS AND RESULTS We exposed transgenic zebrafish Tg(fli1a:Myr-mCherry)ncv1 embryos to chemical inhibitors and observed vascular development. PP1 inhibition by tautomycetin increased length of intersegmental vessels (ISVs), whereas MLCK inhibition by ML7 decreased it; these effects were not accompanied by structural dysplasia. ROCK inhibition by Y-27632 also decreased vessel length. An in vitro angiogenesis model of human umbilical vein endothelial cells (HUVECs) showed that tautomycetin increased vascular cord formation, whereas ML7 and Y-27632 decreased it. These effects appear to be influenced by regulation of cell morphology rather than cell viability or motility. Actin co-localized with phosphorylated MLC2 (pMLC2) was abundant in vascular-like elongated-shaped ECs, but poor in non-elongated ECs. pMLC2 was associated with tightly arranged actin, but not with loosely arranged actin. Moreover, knockdown of MYL9 gene encoding MLC2 reduced total MLC2 and pMLC2 protein and inhibited angiogenesis in HUVECs. CONCLUSION The present study found that MLC2 is a pivotal regulator of angiogenesis. MLC2 phosphorylation may be involved in the regulation of of cell morphogenesis and cell elongation. The functionally opposite inhibitors positively or negatively control angiogenesis, probably through the regulating EC morphology. These findings may provide a unique therapeutic target for angiogenesis.
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Affiliation(s)
- Kiyomi Tsuji-Tamura
- Oral Biochemistry and Molecular Biology, Department of Oral Health Science, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo 060-8586, Japan.
| | - Mari Sato
- Oral Biochemistry and Molecular Biology, Department of Oral Health Science, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo 060-8586, Japan
| | - Masato Tamura
- Oral Biochemistry and Molecular Biology, Department of Oral Health Science, Faculty of Dental Medicine and Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-Ku, Sapporo 060-8586, Japan
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2
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Patil RS, Kovacs-Kasa A, Gorshkov BA, Fulton DJR, Su Y, Batori RK, Verin AD. Serine/Threonine Protein Phosphatases 1 and 2A in Lung Endothelial Barrier Regulation. Biomedicines 2023; 11:1638. [PMID: 37371733 PMCID: PMC10296329 DOI: 10.3390/biomedicines11061638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/28/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Vascular barrier dysfunction is characterized by increased permeability and inflammation of endothelial cells (ECs), which are prominent features of acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and sepsis, and a major complication of the SARS-CoV-2 infection and COVID-19. Functional impairment of the EC barrier and accompanying inflammation arises due to microbial toxins and from white blood cells of the lung as part of a defensive action against pathogens, ischemia-reperfusion or blood product transfusions, and aspiration syndromes-based injury. A loss of barrier function results in the excessive movement of fluid and macromolecules from the vasculature into the interstitium and alveolae resulting in pulmonary edema and collapse of the architecture and function of the lungs, and eventually culminates in respiratory failure. Therefore, EC barrier integrity, which is heavily dependent on cytoskeletal elements (mainly actin filaments, microtubules (MTs), cell-matrix focal adhesions, and intercellular junctions) to maintain cellular contacts, is a critical requirement for the preservation of lung function. EC cytoskeletal remodeling is regulated, at least in part, by Ser/Thr phosphorylation/dephosphorylation of key cytoskeletal proteins. While a large body of literature describes the role of phosphorylation of cytoskeletal proteins on Ser/Thr residues in the context of EC barrier regulation, the role of Ser/Thr dephosphorylation catalyzed by Ser/Thr protein phosphatases (PPases) in EC barrier regulation is less documented. Ser/Thr PPases have been proposed to act as a counter-regulatory mechanism that preserves the EC barrier and opposes EC contraction. Despite the importance of PPases, our knowledge of the catalytic and regulatory subunits involved, as well as their cellular targets, is limited and under-appreciated. Therefore, the goal of this review is to discuss the role of Ser/Thr PPases in the regulation of lung EC cytoskeleton and permeability with special emphasis on the role of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) as major mammalian Ser/Thr PPases. Importantly, we integrate the role of PPases with the structural dynamics of the cytoskeleton and signaling cascades that regulate endothelial cell permeability and inflammation.
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Affiliation(s)
- Rahul S. Patil
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Anita Kovacs-Kasa
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Boris A. Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - David J. R. Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Yunchao Su
- Department of Pharmacology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Robert K. Batori
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
| | - Alexander D. Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA
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Ripamonti M, Lamarca A, Davey NE, Tonoli D, Surini S, de Curtis I. A functional interaction between liprin-α1 and B56γ regulatory subunit of protein phosphatase 2A supports tumor cell motility. Commun Biol 2022; 5:1025. [PMID: 36171301 PMCID: PMC9519923 DOI: 10.1038/s42003-022-03989-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 09/13/2022] [Indexed: 11/25/2022] Open
Abstract
Scaffold liprin-α1 is required to assemble dynamic plasma membrane-associated platforms (PMAPs) at the front of migrating breast cancer cells, to promote protrusion and invasion. We show that the N-terminal region of liprin-α1 contains an LxxIxE motif interacting with B56 regulatory subunits of serine/threonine protein phosphatase 2A (PP2A). The specific interaction of B56γ with liprin-α1 requires an intact motif, since two point mutations strongly reduce the interaction. B56γ mediates the interaction of liprin-α1 with the heterotrimeric PP2A holoenzyme. Most B56γ protein is recovered in the cytosolic fraction of invasive MDA-MB-231 breast cancer cells, where B56γ is complexed with liprin-α1. While mutation of the short linear motif (SLiM) does not affect localization of liprin-α1 to PMAPs, localization of B56γ at these sites specifically requires liprin-α1. Silencing of B56γ or liprin-α1 inhibits to similar extent cell spreading on extracellular matrix, invasion, motility and lamellipodia dynamics in migrating MDA-MB-231 cells, suggesting that B56γ/PP2A is a novel component of the PMAPs machinery regulating tumor cell motility. In this direction, inhibition of cell spreading by silencing liprin-α1 is not rescued by expression of B56γ binding-defective liprin-α1 mutant. We propose that liprin-α1-mediated recruitment of PP2A via B56γ regulates cell motility by controlling protrusion in migrating MDA-MB-231 cells.
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Affiliation(s)
- Marta Ripamonti
- San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milano, Italy
| | - Andrea Lamarca
- San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milano, Italy
| | - Norman E Davey
- Division of Cancer Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK
| | - Diletta Tonoli
- San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milano, Italy
| | - Sara Surini
- San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milano, Italy
| | - Ivan de Curtis
- San Raffaele Scientific Institute and Università Vita-Salute San Raffaele, Milano, Italy.
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4
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Omelchenko T. Cellular protrusions in 3D: Orchestrating early mouse embryogenesis. Semin Cell Dev Biol 2022; 129:63-74. [PMID: 35577698 DOI: 10.1016/j.semcdb.2022.05.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 05/04/2022] [Accepted: 05/04/2022] [Indexed: 12/26/2022]
Abstract
Cellular protrusions generated by the actin cytoskeleton are central to the process of building the body of the embryo. Problems with cellular protrusions underlie human diseases and syndromes, including implantation defects and pregnancy loss, congenital birth defects, and cancer. Cells use protrusive activity together with actin-myosin contractility to create an ordered body shape of the embryo. Here, I review how actin-rich protrusions are used by two major morphological cell types, epithelial and mesenchymal cells, during collective cell migration to sculpt the mouse embryo body. Pre-gastrulation epithelial collective migration of the anterior visceral endoderm is essential for establishing the anterior-posterior body axis. Gastrulation mesenchymal collective migration of the mesoderm wings is crucial for body elongation, and somite and heart formation. Analysis of mouse mutants with disrupted cellular protrusions revealed the key role of protrusions in embryonic morphogenesis and embryo survival. Recent technical approaches have allowed examination of the mechanisms that control cell and tissue movements in vivo in the complex 3D microenvironment of living mouse embryos. Advancing our understanding of protrusion-driven morphogenesis should provide novel insights into human developmental disorders and cancer metastasis.
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Affiliation(s)
- Tatiana Omelchenko
- Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, 1230 York Avenue, New York 10065, USA.
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5
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Di Leo L, Bodemeyer V, Bosisio FM, Claps G, Carretta M, Rizza S, Faienza F, Frias A, Khan S, Bordi M, Pacheco MP, Di Martino J, Bravo-Cordero JJ, Daniel CJ, Sears RC, Donia M, Madsen DH, Guldberg P, Filomeni G, Sauter T, Robert C, De Zio D, Cecconi F. Loss of Ambra1 promotes melanoma growth and invasion. Nat Commun 2021; 12:2550. [PMID: 33953176 PMCID: PMC8100102 DOI: 10.1038/s41467-021-22772-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 03/26/2021] [Indexed: 12/20/2022] Open
Abstract
Melanoma is the deadliest skin cancer. Despite improvements in the understanding of the molecular mechanisms underlying melanoma biology and in defining new curative strategies, the therapeutic needs for this disease have not yet been fulfilled. Herein, we provide evidence that the Activating Molecule in Beclin-1-Regulated Autophagy (Ambra1) contributes to melanoma development. Indeed, we show that Ambra1 deficiency confers accelerated tumor growth and decreased overall survival in Braf/Pten-mutated mouse models of melanoma. Also, we demonstrate that Ambra1 deletion promotes melanoma aggressiveness and metastasis by increasing cell motility/invasion and activating an EMT-like process. Moreover, we show that Ambra1 deficiency in melanoma impacts extracellular matrix remodeling and induces hyperactivation of the focal adhesion kinase 1 (FAK1) signaling, whose inhibition is able to reduce cell invasion and melanoma growth. Overall, our findings identify a function for AMBRA1 as tumor suppressor in melanoma, proposing FAK1 inhibition as a therapeutic strategy for AMBRA1 low-expressing melanoma.
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Affiliation(s)
- Luca Di Leo
- Melanoma Research Team, Cell Stress and Survival Unit, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Valérie Bodemeyer
- Melanoma Research Team, Cell Stress and Survival Unit, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Francesca M Bosisio
- Lab of Translational Cell and Tissue Research, University of Leuven, Leuven, Belgium
| | | | - Marco Carretta
- National Center for Cancer Immune Therapy, Department of Oncology, Copenhagen University Hospital, Herlev, Denmark
| | - Salvatore Rizza
- Redox Biology Group, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Fiorella Faienza
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Alex Frias
- Melanoma Research Team, Cell Stress and Survival Unit, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Shawez Khan
- National Center for Cancer Immune Therapy, Department of Oncology, Copenhagen University Hospital, Herlev, Denmark
| | - Matteo Bordi
- Department of Pediatric Hematology and Oncology, Bambino Gesù Children's Hospital, Rome, Italy
| | - Maria P Pacheco
- Life Sciences Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Julie Di Martino
- School of Medicine, Division of Hematology and Oncology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jose J Bravo-Cordero
- School of Medicine, Division of Hematology and Oncology, The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Colin J Daniel
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA
| | - Rosalie C Sears
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR, USA
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
| | - Marco Donia
- National Center for Cancer Immune Therapy, Department of Oncology, Copenhagen University Hospital, Herlev, Denmark
| | - Daniel H Madsen
- National Center for Cancer Immune Therapy, Department of Oncology, Copenhagen University Hospital, Herlev, Denmark
| | - Per Guldberg
- Molecular Diagnostics Group, Danish Cancer Society Research Center, Copenhagen, Denmark
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Giuseppe Filomeni
- Redox Biology Group, Danish Cancer Society Research Center, Copenhagen, Denmark
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Sauter
- Life Sciences Research Unit, University of Luxembourg, Belvaux, Luxembourg
| | - Caroline Robert
- INSERM U981, Gustave Roussy Institute, Villejuif, France
- Université Paris-Sud, Université Paris-Saclay, Kremlin-Bicêtre, France
- Dermato-Oncology, Gustave Roussy Cancer Campus, Villejuif, France
| | - Daniela De Zio
- Melanoma Research Team, Cell Stress and Survival Unit, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Society Research Center, Copenhagen, Denmark.
| | - Francesco Cecconi
- Department of Biology, University of Rome Tor Vergata, Rome, Italy.
- Department of Pediatric Hematology and Oncology, Bambino Gesù Children's Hospital, Rome, Italy.
- Cell Stress and Survival Unit, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Society Research Center, Copenhagen, Denmark.
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6
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Uzair ID, Flamini MI, Sanchez AM. Rapid Estrogen and Progesterone Signaling to Dendritic Spine Formation via Cortactin/Wave1-Arp2/3 Complex. Neuroendocrinology 2020; 110:535-551. [PMID: 31509830 DOI: 10.1159/000503310] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/11/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Synaptic plasticity is the neuronal capacity to modify the function and structure of dendritic spines (DS) in response to neuromodulators. Sex steroids, particularly 17β-estradiol (E2) and progesterone (P4), are key regulators in the control of DS formation through multiprotein complexes including WAVE1 protein, and are thus fundamental for the development of learning and memory. OBJECTIVES The aim of this work was to evaluate the molecular switch Cdk5 kinase/protein phosphatase 2A (PP2A) in the control of WAVE1 protein (phosphorylation/dephosphorylation) and the regulation of WAVE1 and cortactin to the Arp2/3 complex, in response to rapid treatments with E2 and P4 in cortical neuronal cells. RESULTS Rapid treatment with E2 and P4 modified neuronal morphology and significantly increased the number of DS. This effect was reduced by the use of a Cdk5 inhibitor (Roscovitine). In contrast, inhibition of PP2A with PP2A dominant negative construct significantly increased DS formation, evidencing the participation of kinase/phosphatase in the regulation of WAVE1 in DS formation induced by E2 and P4. Cortactin regulates DS formation via Src and PAK1 kinase induced by E2 and P4. Both cortactin and WAVE1 signal to Arp2/3 complex to synergistically promote actin nucleation. CONCLUSION These results suggest that E2 and P4 dynamically regulate neuron morphology through nongenomic signaling via cortactin/WAVE1-Arp2/3 complex. The control of these proteins is tightly orchestrated by phosphorylation, where kinases and phosphatases are essential for actin nucleation and, finally, DS formation. This work provides a deeper understanding of the biological actions of sex steroids in the regulation of DS turnover and neuronal plasticity processes.
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Affiliation(s)
- Ivonne Denise Uzair
- Laboratory of Signal Transduction and Cell Movement, Institute of Medicine and Experimental Biology of Cuyo (IMBECU), National Scientific and Technical Research Council (CONICET), Mendoza, Argentina
| | - Marina Ines Flamini
- Laboratory of Signal Transduction and Cell Movement, Institute of Medicine and Experimental Biology of Cuyo (IMBECU), National Scientific and Technical Research Council (CONICET), Mendoza, Argentina
| | - Angel Matias Sanchez
- Laboratory of Signal Transduction and Cell Movement, Institute of Medicine and Experimental Biology of Cuyo (IMBECU), National Scientific and Technical Research Council (CONICET), Mendoza, Argentina,
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7
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Wang Y, Xia Y, Kuang D, Duan Y, Wang G. PP2A regulates SCF-induced cardiac stem cell migration through interaction with p38 MAPK. Life Sci 2017; 191:59-67. [DOI: 10.1016/j.lfs.2017.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/22/2017] [Accepted: 10/02/2017] [Indexed: 12/29/2022]
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8
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Janssens V, Zwaenepoel K, Rossé C, Petit MMR, Goris J, Parker PJ. PP2A binds to the LIM domains of lipoma-preferred partner through its PR130/B″ subunit to regulate cell adhesion and migration. J Cell Sci 2016; 129:1605-18. [PMID: 26945059 PMCID: PMC5333791 DOI: 10.1242/jcs.175778] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 02/18/2016] [Indexed: 01/23/2023] Open
Abstract
Here, we identify the LIM protein lipoma-preferred partner (LPP) as a binding partner of a specific protein phosphatase 2A (PP2A) heterotrimer that is characterised by the regulatory PR130/B″α1 subunit (encoded by PPP2R3A). The PR130 subunit interacts with the LIM domains of LPP through a conserved Zn²⁺-finger-like motif in the differentially spliced N-terminus of PR130. Isolated LPP-associated PP2A complexes are catalytically active. PR130 colocalises with LPP at multiple locations within cells, including focal contacts, but is specifically excluded from mature focal adhesions, where LPP is still present. An LPP-PR130 fusion protein only localises to focal adhesions upon deletion of the domain of PR130 that binds to the PP2A catalytic subunit (PP2A/C), suggesting that PR130-LPP complex formation is dynamic and that permanent recruitment of PP2A activity might be unfavourable for focal adhesion maturation. Accordingly, siRNA-mediated knockdown of PR130 increases adhesion of HT1080 fibrosarcoma cells onto collagen I and decreases their migration in scratch wound and Transwell assays. Complex formation with LPP is mandatory for these PR130-PP2A functions, as neither phenotype can be rescued by re-expression of a PR130 mutant that no longer binds to LPP. Our data highlight the importance of specific, locally recruited PP2A complexes in cell adhesion and migration dynamics.
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Affiliation(s)
- Veerle Janssens
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Karen Zwaenepoel
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Carine Rossé
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Research Centre, Institut Curie, Paris 75005, France
| | - Marleen M R Petit
- Molecular Oncology Laboratory, Dept. of Human Genetics, KU Leuven, Herestraat 49 PO-box 602, Leuven B-3000, Belgium
| | - Jozef Goris
- Laboratory of Protein Phosphorylation and Proteomics, Dept. of Cellular and Molecular Medicine, KU Leuven, Herestraat 49 PO-box 901, Leuven B-3000, Belgium
| | - Peter J Parker
- Francis Crick Institute, Protein Phosphorylation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK Division of Cancer Studies King's College London, Guy's Hospital Campus, Thomas Street, London SE1 9RT, UK
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9
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Fogh BS, Multhaupt HAB, Couchman JR. Protein kinase C, focal adhesions and the regulation of cell migration. J Histochem Cytochem 2014; 62:172-84. [PMID: 24309511 PMCID: PMC3935447 DOI: 10.1369/0022155413517701] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 11/21/2013] [Indexed: 12/18/2022] Open
Abstract
Cell adhesion to extracellular matrix is a complex process involving protrusive activity driven by the actin cytoskeleton, engagement of specific receptors, followed by signaling and cytoskeletal organization. Thereafter, contractile and endocytic/recycling activities may facilitate migration and adhesion turnover. Focal adhesions, or focal contacts, are widespread organelles at the cell-matrix interface. They arise as a result of receptor interactions with matrix ligands, together with clustering. Recent analysis shows that focal adhesions contain a very large number of protein components in their intracellular compartment. Among these are tyrosine kinases, which have received a great deal of attention, whereas the serine/threonine kinase protein kinase C has received much less. Here the status of protein kinase C in focal adhesions and cell migration is reviewed, together with discussion of its roles and potential substrates.
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Affiliation(s)
- Betina S Fogh
- Department of Biomedical Sciences, University of Copenhagen, Denmark
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10
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McCole DF. Phosphatase regulation of intercellular junctions. Tissue Barriers 2013; 1:e26713. [PMID: 24868494 DOI: 10.4161/tisb.26713] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 10/03/2013] [Accepted: 10/04/2013] [Indexed: 02/06/2023] Open
Abstract
Intercellular junctions represent the key contact points and sites of communication between neighboring cells. Assembly of these junctions is absolutely essential for the structural integrity of cell monolayers, tissues and organs. Disruption of junctions can have severe consequences such as diarrhea, edema and sepsis, and contribute to the development of chronic inflammatory diseases. Cell junctions are not static structures, but rather they represent highly dynamic micro-domains that respond to signals from the intracellular and extracellular environments to modify their composition and function. This review article will focus on the regulation of tight junctions and adherens junctions by phosphatase enzymes that play an essential role in preserving and modulating the properties of intercellular junction proteins.
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Affiliation(s)
- Declan F McCole
- Division of Biomedical Sciences; University of California, Riverside; Riverside, CA USA
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11
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Impaired expression of protein phosphatase 2A subunits enhances metastatic potential of human prostate cancer cells through activation of AKT pathway. Br J Cancer 2013; 108:2590-600. [PMID: 23598299 PMCID: PMC3694226 DOI: 10.1038/bjc.2013.160] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background: Protein phosphatase 2A (PP2A) is a dephosphorylating enzyme, loss of which can contribute to prostate cancer (PCa) pathogenesis. The aim of this study was to analyse the transcriptional and translational expression patterns of individual subunits of the PP2A holoenzyme during PCa progression. Methods: Immunohistochemistry (IHC), western blot, and real-time PCR was performed on androgen-dependent (AD) and androgen-independent (AI) PCa cells, and benign and malignant prostate tissues for all the three PP2A (scaffold, regulatory, and catalytic) subunits. Mechanistic and functional studies were performed using various biochemical and cellular techniques. Results: Through immunohistochemical analysis we observed significantly reduced levels of PP2A-A and -B′γ subunits (P<0.001 and P=0.0002) in PCa specimens compared with benign prostate. Contemporarily, there was no significant difference in PP2A-C subunit expression between benign and malignant tissues. Similar to the expression pattern observed in tissues, the endogenous levels of PP2A-A and B′γ subunits were abrogated from the low metastatic to high metastatic and AD to AI cell line models, without any change in the catalytic subunit expression. Furthermore, using in vitro studies we demonstrated that PP2A-Aα scaffold subunit has a role in dampening AKT, β-catenin, and FAK (focal adhesion kinase) signalling. Conclusion: We conclude that loss of expression of scaffold and regulatory subunits of PP2A is responsible for its altered function during PCa pathogenesis.
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12
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Seshacharyulu P, Pandey P, Datta K, Batra SK. Phosphatase: PP2A structural importance, regulation and its aberrant expression in cancer. Cancer Lett 2013; 335:9-18. [PMID: 23454242 DOI: 10.1016/j.canlet.2013.02.036] [Citation(s) in RCA: 330] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 02/10/2013] [Accepted: 02/13/2013] [Indexed: 12/28/2022]
Abstract
Protein Phosphatase 2A (PP2A) is an important and ubiquitously expressed serine threonine phosphatase and regulates the function by dephosphorylating many critical cellular molecules like Akt, p53, c-Myc and β-catenin. It plays a critical role in cellular processes, such as cell proliferation, signal transduction and apoptosis. Structurally, it is multifarious as it is composed of catalytic, scaffold and regulatory subunits. The catalytic and scaffold subunits have two isoforms and the regulatory subunit has four different families containing different isoforms. The regulatory subunit is the most diverse with temporal and spatial specificity. PP2A undergoes post-translational modifications (i.e. phosphorylation and methylation), which in turn, regulates its enzymatic activity. Aberrant expression, mutations and somatic alterations of the PP2A scaffold and regulatory subunits have been observed in various human malignancies, including lung, breast, skin and colon cancer, highlighting its role as a 'tumor suppressor'. This review is focused on the structural complexity of serine/threonine phosphatase PP2A and summarizes its expression pattern in cancer. Additionally, the PP2A interacting and regulatory proteins and substrates are also discussed. Finally, the mouse models developed to understand the biological role of PP2A subunits in an in vivo model system are also reviewed in this article.
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Affiliation(s)
- Parthasarathy Seshacharyulu
- Department of Biochemistry and Molecular Biology, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA.
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13
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Liu XP, Zheng HY, Qu M, Zhang Y, Cao FY, Wang Q, Ke D, Liu GP, Wang JZ. Upregulation of astrocytes protein phosphatase-2A stimulates astrocytes migration via inhibiting p38 MAPK in tg2576 mice. Glia 2012; 60:1279-88. [PMID: 22729898 DOI: 10.1002/glia.22347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/13/2012] [Indexed: 12/30/2022]
Abstract
One of the earliest neuropathological changes in Alzheimer disease (AD) is the accumulation of astrocytes at sites of β-amyloid (Aβ) deposits, but the cause of this cellular response is unclear. As the activity of protein phosphatase 2A (PP2A) is significantly decreased in the AD brains, we studied the role of PP2A in astrocytes migration. We observed unexpectedly that PP2A activity associated with glial fibrillary acidic protein, an astrocyte marker, was significantly upregulated in tg2576 mice, demonstrated by an increased enzyme activity, a decreased demethylation at leucine-309 (DM-PP2Ac), and a decreased phosphorylation at tyrosine-307 of PP2A (pY307-PP2Ac). Further studies by using in vitro wound-healing model and transwell assay demonstrated that upregulation of PP2A pharmacologically and genetically could stimulate astrocytes migration. Activation of PP2A promotes actin organization and inhibits p38 mitogen-activated protein kinases (p38 MAPK), while simultaneous activation of p38 MAPK partially abolishes the PP2A-induced astrocytes migration. Our data suggest that activation of astrocytes PP2A in tg2567 mice may stimulate the migration of astrocytes to the amyloid plaques by p38 MAPK inhibition, implying that PP2A deficits observed in AD may cause Aβ accumulation via hindering the astrocytes migration.
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Affiliation(s)
- Xiu-Ping Liu
- Pathophysiology Department, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, HuBei, People's Republic of China
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Abstract
During normal pregnancy, dramatically increased placental blood flow is critical for fetal growth and survival as well as neonatal birth weights and survivability. This increased blood flow results from angiogenesis, vasodilatation, and vascular remodeling. Locally produced growth factors including fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are key regulators of placental endothelial functions including cell proliferation, migration, and vasodilatation. However, the precise signaling mechanisms underlying such regulation in fetoplacental endothelium are less well defined, specifically with regard to the interactions amongst protein kinases (PKs), protein phosphatase, and nitric oxide (NO). Recently, we and other researchers have obtained solid evidence showing that different signaling mechanisms participate in FGF2- and VEGFA-regulated fetoplacental endothelial cell proliferation and migration as well as NO production. This review will briefly summarize currently available data on signaling mediating fetoplacental angiogenesis with a specific emphasis on PKs, ERK1/2, AKT1, and p38 MAPK and protein phosphatases, PPP2 and PPP3.
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Affiliation(s)
- Kai Wang
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai 200040, China
| | - Jing Zheng
- Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53715
- Address correspondence and reprint requests to: Jing Zheng, Ph.D., Departments of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, PAB1 Meriter Hospital, 202 S Park St., Madison, WI 53715. Phone: (608) 417-6314 Fax: (608) 257-1304.
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15
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Wong LL, Zhang D, Chang CF, Koay ES. Silencing of the PP2A catalytic subunit causes HER-2/neu positive breast cancer cells to undergo apoptosis. Exp Cell Res 2010; 316:3387-96. [DOI: 10.1016/j.yexcr.2010.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 06/04/2010] [Accepted: 06/06/2010] [Indexed: 11/30/2022]
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16
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Open-label, phase I dose-escalation study of sodium selenate, a novel activator of PP2A, in patients with castration-resistant prostate cancer. Br J Cancer 2010; 103:462-8. [PMID: 20648008 PMCID: PMC2939789 DOI: 10.1038/sj.bjc.6605798] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Background: Angiogenesis is fundamental to the progression of many solid tumours including prostate cancer. Sodium selenate is a small, water-soluble, orally bioavailable activator of PP2A phosphatase with anti-angiogenic properties. Methods: This was a dose-escalation phase I study in men with asymptomatic, chemotherapy-naïve, castration-resistant prostate cancer. The primary objective was to determine the maximum tolerated dose (MTD). Secondary objectives included establishing the safety, tolerability and pharmacokinetic profile. Results: A total of 19 patients were enrolled. The MTD was 60 mg per day. Dose-limiting toxicity (fatigue and diarrhoea) was observed at 90 mg per day. The most frequently reported treatment-related adverse events across all treatment cohorts were nausea, diarrhoea, fatigue, muscle spasms, alopecia and nail disorders. No grade 4 toxicities were observed and there were no deaths on study. Linear pharmacokinetics was observed. One patient had a PSA response >50%. Median time to PSA progression (for non-responders) was 14.2 weeks. Mean PSA doubling time increased during the main treatment phase from 2.18 months before trial to 3.85 months. Conclusion: Sodium selenate is well tolerated at a dose of 60 mg per day with modest single-agent efficacy similar to other anti-angiogenic agents. Further trials in combination with conventional cytotoxic regimens are warranted.
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17
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Pradhan S, Alrehani N, Patel V, Khatlani T, Vijayan KV. Cross-talk between serine/threonine protein phosphatase 2A and protein tyrosine phosphatase 1B regulates Src activation and adhesion of integrin αIIbβ3 to fibrinogen. J Biol Chem 2010; 285:29059-68. [PMID: 20615878 DOI: 10.1074/jbc.m109.085167] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Integrin α(IIb)β(3) signaling mediated by kinases and phosphatases participate in hemostasis and thrombosis, in part, by supporting stable platelet adhesion. Our previous studies indicate that the genetic manipulation of PP2Acα (α isoform of the catalytic subunit of protein phosphatase 2A) negatively regulate the adhesion of human embryonal kidney 293 cells expressing α(IIb)β(3) to fibrinogen. Here, we demonstrated that small interference RNA (siRNA) mediated knockdown of PP2Acα in 293 α(IIb)β(3) cells led to the dephosphorylation of Src Tyr-529, phosphorylation of Src Tyr-418 and an increased Src kinase activity. Conversely, overexpression of PP2Acα decreased the basal Src activity. Pharmacological inhibition of PP2Ac in human platelets or PP2Acα knockdown in primary murine megakaryocytes resulted in Src activation. PP2Acα-depleted 293 α(IIb)β(3) cells did not alter the serine (Ser) phosphorylation of Src but enhanced the Ser-50 phosphorylation of protein tyrosine phosphatase 1B (PTP-1B) with a concomitant increase in the PTP-1B activity. Src activation in the PP2Acα-depleted 293 α(IIb)β(3) cells was abolished by siRNA mediated knockdown of PTP-1B. Pharmacological inhibition of Src or knockdown of Src, PTP-1B blocked the enhanced activation of extracellular signal-regulated kinase (ERK1/2) and the increased adhesiveness of PP2Acα-depleted 293 α(IIb)β(3) cells to fibrinogen, respectively. Thus, inactivation of PP2Acα promotes hyperphosphorylation of PTP-1B Ser-50, elevates PTP-1B activity, which dephosphorylates Src Tyr-529 to activate Src and its downstream ERK1/2 signaling pathways that regulate α(IIb)β(3) adhesion. Moreover, these studies extend the notion that a cross-talk between Ser/Thr and Tyr phosphatases can fine-tune α(IIb)β(3) outside-in signaling.
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Affiliation(s)
- Subhashree Pradhan
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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18
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Geny B, Grassart A, Manich M, Chicanne G, Payrastre B, Sauvonnet N, Popoff MR. Rac1 inactivation by lethal toxin from Clostridium sordellii modifies focal adhesions upstream of actin depolymerization. Cell Microbiol 2009; 12:217-32. [PMID: 19840028 DOI: 10.1111/j.1462-5822.2009.01392.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inactivation of different small GTPases upon their glucosylation by lethal toxin from Clostridium sordellii strain IP82 (LT-82) is already known to lead to cell rounding, adherens junction (AJ) disorganization and actin depolymerization. In the present work, we observed that LT-82 induces a rapid dephosphorylation of paxillin, a protein regulating focal adhesion (FA), independently of inactivation of paxillin kinases such as Src, Fak and Pyk2. Among the small GTPases inactivated by this toxin, including Rac, Ras, Rap and Ral, we identified Rac1, as responsible for paxillin dephosphorylation using cells overexpressing Rac1(V12). Rac1 inactivation by LT-82 modifies interactions between proteins from AJ and FA complexes as shown by pull-down assays. We showed that in Triton X-100-insoluble membrane proteins from these complexes, namely E-cadherin, beta-catenin, p120-catenin and talin, are decreased upon LT-82 intoxication, a treatment that also induces a rapid decrease in cell phosphoinositide content. Therefore, we proposed that Rac inactivation by LT-82 alters phosphoinositide metabolism leading to FA and AJ complex disorganization and actin depolymerization.
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Affiliation(s)
- Blandine Geny
- Unité des Bactéries Anaérobies et Toxines, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris Cedex 15, France.
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19
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Song Y, Wang K, Chen DB, Magness RR, Zheng J. Suppression of protein phosphatase 2 differentially modulates VEGF- and FGF2-induced signaling in ovine fetoplacental artery endothelial cells. Placenta 2009; 30:907-13. [PMID: 19692121 DOI: 10.1016/j.placenta.2009.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 07/08/2009] [Accepted: 07/09/2009] [Indexed: 10/20/2022]
Abstract
Vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) elicit cellular responses via activation of protein kinases and phosphatases. We have reported that the MEK1/2/ERK1/2 and PI3K/AKT1 pathways are critical for VEGF- and FGF2-stimulated ovine fetoplacental artery endothelial (OFPAE) cell proliferation. We have also shown that protein phosphatase 3 (PPP3) differentially modulates VEGF- and FGF2-stimulated cell proliferation and activation of ERK1/2 and AKT1 in OFPAE cells. Herein, we investigated if protein phosphatase 2 (PPP2) modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation and VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. Small interfering RNA (siRNA) specifically targeting human PPP2CA catalytic subunit alpha (PPP2CA) was used to suppress PPP2CA expression in OFPAE cells. When compared with scrambled siRNA, PPP2CA siRNA decreased (p<0.05) PPP2CA protein levels (approximately 70%) and activity (approximately 50%) without altering protein levels of PPP3 catalytic subunit alpha (PPP3CA), nitric oxide synthase 3 (NOS3), ERK1/2, AKT1, and p38 MAPK. FGF2, but not VEGF rapidly (< or =5 min) induced p38 MAPK phosphorylation. Suppression of PPP2CA enhanced (p<0.05) VEGF-induced AKT1, but not ERK1/2 phosphorylation, whereas inhibited (p<0.05) FGF2-induced ERK1/2 and p38 MAPK and slightly attenuated FGF2-induced AKT1 phosphorylation. Suppression of PPP2CA did not significantly affect VEGF- and FGF2-stimulated OFPAE cell proliferation. Thus, suppression of PPP2CA alone differentially modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation, without altering VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. These data also suggest that signaling molecules other than ERK1/2, AKT1, and p38 MAPK are important mediators for VEGF- and FGF2-stimulated OFPAE cell proliferation after PPP2CA suppression.
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Affiliation(s)
- Y Song
- Department of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, Madison, WI 53715, USA
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20
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Kalén M, Wallgard E, Asker N, Nasevicius A, Athley E, Billgren E, Larson JD, Wadman SA, Norseng E, Clark KJ, He L, Karlsson-Lindahl L, Häger AK, Weber H, Augustin H, Samuelsson T, Kemmet CK, Utesch CM, Essner JJ, Hackett PB, Hellström M. Combination of reverse and chemical genetic screens reveals angiogenesis inhibitors and targets. ACTA ACUST UNITED AC 2009; 16:432-41. [PMID: 19389629 DOI: 10.1016/j.chembiol.2009.02.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 01/26/2009] [Accepted: 02/09/2009] [Indexed: 01/19/2023]
Abstract
We combined reverse and chemical genetics to identify targets and compounds modulating blood vessel development. Through transcript profiling in mice, we identified 150 potentially druggable microvessel-enriched gene products. Orthologs of 50 of these were knocked down in a reverse genetic screen in zebrafish, demonstrating that 16 were necessary for developmental angiogenesis. In parallel, 1280 pharmacologically active compounds were screened in a human cell-based assay, identifying 28 compounds selectively inhibiting endothelial sprouting. Several links were revealed between the results of the reverse and chemical genetic screens, including the serine/threonine (S/T) phosphatases ppp1ca, ppp1cc, and ppp4c and an inhibitor of this gene family; Endothall. Our results suggest that the combination of reverse and chemical genetic screens, in vertebrates, is an efficient strategy for the identification of drug targets and compounds that modulate complex biological systems, such as angiogenesis.
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Affiliation(s)
- Mattias Kalén
- AngioGenetics Sweden AB, Scheeles väg 2, SE 171 77 Stockholm, Sweden
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21
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Hivert V, Pierre J, Raingeaud J. Phosphorylation of human enhancer of filamentation (HEF1) on serine 369 induces its proteasomal degradation. Biochem Pharmacol 2009; 78:1017-25. [PMID: 19539609 DOI: 10.1016/j.bcp.2009.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 05/29/2009] [Accepted: 06/05/2009] [Indexed: 11/29/2022]
Abstract
Human enhancer of filamentation 1 (HEF1) is a multi-domain docking protein of the p130 Cas family. HEF1 is present at focal adhesions and is involved in integrin signalling mediating cytoskeleton reorganization associated with cell migration, adhesion or apoptosis. HEF1 functions are regulated in part by phosphorylation on tyrosine residues. HEF1 is also phosphorylated on serines/threonines leading to two isoforms refered to as p105 and p115. In most cases, the serine/threonine kinase(s) responsible for HEF1 phosphorylation have not been identified. In the present study, we have investigated HEF1 ser/thr phosphorylation. In the HCT-116 cell line transiently overexpressing Flag-HEF1 we showed that Hesperadin, a synthetic indolinone displaying antiproliferative effect and described as an inhibitor of various kinases including Aurora-B, prevented HEF1 phosphorylation induced by the ser/thr phosphatase PP2A inhibitor: okadaic acid (OA). In addition we showed that conversion of endogenous HEF1 p105 to p115 in HaCaT cells was prevented upon treatment with Hesperadin, resulting in accumulation of p105HEF1. We also identified serine 369 as the target site of phosphorylation by this Hesperadin-inhibited kinase in HCT-116. Finally, we provide evidence that phosphorylation on serine 369 but not phosphorylation on serine 296, triggers HEF1 degradation by the proteasomal machinery. These data suggest that conversion of p105 to p115 results from a ser-369-dependent phosphorylation mediated by an Hesperadin-sensitive kinase and regulates the half-life of HEF1.
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Affiliation(s)
- Virginie Hivert
- INSERM U749, Université Paris-sud 11, Faculté de Pharmacie, 5 rue JB Clement, 92296 Chatenay-Malabry, France
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22
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Recruitment of protein phosphatase 2A to dorsal ruffles by platelet-derived growth factor in smooth muscle cells: Dephosphorylation of Hsp27. Exp Cell Res 2009; 315:836-48. [DOI: 10.1016/j.yexcr.2008.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 11/10/2008] [Accepted: 12/03/2008] [Indexed: 01/01/2023]
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23
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Abstract
Okadaic acid (OA) and its analogs, the dinophysistoxins, are potent inhibitors of protein phosphatases 1 and 2A. This action is well known to cause diarrhea and gastrointestinal symptons when the toxins reach the digestive tract by ingestion of mollusks. A less well-known effect of these group of toxins is their effect in the cytoskeleton. OA has been shown to stimulate cell motility, loss of stabilization of focal adhesions and a consequent loss of cytoskeletal organization due to an alteration in the tyrosine-phosphorylated state of the focal adhesion kinases and paxillin. OA causes cell rounding and loss of barrier properties through mechanisms that probably involve disruption of filamentous actin (F-actin) and/or hyperphosphorylation and activation of kinases that stimulate tight junction disassembly. Neither methyl okadaate (a weak phosphatase inhibitor) nor OA modify the total amount of F-actin, but both toxins cause similar changes in the F-actin cytoskeleton, with strong retraction and rounding, and in many cases cell detachment. OA and dinophysistoxin-1 (35S-methylokadaic acid) cause rapid changes in the structural organization of intermediate filaments, followed by a loss of microtubules, solubilization of intermediate filament proteins, and disruption of desmosomes. The detailed pathways that coordinate all these effects are not yet known.
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Affiliation(s)
- Carmen Vale
- Departamento de Farmacología, Facultad de Veterinaria, USC, Lugo, Spain.
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24
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Morris MA, Young LS, Dawson CW. DNA tumour viruses promote tumour cell invasion and metastasis by deregulating the normal processes of cell adhesion and motility. Eur J Cell Biol 2008; 87:677-97. [PMID: 18468721 DOI: 10.1016/j.ejcb.2008.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2007] [Revised: 03/17/2008] [Accepted: 03/17/2008] [Indexed: 01/11/2023] Open
Abstract
Approximately 15-20% of global cancer incidence is causally linked to viral infection, yet the low incidence of cancers in healthy infected individuals suggests that malignant conversion of virus-infected cells occurs after a long period as a result of additional genetic modifications. There are four families of viruses that are now documented to be involved in the development of human cancers which include members of the polyomavirus, hepadnavirus, papillomavirus and herpesvirus families. Although a number of these viruses are implicated in the aetiology of lymphomas or leukaemias, the vast majority are associated with malignancies of epithelial cells. In epithelial tissues, several classes of proteins are involved in maintaining tissue architecture, including those that promote cell-cell adhesion, and others, which mediate cell-matrix interactions. Proteins representative of all classes are frequently altered in malignant tumour cells that possess invasive and metastatic properties. Malignant tumour cells acquire mechanisms to degrade basement membranes and invade the underlying tissue. Many viruses encode proteins which engage signalling pathways that affect one or more of these mechanisms. It is believed that activation of these processes by chronic viral infection can, under certain circumstances, promote tumour cell invasion and metastasis. This review will take a brief look at the current knowledge of viral-induced alterations in cell motility and invasiveness in the context of tumour invasion and metastasis.
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Affiliation(s)
- Mhairi A Morris
- Cancer Research (UK) Institute for Cancer Studies, The Medical School, University of Birmingham, Birmingham B15 2TT, UK.
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25
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Gushiken FC, Patel V, Liu Y, Pradhan S, Bergeron AL, Peng Y, Vijayan KV. Protein phosphatase 2A negatively regulates integrin alpha(IIb)beta(3) signaling. J Biol Chem 2008; 283:12862-9. [PMID: 18334487 DOI: 10.1074/jbc.m708804200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Integrin alpha(IIb)beta(3) activation is critical for platelet physiology and is controlled by signal transduction through kinases and phosphatases. Compared with kinases, a role for phosphatases in platelet integrin alpha(IIb)beta(3) signaling is less understood. We report that the catalytic subunit of protein phosphatase 2A (PP2Ac) associates constitutively with the integrin alpha(IIb)beta(3) in resting platelets and in human embryonal kidney 293 cells expressing alpha(IIb)beta(3). The membrane proximal KVGFFKR sequence within the cytoplasmic domain of integrin alpha(IIb) is sufficient to support a direct interaction with PP2Ac. Fibrinogen binding to alpha(IIb)beta(3) during platelet adhesion decreased integrin-associated PP2A activity and increased the phosphorylation of a PP2A substrate, vasodilator associated phosphoprotein. Overexpression of PP2Ac(alpha) in 293 cells decreased alpha(IIb)beta(3)-mediated adhesion to immobilized fibrinogen. Conversely, small interference RNA mediated knockdown of endogenous PP2Ac(alpha) expression in 293 cells, enhanced extracellular signal-regulated kinase (ERK1/2) and p38 activation, and accelerated alpha(IIb)beta(3) adhesion to fibrinogen and von Willebrand factor. Inhibition of ERK1/2, but not p38 activation, abolished the increased adhesiveness of PP2Ac (alpha)-depleted 293 cells to fibrinogen. Furthermore, knockdown of PP2A(calpha) expression in bone marrow-derived murine megakaryocytes increased soluble fibrinogen binding induced by protease-activated receptor 4-activating peptide. These studies demonstrate that PP2Ac (alpha) can negatively regulate integrin alpha(IIb)beta(3) signaling by suppressing the ERK1/2 signaling pathway.
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Villa-Moruzzi E. Targeting of FAK Ser910 by ERK5 and PP1delta in non-stimulated and phorbol ester-stimulated cells. Biochem J 2007; 408:7-18. [PMID: 17692050 PMCID: PMC2049076 DOI: 10.1042/bj20070058] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ser910 of FAK (focal adhesion kinase) was phosphorylated in fibroblasts treated with the phorbol ester PMA and dephosphorylated by PP1d (protein phosphatase 1d), as indicated by shRNA (small-hairpin RNA) gene silencing. Ser910 of FAK was reported previously to be an ERK (extracellular-signal-regulated kinase) 1/2 target in cells treated with phorbol esters. In contrast, various approaches, including the use of the MEK (mitogen-activated protein kinase/ERK kinase) inhibitors UO126 and CI-1040 to inhibit ERK1/2 pointed to the involvement of ERK5. This hypothesis was confirmed by: (i) shRNA ERK5 gene silencing, which resulted in complete pSer910 loss in non-stimulated and PMA-stimulated cells; (ii) direct phosphorylation of recombinant FAK by ERK5; and (iii) ERK5 activation by PMA. PMA stimulation and ERK5 silencing in MDA-MB 231 and MDA-MB 361 breast cancer cells indicated Ser910 targeting by ERK5 also in these cells. Given the proximity of Ser910 to the FAT (focal adhesion targeting) regulatory domain of FAK, cell proliferation and morphology were investigated in FAK-/- cells expressing S910A mutant FAK. The cell growth rate decreased and exposure to PMA induced peculiar morphological changes in cells expressing S910A, with respect to wild-type FAK, suggesting a role for Ser910 in these processes. The present study indicates, for the first time, the phosphorylation of Ser910 of FAK by ERK5 and its dephosphorylation by PP1d, and suggested a role for Ser910 in the control of cell shape and proliferation.
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Affiliation(s)
- Emma Villa-Moruzzi
- Dipartimento di Patologia Sperimentale, Sezione Patologia Generale, via Roma 55, 56126 Pisa, Italy.
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27
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Eto M, Kirkbride J, Elliott E, Lo SH, Brautigan DL. Association of the tensin N-terminal protein-tyrosine phosphatase domain with the alpha isoform of protein phosphatase-1 in focal adhesions. J Biol Chem 2007; 282:17806-15. [PMID: 17435217 DOI: 10.1074/jbc.m700944200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Focal adhesions attach cultured cells to the extracellular matrix, and we found endogenous protein phosphatase-1alpha isoform (PP1alpha) localized in adhesions across the entire area of adherent fibroblasts. However, in fibroblasts migrating into a scrape wound or spreading after replating PP1alpha did not appear in adhesions near the leading edge but was recruited into other adhesions coincident in time and space with incorporation of tensin. Endogenous tensin and PP1alpha co-precipitated from cell lysates with isoform-specific PP1 antibodies. Chemical cross-linking of focal adhesion preparations with Lomant's reagent demonstrated molecular proximity of endogenous PP1alpha and tensin, whereas neither focal adhesion kinase nor vinculin was cross-linked and co-precipitated with PP1alpha, suggesting distinct spatial subdomains within adhesions. Transient expression of truncated tensin showed the N-terminal 360 residues, which comprise a protein-tyrosine phosphatase domain, alone were sufficient for isoform-selective co-precipitation of co-expressed PP1alpha. Human prostate cancer PC3 cells are deficient in tensin relative to fibroblasts and have fewer, mostly peripheral adhesions. Transient expression of green fluorescent protein tensin in these cancer cells induced formation of adhesions and recruited endogenous PP1alpha into those adhesions. Thus, the protein-tyrosine phosphatase domain of tensin exhibits isoform-specific association with PP1alpha in a restricted spatial region of adhesions that are formed during cell migration.
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Affiliation(s)
- Masumi Eto
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA
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28
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Xu L, Deng X. Suppression of Cancer Cell Migration and Invasion by Protein Phosphatase 2A through Dephosphorylation of μ- and m-Calpains. J Biol Chem 2006; 281:35567-75. [PMID: 16982626 DOI: 10.1074/jbc.m607702200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mu- and m-calpains are major members of the calpain family that play an essential role in regulating cell motility. We have recently discovered that nicotine-activated protein kinase C iota enhances calpain phosphorylation in association with enhanced calpain activity and accelerated migration and invasion of human lung cancer cells. Here we found that specific disruption of protein phosphatase 2A (PP2A) activity by expression of SV40 small tumor antigen up-regulates phosphorylation of mu- and m-calpains whereas C2-ceramide, a potent PP2A activator, reduces nicotine-induced calpain phosphorylation, suggesting that PP2A may function as a physiological calpain phosphatase. PP2A co-localizes and interacts with mu- and m-calpains. Purified, active PP2A directly dephosphorylates mu- and m-calpains in vitro. Overexpression of the PP2A catalytic subunit (PP2A/C) suppresses nicotine-stimulated phosphorylation of mu- and m-calpains, which is associated with inhibition of calpain activity, wound healing, cell migration, and invasion. By contrast, depletion of PP2A/C by RNA interference enhances calpain phosphorylation, calpain activity, cell migration, and invasion. Importantly, C2-ceramide-induced suppression of calpain phosphorylation results in decreased secretion of mu- and m-calpains from lung cancer cells into culture medium, which may have potential clinic relevance in controlling metastasis of lung cancer. These findings reveal a novel role for PP2A as a physiological calpain phosphatase that not only directly dephosphorylates but also inactivates mu- and m-calpains, leading to suppression of migration and invasion of human lung cancer cells.
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Affiliation(s)
- Lijun Xu
- Shands Cancer Center, Department of Medicine, University of Florida Health Science Center, Gainesville, Florida 32610-3633, USA
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29
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Nayal A, Webb DJ, Brown CM, Schaefer EM, Vicente-Manzanares M, Horwitz AR. Paxillin phosphorylation at Ser273 localizes a GIT1-PIX-PAK complex and regulates adhesion and protrusion dynamics. ACTA ACUST UNITED AC 2006; 173:587-9. [PMID: 16717130 PMCID: PMC2063867 DOI: 10.1083/jcb.200509075] [Citation(s) in RCA: 238] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Continuous adhesion formation and disassembly (adhesion turnover) in the protrusions of migrating cells is regulated by unclear mechanisms. We show that p21-activated kinase (PAK)–induced phosphorylation of serine 273 in paxillin is a critical regulator of this turnover. Paxillin-S273 phosphorylation dramatically increases migration, protrusion, and adhesion turnover by increasing paxillin–GIT1 binding and promoting the localization of a GIT1–PIX–PAK signaling module near the leading edge. Mutants that interfere with the formation of this ternary module abrogate the effects of paxillin-S273 phosphorylation. PAK-dependent paxillin-S273 phosphorylation functions in a positive-feedback loop, as active PAK, active Rac, and myosin II activity are all downstream effectors of this turnover pathway. Finally, our studies led us to identify in highly motile cells a class of small adhesions that reside near the leading edge, turnover in 20–30 s, and resemble those seen with paxillin-S273 phosphorylation. These adhesions appear to be regulated by the GIT1–PIX–PAK module near the leading edge.
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Affiliation(s)
- Anjana Nayal
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908, USA
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Young MRI. Tumor-derived prostaglandin E2 and transforming growth factor-beta stimulate endothelial cell motility through inhibition of protein phosphatase-2A and involvement of PTEN and phosphatidylinositide 3-kinase. Angiogenesis 2005; 7:123-31. [PMID: 15516833 DOI: 10.1007/s10456-004-1027-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tumor vascularization is a complex process that requires structural reorganization and increased motility by endothelial cells. Studies were conducted to identify the tumor-derived mediators and signaling pathways that lead to this increased endothelial cell motility. Using the Lewis lung carcinoma (LLC) tumor model, these studies showed that prostaglandin E2 (PGE2) and transforming growth factor-beta (TGFbeta) were the mediators that were responsible for the migration-stimulatory activity produced by the tumor cells. The response of endothelial cells to these tumor-derived motility-stimulatory factors involved a decline in the activity of the serine/threonine phosphatase PP-2A. Inhibition PP-2A either pharmacologically or genetically increased endothelial cell migration. Concurrent with the decline in PP-2A activity as a result of exposure to PGE2/TGFbeta was a loss of PP-2A co-precipitation with the inositol phosphatase PTEN and an increase in the PTEN serine phosphorylation level. Since hyperphosphorylation has been shown to inhibit the ability of PTEN to act as an antagonist to phosphatidylinositide 3-kinase (PI3K), the role of PI3K in PGE2/TGFbeta-stimulated migration was examined. These studies showed that the increased endothelial cell motility that resulted from PGE2/TGFbeta inhibition of PP-2A was dependent on PI3K.
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Affiliation(s)
- M Rita I Young
- Research Service, Ralph H. Johnson VA Medical Center, and the Departments of Medicine and Otolaryngology, Medical University of South Carolina, Charleston, South Carolina 29401, USA.
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Kim B, van Golen CM, Feldman EL. Degradation and dephosphorylation of focal adhesion kinase during okadaic acid-induced apoptosis in human neuroblastoma cells. Neoplasia 2004; 5:405-16. [PMID: 14670178 PMCID: PMC1502611 DOI: 10.1016/s1476-5586(03)80043-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Focal adhesion kinase (FAK) prevents apoptosis in many cell types. We have reported that tyrosine residues in FAK are dephosphorylated and FAK is degraded during mannitol-induced apoptosis in human neuroblastoma cells. Several studies suggest that FAK dephosphorylation and degradation are separate events. The current study defines the relationship between FAK dephosphorylation and degradation in neuroblastoma cells using okadaic acid (OA). OA, a serine phosphatase inhibitor, promotes serine/threonine phosphorylation, which in turn blocks tyrosine phosphorylation. OA induced focal adhesion loss, actin cytoskeleton disorganization, and cellular detachment, which corresponded to a loss of FAK Tyr397 phosphorylation. These changes preceded caspase-3 activation, Akt and MAP kinase activity loss, protein ubiquitination, and cellular apoptosis. Insulin-like growth factor-I prevented mannitol-induced, but not OA-induced, substrate detachment and FAK Tyr397 dephosphorylation, and the effects of OA on FAK Tyr397 phosphorylation were irreversible. The proteolytic degradation of FAK is temporally distinct from its tyrosine dephosphorylation, occurring when apoptotic pathways are already initiated and during a generalized destruction of signaling proteins. Therefore, agents resulting in the dephosphorylation of FAK may be beneficial for therapeutic treatment, irrespective of FAK protein levels, as this may result in apoptosis, which cannot be prevented by growth factor signaling.
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Affiliation(s)
- Bhumsoo Kim
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
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Ishida K, Simizu S, Teruya T, Wierzba MK, Osada H. Rational design and synthesis of novel heparan sulfate mimetic compounds as antiadhesive agents. Bioorg Med Chem Lett 2004; 14:2505-9. [PMID: 15109641 DOI: 10.1016/j.bmcl.2004.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 03/01/2004] [Indexed: 11/30/2022]
Abstract
A biological evaluation of the antiadhesive activity of novel heparan sulfate glycosaminoglycans mimetic compounds (KI-compounds) is described. In an adhesion assay, KI-111 [2-(4-fluoro-3-nitrobenzoyl)benzoic acetic anhydride] was found to exert potent inhibitory activities against the adhesion of human fibrosarcoma HT1080 cells and HeLa cells to fibronectin. Cell growth, migration, and invasion of HT1080 cells were also inhibited by KI-111 at almost equal concentrations.
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Affiliation(s)
- Keisuke Ishida
- Antibiotics Laboratory, RIKEN Discovery Research Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Larsen M, Tremblay ML, Yamada KM. Phosphatases in cell–matrix adhesion and migration. Nat Rev Mol Cell Biol 2003; 4:700-11. [PMID: 14506473 DOI: 10.1038/nrm1199] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Many proteins that have been implicated in cell-matrix adhesion and cell migration are phosphorylated, which regulates their folding, enzymatic activities and protein-protein interactions. Although modulation of cell motility by kinases is well known, increasing evidence confirms that phosphatases are essential at each stage of the migration process. Phosphatases can control the formation and maintenance of the actin cytoskeleton, regulate small GTPase molecular switches, and modulate the dynamics of matrix-adhesion interaction, actin contraction, rear release and migratory directionality.
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Affiliation(s)
- Melinda Larsen
- Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Building 30/Room 421, 30 Convent Drive, MSC 4370, Bethesda, Maryland 20892-4370, USA.
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Laakko T, Juliano RL. Adhesion regulation of stromal cell-derived factor-1 activation of ERK in lymphocytes by phosphatases. J Biol Chem 2003; 278:31621-8. [PMID: 12783869 DOI: 10.1074/jbc.m304700200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated whether chemokine signaling to the extracellular-signal-regulated kinase (ERK) was regulated by beta 1-integrin-mediated adhesion in B- and T-cell lines. Activation of ERK by the chemokine SDF-1 can be regulated by adhesion to beta 1-integrin substrates in the T-cell lines MOLT-3, Jurkat, and H9 and in the Daudi B-cell line. In Jurkat T-cells, adhesion to the immobilized alpha 4 beta 1-integrin ligand VCAM-1 or to the alpha 5 beta 1-integrin ligand fibronectin regulated stromal-cell derived factor-1 (SDF-1) activation of ERK. Adhesion control of SDF-1 signaling was a rapid event, occurring as early as 10 min after adhesion, and loss of signaling occurred within 10 min of deadhesion. In contrast, SDF-1 activation of the ERK kinase MEK was independent of adhesion. Partial restoration of signaling to ERK in suspension was accomplished by pretreatment with pharmacological inhibitors of serine/threonine or protein-tyrosine phosphatases. In addition, we used a non-radioactive phosphatase assay using phosphorylated ERK as the substrate to determine relative ERK dephosphorylation in whole cell extracts. These results showed greater relative ERK dephosphorylation in extracts from Jurkat cells treated in suspension, as compared with adherent cells. Therefore, these data suggest that adhesion influences SDF-1 activation of ERK by regulating the activity of ERK phosphatases. This identifies a novel locus of adhesion regulation of the ERK cascade.
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Affiliation(s)
- Tonya Laakko
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Pullar CE, Chen J, Isseroff RR. PP2A activation by beta2-adrenergic receptor agonists: novel regulatory mechanism of keratinocyte migration. J Biol Chem 2003; 278:22555-62. [PMID: 12697752 DOI: 10.1074/jbc.m300205200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding the mechanisms that regulate cell migration is important for devising novel therapies to control metastasis or enhance wound healing. Previously, we demonstrated that beta2-adrenergic receptor (beta2-AR) activation in keratinocytes inhibited their migration by decreasing the phosphorylation of a critical promigratory signaling component, the extracellular signal-related kinase (ERK). Here we demonstrate that beta2-AR-induced inhibition of migration is mediated by the activation of the serine/threonine phosphatase PP2A. Pretreating human keratinocytes with the PP2A inhibitor, okadaic acid, prevented the beta2-AR-induced inhibition of migration, either as isolated cells or as a confluent sheet of cells repairing an in vitro "wound" and also prevented the beta2-AR-induced reduction in ERK phosphorylation. Similar results were obtained with human corneal epithelial cells. In keratinocytes, immunoprecipitation studies revealed that beta2-AR activation resulted in the rapid association of beta2-AR with PP2A as well as a 37% increase in association of PP2A with ERK2. Finally, beta2-AR activation resulted in a rapid and transient 2-fold increase in PP2A activity. Thus, we provide the first evidence that beta2-AR activation in keratinocytes modulates migration via a novel pathway utilizing PP2A to alter the promigratory signaling cascade. Exploiting this pathway may result in novel therapeutic approaches for control of epithelial cell migration.
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Affiliation(s)
- Christine E Pullar
- Department of Dermatology, University of California, Davis, Davis, California 95616, USA
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