1
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Gao N, Raduka A, Rezaee F. Respiratory syncytial virus disrupts the airway epithelial barrier by decreasing cortactin and destabilizing F-actin. J Cell Sci 2022; 135:jcs259871. [PMID: 35848790 PMCID: PMC9481929 DOI: 10.1242/jcs.259871] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 07/11/2022] [Indexed: 01/26/2023] Open
Abstract
Respiratory syncytial virus (RSV) infection is the leading cause of acute lower respiratory tract infection in young children worldwide. Our group recently revealed that RSV infection disrupts the airway epithelial barrier in vitro and in vivo. However, the underlying molecular pathways were still elusive. Here, we report the critical roles of the filamentous actin (F-actin) network and actin-binding protein cortactin in RSV infection. We found that RSV infection causes F-actin depolymerization in 16HBE cells, and that stabilizing the F-actin network in infected cells reverses the epithelial barrier disruption. RSV infection also leads to significantly decreased cortactin in vitro and in vivo. Cortactin-knockout 16HBE cells presented barrier dysfunction, whereas overexpression of cortactin protected the epithelial barrier against RSV. The activity of Rap1 (which has Rap1A and Rap1B forms), one downstream target of cortactin, declined after RSV infection as well as in cortactin-knockout cells. Moreover, activating Rap1 attenuated RSV-induced epithelial barrier disruption. Our study proposes a key mechanism in which RSV disrupts the airway epithelial barrier via attenuating cortactin expression and destabilizing the F-actin network. The identified pathways will provide new targets for therapeutic intervention toward RSV-related disease. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Nannan Gao
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
| | - Andjela Raduka
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
| | - Fariba Rezaee
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
- Center for Pediatric Pulmonary Medicine, Cleveland Clinic Children's, Cleveland, Ohio 44195, USA
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2
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Hurst V, Challa K, Shimada K, Gasser SM. Cytoskeleton integrity influences XRCC1 and PCNA dynamics at DNA damage. Mol Biol Cell 2021; 32:br6. [PMID: 34379448 PMCID: PMC8684753 DOI: 10.1091/mbc.e20-10-0680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
On induction of DNA damage with 405-nm laser light, proteins involved in base excision repair (BER) are recruited to DNA lesions. We find that the dynamics of factors typical of either short-patch (XRCC1) or long-patch (PCNA) BER are altered by chemicals that perturb actin or tubulin polymerization in human cells. Whereas the destabilization of actin filaments by latrunculin B, cytochalasin B, or Jasplakinolide decreases BER factor accumulation at laser-induced damage, inhibition of tubulin polymerization by nocodazole increases it. We detect no recruitment of actin to sites of laser-induced DNA damage, yet the depolymerization of cytoplasmic actin filaments elevates both actin and tubulin signals in the nucleus. While published evidence suggested a positive role for F-actin in double-strand break repair in mammals, the enrichment of actin in budding yeast nuclei interferes with BER, augmenting sensitivity to Zeocin. Our quantitative imaging results suggest that the depolymerization of cytoplasmic actin may compromise BER efficiency in mammals not only due to elevated levels of nuclear actin but also of tubulin, linking cytoskeletal integrity to BER.
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Affiliation(s)
- Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Klingelbergstrasse 90, CH-4056 Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Klingelbergstrasse 90, CH-4056 Basel, Switzerland
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3
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Andreu I, Falcones B, Hurst S, Chahare N, Quiroga X, Le Roux AL, Kechagia Z, Beedle AEM, Elosegui-Artola A, Trepat X, Farré R, Betz T, Almendros I, Roca-Cusachs P. The force loading rate drives cell mechanosensing through both reinforcement and cytoskeletal softening. Nat Commun 2021; 12:4229. [PMID: 34244477 PMCID: PMC8270983 DOI: 10.1038/s41467-021-24383-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/15/2021] [Indexed: 01/08/2023] Open
Abstract
Cell response to force regulates essential processes in health and disease. However, the fundamental mechanical variables that cells sense and respond to remain unclear. Here we show that the rate of force application (loading rate) drives mechanosensing, as predicted by a molecular clutch model. By applying dynamic force regimes to cells through substrate stretching, optical tweezers, and atomic force microscopy, we find that increasing loading rates trigger talin-dependent mechanosensing, leading to adhesion growth and reinforcement, and YAP nuclear localization. However, above a given threshold the actin cytoskeleton softens, decreasing loading rates and preventing reinforcement. By stretching rat lungs in vivo, we show that a similar phenomenon may occur. Our results show that cell sensing of external forces and of passive mechanical parameters (like tissue stiffness) can be understood through the same mechanisms, driven by the properties under force of the mechanosensing molecules involved.
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Affiliation(s)
- Ion Andreu
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | | | - Sebastian Hurst
- Institute of Cell Biology, Center of Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Nimesh Chahare
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat Politècnica de Catalunya (UPC), Campus Nord, Barcelona, Spain
| | - Xarxa Quiroga
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat de Barcelona, Barcelona, Spain
| | - Anabel-Lise Le Roux
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | - Zanetta Kechagia
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | - Amy E M Beedle
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Department of Physics, King's College London, Strand, London, UK
| | - Alberto Elosegui-Artola
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, MA, USA
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys, Barcelona, Spain
- CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
| | - Ramon Farré
- Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Respiratorias, Madrid, Spain
- Institut d'Investigacions Biomèdiques August Pi Sunyer, Barcelona, Spain
| | - Timo Betz
- Institute of Cell Biology, Center of Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Isaac Almendros
- Universitat de Barcelona, Barcelona, Spain.
- CIBER de Enfermedades Respiratorias, Madrid, Spain.
- Institut d'Investigacions Biomèdiques August Pi Sunyer, Barcelona, Spain.
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain.
- Universitat de Barcelona, Barcelona, Spain.
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4
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Lu HJ, Nguyen TL, Hong GS, Pak S, Kim H, Kim H, Kim DY, Kim SY, Shen Y, Ryu PD, Lee MO, Oh U. Tentonin 3/TMEM150C senses blood pressure changes in the aortic arch. J Clin Invest 2021; 130:3671-3683. [PMID: 32484458 DOI: 10.1172/jci133798] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 03/24/2020] [Indexed: 01/09/2023] Open
Abstract
The baroreceptor reflex is a powerful neural feedback that regulates arterial pressure (AP). Mechanosensitive channels transduce pulsatile AP to electrical signals in baroreceptors. Here we show that tentonin 3 (TTN3/TMEM150C), a cation channel activated by mechanical strokes, is essential for detecting AP changes in the aortic arch. TTN3 was expressed in nerve terminals in the aortic arch and nodose ganglion (NG) neurons. Genetic ablation of Ttn3 induced ambient hypertension, tachycardia, AP fluctuations, and impaired baroreflex sensitivity. Chemogenetic silencing or activation of Ttn3+ neurons in the NG resulted in an increase in AP and heart rate, or vice versa. More important, overexpression of Ttn3 in the NG of Ttn3-/- mice reversed the cardiovascular changes observed in Ttn3-/- mice. We conclude that TTN3 is a molecular component contributing to the sensing of dynamic AP changes in baroreceptors.
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Affiliation(s)
- Huan-Jun Lu
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,College of Pharmacy
| | - Thien-Luan Nguyen
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea.,College of Pharmacy
| | - Gyu-Sang Hong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Sungmin Pak
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Hyesu Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | - Hyungsup Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
| | | | - Sung-Yon Kim
- Institute of Molecular Biology and Genetics, and
| | - Yiming Shen
- College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Pan Dong Ryu
- College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | | | - Uhtaek Oh
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, Korea
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5
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Smith CEL, Lake AVR, Johnson CA. Primary Cilia, Ciliogenesis and the Actin Cytoskeleton: A Little Less Resorption, A Little More Actin Please. Front Cell Dev Biol 2020; 8:622822. [PMID: 33392209 PMCID: PMC7773788 DOI: 10.3389/fcell.2020.622822] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 11/24/2020] [Indexed: 12/13/2022] Open
Abstract
Primary cilia are microtubule-based organelles that extend from the apical surface of most mammalian cells, forming when the basal body (derived from the mother centriole) docks at the apical cell membrane. They act as universal cellular "antennae" in vertebrates that receive and integrate mechanical and chemical signals from the extracellular environment, serving diverse roles in chemo-, mechano- and photo-sensation that control developmental signaling, cell polarity and cell proliferation. Mutations in ciliary genes cause a major group of inherited developmental disorders called ciliopathies. There are very few preventative treatments or new therapeutic interventions that modify disease progression or the long-term outlook of patients with these conditions. Recent work has identified at least four distinct but interrelated cellular processes that regulate cilia formation and maintenance, comprising the cell cycle, cellular proteostasis, signaling pathways and structural influences of the actin cytoskeleton. The actin cytoskeleton is composed of microfilaments that are formed from filamentous (F) polymers of globular G-actin subunits. Actin filaments are organized into bundles and networks, and are attached to the cell membrane, by diverse cross-linking proteins. During cell migration, actin filament bundles form either radially at the leading edge or as axial stress fibers. Early studies demonstrated that loss-of-function mutations in ciliopathy genes increased stress fiber formation and impaired ciliogenesis whereas pharmacological inhibition of actin polymerization promoted ciliogenesis. These studies suggest that polymerization of the actin cytoskeleton, F-actin branching and the formation of stress fibers all inhibit primary cilium formation, whereas depolymerization or depletion of actin enhance ciliogenesis. Here, we review the mechanistic basis for these effects on ciliogenesis, which comprise several cellular processes acting in concert at different timescales. Actin polymerization is both a physical barrier to both cilia-targeted vesicle transport and to the membrane remodeling required for ciliogenesis. In contrast, actin may cause cilia loss by localizing disassembly factors at the ciliary base, and F-actin branching may itself activate the YAP/TAZ pathway to promote cilia disassembly. The fundamental role of actin polymerization in the control of ciliogenesis may present potential new targets for disease-modifying therapeutic approaches in treating ciliopathies.
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Affiliation(s)
| | | | - Colin A. Johnson
- Leeds Institute of Medical Research at St. James’s, University of Leeds, Leeds, United Kingdom
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6
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Pospich S, Merino F, Raunser S. Structural Effects and Functional Implications of Phalloidin and Jasplakinolide Binding to Actin Filaments. Structure 2020; 28:437-449.e5. [PMID: 32084355 DOI: 10.1016/j.str.2020.01.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 01/07/2020] [Accepted: 01/28/2020] [Indexed: 12/15/2022]
Abstract
Actin undergoes structural transitions during polymerization, ATP hydrolysis, and subsequent release of inorganic phosphate. Several actin-binding proteins sense specific states during this transition and can thus target different regions of the actin filament. Here, we show in atomic detail that phalloidin, a mushroom toxin that is routinely used to stabilize and label actin filaments, suspends the structural changes in actin, likely influencing its interaction with actin-binding proteins. Furthermore, high-resolution cryoelectron microscopy structures reveal structural rearrangements in F-actin upon inorganic phosphate release in phalloidin-stabilized filaments. We find that the effect of the sponge toxin jasplakinolide differs from the one of phalloidin, despite their overlapping binding site and similar interactions with the actin filament. Analysis of structural conformations of F-actin suggests that stabilizing agents trap states within the natural conformational space of actin.
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Affiliation(s)
- Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund 44227, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund 44227, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund 44227, Germany.
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7
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Ilicheva NV, Pochukalina GN, Podgornaya OI. Actin depolymerization disrupts karyosphere capsule integrity but not residual transcription in late oocytes of the grass frog Rana temporaria. J Cell Biochem 2019; 120:15057-15068. [PMID: 31081178 DOI: 10.1002/jcb.28767] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/30/2022]
Abstract
Late diplotene oocytes are characterized by an essential decrease in transcriptional activity. At this time, chromosomes condense and form a compact structure named a karyosphere. The karyosphere of grass frogs Rana temporaria is surrounded by a fibrillar karyosphere capsule (KC). One of the main protein constituents of R. temporaria KC is actin. In this study, we used antibodies against different actin epitopes to trace different forms of actin in the KC. We also investigated the effect of F-actin depolymerization on the oocyte nuclear structures and transcription of chromatin DNA and rDNA in the amplified nucleoli. It was determined that disruption of actin filaments leads to chromosome shrinkage, nucleoli fusion, and distortion of the KC structure, but does not inhibit residual transcription in both the karyosphere and the nucleoli.
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Affiliation(s)
- Nadya V Ilicheva
- Institute of Cytology of Russian Academy of Sciences, Saint Petersburg, Russia
| | | | - Olga I Podgornaya
- Institute of Cytology of Russian Academy of Sciences, Saint Petersburg, Russia.,Saint Petersburg University, Saint Petersburg, Russia.,Far Eastern Federal University, Vladivostok, Russia
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8
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He L, Sayers EJ, Watson P, Jones AT. Contrasting roles for actin in the cellular uptake of cell penetrating peptide conjugates. Sci Rep 2018; 8:7318. [PMID: 29743505 PMCID: PMC5943252 DOI: 10.1038/s41598-018-25600-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/25/2018] [Indexed: 12/13/2022] Open
Abstract
The increased need for macromolecular therapeutics, such as peptides, proteins and nucleotides, to reach intracellular targets necessitates more effective delivery vectors and a higher level of understanding of their mechanism of action. Cell penetrating peptides (CPPs) can transport a range of macromolecules into cells, either through direct plasma membrane translocation or endocytosis. All known endocytic pathways involve cell-cortex remodelling, a process shown to be regulated by reorganisation of the actin cytoskeleton. Here using flow cytometry, confocal microscopy and a variety of actin inhibitors we identify how actin disorganisation in different cell types differentially influences the cellular entry of three probes: the CPP octaarginine - Alexa488 conjugate (R8-Alexa488), octaarginine conjugated Enhanced Green Fluorescent Protein (EGFP-R8), and the fluid phase probe dextran. Disrupting actin organisation in A431 skin epithelial cells dramatically increases the uptake of EGFP-R8 and dextran, and contrasts strongly to inhibitory effects observed with transferrin and R8 attached to the fluorophore Alexa488. This demonstrates that uptake of the same CPP can occur via different endocytic processes depending on the conjugated fluorescent entity. Overall this study highlights how cargo influences cell uptake of this peptide and that the actin cytoskeleton may act as a gateway or barrier to endocytosis of drug delivery vectors.
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Affiliation(s)
- L He
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK
| | - E J Sayers
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK
| | - P Watson
- Cardiff School of Biosciences, The Sir Martin Evans Building, Cardiff University, Cardiff, Wales, CF10 3AX, UK.
| | - A T Jones
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Redwood Building, Cardiff University, Cardiff, Wales, CF10 3NB, UK.
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9
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Lopata A, Hughes R, Tiede C, Heissler SM, Sellers JR, Knight PJ, Tomlinson D, Peckham M. Affimer proteins for F-actin: novel affinity reagents that label F-actin in live and fixed cells. Sci Rep 2018; 8:6572. [PMID: 29700342 PMCID: PMC5920084 DOI: 10.1038/s41598-018-24953-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/10/2018] [Indexed: 01/21/2023] Open
Abstract
Imaging the actin cytoskeleton in cells uses a wide range of approaches. Typically, a fluorescent derivative of the small cyclic peptide phalloidin is used to image F-actin in fixed cells. Lifeact and F-tractin are popular for imaging the cytoskeleton in live cells. Here we characterised novel affinity reagents called Affimers that specifically bind to F-actin in vitro to determine if they are suitable alternatives as eGFP-fusion proteins, to label actin in live cells, or for labeling F-actin in fixed cells. In vitro experiments showed that 3 out of the 4 Affimers (Affimers 6, 14 and 24) tested bind tightly to purified F-actin, and appear to have overlapping binding sites. As eGFP-fusion proteins, the same 3 Affimers label F-actin in live cells. FRAP experiments suggest that eGFP-Affimer 6 behaves most similarly to F-tractin and Lifeact. However, it does not colocalise with mCherry-actin in dynamic ruffles, and may preferentially bind stable actin filaments. All 4 Affimers label F-actin in methanol fixed cells, while only Affimer 14 labels F-actin after paraformaldehyde fixation. eGFP-Affimer 6 has potential for use in selectively imaging the stable actin cytoskeleton in live cells, while all 4 Affimers are strong alternatives to phalloidin for labelling F-actin in fixed cells.
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Affiliation(s)
- Anna Lopata
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.,Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, Bethesda, MD, 20892, USA
| | - Ruth Hughes
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Christian Tiede
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, Bethesda, MD, 20892, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, Bethesda, MD, 20892, USA
| | - Peter J Knight
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Darren Tomlinson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Michelle Peckham
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK. .,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
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10
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Kumar S, Mansson A. Covalent and non-covalent chemical engineering of actin for biotechnological applications. Biotechnol Adv 2017; 35:867-888. [PMID: 28830772 DOI: 10.1016/j.biotechadv.2017.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/09/2017] [Accepted: 08/16/2017] [Indexed: 12/26/2022]
Abstract
The cytoskeletal filaments are self-assembled protein polymers with 8-25nm diameters and up to several tens of micrometres length. They have a range of pivotal roles in eukaryotic cells, including transportation of intracellular cargoes (primarily microtubules with dynein and kinesin motors) and cell motility (primarily actin and myosin) where muscle contraction is one example. For two decades, the cytoskeletal filaments and their associated motor systems have been explored for nanotechnological applications including miniaturized sensor systems and lab-on-a-chip devices. Several developments have also revolved around possible exploitation of the filaments alone without their motor partners. Efforts to use the cytoskeletal filaments for applications often require chemical or genetic engineering of the filaments such as specific conjugation with fluorophores, antibodies, oligonucleotides or various macromolecular complexes e.g. nanoparticles. Similar conjugation methods are also instrumental for a range of fundamental biophysical studies. Here we review methods for non-covalent and covalent chemical modifications of actin filaments with focus on critical advantages and challenges of different methods as well as critical steps in the conjugation procedures. We also review potential uses of the engineered actin filaments in nanotechnological applications and in some key fundamental studies of actin and myosin function. Finally, we consider possible future lines of investigation that may be addressed by applying chemical conjugation of actin in new ways.
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Affiliation(s)
- Saroj Kumar
- Department of Biotechnology, Delhi Technological University, Delhi 110042, India; Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
| | - Alf Mansson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
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11
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Spectroscopic characterization of the effect of mouse twinfilin-1 on actin filaments at different pH values. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 164:276-282. [PMID: 27718419 DOI: 10.1016/j.jphotobiol.2016.09.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 09/26/2016] [Accepted: 09/30/2016] [Indexed: 11/22/2022]
Abstract
The effect of mammalian twinfilin-1 on the structure and dynamics of actin filaments were studied with steady state fluorescence spectroscopy, total internal reflection fluorescence microscopy and differential scanning calorimetry techniques. It was proved before that the eukaryotic budding yeast twinfilin-1 can efficiently bind and severe actin filaments in vitro at low pH values. In the present work steady-state anisotropy measurements revealed that twinfilin can bind efficiently to F-actin. Dilution-induced depolymerization assay proved that mammalian twinfilin-1 has an actin filament severing activity. This severing activity was more pronounced at low pH values. Total internal reflection fluorescence microscopy measurements could support the severing activity of mouse twinfilin-1. The average rate of depolymerization was more apparent at low pH values. The differential scanning calorimetry measurements demonstrated that mammalian twinfilin-1 could reduce the stiffness within the actin filaments before the detachment of the actin protomers. The structural and dynamic reorganization of actin can support the twinfilin-1 induced separation of actin protomers. The measured data indicated that mammalian twinfilin-1 was able to accelerate the monomers dissociation and/or sever the filaments effectively at low pH values. It was concluded that twinfilin-1 can affect the F-actin in biological processes or under stress situations when the pH is markedly under the physiological level.
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12
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Serebryannyy LA, Yuen M, Parilla M, Cooper ST, de Lanerolle P. The Effects of Disease Models of Nuclear Actin Polymerization on the Nucleus. Front Physiol 2016; 7:454. [PMID: 27774069 PMCID: PMC5053997 DOI: 10.3389/fphys.2016.00454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 09/21/2016] [Indexed: 01/09/2023] Open
Abstract
Actin plays a crucial role in regulating multiple processes within the nucleus, including transcription and chromatin organization. However, the polymerization state of nuclear actin remains controversial, and there is no evidence for persistent actin filaments in a normal interphase nucleus. Further, several disease pathologies are characterized by polymerization of nuclear actin into stable filaments or rods. These include filaments that stain with phalloidin, resulting from point mutations in skeletal α-actin, detected in the human skeletal disease intranuclear rod myopathy, and cofilin/actin rods that form in response to cellular stressors like heatshock. To further elucidate the effects of these pathological actin structures, we examined the nucleus in both cell culture models as well as isolated human tissues. We find these actin structures alter the distribution of both RNA polymerase II and chromatin. Our data suggest that nuclear actin filaments result in disruption of nuclear organization, which may contribute to the disease pathology.
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Affiliation(s)
- Leonid A Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
| | - Michaela Yuen
- Institute for Neuroscience and Muscle Research, Kids Research Institute, The Children's Hospital at WestmeadSydney, NSW, Australia; Faculty of Medicine, Discipline of Pediatrics and Child Health, University of SydneySydney, NSW, Australia
| | - Megan Parilla
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
| | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, Kids Research Institute, The Children's Hospital at WestmeadSydney, NSW, Australia; Faculty of Medicine, Discipline of Pediatrics and Child Health, University of SydneySydney, NSW, Australia
| | - Primal de Lanerolle
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
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13
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The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly. J Virol 2016; 90:4115-4126. [PMID: 26865720 DOI: 10.1128/jvi.02885-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 02/02/2016] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Baculovirus DNAs are synthesized and inserted into preformed capsids to form nucleocapsids at a site in the infected cell nucleus, termed the virogenic stroma. Nucleocapsid assembly ofAutographa californicamultiple nucleopolyhedrovirus (AcMNPV) requires the major capsid protein VP39 and nine minor capsid proteins, including VP1054. However, how VP1054 participates in nucleocapsid assembly remains elusive. In this study, the VP1054-encoding gene (ac54) was deleted to generate theac54-knockout AcMNPV (vAc54KO). In vAc54KO-transfected cells, nucleocapsid assembly was disrupted, leading to the formation of abnormally elongated capsid structures. Interestingly, unlike cells transfected with AcMNPV mutants lacking other minor capsid proteins, in which capsid structures were distributed within the virogenic stroma,ac54ablation resulted in a distinctive location of capsid structures and VP39 at the periphery of the nucleus. The altered distribution pattern of capsid structures was also observed in cells transfected with AcMNPV lacking BV/ODV-C42 or in cytochalasind-treated AcMNPV-infected cells. BV/ODV-C42, along with PP78/83, has been shown to promote nuclear filamentous actin (F-actin) formation, which is another requisite for nucleocapsid assembly. Immunofluorescence using phalloidin indicated that the formation and distribution of nuclear F-actin were not affected byac54deletion. However, immunoelectron microscopy revealed that BV/ODV-C42, PP78/83, and 38K failed to integrate into capsid structures in the absence of VP1054, and immunoprecipitation further demonstrated that in transient expression assays, VP1054 interacted with BV/ODV-C42 and VP80 but not VP39. Our findings suggest that VP1054 plays an important role in the transport of capsid proteins to the nucleocapsid assembly site prior to the process of nucleocapsid assembly. IMPORTANCE Baculoviruses are large DNA viruses whose replication occurs within the host nucleus. The localization of capsids into the capsid assembly site requires virus-induced nuclear F-actin; the inhibition of nuclear F-actin formation results in the retention of capsid structures at the periphery of the nucleus. In this paper, we note that the minor capsid protein VP1054 is essential for the localization of capsid structures, the major capsid protein VP39, and the minor capsid protein 38K into the capsid assembly site. Moreover, VP1054 is crucial for correct targeting of the nuclear F-actin factors BV/ODV-C42 and PP78/83 for capsid maturation. However, the formation and distribution of nuclear F-actin are not affected by the lack of VP1054. We further reveal that VP1054 interacts with BV/ODV-C42 and a capsid transport-related protein, VP80. Taken together, our findings suggest that VP1054 plays a unique role in the pathway(s) for transport of capsid proteins.
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Cofilin-induced cooperative conformational changes of actin subunits revealed using cofilin-actin fusion protein. Sci Rep 2016; 6:20406. [PMID: 26842224 PMCID: PMC4740740 DOI: 10.1038/srep20406] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 12/31/2015] [Indexed: 11/19/2022] Open
Abstract
To investigate cooperative conformational changes of actin filaments induced by cofilin binding, we engineered a fusion protein made of Dictyostelium cofilin and actin. The filaments of the fusion protein were functionally similar to actin filaments bound with cofilin in that they did not bind rhodamine-phalloidin, had quenched fluorescence of pyrene attached to Cys374 and showed enhanced susceptibility of the DNase loop to cleavage by subtilisin. Quantitative analyses of copolymers made of different ratios of the fusion protein and control actin further demonstrated that the fusion protein affects the structure of multiple neighboring actin subunits in copolymers. Based on these and other recent related studies, we propose a mechanism by which conformational changes induced by cofilin binding is propagated unidirectionally to the pointed ends of the filaments, and cofilin clusters grow unidirectionally to the pointed ends following this path. Interestingly, the fusion protein was unable to copolymerize with control actin at pH 6.5 and low ionic strength, suggesting that the structural difference between the actin moiety in the fusion protein and control actin is pH-sensitive.
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Actin-Dynamics in Plant Cells: The Function of Actin-Perturbing Substances: Jasplakinolide, Chondramides, Phalloidin, Cytochalasins, and Latrunculins. Methods Mol Biol 2016; 1365:243-61. [PMID: 26498789 DOI: 10.1007/978-1-4939-3124-8_13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This chapter gives an overview of the most common F-actin-perturbing substances that are used to study actin dynamics in living plant cells in studies on morphogenesis, motility, organelle movement, or when apoptosis has to be induced. These substances can be divided into two major subclasses: F-actin-stabilizing and -polymerizing substances like jasplakinolide and chondramides and F-actin-severing compounds like chytochalasins and latrunculins. Jasplakinolide was originally isolated form a marine sponge, and can now be synthesized and has become commercially available, which is responsible for its wide distribution as membrane-permeable F-actin-stabilizing and -polymerizing agent, which may even have anticancer activities. Cytochalasins, derived from fungi, show an F-actin-severing function and many derivatives are commercially available (A, B, C, D, E, H, J), also making it a widely used compound for F-actin disruption. The same can be stated for latrunculins (A, B), derived from red sea sponges; however the mode of action is different by binding to G-actin and inhibiting incorporation into the filament. In the case of swinholide a stable complex with actin dimers is formed resulting also in severing of F-actin. For influencing F-actin dynamics in plant cells only membrane permeable drugs are useful in a broad range. We however introduce also the phallotoxins and synthetic derivatives, as they are widely used to visualize F-actin in fixed cells. A particular uptake mechanism has been shown for hepatocytes, but has also been described in siphonal giant algae. In the present chapter the focus is set on F-actin dynamics in plant cells where alterations in cytoplasmic streaming can be particularly well studied; however methods by fluorescence applications including phalloidin and antibody staining as well as immunofluorescence-localization of the inhibitor drugs are given.
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Sun BO, Fang Y, Li Z, Chen Z, Xiang J. Role of cellular cytoskeleton in epithelial-mesenchymal transition process during cancer progression. Biomed Rep 2015; 3:603-610. [PMID: 26405532 DOI: 10.3892/br.2015.494] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/20/2015] [Indexed: 02/06/2023] Open
Abstract
Currently, cancer metastases remain a major clinical problem that highlights the importance of recognition of the metastatic process in cancer diagnosis and treatment. A critical process associated with the metastasis process is the transformation of epithelial cells toward the motile mesenchymal state, a process called epithelial-mesenchymal transition (EMT). Increasing evidence suggests the crucial role of the cytoskeleton in the EMT process. The cytoskeleton is composed of the actin cytoskeleton, the microtubule network and the intermediate filaments that provide structural design and mechanical strength that is necessary for the EMT. The dynamic reorganization of the actin cytoskeleton is a prerequisite for the morphology, migration and invasion of cancer cells. The microtubule network is the cytoskeleton that provides the driving force during cell migration. Intermediate filaments are significantly rearranged, typically switching from cytokeratin-rich to vimentin-rich networks during the EMT process, accompanied by a greatly enhanced cell motility capacity. In the present review, the recent novel insights into the different cytoskeleton underlying EMT are summarized. There are numerous advances in our understanding of the fundamental role of the cytoskeleton in cancer cell invasion and migration.
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Affiliation(s)
- B O Sun
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Yantian Fang
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Zhenyang Li
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Zongyou Chen
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
| | - Jianbin Xiang
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China
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Falahzadeh K, Banaei-Esfahani A, Shahhoseini M. The potential roles of actin in the nucleus. CELL JOURNAL 2015; 17:7-14. [PMID: 25870830 PMCID: PMC4393673 DOI: 10.22074/cellj.2015.507] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 11/05/2013] [Indexed: 11/16/2022]
Abstract
Over the past few decades, actin’s presence in the nucleus has been demonstrated. Actin
is a key protein necessary for different nuclear processes. Although actin is well known for
its functional role in dynamic behavior of the cytoskeleton, emerging studies are now highlighting new roles for actin. At the present time there is no doubt about the presence of actin in the nucleus. A number of studies have uncovered the functional involvement of actin
in nuclear processes. Actin as one of the nuclear components has its own structured and
functional rules, such as nuclear matrix association, chromatin remodeling, transcription
by RNA polymerases I, II, III and mRNA processing. In this historical review, we attempt to
provide an overview of our current understanding of the functions of actin in the nucleus.
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Affiliation(s)
- Khadijeh Falahzadeh
- Department of Genetics at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran ; Department of Cell and Molecular Biology, Faculty of Biological Sciences, Kharazmi University (TMU), Tehran, Iran
| | - Amir Banaei-Esfahani
- Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | - Maryam Shahhoseini
- Department of Genetics at Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
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18
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Povarova OI, Uversky VN, Kuznetsova IM, Turoverov KK. Actinous enigma or enigmatic actin: Folding, structure, and functions of the most abundant eukaryotic protein. INTRINSICALLY DISORDERED PROTEINS 2014; 2:e34500. [PMID: 28232879 PMCID: PMC5314930 DOI: 10.4161/idp.34500] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 08/12/2014] [Accepted: 08/13/2014] [Indexed: 02/06/2023]
Abstract
Being the most abundant protein of the eukaryotic cell, actin continues to keep its secrets for more than 60 years. Everything about this protein, its structure, functions, and folding, is mysteriously counterintuitive, and this review represents an attempt to solve some of the riddles and conundrums commonly found in the field of actin research. In fact, actin is a promiscuous binder with a wide spectrum of biological activities. It can exist in at least three structural forms, globular, fibrillar, and inactive (G-, F-, and I-actin, respectively). G-actin represents a thermodynamically instable, quasi-stationary state, which is formed in vivo as a result of the energy-intensive, complex posttranslational folding events controlled and driven by cellular folding machinery. The G-actin structure is dependent on the ATP and Mg2+ binding (which in vitro is typically substituted by Ca2+) and protein is easily converted to the I-actin by the removal of metal ions and by action of various denaturing agents (pH, temperature, and chemical denaturants). I-actin cannot be converted back to the G-form. Foldable and “natively folded” forms of actin are always involved in interactions either with the specific protein partners, such as Hsp70 chaperone, prefoldin, and the CCT chaperonin during the actin folding in vivo or with Mg2+ and ATP as it takes place in the G-form. We emphasize that the solutions for the mysteries of actin multifunctionality, multistructurality, and trapped unfolding can be found in the quasi-stationary nature of this enigmatic protein, which clearly possesses many features attributed to both globular and intrinsically disordered proteins.
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Affiliation(s)
- Olga I Povarova
- Laboratory of structural dynamics, stability, and folding of proteins; Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia
| | - Vladimir N Uversky
- Laboratory of structural dynamics, stability, and folding of proteins; Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute; Morsani College of Medicine; University of South Florida; Tampa, FL USA; Institute for Biological Instrumentation; Russian Academy of Sciences; Pushchino, Russia; Biology Department; Faculty of Science; King Abdulaziz University; Jeddah, Kingdom of Saudi Arabia
| | - Irina M Kuznetsova
- Laboratory of structural dynamics, stability, and folding of proteins; Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St. Petersburg State Polytechnical University; St. Petersburg, Russia
| | - Konstantin K Turoverov
- Laboratory of structural dynamics, stability, and folding of proteins; Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; St. Petersburg State Polytechnical University; St. Petersburg, Russia
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Platholi J, Herold KF, Hemmings HC, Halpain S. Isoflurane reversibly destabilizes hippocampal dendritic spines by an actin-dependent mechanism. PLoS One 2014; 9:e102978. [PMID: 25068870 PMCID: PMC4113311 DOI: 10.1371/journal.pone.0102978] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 06/24/2014] [Indexed: 12/20/2022] Open
Abstract
General anesthetics produce a reversible coma-like state through modulation of excitatory and inhibitory synaptic transmission. Recent evidence suggests that anesthetic exposure can also lead to sustained cognitive dysfunction. However, the subcellular effects of anesthetics on the structure of established synapses are not known. We investigated effects of the widely used volatile anesthetic isoflurane on the structural stability of hippocampal dendritic spines, a postsynaptic structure critical to excitatory synaptic transmission in learning and memory. Exposure to clinical concentrations of isoflurane induced rapid and non-uniform shrinkage and loss of dendritic spines in mature cultured rat hippocampal neurons. Spine shrinkage was associated with a reduction in spine F-actin concentration. Spine loss was prevented by either jasplakinolide or cytochalasin D, drugs that prevent F-actin disassembly. Isoflurane-induced spine shrinkage and loss were reversible upon isoflurane elimination. Thus, isoflurane destabilizes spine F-actin, resulting in changes to dendritic spine morphology and number. These findings support an actin-based mechanism for isoflurane-induced alterations of synaptic structure in the hippocampus. These reversible alterations in dendritic spine structure have important implications for acute anesthetic effects on excitatory synaptic transmission and synaptic stability in the hippocampus, a locus for anesthetic-induced amnesia, and have important implications for anesthetic effects on synaptic plasticity.
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Affiliation(s)
- Jimcy Platholi
- Division of Biological Sciences, University of California San Diego and Sanford Consortium for Regenerative Medicine, San Diego, California, United States of America
- Departments of Anesthesiology and Pharmacology, Weill Cornell Medical College, New York, New York, United States of America
| | - Karl F. Herold
- Departments of Anesthesiology and Pharmacology, Weill Cornell Medical College, New York, New York, United States of America
| | - Hugh C. Hemmings
- Departments of Anesthesiology and Pharmacology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (SH); (HCH)
| | - Shelley Halpain
- Division of Biological Sciences, University of California San Diego and Sanford Consortium for Regenerative Medicine, San Diego, California, United States of America
- * E-mail: (SH); (HCH)
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20
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Futó K, Bódis E, Machesky LM, Nyitrai M, Visegrády B. Membrane binding properties of IRSp53-missing in metastasis domain (IMD) protein. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1831:1651-5. [PMID: 23872532 DOI: 10.1016/j.bbalip.2013.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/05/2013] [Accepted: 07/10/2013] [Indexed: 12/31/2022]
Abstract
The 53-kDa insulin receptor substrate protein (IRSp53) organizes the actin cytoskeleton in response to stimulation of small GTPases, promoting the formation of cell protrusions such as filopodia and lamellipodia. IMD is the N-terminal 250 amino acid domain (IRSp53/MIM Homology Domain) of IRSp53 (also called I-BAR), which can bind to negatively charged lipid molecules. Overexpression of IMD induces filopodia formation in cells and purified IMD assembles finger-like protrusions in reconstituted lipid membranes. IMD was shown by several groups to bundle actin filaments, but other groups showed that it also binds to membranes. IMD binds to negatively charged lipid molecules with preference to clusters of PI(4,5)P2. Here, we performed a range of different in vitro fluorescence experiments to determine the binding properties of the IMD to phospholipids. We used different constructs of large unilamellar vesicles (LUVETs), containing neutral or negatively charged phospholipids. We found that IMD has a stronger binding interaction with negatively charged PI(4,5)P2 or PS lipids than PS/PC or neutral PC lipids. The equilibrium dissociation constant for the IMD-lipid interaction falls into the 78-170μM range for all the lipids tested. The solvent accessibility of the fluorescence labels on the IMD during its binding to lipids is also reduced as the lipids become more negatively charged. Actin affects the IMD-lipid interaction, depending on its polymerization state. Monomeric actin partially disrupts the binding, while filamentous actin can further stabilize the IMD-lipid interaction.
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Affiliation(s)
- Kinga Futó
- Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs H-7624, Hungary
| | - Emőke Bódis
- Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs H-7624, Hungary
| | - Laura M Machesky
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Miklós Nyitrai
- Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs H-7624, Hungary; Szentágothai Research Center, Pécs, Ifjúság str. 34, H-7624, Hungary; Hungarian Academy of Sciences, Office for Subsidized Research Units, Budapest, Nádor str. 7, H-1051, Hungary
| | - Balázs Visegrády
- Department of Biophysics, Medical School, University of Pécs, Szigeti str. 12, Pécs H-7624, Hungary.
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21
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Ujfalusi Z, Kovács M, Nagy NT, Barkó S, Hild G, Lukács A, Nyitrai M, Bugyi B. Myosin and tropomyosin stabilize the conformation of formin-nucleated actin filaments. J Biol Chem 2012; 287:31894-904. [PMID: 22753415 PMCID: PMC3442522 DOI: 10.1074/jbc.m112.341230] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The conformational elasticity of the actin cytoskeleton is essential for its versatile biological functions. Increasing evidence supports that the interplay between the structural and functional properties of actin filaments is finely regulated by actin-binding proteins; however, the underlying mechanisms and biological consequences are not completely understood. Previous studies showed that the binding of formins to the barbed end induces conformational transitions in actin filaments by making them more flexible through long range allosteric interactions. These conformational changes are accompanied by altered functional properties of the filaments. To get insight into the conformational regulation of formin-nucleated actin structures, in the present work we investigated in detail how binding partners of formin-generated actin structures, myosin and tropomyosin, affect the conformation of the formin-nucleated actin filaments using fluorescence spectroscopic approaches. Time-dependent fluorescence anisotropy and temperature-dependent Förster-type resonance energy transfer measurements revealed that heavy meromyosin, similarly to tropomyosin, restores the formin-induced effects and stabilizes the conformation of actin filaments. The stabilizing effect of heavy meromyosin is cooperative. The kinetic analysis revealed that despite the qualitatively similar effects of heavy meromyosin and tropomyosin on the conformational dynamics of actin filaments the mechanisms of the conformational transition are different for the two proteins. Heavy meromyosin stabilizes the formin-nucleated actin filaments in an apparently single step reaction upon binding, whereas the stabilization by tropomyosin occurs after complex formation. These observations support the idea that actin-binding proteins are key elements of the molecular mechanisms that regulate the conformational and functional diversity of actin filaments in living cells.
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Affiliation(s)
- Zoltán Ujfalusi
- Department of Biophysics, Medical School, University of Pécs, Szigeti Street 12, H-7624 Pécs, Hungary
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22
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Okada I, Fujiki S, Iwase S, Abe H. Stabilization of actin filaments prevents germinal vesicle breakdown and affects microtubule organization in Xenopus oocytes. Cytoskeleton (Hoboken) 2012; 69:312-23. [PMID: 22422719 DOI: 10.1002/cm.21028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 02/03/2012] [Accepted: 03/08/2012] [Indexed: 02/04/2023]
Abstract
In Xenopus oocytes, extremely giant nuclei, termed germinal vesicles, contain a large amount of actin filaments most likely for mechanical integrity. Here, we show that microinjection of phalloidin, an F-actin-stabilizing drug, prevents the germinal vesicle breakdown (GVBD) in oocytes treated with progesterone. These nuclei remained for more 12 h after control oocytes underwent GVBD. Immunostaining showed significant elevation of actin in the remaining nuclei and many actin filament bundles in the cytoplasm. Furthermore, microtubules formed unusual structures in both nuclei and cytoplasm of phalloidin-injected oocytes stimulated by progesterone. Cytoplasmic microtubule arrays and intranuclear microtubules initially formed in phalloidin-injected oocytes as control oocytes exhibited white maturation spots; these structures gradually disappeared and finally converged upon intranuclear short bundles when control oocytes completed maturation. In contrast, treatment of oocytes with jasplakinolide, a cell membrane-permeable actin filament-stabilizing drug, did not affect GVBD. This drug preferentially induced accumulation of actin filaments at the cortex without any increase in cytoplasmic actin staining. Based on these results, intranuclear and cytoplasmic actin filament dynamics appear to be required for the completion of GVBD and critically involved in the regulation of microtubule assembly during oocyte maturation in Xenopus laevis.
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Affiliation(s)
- Iyo Okada
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan
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Spencer VA. Actin-towards a deeper understanding of the relationship between tissue context, cellular function and tumorigenesis. Cancers (Basel) 2011; 3:4269-80. [PMID: 24213138 PMCID: PMC3763423 DOI: 10.3390/cancers3044269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/26/2011] [Accepted: 12/07/2011] [Indexed: 02/06/2023] Open
Abstract
It is well-established that the actin cytoskeleton plays an important role in tumor development yet the contribution made by nuclear actin is ill-defined. In a recent study, nuclear actin was identified as a key mediator through which laminin type III (LN1) acts to control epithelial cell growth. In the breast, epithelial tumors are surrounded by an environment which lacks LN1. These findings point to actin as a potential mediator of tumor development. Here our current understanding of the roles of cytoplasmic and nuclear actin in normal and tumor cell growth is reviewed, relating these functions to cell phenotype in a tissue context.
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Affiliation(s)
- Virginia A Spencer
- Cell Culture Essentials, Life Technologies, 7335 Executive Way, Frederick, MD 21703, USA.
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Benken KA, Sabaneyeva EV. Fibrillar actin in nuclear apparatus of ciliate Paramecium Caudatum. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s1990519x11050026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Phalloidin perturbs the interaction of human non-muscle myosin isoforms 2A and 2C1 with F-actin. FEBS Lett 2011; 585:767-71. [PMID: 21295570 DOI: 10.1016/j.febslet.2011.01.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/24/2011] [Accepted: 01/28/2011] [Indexed: 11/23/2022]
Abstract
Phalloidin and fluorescently labeled phalloidin analogs are established reagents to stabilize and mark actin filaments for the investigation of acto-myosin interactions. In the present study, we employed transient and steady-state kinetic measurements as well as in vitro motility assays to show that phalloidin perturbs the productive interaction of human non-muscle myosin-2A and -2C1 with filamentous actin. Phalloidin binding to F-actin results in faster dissociation of the complex formed with non-muscle myosin-2A and -2C1, reduced actin-activated ATP turnover, and slower velocity of actin filaments in the in vitro motility assay. In contrast, phalloidin binding to F-actin does not affect the interaction with human non-muscle myosin isoform 2B and Dictyostelium myosin-2 and myosin-5b.
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26
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Vig A, Ohmacht R, Jámbor E, Bugyi B, Nyitrai M, Hild G. The effect of toxins on inorganic phosphate release during actin polymerization. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:619-26. [PMID: 21203885 DOI: 10.1007/s00249-010-0659-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 12/09/2010] [Accepted: 12/14/2010] [Indexed: 11/29/2022]
Abstract
During the polymerization of actin, hydrolysis of bound ATP occurs in two consecutive steps: chemical cleavage of the high-energy nucleotide and slow release of the γ-phosphate. In this study the effect of phalloidin and jasplakinolide on the kinetics of P(i) release was monitored during the formation of actin filaments. An enzyme-linked assay based spectrophotometric technique was used to follow the liberation of inorganic phosphate. It was verified that jasplakinolide reduced the P(i) release in the same way as phalloidin. It was not possible to demonstrate long-range allosteric effects of the toxins by release of P(i) from F-actin. The products of ATP hydrolysis were released by denaturation of the actin filaments. HPLC analysis of the samples revealed that the ATP in the toxin-bound region was completely hydrolysed into ADP and P(i). The effect of both toxins can be sufficiently explained by local and mechanical blockade of P(i) dissociation.
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Affiliation(s)
- Andrea Vig
- Department of Biophysics, Faculty of Medicine, University of Pécs, Hungary
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Schmitz S, Schaap IAT, Kleinjung J, Harder S, Grainger M, Calder L, Rosenthal PB, Holder AA, Veigel C. Malaria parasite actin polymerization and filament structure. J Biol Chem 2010; 285:36577-85. [PMID: 20826799 PMCID: PMC2978586 DOI: 10.1074/jbc.m110.142638] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 09/02/2010] [Indexed: 11/06/2022] Open
Abstract
A novel form of acto-myosin regulation has been proposed in which polymerization of new actin filaments regulates motility of parasites of the apicomplexan class of protozoa. In vivo and in vitro parasite F-actin is very short and unstable, but the structural basis and details of filament dynamics remain unknown. Here, we show that long actin filaments can be obtained by polymerizing unlabeled rabbit skeletal actin (RS-actin) onto both ends of the short rhodamine-phalloidin-stabilized Plasmodium falciparum actin I (Pf-actin) filaments. Following annealing, hybrid filaments of micron length and "zebra-striped" appearance are observed by fluorescence microscopy that are stable enough to move over myosin class II motors in a gliding filament assay. Using negative stain electron microscopy we find that pure Pf-actin stabilized by jasplakinolide (JAS) also forms long filaments, indistinguishable in length from RS-actin filaments, and long enough to be characterized structurally. To compare structures in near physiological conditions in aqueous solution we imaged Pf-actin and RS-actin filaments by atomic force microscopy (AFM). We found the monomer stacking to be distinctly different for Pf-actin compared with RS-actin, such that the pitch of the double helix of Pf-actin filaments was 10% larger. Our results can be explained by a rotational angle between subunits that is larger in the parasite compared with RS-actin. Modeling of the AFM data using high-resolution actin filament models supports our interpretation of the data. The structural differences reported here may be a consequence of weaker inter- and intra-strand contacts, and may be critical for differences in filament dynamics and for regulation of parasite motility.
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Affiliation(s)
| | | | | | - Simone Harder
- From the Division of Physical Biochemistry
- the Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom
| | - Munira Grainger
- the Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom
| | | | | | - Anthony A. Holder
- the Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom
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Hild G, Bugyi B, Nyitrai M. Conformational dynamics of actin: effectors and implications for biological function. Cytoskeleton (Hoboken) 2010; 67:609-29. [PMID: 20672362 PMCID: PMC3038201 DOI: 10.1002/cm.20473] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Accepted: 07/15/2010] [Indexed: 12/30/2022]
Abstract
Actin is a protein abundant in many cell types. Decades of investigations have provided evidence that it has many functions in living cells. The diverse morphology and dynamics of actin structures adapted to versatile cellular functions is established by a large repertoire of actin-binding proteins. The proper interactions with these proteins assume effective molecular adaptations from actin, in which its conformational transitions play essential role. This review attempts to summarise our current knowledge regarding the coupling between the conformational states of actin and its biological function.
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Affiliation(s)
- Gábor Hild
- Department of Biophysics, University of Pécs, Faculty of Medicine, Pécs, Szigeti str. 12, H-7624, Hungary
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29
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Pivovarova AV, Khaitlina SY, Levitsky DI. Specific cleavage of the DNase-I binding loop dramatically decreases the thermal stability of actin. FEBS J 2010; 277:3812-22. [PMID: 20718862 DOI: 10.1111/j.1742-4658.2010.07782.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Differential scanning calorimetry was used to investigate the thermal unfolding of actin specifically cleaved within the DNaseI-binding loop between residues Met47-Gly48 or Gly42-Val43 by two bacterial proteases, subtilisin or ECP32/grimelysin (ECP), respectively. The results obtained show that both cleavages strongly decreased the thermal stability of monomeric actin with either ATP or ADP as a bound nucleotide. An even more pronounced difference in the thermal stability between the cleaved and intact actin was observed when both actins were polymerized into filaments. Similar to intact F-actin, both cleaved F-actins were significantly stabilized by phalloidin and aluminum fluoride; however, in all cases, the thermal stability of the cleaved F-actins was much lower than that of intact F-actin, and the stability of ECP-cleaved F-actin was lower than that of subtilisin-cleaved F-actin. These results confirm that the DNaseI-binding loop is involved in the stabilization of the actin structure, both in monomers and in the filament subunits, and suggest that the thermal stability of actin depends, at least partially, on the conformation of the nucleotide-binding cleft. Moreover, an additional destabilization of the unstable cleaved actin upon ATP/ADP replacement provides experimental evidence for the highly dynamic actin structure that cannot be simply open or closed, but rather should be considered as being able to adopt multiple conformations.
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30
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Ellis C, Naicker D, Basson K, Botha C, Meintjes R, Schultz R. A fluorescent investigation of subcellular damage in H9c2 cells caused by pavetamine, a novel polyamine. Toxicol In Vitro 2010; 24:1258-65. [DOI: 10.1016/j.tiv.2010.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 12/09/2009] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
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31
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Holzinger A. Jasplakinolide: an actin-specific reagent that promotes actin polymerization. Methods Mol Biol 2010; 586:71-87. [PMID: 19768425 DOI: 10.1007/978-1-60761-376-3_4] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Jasplakinolide, a cyclo-depsipeptide is a commonly used actin filament polymerizing and stabilizing drug. The substance has originally been isolated from a marine sponge, and can now be synthesized and has become commercially available. This, together with the benefit that jasplakinolide is membrane permeable has made it a commonly used tool in cell biology, when actin filament stabilization or polymerization has to be achieved. This may either be the case in studies on morphogenesis, motility, organelle movement, or when apoptosis has to be induced. Its use as a potent anticancer drug is discussed. The direct action on actin filaments may have further consequences in golgi body and membrane raft protein organization. In this chapter, the visualization of jasplaklinolide effects by different fluorescent and transmission electron microscopic methods is described. As competitive binding capacities of jasplakinolide and phalloidin make the detection of actin filaments by fluorescently labeled phalloidin problematic, alternatives are given here.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Department of Physiology and Cell Physiology, University of Innsbruck, Innsbruck, Austria
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32
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Vig A, Dudás R, Kupi T, Orbán J, Hild G, Lőrinczy D, Nyitrai M. EFFECT OF PHALLOIDIN ON FILAMENTS POLYMERIZED FROM HEART MUSCLE ADP-ACTIN MONOMERS. JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 2009; 95:721-725. [PMID: 20582250 PMCID: PMC2892334 DOI: 10.1007/s10973-008-9404-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The effect of phalloidin on filaments polymerized from ADP-actin monomers of the heart muscle was investigated with differential scanning calorimetry. Heart muscle contains alpha-skeletal and alpha-cardiac actin isoforms. In the absence of phalloidin the melting temperature was 55 degrees C for the alpha-cardiac actin isoform and 58 degrees C for the alpha-skeletal one when the filaments were generated from ADP-actin monomers. After the binding of phalloidin the melting temperature was isoform independent (85.5 degrees C). We concluded that phalloidin stabilized the actin filaments of alpha-skeletal and alpha-cardiac actin isoforms to the same extent when they were polymerized from ADP-actin monomers.
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Affiliation(s)
- Andrea Vig
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - Réka Dudás
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - Tünde Kupi
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - J. Orbán
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - G. Hild
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - D. Lőrinczy
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
| | - M. Nyitrai
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, Pécs 7624, Hungary
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33
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Goeckeler ZM, Bridgman PC, Wysolmerski RB. Nonmuscle myosin II is responsible for maintaining endothelial cell basal tone and stress fiber integrity. Am J Physiol Cell Physiol 2008; 295:C994-1006. [PMID: 18701651 DOI: 10.1152/ajpcell.00318.2008] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cultured confluent endothelial cells exhibit stable basal isometric tone associated with constitutive myosin II regulatory light chain (RLC) phosphorylation. Thrombin treatment causes a rapid increase in isometric tension concomitant with myosin II RLC phosphorylation, actin polymerization, and stress fiber reorganization while inhibitors of myosin light chain kinase (MLCK) and Rho-kinase prevent these responses. These findings suggest a central role for myosin II in the regulation of endothelial cell tension. The present studies examine the effects of blebbistatin, a specific inhibitor of myosin II activity, on basal tone and thrombin-induced tension development. Although blebbistatin treatment abolished basal tension, this was accompanied by an increase in myosin II RLC phosphorylation. The increase in RLC phosphorylation was Ca(2+) dependent and mediated by MLCK. Similarly, blebbistatin inhibited thrombin-induced tension without interfering with the increase in RLC phosphorylation or in F-actin polymerization. Blebbistatin did prevent myosin II filament incorporation and association with polymerizing or reorganized actin filaments leading to the disappearance of stress fibers. Thus the inhibitory effects of blebbistatin on basal tone and induced tension are consistent with a requirement for myosin II activity to maintain stress fiber integrity.
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Affiliation(s)
- Zoe M Goeckeler
- Department of Neurobiology and Anatomy, West Virginia University School of Medicine, Morgantown, West Virginia 26506, USA
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34
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Moore SW, Correia JP, Lai Wing Sun K, Pool M, Fournier AE, Kennedy TE. Rho inhibition recruits DCC to the neuronal plasma membrane and enhances axon chemoattraction to netrin 1. Development 2008; 135:2855-64. [PMID: 18653556 DOI: 10.1242/dev.024133] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Molecular cues, such as netrin 1, guide axons by influencing growth cone motility. Rho GTPases are a family of intracellular proteins that regulate the cytoskeleton, substrate adhesion and vesicle trafficking. Activation of the RhoA subfamily of Rho GTPases is essential for chemorepellent axon guidance; however, their role during axonal chemoattraction is unclear. Here, we show that netrin 1, through its receptor DCC, inhibits RhoA in embryonic spinal commissural neurons. To determine whether netrin 1-mediated chemoattraction requires Rho function, we inhibited Rho signaling and assayed axon outgrowth and turning towards netrin 1. Additionally, we examined two important mechanisms that influence the guidance of axons to netrin 1: substrate adhesion and transport of the netrin receptor DCC to the plasma membrane. We found that inhibiting Rho signaling increased plasma membrane DCC and adhesion to substrate-bound netrin 1, and also enhanced netrin 1-mediated axon outgrowth and chemoattractive axon turning. Conversely, overexpression of RhoA or constitutively active RhoA inhibited axonal responses to netrin 1. These findings provide evidence that Rho signaling reduces axonal chemoattraction to netrin 1 by limiting the amount of plasma membrane DCC at the growth cone, and suggest that netrin 1-mediated inhibition of RhoA activates a positive-feedback mechanism that facilitates chemoattraction to netrin 1. Notably, these findings also have relevance for CNS regeneration research. Inhibiting RhoA promotes axon regeneration by disrupting inhibitory responses to myelin and the glial scar. By contrast, we demonstrate that axon chemoattraction to netrin 1 is not only maintained but enhanced, suggesting that this might facilitate directing regenerating axons to appropriate targets.
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Affiliation(s)
- Simon W Moore
- Centre for Neuronal Survival, Montreal Neurological Institute, Program in NeuroEngineering, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 2B4, Canada
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35
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Levitsky DI, Pivovarova AV, Mikhailova VV, Nikolaeva OP. Thermal unfolding and aggregation of actin. FEBS J 2008; 275:4280-95. [DOI: 10.1111/j.1742-4658.2008.06569.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Vartiainen MK. Nuclear actin dynamics--from form to function. FEBS Lett 2008; 582:2033-40. [PMID: 18423404 DOI: 10.1016/j.febslet.2008.04.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 03/28/2008] [Accepted: 04/09/2008] [Indexed: 01/10/2023]
Abstract
Cell biological functions of actin have recently expanded from cytoplasm to nucleus, with actin implicated in such diverse processes as gene expression, transcription factor regulation and intranuclear motility. Actin in the nucleus seems to behave differently than in the cytoplasm, raising new questions regarding the molecular mechanisms by which actin functions in cells. In this review, I will discuss dynamic properties of nuclear actin that are related to its polymerization cycle and nucleocytoplasmic shuttling. By comparing the behaviour of nuclear and cytoplasmic actin and their regulators, I try to dissect the underlying differences of these equally important cellular actin pools.
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Affiliation(s)
- Maria K Vartiainen
- Research Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Viikinkaari 9, 00014 Helsinki, Finland.
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37
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Orbán J, Lőrinczy D, Hild G, Nyitrai M. Noncooperative stabilization effect of phalloidin on ADP.BeFx- and ADP.AlF4-actin filaments. Biochemistry 2008; 47:4530-4. [PMID: 18361506 PMCID: PMC2726639 DOI: 10.1021/bi800068e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Actin plays important roles in eukaryotic cell motility. During actin polymerization, the actin-bound ATP is hydrolyzed to ADP and P i. We carried out differential scanning calorimetry experiments to characterize the cooperativity of the stabilizing effect of phalloidin on actin filaments in their ADP.P i state. The ADP.P i state was mimicked by using ADP.BeF x or ADP.AlF 4. The results showed that the binding of the nucleotide analogues or phalloidin stabilized the actin filaments to a similar extent when added separately. Phalloidin binding to ADP.BeF x- or ADP.AlF 4-actin filaments further stabilized them, indicating that the mechanism by which phalloidin and the nucleotide analogues affect the filament structure was different. The results also showed that the stabilization effect of phalloidin binding to ADP.BeF x or ADP.AlF 4-bound actin filaments was not cooperative. Since the effect of phalloidin binding was cooperative in the absence of these nucleotide analogues, these results suggest that the binding of ADP.BeF x or ADP.AlF 4 to the actin modified the protomer-protomer interactions along the actin filaments.
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Affiliation(s)
- József Orbán
- Department of Biophysics, Faculty of Medicine, University of Pécs, Pécs, Szigeti str. 12, H-7624 Hungary
| | - Dénes Lőrinczy
- Department of Biophysics, Faculty of Medicine, University of Pécs, Pécs, Szigeti str. 12, H-7624 Hungary
| | - Gábor Hild
- Department of Biophysics, Faculty of Medicine, University of Pécs, Pécs, Szigeti str. 12, H-7624 Hungary
| | - Miklós Nyitrai
- Department of Biophysics, Faculty of Medicine, University of Pécs, Pécs, Szigeti str. 12, H-7624 Hungary
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38
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Kardos R, Vig A, Orbán J, Hild G, Nyitrai M, Lőrinczy D. The effect of jasplakinolide on the thermodynamic properties of ADP.BeF(x) bound actin filaments. THERMOCHIMICA ACTA 2007; 463:77-80. [PMID: 20543906 PMCID: PMC2883441 DOI: 10.1016/j.tca.2007.07.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The effect of BeF(x) and a natural toxin (jasplakinolide) was examined on the thermal stability of actin filaments by using differential scanning calorimetry. The phosphate analogue beryllium fluoride shifted the melting temperature of actin filaments (67.4 degrees C) to 83.7 degrees C indicating that the filaments were thermodynamically more stable in their complex with ADP.BeF(x). A similar tendency was observed when the jasplakinolide was used in the absence of BeF(x). When both the ADP.BeF(x) and the jasplakinolide bound to the actin filaments their collective effect was similar to that observed with ADP.BeF(x) or jasplakinolide alone. These results suggested that ADP.BeF(x) and jasplakinolide probably stabilize the actin filaments by similar molecular mechanisms.
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Affiliation(s)
- Roland Kardos
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
| | - Andrea Vig
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
| | - József Orbán
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
| | - Gábor Hild
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
| | - Miklós Nyitrai
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
| | - Dénes Lőrinczy
- University of Pécs, Faculty of Medicine, Department of Biophysics, Szigeti str. 12, H-7624 Pécs, Hungary
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39
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Differential scanning calorimetry study of glycerinated rabbit psoas muscle fibres in intermediate state of ATP hydrolysis. BMC STRUCTURAL BIOLOGY 2007; 7:41. [PMID: 17588264 PMCID: PMC1913527 DOI: 10.1186/1472-6807-7-41] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 06/24/2007] [Indexed: 11/12/2022]
Abstract
Background Thermal denaturation experiments were extended to study the thermal behaviour of the main motor proteins (actin and myosin) in their native environment in striated muscle fibres. The interaction of actin with myosin in the highly organized muscle structure is affected by internal forces; therefore their altered conformation and interaction may differ from those obtained in solution. The energetics of long functioning intermediate states of ATP hydrolysis cycle was studied in muscle fibres by differential scanning calorimetry (DSC). Results SETARAM Micro DSC-II was used to monitor the thermal denaturation of the fibre system in rigor and in the presence of nucleotide and nucleotide analogues. The AM.ADP.Pi state of the ATP hydrolysis cycle has a very short lifetime therefore, we mimicked the different intermediate states with AMP.PNP and/or inorganic phosphate analogues Vi and AlF4 or BeFx. Studying glycerol-extracted muscle fibres from the rabbit psoas muscle by DSC, three characteristic thermal transitions were detected in rigor. The thermal transitions can be assigned to myosin heads, myosin rods and actin with transition temperatures (Tm) of 52.9 ± 0.7°C, 57.9 ± 0.7°C, 63.7 ± 1.0°C. In different intermediate states of the ATP hydrolysis mimicked by nucleotide analogues a fourth thermal transition was also detected which is very likely connected with nucleotide binding domain of myosin and/or actin filaments. This transition temperature Tm4 depended on the mimicked intermediate states, and varied in the range of 66°C – 77°C. Conclusion According to DSC measurements, strongly and weakly binding states of myosin to actin were significantly different. In the presence of ADP only a moderate change of the DSC pattern was detected in comparison with rigor, whereas in ADP.Pi state trapped by Vi, AlF4 or BeFx a remarkable stabilization was detected on the myosin head and actin filament which is reflected in a 3.0 – 10.0°C shift in Tm to higher temperature. A similar effect was observed in the case of the nonhydrolyzable AMP.PNP analogue. Differential DSC measurements suggest that stabilization actin structure in the intermediate states of ATP hydrolysis may play an additional role in actin-myosin interaction.
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Gala F, D'Auria MV, De Marino S, Zollo F, Smith CD, Copper JE, Zampella A. New jaspamide derivatives with antimicrofilament activity from the sponge Jaspis splendans. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.03.162] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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41
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Feierbach B, Piccinotti S, Bisher M, Denk W, Enquist LW. Alpha-herpesvirus infection induces the formation of nuclear actin filaments. PLoS Pathog 2006; 2:e85. [PMID: 16933992 PMCID: PMC1550268 DOI: 10.1371/journal.ppat.0020085] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Accepted: 06/12/2006] [Indexed: 02/07/2023] Open
Abstract
Herpesviruses are large double-stranded DNA viruses that replicate in the nuclei of infected cells. Spatial control of viral replication and assembly in the host nucleus is achieved by the establishment of nuclear compartments that serve to concentrate viral and host factors. How these compartments are established and maintained remains poorly understood. Pseudorabies virus (PRV) is an alpha-herpesvirus often used to study herpesvirus invasion and spread in the nervous system. Here, we report that PRV and herpes simplex virus type 1 infection of neurons results in formation of actin filaments in the nucleus. Filamentous actin is not found in the nucleus of uninfected cells. Nuclear actin filaments appear physically associated with the viral capsids, as shown by serial block-face scanning electron micropscopy and confocal microscopy. Using a green fluorescent protein-tagged viral capsid protein (VP26), we show that nuclear actin filaments form prior to capsid assembly and are required for the efficient formation of viral capsid assembly sites. We find that actin polymerization dynamics (e.g., treadmilling) are not necessary for the formation of these sites. Green fluorescent protein-VP26 foci co-localize with the actin motor myosin V, suggesting that viral capsids travel along nuclear actin filaments using myosin-based directed transport. Viral transcription, but not viral DNA replication, is required for actin filament formation. The finding that infection, by either PRV or herpes simplex virus type 1, results in formation of nuclear actin filaments in neurons, and that PRV infection of an epithelial cell line results in a similar phenotype is evidence that F-actin plays a conserved role in herpesvirus assembly. Our results suggest a mechanism by which assembly domains are organized within infected cells and provide insight into how the viral infectious cycle and host actin cytoskeleton are integrated to promote the infection process. Regulation of subcellular organization and transport is essential for control of crucial biological processes. However, our knowledge often is hampered because these processes tend to be transient and difficult to study. Studies of how opportunistic microbes hijack cellular machinery have provided insights into various normal cell processes. For example, studies with intracellular microorganisms, such as Listeria monocytogenes, Shigella spp., Rickettsia spp., and vaccinia virus, have significantly increased our understanding of the dynamic nature of the actin cytoskeleton. However, much less is known about subcellular organization and transport of cargo in the nucleus. The authors have discovered that alpha-herpesvirus infection of neurons leads to the transient formation of actin filaments in the nucleus. These filaments do not fill the nucleus, but rather associate with newly formed viral capsids. The nuclear actin filaments were initially identified in peripheral nervous system tissue using a new imaging technology, serial section scanning electron microscopy pioneered by Winfried Denk (a co-author). Their results suggest that nuclear actin filaments form as part of a general stress response to infection, but then are co-opted, perhaps to direct capsid transport to sites of budding along the nuclear envelope. This work illuminates a less well understood part of the viral life cycle and sets the stage for future work investigating control of how cargo is organized and moved in the nucleus.
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Affiliation(s)
- Becket Feierbach
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA.
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42
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Papp G, Bugyi B, Ujfalusi Z, Barkó S, Hild G, Somogyi B, Nyitrai M. Conformational changes in actin filaments induced by formin binding to the barbed end. Biophys J 2006; 91:2564-72. [PMID: 16829561 PMCID: PMC1562385 DOI: 10.1529/biophysj.106.087775] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Formins bind actin filaments and play an essential role in the regulation of the actin cytoskeleton. In this work we describe details of the formin-induced conformational changes in actin filaments by fluorescence-lifetime and anisotropy-decay experiments. The results show that the binding of the formin homology 2 domain of a mammalian formin (mouse mDia1) to actin filaments resulted in a less rigid protein structure in the microenvironment of the Cys374 of actin, weakening of the interactions between neighboring actin protomers, and greater overall flexibility of the actin filaments. The formin effect is smaller at greater ionic strength. The results show that formin binding to the barbed end of actin filaments is responsible for the increase of flexibility of actin filaments. One formin dimer can affect the dynamic properties of an entire filament. Analyses of the results obtained at various formin/actin concentration ratios indicate that at least 160 actin protomers are affected by the binding of a single formin dimer to the barbed end of a filament.
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Affiliation(s)
- Gábor Papp
- Department of Biophysics, Faculty of Medicine, Office for Academy Research Groups, University of Pécs, Pécs, Hungary
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Abstract
The form and function of actin in the nucleus have been enigmatic for over 30 years. Recently actin has been assigned numerous functional roles in the nucleus, but its form remains a mystery. The intricate relationship between actin form and function in the cytoplasm implies that understanding the structural properties of nuclear actin is elementary to fully understanding its function. In this issue, McDonald et al. (p. 541) use fluorescence recovery after photobleaching (FRAP) to tackle the question of whether nuclear actin exists as monomers or polymers.
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Affiliation(s)
- Wilma A Hofmann
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
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44
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de Lanerolle P, Johnson T, Hofmann WA. Actin and myosin I in the nucleus: what next? Nat Struct Mol Biol 2005; 12:742-6. [PMID: 16142228 DOI: 10.1038/nsmb983] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 08/04/2005] [Indexed: 11/09/2022]
Abstract
Several recent publications have demonstrated the importance of nuclear actin and nuclear myosin I in transcription. Here we review these publications and their implications. In addition, we discuss some important issues that should be addressed to gain a more comprehensive understanding of how these traditionally 'cytoplasmic' proteins are involved in transcription. We propose highly speculative models and mechanisms solely to stimulate thought and experimentation in this area.
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Affiliation(s)
- Primal de Lanerolle
- the Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
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