1
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Cui S, Zhang T, Xiong X, Zhao J, Cao Q, Zhou H, Xia XG. Detergent-insoluble PFN1 inoculation expedites disease onset and progression in PFN1 transgenic rats. Front Neurosci 2023; 17:1279259. [PMID: 37817804 PMCID: PMC10560758 DOI: 10.3389/fnins.2023.1279259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 09/13/2023] [Indexed: 10/12/2023] Open
Abstract
Accumulating evidence suggests a gain of elusive toxicity in pathogenically mutated PFN1. The prominence of PFN1 aggregates as a pivotal pathological hallmark in PFN1 transgenic rats underscores the crucial involvement of protein aggregation in the initiation and progression of neurodegeneration. Detergent-insoluble materials were extracted from the spinal cords of paralyzed rats afflicted with ALS and were intramuscularly administered to asymptomatic recipient rats expressing mutant PFN1, resulting in an accelerated development of PFN1 inclusions and ALS-like phenotypes. This effect diminished when the extracts derived from wildtype PFN1 transgenic rats were employed, as detergent-insoluble PFN1 was detected exclusively in mutant PFN1 transgenic rats. Consequently, the factor influencing the progression of ALS pathology in recipient rats is likely associated with the presence of detergent-insoluble PFN1 within the extracted materials. Noteworthy is the absence of disease course modification upon administering detergent-insoluble extracts to rats that already displayed PFN1 inclusions, suggesting a seeding rather than augmenting role of such extracts in initiating neuropathological changes. Remarkably, pathogenic PFN1 exhibited an enhanced affinity for the molecular chaperone DNAJB6, leading to the sequestration of DNAJB6 within protein inclusions, thereby depleting its availability for cellular functions. These findings shed light on a novel mechanism that underscores the prion-like characteristics of pathogenic PFN1 in driving neurodegeneration in the context of PFN1-related ALS.
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Affiliation(s)
- Shiquan Cui
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
| | - Tingting Zhang
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
| | - Xinrui Xiong
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
| | - Jihe Zhao
- Burnett School of Biomedical Sciences, University of Central Florida College of Medicine, Orlando, FL, United States
| | - Qilin Cao
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
- The Center for Translational Sciences, Florida International University, Miami, FL, United States
| | - Hongxia Zhou
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
- The Center for Translational Sciences, Florida International University, Miami, FL, United States
| | - Xu-Gang Xia
- Department of Environmental Health Sciences, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, United States
- The Center for Translational Sciences, Florida International University, Miami, FL, United States
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2
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Schutt CE, Karlén M, Karlsson R. A structural model of the profilin-formin pacemaker system for actin filament elongation. Sci Rep 2022; 12:20515. [PMID: 36443454 PMCID: PMC9705415 DOI: 10.1038/s41598-022-25011-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
The formins constitute a large class of multi-domain polymerases that catalyze the localization and growth of unbranched actin filaments in cells from yeast to mammals. The conserved FH2 domains form dimers that bind actin at the barbed end of growing filaments and remain attached as new subunits are added. Profilin-actin is recruited and delivered to the barbed end by formin FH1 domains via the binding of profilin to interspersed tracts of poly-L-proline. We present a structural model showing that profilin-actin can bind the FH2 dimer at the barbed end stabilizing a state where profilin prevents its associated actin subunit from directly joining the barbed end. It is only with the dissociation of profilin from the polymerase that an actin subunit rotates and docks into its helical position, consistent with observations that under physiological conditions optimal elongation rates depend on the dissociation rate of profilin, independently of cellular concentrations of actin subunits.
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Affiliation(s)
- Clarence E. Schutt
- grid.16750.350000 0001 2097 5006Department of Chemistry, Princeton University, Princeton, NJ USA
| | | | - Roger Karlsson
- Department of Molecular Biosciences, WGI, Stockholm University, Stockholm, Sweden.
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3
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Steinz MM, Persson M, Aresh B, Olsson K, Cheng AJ, Ahlstrand E, Lilja M, Lundberg TR, Rullman E, Möller KÄ, Sandor K, Ajeganova S, Yamada T, Beard N, Karlsson BC, Tavi P, Kenne E, Svensson CI, Rassier DE, Karlsson R, Friedman R, Gustafsson T, Lanner JT. Oxidative hotspots on actin promote skeletal muscle weakness in rheumatoid arthritis. JCI Insight 2019; 5:126347. [PMID: 30920392 DOI: 10.1172/jci.insight.126347] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Skeletal muscle weakness in patients suffering from rheumatoid arthritis (RA) adds to their impaired working abilities and reduced quality of life. However, little molecular insight is available on muscle weakness associated with RA. Oxidative stress has been implicated in the disease pathogenesis of RA. Here we show that oxidative post-translational modifications of the contractile machinery targeted to actin result in impaired actin polymerization and reduced force production. Using mass spectrometry, we identified the actin residues targeted by oxidative 3-nitrotyrosine (3-NT) or malondialdehyde adduct (MDA) modifications in weakened skeletal muscle from mice with arthritis and patients afflicted by RA. The residues were primarily located to three distinct regions positioned at matching surface areas of the skeletal muscle actin molecule from arthritis mice and RA patients. Moreover, molecular dynamic simulations revealed that these areas, here coined "hotspots", are important for the stability of the actin molecule and its capacity to generate filaments and interact with myosin. Together, these data demonstrate how oxidative modifications on actin promote muscle weakness in RA patients and provide novel leads for targeted therapeutic treatment to improve muscle function.
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Affiliation(s)
- Maarten M Steinz
- Department of Physiology and Pharmacology, Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
| | - Malin Persson
- Department of Kinesiology and Physical Education, McGill University, Montreal, Canada
| | - Bejan Aresh
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Karl Olsson
- Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Arthur J Cheng
- Department of Physiology and Pharmacology, Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
| | - Emma Ahlstrand
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Mats Lilja
- Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Tommy R Lundberg
- Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Eric Rullman
- Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden
| | | | - Katalin Sandor
- Department of Physiology and Pharmacology, Center for Molecular Medicine, and
| | - Sofia Ajeganova
- Department of Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Takashi Yamada
- Department of Physical Therapy, Sapporo Medical University, Sapporo, Japan
| | - Nicole Beard
- Faculty of Science and Technology, University of Canberra, Australia
| | - Björn Cg Karlsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Pasi Tavi
- Department of Physiology and Pharmacology, Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden.,A.I. Virtanen Institute, University of Eastern Finland, Kuopio, Finland
| | - Ellinor Kenne
- Department of Physiology and Pharmacology, Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
| | - Camilla I Svensson
- Department of Physiology and Pharmacology, Center for Molecular Medicine, and
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Canada
| | - Roger Karlsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Ran Friedman
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Thomas Gustafsson
- Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Johanna T Lanner
- Department of Physiology and Pharmacology, Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
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4
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Marzook NB, Latham SL, Lynn H, Mckenzie C, Chaponnier C, Grau GE, Newsome TP. Divergent roles of β- and γ-actin isoforms during spread of vaccinia virus. Cytoskeleton (Hoboken) 2017; 74:170-183. [PMID: 28218453 PMCID: PMC7162416 DOI: 10.1002/cm.21356] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 01/31/2017] [Accepted: 02/16/2017] [Indexed: 01/20/2023]
Abstract
Actin is a major component of the cytoskeleton and is present as two isoforms in non‐muscle cells: β‐ and γ‐cytoplasmic actin. These isoforms are strikingly conserved, differing by only four N‐terminal amino acids. During spread from infected cells, vaccinia virus (VACV) particles induce localized actin nucleation that propel virus to surrounding cells and facilitate cell‐to‐cell spread of infection. Here we show that virus‐tipped actin comets are composed of β‐ and γ‐actin. We employed isoform‐specific siRNA knockdown to examine the role of the two isoforms in VACV‐induced actin comets. Despite the high level of similarity between the actin isoforms, and their colocalization, VACV‐induced actin nucleation was dependent exclusively on β‐actin. Knockdown of β‐actin led to a reduction in the release of virus from infected cells, a phenotype dependent on virus‐induced Arp2/3 complex activity. We suggest that local concentrations of actin isoforms may regulate the activity of cellular actin nucleator complexes.
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Affiliation(s)
- N Bishara Marzook
- School of Life and Environmental Sciences, The University of Sydney, Australia
| | - Sharissa L Latham
- Vascular Immunology Unit, Department of Pathology, School of Medical Sciences & Marie Bashir Institute, The University of Sydney, Australia
| | - Helena Lynn
- School of Life and Environmental Sciences, The University of Sydney, Australia
| | | | - Christine Chaponnier
- Department of Pathology-Immunology, Faculty of Medicine, University of Geneva, Switzerland
| | - Georges E Grau
- Vascular Immunology Unit, Department of Pathology, School of Medical Sciences & Marie Bashir Institute, The University of Sydney, Australia
| | - Timothy P Newsome
- School of Life and Environmental Sciences, The University of Sydney, Australia
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5
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Wen PJ, Grenklo S, Arpino G, Tan X, Liao HS, Heureaux J, Peng SY, Chiang HC, Hamid E, Zhao WD, Shin W, Näreoja T, Evergren E, Jin Y, Karlsson R, Ebert SN, Jin A, Liu AP, Shupliakov O, Wu LG. Actin dynamics provides membrane tension to merge fusing vesicles into the plasma membrane. Nat Commun 2016; 7:12604. [PMID: 27576662 PMCID: PMC5013665 DOI: 10.1038/ncomms12604] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 07/13/2016] [Indexed: 01/22/2023] Open
Abstract
Vesicle fusion is executed via formation of an Ω-shaped structure (Ω-profile), followed by closure (kiss-and-run) or merging of the Ω-profile into the plasma membrane (full fusion). Although Ω-profile closure limits release but recycles vesicles economically, Ω-profile merging facilitates release but couples to classical endocytosis for recycling. Despite its crucial role in determining exocytosis/endocytosis modes, how Ω-profile merging is mediated is poorly understood in endocrine cells and neurons containing small ∼30–300 nm vesicles. Here, using confocal and super-resolution STED imaging, force measurements, pharmacology and gene knockout, we show that dynamic assembly of filamentous actin, involving ATP hydrolysis, N-WASP and formin, mediates Ω-profile merging by providing sufficient plasma membrane tension to shrink the Ω-profile in neuroendocrine chromaffin cells containing ∼300 nm vesicles. Actin-directed compounds also induce Ω-profile accumulation at lamprey synaptic active zones, suggesting that actin may mediate Ω-profile merging at synapses. These results uncover molecular and biophysical mechanisms underlying Ω-profile merging. As vesicles fuse to the plasma membrane, they form intermediate Ω-shaped structures followed by either closure of the pore or full merging with the plasma membrane. Here Wen et al. show that dynamic actin assembly provides membrane tension to promote Ω merging in neuroendocrine cells and synapses.
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Affiliation(s)
- Peter J Wen
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Staffan Grenklo
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Gianvito Arpino
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA.,Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Xinyu Tan
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Hsien-Shun Liao
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Johanna Heureaux
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Shi-Yong Peng
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Hsueh-Cheng Chiang
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Edaeni Hamid
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wei-Dong Zhao
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Wonchul Shin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Tuomas Näreoja
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Emma Evergren
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Yinghui Jin
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
| | - Roger Karlsson
- Department of Cell Biology, WGI, Stockholm University, 106 91 Stockholm, Sweden
| | - Steven N Ebert
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USA
| | - Albert Jin
- National Institute of Biomedical Imaging and Bioengineering (NIBIB), Bethesda, Maryland 20892, USA
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Oleg Shupliakov
- Center of Excellence in Developmental Biology, Department of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden.,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, 35 Convent Drive, Building 35, Room 2B-1012, Bethesda, Maryland 20892, USA
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6
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Nejedla M, Sadi S, Sulimenko V, de Almeida FN, Blom H, Draber P, Aspenström P, Karlsson R. Profilin connects actin assembly with microtubule dynamics. Mol Biol Cell 2016; 27:2381-93. [PMID: 27307590 PMCID: PMC4966980 DOI: 10.1091/mbc.e15-11-0799] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 06/09/2016] [Indexed: 12/29/2022] Open
Abstract
Profilin is a well-known regulator of actin filament formation. It indirectly associates with microtubules and influences their growth rate. Formins are the linker molecules, and the turnover of the actin microfilament system balances profilin association with the microtubules. Profilin controls actin nucleation and assembly processes in eukaryotic cells. Actin nucleation and elongation promoting factors (NEPFs) such as Ena/VASP, formins, and WASP-family proteins recruit profilin:actin for filament formation. Some of these are found to be microtubule associated, making actin polymerization from microtubule-associated platforms possible. Microtubules are implicated in focal adhesion turnover, cell polarity establishment, and migration, illustrating the coupling between actin and microtubule systems. Here we demonstrate that profilin is functionally linked to microtubules with formins and point to formins as major mediators of this association. To reach this conclusion, we combined different fluorescence microscopy techniques, including superresolution microscopy, with siRNA modulation of profilin expression and drug treatments to interfere with actin dynamics. Our studies show that profilin dynamically associates with microtubules and this fraction of profilin contributes to balance actin assembly during homeostatic cell growth and affects microtubule dynamics. Hence profilin functions as a regulator of microtubule (+)-end turnover in addition to being an actin control element.
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Affiliation(s)
- Michaela Nejedla
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Sara Sadi
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Vadym Sulimenko
- Institute of Molecular Genetics, ASCR, 142 20 Prague 4, Czech Republic
| | | | - Hans Blom
- Science for Life Laboratory, SE-171 21 Solna, Sweden
| | - Pavel Draber
- Institute of Molecular Genetics, ASCR, 142 20 Prague 4, Czech Republic
| | - Pontus Aspenström
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Roger Karlsson
- Department of Molecular Biosciences, Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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7
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Actoclampin (+)-end-tracking motors: How the pursuit of profilin's role(s) in actin-based motility twice led to the discovery of how cells crawl. Biophys Chem 2015; 209:41-55. [PMID: 26720287 DOI: 10.1016/j.bpc.2015.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 10/05/2015] [Indexed: 11/21/2022]
Abstract
The path to the discovery of the actoclampins began with efforts to define profilin's role in actin-based pathogen and endosome rocketing. That research identified a set of FPPPP-containing cargo proteins and FPPPP-binding proteins that are consistently stationed within the polymerization zone during episodes of active motility. The very same biophysical clues that forced us to abandon Brownian Ratchet models guided us to the Actoclampin Hypothesis, which asserts that every propulsive filament possesses a (+)-end-tracking motor that generates the forces cells need to crawl. Each actoclampin motor is a multi-arm oligomeric complex, employing one arm to recruit/deliver Profilin•Actin•ATP to a growth-site located at the (+)-end of the lagging subfilament, while a second arm maintains an affinity-modulated binding interaction with the extreme (+)-end of the other subfilament. The alternating actions of these arms define a true molecular motor, the processivity of which explains why propelling filaments maintain full possession of their cargo. The Actoclampin Hypothesis also suggests how the energetics of tracker interactions with the (+)-end determines whether a given actoclampin is a passive (low force-producing) or active (high force-producing) motor, the latter requiring the Gibbs free energy of ATP hydrolysis. Another aim of this review is to acknowledge an earlier notional model that emerged from efforts to comprehend profilin's pivotal role(s) in actin-based cell motility.
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8
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Grantham J, Lassing I, Karlsson R. Controlling the cortical actin motor. PROTOPLASMA 2012; 249:1001-1015. [PMID: 22526202 PMCID: PMC3459087 DOI: 10.1007/s00709-012-0403-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 03/21/2012] [Indexed: 05/31/2023]
Abstract
Actin is the essential force-generating component of the microfilament system, which powers numerous motile processes in eukaryotic cells and undergoes dynamic remodeling in response to different internal and external signaling. The ability of actin to polymerize into asymmetric filaments is the inherent property behind the site-directed force-generating capacity that operates during various intracellular movements and in surface protrusions. Not surprisingly, a broad variety of signaling pathways and components are involved in controlling and coordinating the activities of the actin microfilament system in a myriad of different interactions. The characterization of these processes has stimulated cell biologists for decades and has, as a consequence, resulted in a huge body of data. The purpose here is to present a cellular perspective on recent advances in our understanding of the microfilament system with respect to actin polymerization, filament structure and specific folding requirements.
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Affiliation(s)
- Julie Grantham
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ingrid Lassing
- Department of Cell Biology, Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Roger Karlsson
- Department of Cell Biology, Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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9
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Ding Z, Bae YH, Roy P. Molecular insights on context-specific role of profilin-1 in cell migration. Cell Adh Migr 2012; 6:442-9. [PMID: 23076048 DOI: 10.4161/cam.21832] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Profilin-1 (Pfn1) is a ubiquitously expressed actin-monomer binding protein that has been linked to many cellular activities ranging from control of actin polymerization to gene transcription. Traditionally, Pfn1 has been considered to be an essential control element for actin polymerization and cell migration. Seemingly contrasting this view, a few recent studies have shown evidence of an inhibitory action of Pfn1 on motility of certain types of carcinoma cells. In this review, we summarize biochemistry and functional aspects of Pfn1 in normal cells and bring in newly emerged action of Pfn1 in cancer cells that may explain its context-specific role in cell migration.
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Affiliation(s)
- Zhijie Ding
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
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10
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Johnsson AK, Karlsson R. Microtubule-dependent localization of profilin I mRNA to actin polymerization sites in serum-stimulated cells. Eur J Cell Biol 2010; 89:394-401. [PMID: 20129697 DOI: 10.1016/j.ejcb.2009.10.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 10/29/2009] [Accepted: 10/29/2009] [Indexed: 12/12/2022] Open
Abstract
Specific localization of messenger RNA (mRNA) appears to be a general mechanism to accumulate certain proteins to subcellular compartments for participation in local processes, thereby maintaining cell polarity under strict spatiotemporal control. Transportation of mRNA with associated protein components (RNP granules) by the actin microfilament or the microtubule systems is one important mechanism to achieve this locally distributed protein production. Here we provide evidence for a microtubule-dependent localization of mRNA encoding the actin regulatory protein profilin to sites in mouse embryonic fibroblasts, which express enhanced actin polymerization.
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Affiliation(s)
- Anna-Karin Johnsson
- Department of Cell Biology, WGI, Stockholm University, SE-106 91 Stockholm, Sweden
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11
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Li Y, Grenklo S, Higgins T, Karlsson R. The profilin:actin complex localizes to sites of dynamic actin polymerization at the leading edge of migrating cells and pathogen-induced actin tails. Eur J Cell Biol 2008; 87:893-904. [PMID: 18707793 DOI: 10.1016/j.ejcb.2008.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 06/11/2008] [Accepted: 06/12/2008] [Indexed: 12/11/2022] Open
Abstract
A unique set of affinity-purified anti-profilin and anti-actin antibodies generated against a covalently coupled version of the profilin:actin complex was used to assess the distribution of profilin and non-filamentous actin in mouse melanoma cells. In agreement with the profilin:actin complex being the principal source of actin for filament formation, we observed extensive co-distribution of both antibody preparations with vasodilator-stimulated phosphoprotein (VASP) and the p34 subunit of the Arp2/3 complex, both of which are components of actin polymer-forming protein complexes in the cell. This suggests that the localization of profilin and actin revealed with these antibodies in fact reflects the distribution of the profilin:actin complex rather than the two proteins separately. Significantly, protruding lamellipodia and filopodia showed intensive labeling. The two antibody preparations were also used to stain HeLa cells infected with Listeria monocytogenes or vaccinia virus. In both cases, the pattern of antibody staining of the pathogen-induced microfilament arrangement differed, suggesting a varying accessibility for the antibody-binding epitopes.
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Affiliation(s)
- Yu Li
- Department of Cell Biology, WGI, Stockholm University, S-10691 Stockholm, Sweden
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12
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Lindberg U, Karlsson R, Lassing I, Schutt CE, Höglund AS. The microfilament system and malignancy. Semin Cancer Biol 2007; 18:2-11. [PMID: 18024149 DOI: 10.1016/j.semcancer.2007.10.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Increased motile activity, increased rate of cell proliferation and removal of growth inhibiting cell-cell contacts are hallmarks of tumorigenesis. Activation of cell motility and migration is caused by activation of receptors, turning on the growth cycle. Increased expression of metalloproteinases, breaking cell:cell contacts and organ confines, allows the spread of malignant cancer cells to other sites in the organism. It has become increasingly clear that most transmembrane proteins (growth factor receptors, adhesion proteins and ion channels) are either permanently or transiently associated with the sub-membraneous system of actin microfilaments (MF), whose force generating capacity they control. Although there has been great progress in our understanding of the physiological importance of the MF-system, as will be exemplified in this issue of SCB, many aspects of actin microfilament formation and its regulation are still unclear. Redox control of the actin (MF)-system in cell motility and migration and its perturbations in pathophysiology, including cancer, is an emerging field of research.
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Affiliation(s)
- Uno Lindberg
- Department of Microbiology, Tumor Biology, and Cell Biology, The Karolinska Institute, Stockholm, Sweden.
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13
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Ding Z, Lambrechts A, Parepally M, Roy P. Silencing profilin-1 inhibits endothelial cell proliferation, migration and cord morphogenesis. J Cell Sci 2006; 119:4127-37. [PMID: 16968742 DOI: 10.1242/jcs.03178] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Expression of several actin-binding proteins including profilin-1 is up-regulated during capillary morphogenesis of endothelial cells, the biological significance of which remains unknown. Specifically, we hypothesized that profilin-1 is important for endothelial migration and proliferation. In this study, we suppressed profilin-1 expression in human umbilical vein endothelial cells by RNA-interference. Gene silencing of profilin-1 led to significant reduction in the formation of actin filaments and focal adhesions. Loss of profilin-1 expression was also associated with reduced dynamics of cell-cell adhesion. Data from both wound-healing experiments and time-lapse imaging of individual cells showed inhibition of cell migration when profilin-1 expression was suppressed. Cells lacking profilin-1 exhibited defects in membrane protrusion, both in terms of its magnitude and directional persistence. Furthermore, loss of profilin-1 expression inhibited cell growth without compromising cell survival, at least in the short-term, thus suggesting that profilin-1 also plays an important role in endothelial proliferation as hypothesized. Finally, silencing profilin-1 expression suppressed matrigel-induced early cord morphogenesis of endothelial cells. Taken together, our data suggest that profilin-1 may play important role in biological events that involve endothelial proliferation, migration and morphogenesis.
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Affiliation(s)
- Zhijie Ding
- Department of Bioengineering, University of Pittsburgh, 749 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15261, USA
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14
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Hillberg L, Zhao Rathje LS, Nyåkern-Meazza M, Helfand B, Goldman RD, Schutt CE, Lindberg U. Tropomyosins are present in lamellipodia of motile cells. Eur J Cell Biol 2006; 85:399-409. [PMID: 16524642 DOI: 10.1016/j.ejcb.2005.12.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 12/12/2022] Open
Abstract
This paper shows that high-molecular-weight tropomyosins (TMs), as well as shorter isoforms of this protein, are present in significant amounts in lamellipodia and filopodia of spreading normal and transformed cells. The presence of TM in these locales was ascertained by staining of cells with antibodies reacting with endogenous TMs and through the expression of hemaglutinin- and green fluorescent protein-tagged TM isoforms. The observations are contrary to recent reports suggesting the absence of TMs in regions,where polymerization of actin takes place, and indicate that the view of the role of TM in the formation of actin filaments needs to be significantly revised.
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Affiliation(s)
- Louise Hillberg
- Department of Cell Biology, The Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
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15
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Boukhelifa M, Moza M, Johansson T, Rachlin A, Parast M, Huttelmaier S, Roy P, Jockusch BM, Carpen O, Karlsson R, Otey CA. The proline-rich protein palladin is a binding partner for profilin. FEBS J 2006; 273:26-33. [PMID: 16367745 DOI: 10.1111/j.1742-4658.2005.05036.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Palladin is an actin-associated protein that has been suggested to play critical roles in establishing cell morphology and maintaining cytoskeletal organization in a wide variety of cell types. Palladin has been shown previously to bind directly to three different actin-binding proteins vasodilator-stimulated phosphoprotein (VASP), alpha-actinin and ezrin, suggesting that it functions as an organizing unit that recruits actin-regulatory proteins to specific subcellular sites. Palladin contains sequences resembling a motif known to bind profilin. Here, we demonstrate that palladin is a binding partner for profilin, interacting with profilin via a poly proline-containing sequence in the amino-terminal half of palladin. Double-label immunofluorescence staining shows that palladin and profilin partially colocalize in actin-rich structures in cultured astrocytes. Our results suggest that palladin may play an important role in recruiting profilin to sites of actin dynamics.
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Affiliation(s)
- Malika Boukhelifa
- Department of Cell and Molecular Physiology and Neuroscience Center, University of North Carolina at Chapel Hill, 27599-7545, USA
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16
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Johansson T, Grenklo S, Karlsson R. Detection of binding partners to the profilin:actin complex by far Western and mass spectrometry analyses. Anal Biochem 2004; 335:228-34. [PMID: 15556561 DOI: 10.1016/j.ab.2004.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Indexed: 11/19/2022]
Abstract
A method to search for interaction partners to the profilin:actin complex that can distinguish molecules that preferentially bind the complex from those that interact with profilin or actin separately is described. The procedure should be applicable for any situation where cell extracts or other complex samples are screened for the presence of protein molecules specifically recognizing a protein complex but having no or low affinity for its individual components. The method is readily combined with mass spectrometry for direct identification of detected proteins. In this study, Mena and Hsp70 were detected as interaction partners to profilin:actin.
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Affiliation(s)
- Thomas Johansson
- Department of Cell Biology, WGI, Stockholm University, S-106 91 Stockholm, Sweden
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17
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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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18
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Grenklo S, Johansson T, Bertilson L, Karlsson R. Anti-actin antibodies generated against profilin:actin distinguish between non-filamentous and filamentous actin, and label cultured cells in a dotted pattern. Eur J Cell Biol 2004; 83:413-23. [PMID: 15506565 DOI: 10.1078/0171-9335-00400] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Actin polymerization is a prominent feature of migrating cells, where it powers the protrusion of the leading edge. Many studies have characterized the well-ordered and dynamic arrangement of filamentous actin in this submembraneous space. However, less is known about the organization of unpolymerized actin. Previously, we reported on the use of covalently coupled profilin:actin to study actin dynamics and presented evidence that profilin-bound actin is a major source of actin for filament growth. To locate profilin:actin in the cell we have now used this non-dissociable complex for antibody generation, and obtained monospecific anti-actin and anti-profilin antibodies from two separate immunizations. Fluorescence microscopy revealed drastic differences in the staining pattern generated by the anti-actin antibody preparations. With one, distinct puncta appeared at the actin-rich leading edge and sometimes aligned with microtubules in the interior of the lamella, while the other displayed typical actin filament staining. Labelling experiments in vitro demonstrated failure of the first antibody to recognize filamentous actin and none of the two bound microtubules. The two anti-profilin antibodies purified in parallel generated a punctated pattern similar to that seen with the first anti-actin antibody. All antibody preparations labelled the nuclei.
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Affiliation(s)
- Staffan Grenklo
- Department of Cell Biology, WGI, Stockholm University, S-10691 Stockholm, Sweden
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19
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Ackermann M, Matus A. Activity-induced targeting of profilin and stabilization of dendritic spine morphology. Nat Neurosci 2003; 6:1194-200. [PMID: 14555951 DOI: 10.1038/nn1135] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2003] [Accepted: 09/15/2003] [Indexed: 11/09/2022]
Abstract
Morphological changes in dendritic spines have been implicated in connective plasticity in brain circuitry, but the underlying pathway leading from synaptic transmission to structural change is unknown. Using primary neurons expressing GFP-tagged proteins, we found that profilin, a regulator of actin polymerization, is targeted to spine heads when postsynaptic NMDA receptors are activated and that actin-based changes in spine shape are concomitantly blocked. Profilin targeting was triggered by electrical stimulation patterns known to induce the long-term changes in synaptic responsiveness associated with memory formation. These results suggest that, in addition to electrophysiological changes, NMDA receptor activation initiates changes in the actin cytoskeleton of dendritic spines that stabilize synaptic structure.
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20
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Skare P, Kreivi JP, Bergström A, Karlsson R. Profilin I colocalizes with speckles and Cajal bodies: a possible role in pre-mRNA splicing. Exp Cell Res 2003; 286:12-21. [PMID: 12729790 DOI: 10.1016/s0014-4827(03)00102-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Profilin is one of the major components controlling actin polymerization. Here, profilin I was located in fibroblasts and HeLa cells by the use of two different sets of affinity-purified antibodies. Both antibody preparations labeled nuclei in a speckle-like pattern and displayed extensive colocalization with small nuclear ribonucleoprotein particle (snRNP)-core proteins and p80 coilin-containing Cajal bodies. Treatment with actinomycin D led to largely similar reorganizations of snRNPs and profilin, while profilin and Cajal bodies separated under these conditions. One of the profilin antibodies interfered with pre-mRNA splicing in vitro, further indicating a role for profilin during pre-mRNA processing.
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Affiliation(s)
- Petra Skare
- Department of Cell Biology, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
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21
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Grenklo S, Geese M, Lindberg U, Wehland J, Karlsson R, Sechi AS. A crucial role for profilin-actin in the intracellular motility of Listeria monocytogenes. EMBO Rep 2003; 4:523-9. [PMID: 12776739 PMCID: PMC1319178 DOI: 10.1038/sj.embor.embor823] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have examined the effect of covalently crosslinked profilin-actin (PxA), which closely matches the biochemical properties of ordinary profilin-actin and interferes with actin polymerization in vitro and in vivo, on Listeria monocytogenes motility. PxA caused a marked reduction in bacterial motility, which was accompanied by the detachment of bacterial tails. The effect of PxA was dependent on its binding to proline-rich sequences, as shown by the inability of PH133SxA, which cannot interact with such sequences, to impair Listeria motility. PxA did not alter the motility of a Listeria mutant that is unable to recruit Ena (Enabled)/VASP (vasodilator-stimulated phosphoprotein) proteins and profilin to its surface. Finally, PxA did not block the initiation of actin-tail formation, indicating that profilin-actin is only required for the elongation of actin filaments at the bacterial surface. Our findings provide further evidence that profilin-actin is important for actin-based processes, and show that it has a key function in Listeria motility.
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Affiliation(s)
- Staffan Grenklo
- Department of Cell Biology, The Wenner–Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | - Marcus Geese
- Department of Cell Biology, Gesellschaft für Biotechnologische Forschung (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
| | - Uno Lindberg
- Department of Cell Biology, The Wenner–Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | - Jürgen Wehland
- Department of Cell Biology, Gesellschaft für Biotechnologische Forschung (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
| | - Roger Karlsson
- Department of Cell Biology, The Wenner–Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | - Antonio S. Sechi
- Department of Cell Biology, Gesellschaft für Biotechnologische Forschung (GBF), Mascheroder Weg 1, D-38124 Braunschweig, Germany
- Tel: +49 531 6181241; Fax: +49 531 6181444;
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Skare P, Karlsson R. Evidence for two interaction regions for phosphatidylinositol(4,5)-bisphosphate on mammalian profilin I. FEBS Lett 2002; 522:119-24. [PMID: 12095630 DOI: 10.1016/s0014-5793(02)02913-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The binding of phosphatidylinositol(4,5)-bisphosphate (PI(4,5)P(2)) to profilin at a region distinct from the actin interaction surface is demonstrated by experiments with covalently cross-linked profilin:beta-actin. The result is in agreement with observations made with several mutant profilins and provides strong evidence for two regions on mammalian profilin mediating electrostatic interaction with phosphatidylinositol lipids; one close to the binding site for poly(L-proline), and one partially overlapping with the actin-binding surface. Congruent with this, two plant profilins, which have a reduced number of positive amino acids in one of these regions, displayed a dramatically lower binding to PI(4,5)P(2) compared to human profilin I.
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Affiliation(s)
- Petra Skare
- Department of Cell Biology, Wenner Gren Institute, Stockholm University, Sweden
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23
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Nyman T, Page R, Schutt CE, Karlsson R, Lindberg U. A cross-linked profilin-actin heterodimer interferes with elongation at the fast-growing end of F-actin. J Biol Chem 2002; 277:15828-33. [PMID: 11844798 DOI: 10.1074/jbc.m112195200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Profilin and beta/gamma-actin from calf thymus were covalently linked using the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide in combination with N-hydroxysuccinimide, yielding a single product with an apparent molecular mass of 60 kDa. Sequence analysis and x-ray crystallographic investigations showed that the cross-linked residues were glutamic acid 82 of profilin and lysine 113 of actin. The cross-linked complex was shown to bind with high affinity to deoxyribonuclease I and poly(l-proline). It also bound and exchanged ATP with kinetics close to that of unmodified profilin-actin and inhibited the intrinsic ATPase activity of actin. This inhibition occurred even in conditions where actin normally forms filaments. By these criteria the cross-linked profilin-actin complex retains the characteristics of unmodified profilin-actin. However, the cross-linked complex did not form filaments nor copolymerized with unmodified actin, but did interfere with elongation of actin filaments in a concentration-dependent manner. These results support a polymerization mechanism where the profilin-actin heterodimer binds to the (+)-end of actin filaments, followed by dissociation of profilin, and ATP hydrolysis and P(i) release from the actin subunit as it assumes its stable conformation in the helical filament.
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Affiliation(s)
- Tomas Nyman
- Department of Cell Biology, the Wenner-Gren Institute, Stockholm University, S-106 91 Stockholm, Sweden
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24
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Abstract
Although actin-based motility drives cell crawling and intracellular locomotion of organelles and certain pathogens, the underlying mechanism of force generation remains a mystery. Recent experiments demonstrated that Listeria exhibit episodes of 5.4-nm stepwise motion corresponding to the periodicity of the actin filament subunits, and extremely small positional fluctuations during the intermittent pauses [S. C. Kuo and J. L. McGrath. 2000. Nature. 407:1026-1029]. These findings suggest that motile bacteria remain firmly bound to actin filament ends as they elongate, a behavior that appears to rule out previous models for actin-based motility. We propose and analyze a new mechanochemical model (called the "Lock, Load & Fire" mechanism) for force generation by means of affinity-modulated, clamped-filament elongation. During the locking step, the filament's terminal ATP-containing subunit binds tightly to a clamp situated on the surface of a motile object; in the loading step, actin.ATP monomer(s) bind to the filament end, an event that triggers the firing step, wherein ATP hydrolysis on the clamped subunit attenuates the filament's affinity for the clamp. This last step initiates translocation of the new ATP-containing terminus to the clamp, whereupon another cycle begins anew. This model explains how surface-tethered filaments can grow while exerting flexural or tensile force on the motile surface. Moreover, stochastic simulations of the model reproduce the signature motions of Listeria. This elongation motor, which we term actoclampin, exploits actin's intrinsic ATPase activity to provide a simple, high-fidelity enzymatic reaction cycle for force production that does not require elongating filaments to dissociate from the motile surface. This mechanism may operate whenever actin polymerization is called upon to generate the forces that drive cell crawling or intracellular organelle motility.
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Affiliation(s)
- Richard B Dickinson
- Department of Chemical Engineering, University of Florida College of Engineering, Gainesville, Florida 32610-0245 USA
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