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Rajendran AK, Sankar D, Amirthalingam S, Kim HD, Rangasamy J, Hwang NS. Trends in mechanobiology guided tissue engineering and tools to study cell-substrate interactions: a brief review. Biomater Res 2023; 27:55. [PMID: 37264479 DOI: 10.1186/s40824-023-00393-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/09/2023] [Indexed: 06/03/2023] Open
Abstract
Sensing the mechanical properties of the substrates or the matrix by the cells and the tissues, the subsequent downstream responses at the cellular, nuclear and epigenetic levels and the outcomes are beginning to get unraveled more recently. There have been various instances where researchers have established the underlying connection between the cellular mechanosignalling pathways and cellular physiology, cellular differentiation, and also tissue pathology. It has been now accepted that mechanosignalling, alone or in combination with classical pathways, could play a significant role in fate determination, development, and organization of cells and tissues. Furthermore, as mechanobiology is gaining traction, so do the various techniques to ponder and gain insights into the still unraveled pathways. This review would briefly discuss some of the interesting works wherein it has been shown that specific alteration of the mechanical properties of the substrates would lead to fate determination of stem cells into various differentiated cells such as osteoblasts, adipocytes, tenocytes, cardiomyocytes, and neurons, and how these properties are being utilized for the development of organoids. This review would also cover various techniques that have been developed and employed to explore the effects of mechanosignalling, including imaging of mechanosensing proteins, atomic force microscopy (AFM), quartz crystal microbalance with dissipation measurements (QCMD), traction force microscopy (TFM), microdevice arrays, Spatio-temporal image analysis, optical tweezer force measurements, mechanoscanning ion conductance microscopy (mSICM), acoustofluidic interferometric device (AID) and so forth. This review would provide insights to the researchers who work on exploiting various mechanical properties of substrates to control the cellular and tissue functions for tissue engineering and regenerative applications, and also will shed light on the advancements of various techniques that could be utilized to unravel the unknown in the field of cellular mechanobiology.
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Affiliation(s)
- Arun Kumar Rajendran
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Deepthi Sankar
- Polymeric Biomaterials Lab, School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, 682041, India
| | - Sivashanmugam Amirthalingam
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
- Institute of Engineering Research, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hwan D Kim
- Department of Polymer Science and Engineering, Korea National University of Transportation, Chungju, 27469, Republic of Korea
- Department of Biomedical Engineering, Korea National University of Transportation, Chungju, 27469, Republic of Korea
| | - Jayakumar Rangasamy
- Polymeric Biomaterials Lab, School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, 682041, India.
| | - Nathaniel S Hwang
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea.
- Institute of Engineering Research, Seoul National University, Seoul, 08826, Republic of Korea.
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, 08826, Republic of Korea.
- Bio-MAX/N-Bio Institute, Institute of Bio-Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
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PI(4,5)P2: signaling the plasma membrane. Biochem J 2022; 479:2311-2325. [PMID: 36367756 PMCID: PMC9704524 DOI: 10.1042/bcj20220445] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022]
Abstract
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
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MoCAP proteins regulated by MoArk1-mediated phosphorylation coordinate endocytosis and actin dynamics to govern development and virulence of Magnaporthe oryzae. PLoS Genet 2017; 13:e1006814. [PMID: 28542408 PMCID: PMC5466339 DOI: 10.1371/journal.pgen.1006814] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 06/09/2017] [Accepted: 05/12/2017] [Indexed: 12/22/2022] Open
Abstract
Actin organization is a conserved cellular process that regulates the growth and development of eukaryotic cells. It also governs the virulence process of pathogenic fungi, such as the rice blast fungus Magnaporthe oryzae, with mechanisms not yet fully understood. In a previous study, we found that actin-regulating kinase MoArk1 displays conserved functions important in endocytosis and actin organization, and MoArk1 is required for maintaining the growth and full virulence of M. oryzae. To understand how MoArk1 might function, we identified capping protein homologs from M. oryzae (MoCAP) that interact with MoArk1 in vivo. MoCAP is heterodimer consisting of α and β subunits MoCapA and MoCapB. Single and double deletions of MoCAP subunits resulted in abnormal mycelial growth and conidia formation. The ΔMocap mutants also exhibited reduced appressorium penetration and invasive hyphal growth within host cells. Furthermore, the ΔMocap mutants exhibited delayed endocytosis and abnormal cytoskeleton assembly. Consistent with above findings, MoCAP proteins interacted with MoAct1, co-localized with actin during mycelial development, and participated in appressorial actin ring formation. Further analysis revealed that the S85 residue of MoCapA and the S285 residue of MoCapB were subject to phosphorylation by MoArk1 that negatively regulates MoCAP functions. Finally, the addition of exogenous phosphatidylinositol 4,5-bisphosphate (PIP2) failed to modulate actin ring formation in ΔMocap mutants, in contrast to the wild-type strain, suggesting that MoCAP may also mediate phospholipid signaling in the regulation of the actin organization. These results together demonstrate that MoCAP proteins whose functions are regulated by MoArk1 and PIP2 are important for endocytosis and actin dynamics that are directly linked to growth, conidiation and pathogenicity of M. oryzae. The actin-regulating kinase MoArk1 plays a conserved function in endocytosis and actin organization and is also essential for growth and full virulence of the rice blast fungus Magnaporthe oryzae. To understand how MoArk1 functions, we identified the F-actin capping protein α (MoCapA) and β (MoCapB) subunits that interact with MoArk1. We showed that single and double deletions of MoCAPA and MoCAPB result in slowed growth, reduced conidia production, abnormal morphogenesis, and attenuated virulence. We found that ΔMocap mutants are defective in endocytosis and actin organization and that MoCAP proteins are subject to regulation by MoArk1 through protein phosphorylation. Finally, we provided evidence demonstrating that MoCAP proteins modulate actin dynamics in response to phosphatidylinositol 4,5-biphosphate (PIP2). These combined results suggest that MoCAP proteins play an important role in endocytosis, actin organization, and virulence. Further studies of MoCAP proteins could lead to a better understanding of the connections between actin organization and host infection by M. oryzae.
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Marzook NB, Newsome TP. Viruses That Exploit Actin-Based Motility for Their Replication and Spread. Handb Exp Pharmacol 2016; 235:237-261. [PMID: 27757755 DOI: 10.1007/164_2016_41] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The actin cytoskeleton is a crucial part of the eukaryotic cell. Viruses depend on host cells for their replication, and, as a result, many have developed ways of manipulating the actin network to promote their spread. This chapter reviews the various ways in which viruses utilize the actin cytoskeleton at discrete steps in their life cycle, from entry into the host cell, replication, and assembly of new progeny to virus release. Various actin inhibitors that function in different ways to affect proper actin dynamics can be used to parse the role of actin at these steps.
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Affiliation(s)
- N Bishara Marzook
- The School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Timothy P Newsome
- The School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia.
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Phosphatidylinositol (3,4) bisphosphate-specific phosphatases and effector proteins: A distinct branch of PI3K signaling. Cell Signal 2015; 27:1789-98. [DOI: 10.1016/j.cellsig.2015.05.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/16/2015] [Accepted: 05/20/2015] [Indexed: 01/22/2023]
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Terzi YK, Kocaefe YC, Ayter S. Coronin 1A inhibits neurite outgrowth in PC12 cells. Neurosci Lett 2014; 582:38-42. [PMID: 25179994 DOI: 10.1016/j.neulet.2014.08.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/21/2014] [Accepted: 08/25/2014] [Indexed: 11/30/2022]
Abstract
Regenerative response to central nervous system damage in mammals is limited because of inhibitor signals which consist of myelin associated inhibitor proteins and chondroitin sulfate proteoglycans. Inhibitor signals mainly affect cytoskeleton elements which are important for axonal sprouting and neurite outgrowth. Coronin 1A is an actin cytoskeleton associated protein. Coronin 1A shows its effect on actin cytoskeleton through binding to the Arp2/3 complex which is a key nucleator of actin polymerization and regulates its activation on actin cytoskeleton. Coronin 1A-Arp2/3 interaction is regulated by phosphorylation of Coronin 1A from the C and N terminal region. Thus, Coronin 1A-Arp2/3 complex is one of the targets of inhibitory signaling cascades. The aim of this study was to investigate the effect of Coronin 1A on neurite outgrowth in PC12 cells in vitro. The results showed that Coronin 1A is expressed in differentiated PC12 cells and localized along axonal sprouting region of the neurites. Other results showed that overexpression of Coronin 1A in PC12 cells effects neurite outgrowth. Neurite lengths of the Coronin 1A overexpressing PC12 cells were lower than the untransfected (p<0.001) and control transfected (p=0.002) PC12 cells. These results indicate that Coronin 1A has an inhibitory effect on neurite outgrowth in vitro.
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Affiliation(s)
- Yunus Kasim Terzi
- Hacettepe University, Faculty of Medicine, Department of Medical Biology, Sihhiye, 06100, Ankara, Turkey
| | - Yusuf Cetin Kocaefe
- Hacettepe University, Faculty of Medicine, Department of Medical Biology, Sihhiye, 06100, Ankara, Turkey
| | - Sukriye Ayter
- Hacettepe University, Faculty of Medicine, Department of Medical Biology, Sihhiye, 06100, Ankara, Turkey.
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Zhang QP, Zhang HY, Zhang XF, Zhao JH, Ma ZJ, Zhao D, Yi XN. srGAP3 promotes neurite outgrowth of dorsal root ganglion neurons by inactivating RAC1. ASIAN PAC J TROP MED 2014; 7:630-638. [DOI: 10.1016/s1995-7645(14)60106-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/15/2014] [Accepted: 07/15/2014] [Indexed: 11/30/2022] Open
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Artman L, Dormoy-Raclet V, von Roretz C, Gallouzi IE. Planning your every move: the role of β-actin and its post-transcriptional regulation in cell motility. Semin Cell Dev Biol 2014; 34:33-43. [PMID: 24878350 DOI: 10.1016/j.semcdb.2014.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 05/21/2014] [Indexed: 01/23/2023]
Abstract
Cell motility is a tightly regulated process that involves the polymerization of actin subunits. The formation of actin filaments is controlled through a variety of protein factors that accelerate or perturb the polymerization process. As is the case for most biological events, cell movement is also controlled at the level of gene expression. Growing research explains how the β-actin isoform of actin is particularly regulated through post-transcriptional events. This includes the discovery of multiple sites in the 3' untranslated region of β-actin mRNA to which RNA-binding proteins can associate. The control such proteins have on β-actin expression, and as a result, cell migration, continues to develop, and presents a thorough process that involves guiding an mRNA out of the nucleus, to a specific cytosolic destination, and then controlling the translation and decay of this message. In this review we will provide an overview on the recent progress regarding the mechanisms by which actin polymerization modulates cell movement and invasion and we will discuss the importance of post-transcriptional regulatory events in β-actin mediated effects on these processes.
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Affiliation(s)
- Lise Artman
- McGill University, Biochemistry Department and Rosalind and Morris Goodman Cancer Center, Montreal, Canada
| | | | | | - Imed-Eddine Gallouzi
- McGill University, Biochemistry Department and Rosalind and Morris Goodman Cancer Center, Montreal, Canada.
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Law AL, Vehlow A, Kotini M, Dodgson L, Soong D, Theveneau E, Bodo C, Taylor E, Navarro C, Perera U, Michael M, Dunn GA, Bennett D, Mayor R, Krause M. Lamellipodin and the Scar/WAVE complex cooperate to promote cell migration in vivo. J Cell Biol 2013; 203:673-89. [PMID: 24247431 PMCID: PMC3840943 DOI: 10.1083/jcb.201304051] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 10/21/2013] [Indexed: 12/12/2022] Open
Abstract
Cell migration is essential for development, but its deregulation causes metastasis. The Scar/WAVE complex is absolutely required for lamellipodia and is a key effector in cell migration, but its regulation in vivo is enigmatic. Lamellipodin (Lpd) controls lamellipodium formation through an unknown mechanism. Here, we report that Lpd directly binds active Rac, which regulates a direct interaction between Lpd and the Scar/WAVE complex via Abi. Consequently, Lpd controls lamellipodium size, cell migration speed, and persistence via Scar/WAVE in vitro. Moreover, Lpd knockout mice display defective pigmentation because fewer migrating neural crest-derived melanoblasts reach their target during development. Consistently, Lpd regulates mesenchymal neural crest cell migration cell autonomously in Xenopus laevis via the Scar/WAVE complex. Further, Lpd's Drosophila melanogaster orthologue Pico binds Scar, and both regulate collective epithelial border cell migration. Pico also controls directed cell protrusions of border cell clusters in a Scar-dependent manner. Taken together, Lpd is an essential, evolutionary conserved regulator of the Scar/WAVE complex during cell migration in vivo.
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Affiliation(s)
- Ah-Lai Law
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Anne Vehlow
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Maria Kotini
- Department of Cell and Developmental Biology, University College London, London WC1 6BT, England, UK
| | - Lauren Dodgson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England, UK
| | - Daniel Soong
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Eric Theveneau
- Department of Cell and Developmental Biology, University College London, London WC1 6BT, England, UK
| | - Cristian Bodo
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Eleanor Taylor
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England, UK
| | - Christel Navarro
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Upamali Perera
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Magdalene Michael
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Graham A. Dunn
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
| | - Daimark Bennett
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, England, UK
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, London WC1 6BT, England, UK
| | - Matthias Krause
- Randall Division of Cell and Molecular Biophysics, and British Heart Foundation Centre of Excellence, James Black Centre, Cardiovascular Division, King’s College London, London SE1 1UL, England, UK
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Leerberg JM, Yap AS. Vinculin, cadherin mechanotransduction and homeostasis of cell-cell junctions. PROTOPLASMA 2013; 250:817-829. [PMID: 23274283 DOI: 10.1007/s00709-012-0475-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 06/01/2023]
Abstract
Cell adhesion junctions characteristically arise from the cooperative integration of adhesion receptors, cell signalling pathways and the cytoskeleton. This is exemplified by cell-cell interactions mediated by classical cadherin adhesion receptors. These junctions are sites where cadherin adhesion systems functionally couple to the dynamic actin cytoskeleton, a process that entails physical interactions with many actin regulators and regulation by cell signalling pathways. Such integration implies a potential role for molecules that may stand at the interface between adhesion, signalling and the cytoskeleton. One such candidate is the cortical scaffolding protein, vinculin, which is a component of both cell-cell and cell-matrix adhesions. While its contribution to integrin-based adhesions has been extensively studied, less is known about how vinculin contributes to cell-cell adhesions. A major recent advance has come with the realisation that cadherin adhesions are active mechanical structures, where cadherin serves as part of a mechanotransduction pathway by which junctions sense and elicit cellular responses to mechanical stimuli. Vinculin has emerged as an important element in cadherin mechanotransduction, a perspective that illuminates its role in cell-cell interactions. We now review its role as a cortical scaffold and its role in cadherin mechanotransduction.
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Affiliation(s)
- Joanne M Leerberg
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Queensland, Australia
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Kushner AM, Guan Z. Modulares Design in natürlichen und biomimetischen elastischen Materialien. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201006496] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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12
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Kushner AM, Guan Z. Modular design in natural and biomimetic soft materials. Angew Chem Int Ed Engl 2011; 50:9026-57. [PMID: 21898722 DOI: 10.1002/anie.201006496] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Indexed: 11/09/2022]
Abstract
Under eons of evolutionary and environmental pressure, biological systems have developed strong and lightweight peptide-based polymeric materials by using the 20 naturally occurring amino acids as principal monomeric units. These materials outperform their man-made counterparts in the following ways: 1) multifunctionality/tunability, 2) adaptability/stimuli-responsiveness, 3) synthesis and processing under ambient and aqueous conditions, and 4) recyclability and biodegradability. The universal design strategy that affords these advanced properties involves "bottom-up" synthesis and modular, hierarchical organization both within and across multiple length-scales. The field of "biomimicry"-elucidating and co-opting nature's basic material design principles and molecular building blocks-is rapidly evolving. This Review describes what has been discovered about the structure and molecular mechanisms of natural polymeric materials, as well as the progress towards synthetic "mimics" of these remarkable systems.
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Affiliation(s)
- Aaron M Kushner
- Department of Chemistry, University of California, Irvine, CA 92697-2025, USA
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Schedin P, Keely PJ. Mammary gland ECM remodeling, stiffness, and mechanosignaling in normal development and tumor progression. Cold Spring Harb Perspect Biol 2011; 3:a003228. [PMID: 20980442 DOI: 10.1101/cshperspect.a003228] [Citation(s) in RCA: 321] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cells of the mammary gland are in intimate contact with other cells and with the extracellular matrix (ECM), both of which provide not only a biochemical context, but a mechanical context as well. Cell-mediated contraction allows cells to sense the stiffness of their microenvironment, and respond with appropriate mechanosignaling events that regulate gene expression and differentiation. ECM composition and organization are tightly regulated throughout development of the mammary gland, resulting in corresponding regulation of the mechanical environment and proper tissue architecture. Mechanical regulation is also at play during breast carcinoma progression, as changes in ECM deposition, composition, and organization accompany breast carcinoma. These changes result in stiffer matrices that activate mechanosignaling pathways and thereby induce cell proliferation, facilitate local tumor cell invasion, and promote progression. Thus, understanding the role of forces in the mammary gland is crucial to understanding both normal developmental and pathological processes.
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Affiliation(s)
- Pepper Schedin
- Department of Medicine, Division of Medical Oncology, University of Colorado, Denver, Colorado 80045, USA
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Gad AK, Aspenström P. Rif proteins take to the RhoD: Rho GTPases at the crossroads of actin dynamics and membrane trafficking. Cell Signal 2010; 22:183-9. [DOI: 10.1016/j.cellsig.2009.10.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 10/01/2009] [Indexed: 01/03/2023]
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Kanaho Y, Funakoshi Y, Hasegawa H. Phospholipase D signalling and its involvement in neurite outgrowth. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:898-904. [DOI: 10.1016/j.bbalip.2009.03.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 03/12/2009] [Accepted: 03/19/2009] [Indexed: 11/26/2022]
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16
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Kähler AK, Djurovic S, Kulle B, Jönsson EG, Agartz I, Hall H, Opjordsmoen S, Jakobsen KD, Hansen T, Melle I, Werge T, Steen VM, Andreassen OA. Association analysis of schizophrenia on 18 genes involved in neuronal migration: MDGA1 as a new susceptibility gene. Am J Med Genet B Neuropsychiatr Genet 2008; 147B:1089-100. [PMID: 18384059 DOI: 10.1002/ajmg.b.30726] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Several lines of evidence support the theory of schizophrenia (SZ) being a neurodevelopmental disorder. The structural, cytoarchitectural and functional brain abnormalities reported in patients with SZ, might be due to aberrant neuronal migration, since the final position of neurons affects neuronal function, morphology, and formation of synaptic connections. We have investigated the putative association between SZ and gene variants engaged in the neuronal migration process, by performing an association study on 839 cases and 1,473 controls of Scandinavian origin. Using a gene-wide approach, tagSNPs in 18 candidate genes have been genotyped, with gene products involved in the neuron-to-glial cell adhesion, interactions with the DISC1 protein and/or rearrangements of the cytoskeleton. Of the 289 markers tested, 19 markers located in genes MDGA1, RELN, ITGA3, DLX1, SPARCL1, and ASTN1, attained nominal significant P-values (P < 0.05) in either a genotypic or allelic association test. All of these genes, except transcription factor DLX1, are involved in the adhesion between neurons and radial glial cells. Eight markers obtained nominal significance in both tests, and were located in intronic or 3'UTR regions of adhesion molecule MDGA1 and previously reported SZ candidate RELN. The most significant result was attained for MDGA1 SNP rs9462341 (unadjusted association results: genotypic P = 0.00095; allelic P = 0.010). Several haplotypes within MDGA1, RELN, ITGA3, and ENAH were nominally significant. Further studies in independent samples are needed, including upcoming genome wide association study results, but our data suggest that MDGA1 is a new SZ susceptibility gene, and that altered neuronal migration is involved in SZ pathology.
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Affiliation(s)
- Anna K Kähler
- TOP Project, Institute of Psychiatry, University of Oslo, Oslo, Norway.
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Abstract
The actin cytoskeleton is required for many important processes during embryonic development. In later stages of life, important homeostatic processes depend on the actin cytoskeleton, such as immune response, haemostasis and blood vessel preservation. Therefore, the function of the actin cytoskeleton must be tightly regulated, and aberrant regulation may cause disease. A growing number of proteins have been described to bind and regulate the actin cytoskeleton. Amongst them, Ena/VASP proteins function as anti-capping proteins, thereby directly modulating the actin ultrastructure. Ena/VASP function is regulated by their recruitment into protein complexes downstream of plasma membrane receptors and by phosphorylation. As regulators of the actin ultrastructure, Ena/VASP proteins are involved in crucial cellular functions, such as shape change, adhesion, migration and cell-cell interaction and hence are important targets for therapeutic intervention. In this chapter, we will first describe the structure, function and regulation of Ena/VASP proteins. Then, we will review the involvement of Ena/VASP proteins in the development of human diseases. Growing evidence links Ena/VASP proteins to important human diseases, such as thrombosis, cancer, arteriosclerosis, cardiomyopathy and nephritis. Finally, present and future perspectives for the development of therapeutic molecules interfering with Ena/VASP-mediated protein-protein interactions are presented.
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Affiliation(s)
- G Pula
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus, London, UK
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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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Wanner SJ, Miller JR. Regulation of otic vesicle and hair cell stereocilia morphogenesis by Ena/VASP-like (Evl) in Xenopus. J Cell Sci 2007; 120:2641-51. [PMID: 17635997 DOI: 10.1242/jcs.004556] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The inner ear is derived from a thickening in the embryonic ectoderm, called the otic placode. This structure undergoes extensive morphogenetic movements throughout its development and gives rise to all components of the inner ear. Ena/VASP-like (Evl) is an actin binding protein involved in the regulation of cytoskeletal dynamics and organization. We have examined the role of Evl during the morphogenesis of the Xenopus inner ear. Evl (hereafter referred to as Xevl) is expressed throughout otic vesicle formation and is enriched in the neuroblasts that delaminate to form the vestibulocochlear ganglion and in hair cells that possess mechanosensory stereocilia. Knockdown of Xevl perturbs epithelial morphology and intercellular adhesion in the otic vesicle and disrupts formation of the vestibulocochlear ganglion, evidenced by reduction of ganglion size, disorganization of the ganglion, and defects in neurite outgrowth. Later in embryogenesis, Xevl is required for development of mechanosensory hair cells. In Xevl knockdown embryos, hair cells of the ventromedial sensory epithelium display multiple abnormalities including disruption of the cuticular plate at the base of stereocilia and disorganization of the normal staircase appearance of stereocilia. Based on these data, we propose that Xevl plays an integral role in regulating morphogenesis of the inner ear epithelium and the subsequent development of the vestibulocochlear ganglion and mechanosensory hair cells.
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Affiliation(s)
- Sarah J Wanner
- Department of Genetics, Cell Biology and Development and Developmental Biology Center, University of Minnesota, Minneapolis, MN 55455, USA
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20
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Abstract
Coronins are conserved F-actin binding proteins that have been implicated in a variety of processes including fibroblast migration, phagocytosis, and chemotaxis. Recent data from our lab indicate that coronin 1B coordinates Arp2/3-dependent actin filament nucleation and cofilin-mediated filament turnover at the leading edge of migrating fibroblasts. Analysis of coronin function has been hampered by the lack of a clear understanding of how coronin interacts with F-actin. Here, we identify a surface-exposed conserved arginine residue at position 30 (R30), which is crucial for coronin 1B binding to F-actin both in vitro and in vivo. Using actin co-sedimentation, we demonstrate that coronin 1B binds with high affinity to ATP/ADP-P(i)-F-actin (170 nM) and with 47-fold lower affinity to ADP-F-actin (8 microM). In contrast to a previous study, we find no evidence for enhanced cofilin binding to F-actin in the presence of either coronin 1B or coronin 1A. Instead, we find that coronin 1B protects actin filaments from cofilin-induced depolymerization. Consistent with an important role for interactions between coronin 1B and F-actin in vivo, an R30D coronin mutant that does not bind F-actin localizes inefficiently to the leading edge. Furthermore, our analysis indicates that F-actin binding is absolutely required for coronin 1B to exert its effects on whole-cell motility and lamellipodial dynamics.
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Affiliation(s)
- Liang Cai
- Lineberger Comprehensive Cancer Center, Department of Cell & Developmental Biology, University of North Carolina at Chapel Hill, North Carolina 27599-7295, USA
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21
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Yoo Y, Wu X, Guan JL. A novel role of the actin-nucleating Arp2/3 complex in the regulation of RNA polymerase II-dependent transcription. J Biol Chem 2007; 282:7616-23. [PMID: 17220302 DOI: 10.1074/jbc.m607596200] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
It has been well documented that actin is present in the nucleus and involved in numerous nuclear functions including regulation of transcription. The actin-nucleating Arp2/3 complex is an essential, evolutionarily conserved seven-subunit protein complex that promotes actin cytoskeleton assembly in the cytoplasm upon stimulation by WASP family proteins. Our recent study indicates that the nuclear localized neural Wiskott-Aldrich syndrome protein (N-WASP) can induce de novo actin polymerization in the nucleus, and this function is important for the role of N-WASP in the regulation of RNA polymerase II-dependent transcription. Here, we have presented evidence to show that the Arp2/3 complex is also localized in the nucleus and plays an essential role in mediating nuclear actin polymerization induced by N-WASP. We have also demonstrated that the Arp2/3 complex physically associates with RNA polymerase II and is involved in the RNA polymerase II-dependent transcriptional regulation both in vivo and in vitro. Together, these data provide strong support for the hypothesis that N-WASP and the Arp2/3 complex regulate transcription, at least in part, through the regulation of nuclear actin polymerization in a manner similar to their function in the cytoplasm.
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Affiliation(s)
- Youngdong Yoo
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
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22
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Li X, Chen Y, Liu Y, Gao J, Gao F, Bartlam M, Wu JY, Rao Z. Structural basis of Robo proline-rich motif recognition by the srGAP1 Src homology 3 domain in the Slit-Robo signaling pathway. J Biol Chem 2006; 281:28430-7. [PMID: 16857672 PMCID: PMC2031215 DOI: 10.1074/jbc.m604135200] [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: 11/06/2022] Open
Abstract
The Slit-Robo (sr) GTPase-activating protein (GAPs) are important components in the intracellular pathway mediating Slit-Robo signaling in axon guidance and cell migration. We report the first crystal structure of the srGAP1 SH3 domain at 1.8-A resolution. The unusual side chain conformation of the conserved Phe-13 in the P1 pocket renders the ligand binding pocket shallow and narrow, which contributes toward the low binding affinity. Moreover, the opposing electrostatic charge and the hydrophobic properties of the P3 specificity pocket are consistent with the observed binding characteristics of the srGAP1 SH3 domain to its ligand. Surface plasmon resonance experiments indicate that the srGAP1 SH3 domain interacts with its natural ligand inaCtoN orientation. The srGAP1 SH3 domain can bind to both the CC2 and CC3 motifs in vitro. The N-terminal two acidic residues in the CC3 motif recognition site are necessary for srGAP1 SH3 domain binding. A longer CC3 peptide (CC3-FL) binds with greater affinity than its shorter counterpart, suggesting that the residues surrounding the proline-rich core are important for protein-peptide interactions. Our study reveals previously unknown properties of the srGAP-Robo interaction. Our data provide a structural basis for the srGAP-Robo interaction, consistent with the role of the Robo intracellular domain in interacting with other downstream signaling molecules and mediating versatile and dynamic responses to axon guidance and cell migration cues.
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Affiliation(s)
- Xiaofeng Li
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
- National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, Beijing 100101, China
| | - Yushu Chen
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
- National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, Beijing 100101, China
| | - Yiwei Liu
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
| | - Jia Gao
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
| | - Feng Gao
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
| | - Mark Bartlam
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
- National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, Beijing 100101, China
| | - Jane Y. Wu
- National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, Beijing 100101, China
- Department of Neurology; Center of Genetic Medicine, Lurie Cancer Center; Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Zihe Rao
- “Tsinghua-IBP Joint Research Group for Structural Biology”, Tsinghua University, Beijing 100084, China
- National Laboratory of Biomacromolecules, Institute of Biophysics (IBP), Chinese Academy of Sciences, Beijing 100101, China
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23
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Zheng H, Koo EH. The amyloid precursor protein: beyond amyloid. Mol Neurodegener 2006; 1:5. [PMID: 16930452 PMCID: PMC1538601 DOI: 10.1186/1750-1326-1-5] [Citation(s) in RCA: 258] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 07/03/2006] [Indexed: 12/28/2022] Open
Abstract
The amyloid precursor protein (APP) takes a central position in Alzheimer's disease (AD) pathogenesis: APP processing generates the beta-amyloid (Abeta) peptides, which are deposited as the amyloid plaques in brains of AD individuals; Point mutations and duplications of APP are causal for a subset of early onset of familial Alzheimer's disease (FAD). Not surprisingly, the production and pathogenic effect of Abeta has been the central focus in AD field. Nevertheless, the biological properties of APP have also been the subject of intense investigation since its identification nearly 20 years ago as it demonstrates a number of interesting putative physiological roles. Several attractive models of APP function have been put forward recently based on in vitro biochemical studies. Genetic analyses of gain- and loss-of-function mutants in Drosophila and mouse have also revealed important insights into its biological activities in vivo. This article will review the current understanding of APP physiological functions.
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Affiliation(s)
- Hui Zheng
- Huffington Center on Aging and Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Edward H Koo
- Huffington Center on Aging and Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
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24
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Wu X, Yoo Y, Okuhama NN, Tucker PW, Liu G, Guan JL. Regulation of RNA-polymerase-II-dependent transcription by N-WASP and its nuclear-binding partners. Nat Cell Biol 2006; 8:756-63. [PMID: 16767080 DOI: 10.1038/ncb1433] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 04/24/2006] [Indexed: 12/16/2022]
Abstract
The presence of actin in the nucleus has been well established, and several studies have implicated nuclear actin in transcriptional regulation. Neuronal Wiskott-Aldrich syndrome protein (N-WASP) is a member of the WASP family of proteins; these proteins function in the cytoplasm as key regulators of cortical actin filament. Interestingly, N-WASP has also been observed in the nucleus. However, a potential nuclear function for N-WASP has not been established. Here, we report the identification of nuclear N-WASP within a large nuclear-protein complex containing PSF-NonO (polypyrimidine-tract-binding-protein-associated splicing factor-non-Pou-domain octamer-binding protein/p54(nrb)), nuclear actin and RNA polymerase II. The PSF-NonO complex is involved in the regulation of many cellular processes, such as transcription, RNA processing, DNA unwinding and repair. We demonstrate that the interaction of N-WASP with the PSF-NonO complex can couple N-WASP with RNA polymerase II to regulate transcription. We also provide evidence that the potential function of N-WASP in promoting polymerization of nuclear actins has an important role in this process. Based on these results, we propose a nuclear function for N-WASP in transcriptional regulation.
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Affiliation(s)
- Xiaoyang Wu
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
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25
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Samarin SN. WASP family proteins act between cytoskeleton and cellular signaling pathways. BIOCHEMISTRY (MOSCOW) 2006; 70:1305-9. [PMID: 16417451 DOI: 10.1007/s10541-005-0262-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This review considers the proteins of the WASP (Wiskott-Aldrich syndrome protein) family and their role in the regulation of actin-based motility. It contains detailed classification of the WASP family proteins and data on their subcellular localization. Impairments of expression of the WASP family proteins cause certain cell pathologies. The review also deals with domain organization of these proteins and proteins interacting with various domains of the WASP proteins. Special attention is given to analysis of the role of the WASP family proteins in initiating directed actin assembly in the leading edge of the migrating cell and on the surface of some bacteria. Putative pathways of regulation of WASP proteins by various protein ligands and their links with cell signaling systems are considered.
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Affiliation(s)
- S N Samarin
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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26
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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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27
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Gonzalez-Quevedo R, Shoffer M, Horng L, Oro AE. Receptor tyrosine phosphatase-dependent cytoskeletal remodeling by the hedgehog-responsive gene MIM/BEG4. ACTA ACUST UNITED AC 2005; 168:453-63. [PMID: 15684034 PMCID: PMC2171717 DOI: 10.1083/jcb.200409078] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
During development, dynamic remodeling of the actin cytoskeleton allows the precise placement and morphology of tissues. Morphogens such as Sonic hedgehog (Shh) and local cues such as receptor protein tyrosine phosphatases (RPTPs) mediate this process, but how they regulate the cytoskeleton is poorly understood. We previously identified Basal cell carcinoma-enriched gene 4 (BEG4)/Missing in Metastasis (MIM), a Shh-inducible, Wiskott-Aldrich homology 2 domain-containing protein that potentiates Gli transcription (Callahan, C.A., T. Ofstad, L. Horng, J.K. Wang, H.H. Zhen, P.A. Coulombe, and A.E. Oro. 2004. Genes Dev. 18:2724-2729). Here, we show that endogenous MIM is induced in a patched1-dependent manner and regulates the actin cytoskeleton. MIM functions by bundling F-actin, a process that requires self-association but is independent of G-actin binding. Cytoskeletal remodeling requires an activation domain distinct from sequences required for bundling in vitro. This domain associates with RPTPdelta and, in turn, enhances RPTPdelta membrane localization. MIM-dependent cytoskeletal changes can be inhibited using a soluble RPTPdelta-D2 domain. Our data suggest that the hedgehog-responsive gene MIM cooperates with RPTP to induce cytoskeletal changes.
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Affiliation(s)
- Rosa Gonzalez-Quevedo
- Program in Epithelial Biology, School of Medicine, Stanford University, Stanford, CA 94305, USA
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28
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Wechezak AR, Coan DE. Dvl2 silencing in postdevelopmental cells results in aberrant cell membrane activity and actin disorganization. J Cell Physiol 2005; 202:867-73. [PMID: 15593083 DOI: 10.1002/jcp.20176] [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: 11/12/2022]
Abstract
The upstream events by which endothelial cells perceive the necessity for migration and how this signal results in coordinated movement is unknown. The synchrony underlying these events shares parallels to events occurring during the movement of tissues in embryogenesis. While Wnt signaling is an important pathway in development, components of the cascade exist in postdevelopment endothelial cells. The objective of this study was to determine whether Dishevelled, a key modulation protein in canonical and PCP-CE Wnt signaling was present in endothelium and its potential function. Western blots of cell lysates and immunolabeling studies confirmed that Dishevelled 2 (Dvl2) is an abundant phosphoprotein in endothelial cells. Dvl2 was localized within the cytoplasm of cells as either F-actin-free or F-actin-associated. The disappearance of F-actin-free Dvl2 in vesicle-like organelles and targeting of actin filaments correlated with a loss in cell motility. Gene silencing of Dishevelled by siRNA duplexes resulted in cells with aberrant membrane activity and an inability to extend lamellipodia. Underlying these abnormalities was a disorganization of the actin filament system, including loss of actin-rich densities, indistinct stress fibers and an accompanying increase in diffuse and aggregate cytoplasmic actin. This study represents the first documentation of Dvl2 in postdevelopmental endothelial cells and its possible role in cell migration via manipulation of actin filament bundles.
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Affiliation(s)
- Arlene R Wechezak
- Department of Cell Biology, Hope Heart Institute, Seattle, Washington 98122, USA.
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29
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Garmendia J, Phillips AD, Carlier MF, Chong Y, Schüller S, Marches O, Dahan S, Oswald E, Shaw RK, Knutton S, Frankel G. TccP is an enterohaemorrhagic Escherichia coli O157:H7 type III effector protein that couples Tir to the actin-cytoskeleton. Cell Microbiol 2005; 6:1167-83. [PMID: 15527496 DOI: 10.1111/j.1462-5822.2004.00459.x] [Citation(s) in RCA: 219] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Subversion of host cell actin microfilaments is the hallmark of enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli infections. Both pathogens translocate the trans-membrane receptor protein-translocated intimin receptor (Tir), which links the extracellular bacterium to the cell cytoskeleton. While both converge on neural Wiskott-Aldrich syndrome protein (N-WASP), Tir-mediated actin accretion by EPEC and EHEC differ in that Tir(EPEC) requires both tyrosine phosphorylation and the host adaptor protein Nck, whereas Tir(EHEC) is not phosphorylated and utilizes an unidentified linker. Here we report the identification of Tir-cytoskeleton coupling protein (TccP), a novel EHEC effector that displays an Nck-like coupling activity following translocation into host cells. A tccP mutant did not affect Tir translocation and focusing but failed to recruit alpha-actinin, Arp3, N-WASP and actin to the site of bacterial adhesion. When expressed in EPEC, bacterial-derived TccP restored actin polymerization activity following infection of an Nck-deficient cell line. TccP has a similar biological activity on infected human intestinal explants ex vivo. Purified TccP activates N-WASP stimulating, in the presence of Arp2/3, actin polymerization in vitro. These results show that EHEC translocates both its own receptor (Tir) and an Nck-like protein (TccP) to facilitate actin polymerization.
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Affiliation(s)
- Junkal Garmendia
- Centre for Molecular Microbiology and Infection, Department of Biological Sciences, Imperial College London, UK
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30
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Wozniak MA, Modzelewska K, Kwong L, Keely PJ. Focal adhesion regulation of cell behavior. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1692:103-19. [PMID: 15246682 DOI: 10.1016/j.bbamcr.2004.04.007] [Citation(s) in RCA: 695] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Accepted: 04/22/2004] [Indexed: 12/18/2022]
Abstract
Focal adhesions lie at the convergence of integrin adhesion, signaling and the actin cytoskeleton. Cells modify focal adhesions in response to changes in the molecular composition, two-dimensional (2D) vs. three-dimensional (3D) structure, and physical forces present in their extracellular matrix environment. We consider here how cells use focal adhesions to regulate signaling complexes and integrin function. Furthermore, we examine how this regulation controls complex cellular behaviors in response to matrices of diverse physical and biochemical properties. One event regulated by the physical structure of the ECM is phosphorylation of focal adhesion kinase (FAK) at Y397, which couples FAK to several signaling pathways that regulate cell proliferation, survival, migration, and invasion.
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Affiliation(s)
- Michele A Wozniak
- Department of Pharmacology, University of Wisconsin, 3630 MSC, 1300 University Ave, Madison 53706, USA
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31
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Disanza A, Carlier MF, Stradal TEB, Didry D, Frittoli E, Confalonieri S, Croce A, Wehland J, Di Fiore PP, Scita G. Eps8 controls actin-based motility by capping the barbed ends of actin filaments. Nat Cell Biol 2004; 6:1180-8. [PMID: 15558031 DOI: 10.1038/ncb1199] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Accepted: 10/27/2004] [Indexed: 12/15/2022]
Abstract
Actin filament barbed-end capping proteins are essential for cell motility, as they regulate the growth of actin filaments to generate propulsive force. One family of capping proteins, whose prototype is gelsolin, shares modular architecture, mechanism of action, and regulation through signalling-dependent mechanisms, such as Ca(2+) or phosphatidylinositol-4,5-phosphate binding. Here we show that proteins of another family, the Eps8 family, also show barbed-end capping activity, which resides in their conserved carboxy-terminal effector domain. The isolated effector domain of Eps8 caps barbed ends with an affinity in the nanomolar range. Conversely, full-length Eps8 is auto-inhibited in vitro, and interaction with the Abi1 protein relieves this inhibition. In vivo, Eps8 is recruited to actin dynamic sites, and its removal impairs actin-based propulsion. Eps8-family proteins do not show any similarity to gelsolin-like proteins. Thus, our results identify a new family of actin cappers, and unveil novel modalities of regulation of capping through protein-protein interactions. One established function of the Eps8-Abi1 complex is to participate in the activation of the small GTPase Rac, suggesting a multifaceted role for this complex in actin dynamics, possibly through the participation in alternative larger complexes.
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Affiliation(s)
- Andrea Disanza
- IFOM Istituto FIRC di Oncologia Molecolare Via Adamello 16, 20139, Milan, Italy
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32
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Boukhelifa M, Parast MM, Bear JE, Gertler FB, Otey CA. Palladin is a novel binding partner for Ena/VASP family members. ACTA ACUST UNITED AC 2004; 58:17-29. [PMID: 14983521 DOI: 10.1002/cm.10173] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Palladin is an actin-associated protein that contains proline-rich motifs within its amino-terminal sequence that are similar to motifs found in zyxin, vinculin, and the Listeria protein ActA. These motifs are known to be potential binding sites for the Vasodilator-Stimulated Phosphoprotein (VASP). Here, we demonstrate that palladin is an additional direct binding partner for VASP, by using co-immunoprecipitation and blot overlay techniques with both endogenous palladin and recombinant myc-tagged palladin. These results show that VASP binds to full-length palladin and also to the amino-terminal half of palladin, where the polyproline motifs are located. Using a synthetic peptide array, two discrete binding sites for VASP were identified within palladin's proline-rich amino-terminal domain. Using double-label immunofluorescence staining of fully-spread and actively-spreading fibroblasts, the extent of co-localization of palladin and VASP was explored. These proteins were found to strongly co-localize along stress fibers, and partially co-localize in focal adhesions, lamellipodia, and focal complexes. These results suggest that the recently described actin-associated protein palladin may play an important role in recruiting VASP to sites of actin filament growth, anchorage, and crosslinking.
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Affiliation(s)
- Malika Boukhelifa
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, 27599-7545, USA
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33
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Roy P, Jacobson K. Overexpression of profilin reduces the migration of invasive breast cancer cells. ACTA ACUST UNITED AC 2004; 57:84-95. [PMID: 14691948 DOI: 10.1002/cm.10160] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The exact role profilin plays in cell migration is not clear. In this study, we have evaluated the effect of overexpression of profilin on the migration of breast cancer cells. Overexpression was carried out by stably expressing GFP-profilin in BT474 cells. It was observed that even a moderate level of overexpression of profilin significantly impaired the ability of BT474 cells to spread on fibronectin-coated substrate and migrate in response to EGF. GFP-profilin expressing cells also showed increased resistance to detachment in response to trypsin and increased tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin compared to the parental and GFP-expressing (control) cell lines. These results suggest that perturbation of profilin levels may offer a good strategy for controlling the metastatic potential of breast cancer cells.
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Affiliation(s)
- Partha Roy
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC, USA.
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34
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Abstract
Temporal and spatial control of the actin cytoskeleton are crucial for a range of eukaryotic cellular processes. Capping protein (CP), a ubiquitous highly conserved heterodimer, tightly caps the barbed (fast-growing) end of the actin filament and is an important component in the assembly of various actin structures, including the dynamic branched filament network at the leading edge of motile cells. New research into the molecular mechanism of how CP interacts with the actin filament in vitro and the function of CP in vivo, including discoveries of novel interactions of CP with other proteins, has greatly enhanced our understanding of the role of CP in regulating the actin cytoskeleton.
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Affiliation(s)
- Martin A Wear
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MI 63110, USA
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35
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Martinez JJ, Cossart P. Early signaling events involved in the entry of Rickettsia conorii into mammalian cells. J Cell Sci 2004; 117:5097-106. [PMID: 15383620 DOI: 10.1242/jcs.01382] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Rickettsia conorii, the causative agent of Mediterranean spotted fever, is able to attach to and invade a variety of cell types both in vitro and in vivo. Although previous studies show that entry of R. conorii into non-phagocytic cells relies on actin polymerization, little else is known about the molecular details governing Rickettsia-host cell interactions and actin rearrangements. We determined that R. conorii recruits the Arp2/3 complex to the site of entry foci and that expression of an Arp 2/3 binding derivative of the WASP-family member, Scar, inhibited bacterial entry into Vero cells, establishing that Arp2/3 is an active component of this process. Using transient transfection with plasmids expressing dominant negative versions of small GTPases, we showed that Cdc42, but not Rac1 is involved in R. conorii invasion into Vero cells. Using pharmacological approaches, we show that this invasion is dependent on phosphoinositide (PI) 3-kinase and on protein tyrosine kinase (PTK) activities, in particular Src-family kinases. C-Src and its downstream target, p80/85 cortactin, colocalize at entry sites early in the infection process. R. conorii internalization correlated with the tyrosine phosphorylation of several other host proteins, including focal adhesion kinase (FAK), within minutes of R. conorii infection. Our results reveal that R. conorii entry into nonphagocytic cells is dependent on the Arp2/3 complex and that the interplay of pathways involving Cdc42, PI 3-kinase, c-Src, cortactin and tyrosine-phosphorylated proteins regulates Arp2/3 activation leading to the localized actin rearrangements observed during bacterial entry. This is the first report that documents the mechanism of entry of a rickettsial species into mammalian cells.
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Affiliation(s)
- Juan J Martinez
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, INSERM U604, Département de Biologie Cellulaire et Infection, 25 Rue du Dr Roux, 75724 Paris CEDEX 15, France
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36
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Kotlikoff MI, Kannan MS, Solway J, Deng KY, Deshpande DA, Dowell M, Feldman M, Green KS, Ji G, Johnston R, Lakser O, Lee J, Lund FE, Milla C, Mitchell RW, Nakai J, Rishniw M, Walseth TF, White TA, Wilson J, Xin HB, Woodruff PG. Methodologic advancements in the study of airway smooth muscle. J Allergy Clin Immunol 2004; 114:S18-31. [PMID: 15309016 DOI: 10.1016/j.jaci.2004.04.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The study of isolated airway myocytes has provided important information relative to specific processes that regulate contraction, proliferation, and synthetic properties of airway smooth muscle (ASM). To place this information in physiological context, however, improved methods to examine airway biology in vivo are needed. Advances in genetic, biochemical, and optical methods provide unprecedented opportunities to improve our understanding of in vivo physiology and pathophysiology. This article describes 4 important methodologic advances in the study of ASM: (1) the development of transgenic mice that could be used to investigate ASM proliferation and phenotype switching during the development of hypersensitivity, and to investigate excitation-contraction coupling; (2) the use of CD38-deficient mice to confirm the role of CD38-dependent, cyclic adenosine diphosphate-ribose-mediated calcium release in airway responsiveness; (3) investigation of the role of actin filament length and p38 mitogen-activated protein kinase activity in regulating the mechanical plasticity-elasticity balance in contracted ASM; and (d) the use of bronchial biopsies to study ASM structure and phenotype in respiratory science.
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Affiliation(s)
- Michael I Kotlikoff
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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37
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Verma S, Shewan AM, Scott JA, Helwani FM, den Elzen NR, Miki H, Takenawa T, Yap AS. Arp2/3 Activity Is Necessary for Efficient Formation of E-cadherin Adhesive Contacts. J Biol Chem 2004; 279:34062-70. [PMID: 15159390 DOI: 10.1074/jbc.m404814200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Classical cadherin adhesion molecules are fundamental determinants of cell-cell recognition that function in cooperation with the actin cytoskeleton. Productive cadherin-based cell recognition is characterized by a distinct morphological process of contact zone extension, where limited initial points of adhesion are progressively expanded into broad zones of contact. We recently demonstrated that E-cadherin ligation recruits the Arp2/3 actin nucleator complex to the plasma membrane in regions where cell contacts are undergoing protrusion and extension. This suggested that Arp2/3 might generate the protrusive forces necessary for cell surfaces to extend upon one another during contact assembly. We tested this hypothesis in mammalian cells by exogenously expressing the CA region of N-WASP. This fragment, which potently inhibits Arp2/3-mediated actin assembly in vitro, also effectively reduced actin assembly at cadherin adhesive contacts. Blocking Arp2/3 activity by this strategy profoundly reduced the ability of cells to extend cadherin adhesive contacts but did not affect cell adhesiveness. These findings demonstrate that Arp2/3 activity is necessary for cells to efficiently extend and assemble cadherin-based adhesive contacts.
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Affiliation(s)
- Suzie Verma
- Institute for Molecular Bioscience, School for Biomedical Science, The University of Queensland, St. Lucia, Queensland 4072, Australia
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38
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Lebrand C, Dent EW, Strasser GA, Lanier LM, Krause M, Svitkina TM, Borisy GG, Gertler FB. Critical role of Ena/VASP proteins for filopodia formation in neurons and in function downstream of netrin-1. Neuron 2004; 42:37-49. [PMID: 15066263 DOI: 10.1016/s0896-6273(04)00108-4] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Revised: 12/23/2003] [Accepted: 02/05/2004] [Indexed: 11/29/2022]
Abstract
Ena/VASP proteins play important roles in axon outgrowth and guidance. Ena/VASP activity regulates the assembly and geometry of actin networks within fibroblast lamellipodia. In growth cones, Ena/VASP proteins are concentrated at filopodia tips, yet their role in growth cone responses to guidance signals has not been established. We found that Ena/VASP proteins play a pivotal role in formation and elongation of filopodia along neurite shafts and growth cone. Netrin-1-induced filopodia formation was dependent upon Ena/VASP function and directly correlated with Ena/VASP phosphorylation at a regulatory PKA site. Accordingly, Ena/VASP function was required for filopodial formation from the growth cone in response to global PKA activation. We propose that Ena/VASP proteins control filopodial dynamics in neurons by remodeling the actin network in response to guidance cues.
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Affiliation(s)
- Cecile Lebrand
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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39
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Gustavsson A, Yuan M, Fällman M. Temporal dissection of beta1-integrin signaling indicates a role for p130Cas-Crk in filopodia formation. J Biol Chem 2004; 279:22893-901. [PMID: 15044442 DOI: 10.1074/jbc.m309693200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Invasin-promoted spreading of beta1-integrin-deficient cells, transfected with the beta1A- or beta1B-integrin splice variants, were used to dissect early beta1-integrin signaling events. The beta1B isoform, which has a different membrane-distal part of the cytoplasmic tail from beta1A, is defective in signaling and function. When plated on surfaces coated with the high affinity ligand invasin, beta1B-integrin-expressing cells spread by forming filopodia with distinct adhesive phosphotyrosine complexes at the tips, without signs of lamellipodia. This suggested that the beta1B-integrin mediated a partial signaling sufficient for formation of filopodia but insufficient for lamellipodia formation. When screening for proteins present in the distal filopodial phosphotyrosine complexes of beta1B cells, p130Cas and the filopodia proteins vasodilator-stimulated phosphoprotein and talin were found, whereas the typical focal complex proteins focal adhesion kinase, paxillin, and vinculin were not. Invasin-promoted adhesion induced complex formation of p130Cas and the adapter Crk. Moreover, Crk together with Dock180 were present at the filopodial tips of beta1B-integrin-expressing cells, and there was a prominent Rac1 activation. Expression of dominant negative variants of p130Cas or CrkII blocked beta1B-integrin-mediated filopodia formation, indicating that this signaling scaffold is central in this process.
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Affiliation(s)
- Anna Gustavsson
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
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40
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Ishiguro K, Xavier R. Homer-3 regulates activation of serum response element in T cells via its EVH1 domain. Blood 2004; 103:2248-56. [PMID: 14645007 DOI: 10.1182/blood-2003-08-2671] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Abstract
Drosophila enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) homology 1 (EVH1) domain proteins regulate signal transduction at the neuronal and immunologic synapse. Despite shared cell biologic machinery at these synapses, the regulation of client proteins that transmit synaptic activity to the nucleus is likely to be different. Homer-3, a member of the EVH1 family, is expressed in the thymus, suggesting a role for this protein in T-cell signal transduction. Upon T-cell receptor (TCR) engagement, Homer-3 was recruited to the contact area of Jurkat cells to anti-CD3 and CD28 antibody–coated beads prior to actin accumulation and was subsequently translocated into the nucleus. Overexpression of Homer-3 reduced transcriptional activation via the serum response element (SRE) in response to anti-CD3 antibody, phorbol ester, or dominant active Ha-Ras. Consistent with these results, knockdown of Homer-3 increased SRE activation. Homer-3 coprecipitated with CCAAT/enhancer binding protein β (C/EBPβ), one of the transcription factors that binds to the SRE and has a consensus motif binding to EVH1 domain. Moreover, Homer-3 and its EVH1 domain fragment reduced transcriptional activation of C/EBPβ. These findings suggest that Homer-3 may be involved in the regulation of SRE activation in T cells via interaction between its EVH1 domain and C/EBPβ.
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Affiliation(s)
- Kazuhiro Ishiguro
- Department of Medicine, Massachusetts General Hospital, 55 Fruit St, Boston, MA, 02114, USA
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41
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Wu X, Suetsugu S, Cooper LA, Takenawa T, Guan JL. Focal Adhesion Kinase Regulation of N-WASP Subcellular Localization and Function. J Biol Chem 2004; 279:9565-76. [PMID: 14676198 DOI: 10.1074/jbc.m310739200] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
N-WASP is a member of the WASP family of proteins that regulate actin cytoskeleton remodeling. FAK is a cytoplasmic tyrosine kinase implicated in integrin signaling during cell migration. Here we identify a direct interaction between N-WASP and FAK and show that N-WASP is phosphorylated by FAK at a conserved tyrosine residue, Tyr(256). We found that phosphorylation of Tyr(256) affected N-WASP nuclear localization, suggesting that phosphorylation of N-WASP by FAK may regulate its activity in vivo by altering its subcellular localization. We also showed that the nuclear localization of N-WASP is dependent on its being in the open conformation either after its activation by Cdc42 or the truncation of the C-terminal VCA domain. Phosphorylation of Tyr(256) of N-WASP could reduce its interaction with nuclear importin NPI-1, which might be responsible for its decreased nuclear localization. Lastly, we show that phosphorylation of Tyr(256) plays an important role in promoting cell migration. Together, these results suggest a novel regulatory mechanism of N-WASP by tyrosine phosphorylation and subcellular localization and its potential role in the regulation of cell migration.
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Affiliation(s)
- Xiaoyang Wu
- Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA
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42
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Guan KL, Rao Y. Signalling mechanisms mediating neuronal responses to guidance cues. Nat Rev Neurosci 2004; 4:941-56. [PMID: 14682358 DOI: 10.1038/nrn1254] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Several families of extracellular guidance cues have been implicated in guiding neurons and axons to their appropriate destinations in the nervous system. Their receptors include single- and seven-transmembrane receptors, and their signal transduction pathways converge onto the Rho family of small GTPases, which control the cytoskeleton. A single guidance protein can use different mechanisms to regulate different kinds of motility or the motilities of different cell types. There is crosstalk between the signalling pathways initiated by distinct guidance cues. Studies of neuronal guidance mechanisms have shed light not only on neural development, but also on other processes that involve the extracellular regulation of the cytoskeleton.
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Affiliation(s)
- Kun-Liang Guan
- Life Sciences Institute, Department of Biological Chemistry and Institute of Gerontology, University of Michigan, Ann Arbor, Michigan 48109, USA.
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43
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Quinlan MP. Vinculin, VASP, and profilin are coordinately regulated during actin remodeling in epithelial cells, which requires de novo protein synthesis and protein kinase signal transduction pathways. J Cell Physiol 2004; 200:277-90. [PMID: 15174098 DOI: 10.1002/jcp.20009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transformation progression of epithelial cells involves alterations in their morphology, polarity, and adhesive characteristics, all of which are associated with the loss and/or reorganization of actin structures. To identify the underlying mechanism of formation of the adhesion-dependent, circumferential actin network, the expression and localization of the actin binding and regulating proteins (ABPs), vinculin, VASP, and profilin were evaluated. Experimental depolarization of epithelial cells results in the loss of normal F-actin structures and the transient upregulation of vinculin, VASP, and profilin. This response is due to the loss of cell-cell, and not cell-substrate interactions, since cells that no longer express focal adhesions or stress fibers are still sensitive to changes in adhesion and manifest this in the altered profile of expression of these ABPs. Transient upregulation is dependent upon de novo protein synthesis, and protein kinase-, but not phosphatase-sensitive signal transduction pathway(s). Inhibition of the synthesis of these proteins is accompanied by dephosphorylation of the ribosomal S6 protein, but does not involve inhibition of the PI3-kinase-Akt-mTOR pathway. Constitutive expression of VASP results in altered cell morphology and adhesion and F-actin and vinculin structures. V12rac1 expressing epithelial cells are constitutively nonadhesive, malignantly transformed, and constitutively express high levels of these ABPs, with altered subcellular localizations. Transformation suppression is accompanied by the restoration of normal levels of the three ABPs, actin structures, adhesion, and epithelial morphology. Thus, vinculin, VASP, and profilin are coordinately regulated by signal transduction pathways that effect a translational response. Additionally, their expression profile maybe indicative of the adhesion and transformation status of epithelial cells.
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Affiliation(s)
- Margaret P Quinlan
- Laboratory of Molecular Cell Biology, Guthrie Research Institute, 1 Guthrie Square, Sayre, Pennsylvania 18840, USA.
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44
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Abstract
Accumulations of particular lipids in ordered arrays in the membrane (termed microdomains or lipid rafts) can attract proteins with specific targeting domains. Both the lipid and protein components of rafts communicate with the cytoskeleton directly thereby regulating cellular responses. Recent evidence implicating phosphoinositide 1,5 bisphosphate (PIP2) in cytoskeletal regulation shows that agonist sensitive regulation of PIP2 homoeostasis occurs specifically rafts, which appear to provide a major structural substrate for its function. The crucial role of PIP2 in generating cytoskeletal responses is chiefly achieved by regulating proteins that control actin dynamics directly. Many of these regulatory proteins are also specifically enriched in rafts either directly (by insertion into the lipid bilayer via acetylation motifs), or indirectly via interactions with other raft components. The notion that rafts form membrane platforms or modules that mediate signaling responses has been most extensively demonstrated in the immune synapse (IS) of T cells, a complex assemblage of rafts that integrates signaling cascades originating from the simultaneous activation of a wide variety of receptors. The IS is essential for both the amplification and maintenance of T-cell activation, and its assembly at the antigen presenting site depends on the interactions between rafts and the actin cytoskeleton that regulates coalescence of smaller raft components into the larger IS complex. Likewise the neuron, which represents the most highly polarized cell in the body, utilizes the regulation of actin dynamics in response to a plethora of extracellular signals to control axon pathfinding thereby sculpting nervous system cytoarchitecture with utmost precision. It is now becoming clear, that as in the T-cell, lipid rafts in the growing axon can assemble into highly specific, yet malleable and dynamic, signaling modules that regulate actin dynamics in a fashion that is also PIP2-dependent and that utilizes both familiar and novel regulatory mechanisms. It seems clear that raft mediated cytoskeletal regulation represents a highly conserved mechanism to integrate cellular responses to diverse signals.
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Affiliation(s)
- Karina F Meiri
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA
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45
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Dent EW, Tang F, Kalil K. Axon guidance by growth cones and branches: common cytoskeletal and signaling mechanisms. Neuroscientist 2003; 9:343-53. [PMID: 14580119 DOI: 10.1177/1073858403252683] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Growing axons are guided to appropriate targets by responses of their motile growth cones to environmental cues. Interstitial axon branching is also an important form of axon guidance in the mammalian CNS. Visualization of growing axons in cortical slices and in dissociated cortical cultures showed that growth cone pausing behaviors demarcate sites of future axon branching. Studies of vertebrate and invertebrate growth cones suggest common mechanisms that regulate growth cone behaviors and axon branching. These include reorganization of the actin and microtubule cytoskeleton, dynamic interactions between microtubules and actin filaments, effects of axon guidance molecules, actions of actin regulatory proteins, and dynamic changes in intracellular calcium signaling. Future challenges will be to extend high-resolution imaging of single neurons to studies of intracellular events in the intact nervous system and to apply knowledge of developmental mechanisms to the promotion of axon sprouting after injury in the adult CNS.
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Affiliation(s)
- Erik W Dent
- Department of Anatomy, University of Wisconsin, Madison 53706, USA
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46
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Samarin S, Romero S, Kocks C, Didry D, Pantaloni D, Carlier MF. How VASP enhances actin-based motility. J Cell Biol 2003; 163:131-42. [PMID: 14557252 PMCID: PMC2173428 DOI: 10.1083/jcb.200303191] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 08/21/2003] [Indexed: 12/28/2022] Open
Abstract
The function of vasodilator-stimulated phosphoprotein (VASP) in motility is analyzed using a biomimetic motility assay in which ActA-coated microspheres propel themselves in a medium containing actin, the Arp2/3 complex, and three regulatory proteins in the absence or presence of VASP. Propulsion is linked to cycles of filament barbed end attachment-branching-detachment-growth in which the ActA-activated Arp2/3 complex incorporates at the junctions of branched filaments. VASP increases the velocity of beads. VASP increases branch spacing of filaments in the actin tail, as it does in lamellipodia in living cells. The effect of VASP on branch spacing of Arp2/3-induced branched actin arrays is opposed to the effect of capping proteins. However, VASP does not compete with capping proteins for binding barbed ends of actin filaments. VASP enhances branched actin polymerization only when ActA is immobilized on beads or on Listeria. VASP increases the rate of dissociation of the branch junction from immobilized ActA, which is the rate-limiting step in the catalytic cycle of site-directed filament branching.
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Affiliation(s)
- Stanislav Samarin
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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47
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Carnahan RH, Gould KL. The PCH family protein, Cdc15p, recruits two F-actin nucleation pathways to coordinate cytokinetic actin ring formation in Schizosaccharomyces pombe. J Cell Biol 2003; 162:851-62. [PMID: 12939254 PMCID: PMC2172828 DOI: 10.1083/jcb.200305012] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytokinetic actin ring (CAR) formation in Schizosaccharomyces pombe requires two independent actin nucleation pathways, one dependent on the Arp2/3 complex and another involving the formin Cdc12p. Here we investigate the role of the S. pombe Cdc15 homology family protein, Cdc15p, in CAR assembly and find that it interacts with proteins from both of these nucleation pathways. Cdc15p binds directly to the Arp2/3 complex activator Myo1p, which likely explains why actin patches and the Arp2/3 complex fail to be medially recruited during mitosis in cdc15 mutants. Cdc15p also binds directly to Cdc12p. Cdc15p and Cdc12p not only display mutual dependence for CAR localization, but also exist together in a ring-nucleating structure before CAR formation. The disruption of these interactions in cdc15 null cells is likely to be the reason for their complete lack of CARs. We propose a model in which Cdc15p plays a critical role in recruiting and coordinating the pathways essential for the assembly of medially located F-actin filaments and construction of the CAR.
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Affiliation(s)
- Robert H Carnahan
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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48
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Grosse R, Copeland JW, Newsome TP, Way M, Treisman R. A role for VASP in RhoA-Diaphanous signalling to actin dynamics and SRF activity. EMBO J 2003; 22:3050-61. [PMID: 12805219 PMCID: PMC162139 DOI: 10.1093/emboj/cdg287] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is involved in multiple actin-mediated processes, including regulation of serum response factor (SRF) activity. We used the SRF transcriptional assay to define functional domains in VASP and to show that they coincide with those required for F-actin accumulation, as determined by a quantitative FACS assay. We identified inactive VASP mutants that can interfere both with F-actin assembly and with SRF activation by wild-type VASP. These VASP mutants also inhibit actin-based motility of Vaccinia virus and Shigella flexneri. VASP-induced F-actin accumulation and SRF activation require both functional Rho and its effector mDia, and conversely, mDia-mediated SRF activation is critically dependent on functional VASP. VASP and mDia also associate physically in vivo. These findings show that VASP and mDia function cooperatively downstream of Rho to control F-actin assembly and SRF activity.
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Affiliation(s)
- Robert Grosse
- Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, Transcription Laboratory, Room 401, 44 Lincoln's Inn Fields, London
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49
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Solway J, Bellam S, Dowell M, Camoretti-Mercado B, Dulin N, Fernandes D, Halayko A, Kocieniewski P, Kogut P, Lakser O, Liu HW, McCauley J, McConville J, Mitchell R. Actin dynamics: a potential integrator of smooth muscle (Dys-)function and contractile apparatus gene expression in asthma. Parker B. Francis lecture. Chest 2003; 123:392S-8S. [PMID: 12629000 DOI: 10.1378/chest.123.3_suppl.392s] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Julian Solway
- Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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50
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Mogilner A, Oster G. Force generation by actin polymerization II: the elastic ratchet and tethered filaments. Biophys J 2003; 84:1591-605. [PMID: 12609863 PMCID: PMC1302730 DOI: 10.1016/s0006-3495(03)74969-8] [Citation(s) in RCA: 342] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Accepted: 11/11/2002] [Indexed: 10/21/2022] Open
Abstract
The motion of many intracellular pathogens is driven by the polymerization of actin filaments. The propulsive force developed by the polymerization process is thought to arise from the thermal motions of the polymerizing filament tips. Recent experiments suggest that the nucleation of actin filaments involves a phase when the filaments are attached to the pathogen surface by a protein complex. Here we extend the "elastic ratchet model" of Mogilner and Oster to incorporate these new findings. We apply this "tethered ratchet" model to derive the force-velocity relation for Listeria and discuss relations of our theoretical predictions to experimental measurements. We also discuss "symmetry breaking" dynamics observed in ActA-coated bead experiments, and the implications of the model for lamellipodial protrusion in migrating cells.
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Affiliation(s)
- Alex Mogilner
- Department of Mathematics and Center for Genetics and Development, University of California, Davis 95616, USA
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