1
|
Papalazarou V, Swaminathan K, Jaber-Hijazi F, Spence H, Lahmann I, Nixon C, Salmeron-Sanchez M, Arnold HH, Rottner K, Machesky LM. The Arp2/3 complex is crucial for colonisation of the mouse skin by melanoblasts. Development 2020; 147:dev194555. [PMID: 33028610 PMCID: PMC7687863 DOI: 10.1242/dev.194555] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/22/2020] [Indexed: 01/10/2023]
Abstract
The Arp2/3 complex is essential for the assembly of branched filamentous actin, but its role in physiology and development is surprisingly little understood. Melanoblasts deriving from the neural crest migrate along the developing embryo and traverse the dermis to reach the epidermis, colonising the skin and eventually homing within the hair follicles. We have previously established that Rac1 and Cdc42 direct melanoblast migration in vivo We hypothesised that the Arp2/3 complex might be the main downstream effector of these small GTPases. Arp3 depletion in the melanocyte lineage results in severe pigmentation defects in dorsal and ventral regions of the mouse skin. Arp3 null melanoblasts demonstrate proliferation and migration defects and fail to elongate as their wild-type counterparts. Conditional deletion of Arp3 in primary melanocytes causes improper proliferation, spreading, migration and adhesion to extracellular matrix. Collectively, our results suggest that the Arp2/3 complex is absolutely indispensable in the melanocyte lineage in mouse development, and indicate a significant role in developmental processes that require tight regulation of actin-mediated motility.
Collapse
Affiliation(s)
- Vassilis Papalazarou
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Campus, Switchback Road, Bearsden, Glasgow G61 1QH, UK
- Centre for the Cellular Microenvironment, University of Glasgow, Glasgow G12 8LT, UK
| | - Karthic Swaminathan
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Farah Jaber-Hijazi
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Heather Spence
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Ines Lahmann
- Cell and Molecular Biology, Institute of Biochemistry and Biotechnology, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Colin Nixon
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | | | - Hans-Henning Arnold
- Cell and Molecular Biology, Institute of Biochemistry and Biotechnology, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Laura M Machesky
- CRUK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Campus, Switchback Road, Bearsden, Glasgow G61 1QH, UK
| |
Collapse
|
2
|
Chakrabarty N, Dubey P, Tang Y, Ganguly A, Ladt K, Leterrier C, Jung P, Roy S. Processive flow by biased polymerization mediates the slow axonal transport of actin. J Cell Biol 2018; 218:112-124. [PMID: 30401699 PMCID: PMC6314539 DOI: 10.1083/jcb.201711022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 09/02/2018] [Accepted: 10/25/2018] [Indexed: 12/15/2022] Open
Abstract
Chakrabarty et al. propose a model in which slow axonal transport of actin can occur by a biased polymerization of actin filaments along the axon shaft without the involvement of microtubules (MTs) or MT-based motors. These dynamics are distinct from polymer sliding—the canonical mechanism thought to convey cytoskeletal cargoes in slow transport. Classic pulse-chase studies have shown that actin is conveyed in slow axonal transport, but the mechanistic basis for this movement is unknown. Recently, we reported that axonal actin was surprisingly dynamic, with focal assembly/disassembly events (“actin hotspots”) and elongating polymers along the axon shaft (“actin trails”). Using a combination of live imaging, superresolution microscopy, and modeling, in this study, we explore how these dynamic structures can lead to processive transport of actin. We found relatively more actin trails elongated anterogradely as well as an overall slow, anterogradely biased flow of actin in axon shafts. Starting with first principles of monomer/filament assembly and incorporating imaging data, we generated a quantitative model simulating axonal hotspots and trails. Our simulations predict that the axonal actin dynamics indeed lead to a slow anterogradely biased flow of the population. Collectively, the data point to a surprising scenario where local assembly and biased polymerization generate the slow axonal transport of actin without involvement of microtubules (MTs) or MT-based motors. Mechanistically distinct from polymer sliding, this might be a general strategy to convey highly dynamic cytoskeletal cargoes.
Collapse
Affiliation(s)
- Nilaj Chakrabarty
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Ohio University, Athens, OH
| | - Pankaj Dubey
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
| | - Yong Tang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA
| | - Archan Ganguly
- Department of Neurosciences, University of California, San Diego, La Jolla, CA
| | - Kelsey Ladt
- Department of Neurosciences, University of California, San Diego, La Jolla, CA
| | - Christophe Leterrier
- Aix-Marseille Université, Centre National de la Recherche Scientifique, Institut Neurophysiopathol, NeuroCyto, Marseille, France
| | - Peter Jung
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Ohio University, Athens, OH
| | - Subhojit Roy
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI .,Department of Neuroscience, University of Wisconsin-Madison, Madison, WI
| |
Collapse
|
3
|
Kulkarni SS, Griffin JN, Date PP, Liem KF, Khokha MK. WDR5 Stabilizes Actin Architecture to Promote Multiciliated Cell Formation. Dev Cell 2018; 46:595-610.e3. [PMID: 30205038 PMCID: PMC6177229 DOI: 10.1016/j.devcel.2018.08.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/18/2018] [Accepted: 08/11/2018] [Indexed: 12/16/2022]
Abstract
The actin cytoskeleton is critical to shape cells and pattern intracellular organelles, which collectively drives tissue morphogenesis. In multiciliated cells (MCCs), apical actin drives expansion of the cell surface necessary to host hundreds of cilia. The apical actin also forms a lattice to uniformly distribute basal bodies. This apical actin network is dynamically remodeled, but the molecules that regulate its architecture remain poorly understood. We identify the chromatin modifier, WDR5, as a regulator of apical F-actin in MCCs. Unexpectedly in MCCs, WDR5 has a function independent of chromatin modification. We discover a scaffolding role for WDR5 between the basal body and F-actin. Specifically, WDR5 binds to basal bodies and migrates apically, where F-actin organizes around WDR5. Using a monomer trap for G-actin, we show that WDR5 stabilizes F-actin to maintain lattice architecture. In summary, we identify a non-chromatin role for WDR5 in stabilizing F-actin in MCCs.
Collapse
Affiliation(s)
- Saurabh S Kulkarni
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - John N Griffin
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Priya P Date
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Karel F Liem
- Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Mustafa K Khokha
- Pediatric Genomics Discovery Program, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Pediatrics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Genetics, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
| |
Collapse
|
4
|
Phippen SW, Stevens CA, Vance TDR, King NP, Baker D, Davies PL. Multivalent Display of Antifreeze Proteins by Fusion to Self-Assembling Protein Cages Enhances Ice-Binding Activities. Biochemistry 2016; 55:6811-6820. [PMID: 27951652 DOI: 10.1021/acs.biochem.6b00864] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Antifreeze proteins (AFPs) are small monomeric proteins that adsorb to the surface of ice to inhibit ice crystal growth and impart freeze resistance to the organisms producing them. Previously, monomeric AFPs have been conjugated to the termini of branched polymers to increase their activity through the simultaneous binding of more than one AFP to ice. Here, we describe a superior approach to increasing AFP activity through oligomerization that eliminates the need for conjugation reactions with varying levels of efficiency. A moderately active AFP from a fish and a hyperactive AFP from an Antarctic bacterium were genetically fused to the C-termini of one component of the 24-subunit protein cage T33-21, resulting in protein nanoparticles that multivalently display exactly 12 AFPs. The resulting nanoparticles exhibited freezing point depression >50-fold greater than that seen with the same concentration of monomeric AFP and a similar increase in the level of ice-recrystallization inhibition. These results support the anchored clathrate mechanism of binding of AFP to ice. The enhanced freezing point depression could be due to the difficulty of overgrowing a larger AFP on the ice surface and the improved ice-recrystallization inhibition to the ability of the nanoparticle to simultaneously bind multiple ice grains. Oligomerization of these proteins using self-assembling protein cages will be useful in a variety of biotechnology and cryobiology applications.
Collapse
Affiliation(s)
- Sean W Phippen
- Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - Corey A Stevens
- Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - Tyler D R Vance
- Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario K7L 3N6, Canada
| | - Neil P King
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States.,Institute for Protein Design, University of Washington , Seattle, Washington 98195, United States
| | - David Baker
- Department of Biochemistry, University of Washington , Seattle, Washington 98195, United States.,Institute for Protein Design, University of Washington , Seattle, Washington 98195, United States.,Howard Hughes Medical Institute, University of Washington , Seattle, Washington 98195, United States
| | - Peter L Davies
- Department of Biomedical and Molecular Sciences, Queen's University , Kingston, Ontario K7L 3N6, Canada
| |
Collapse
|
5
|
Rosin C, Schummel PH, Winter R. Cosolvent and crowding effects on the polymerization kinetics of actin. Phys Chem Chem Phys 2015; 17:8330-7. [DOI: 10.1039/c4cp04431b] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Effects of cosolvents and macromolecular crowding agents on the G-to-F-transformation of actin are studied. Drastic and diverse changes in the lag phase and association rates of polymerizing actin are observed under different solvent conditions.
Collapse
Affiliation(s)
- Christopher Rosin
- TU Dortmund University
- Department of Chemistry and Chemical Biology
- Physical Chemistry I - Biophysical Chemistry
- D-44227 Dortmund
- Germany
| | - Paul Hendrik Schummel
- TU Dortmund University
- Department of Chemistry and Chemical Biology
- Physical Chemistry I - Biophysical Chemistry
- D-44227 Dortmund
- Germany
| | - Roland Winter
- TU Dortmund University
- Department of Chemistry and Chemical Biology
- Physical Chemistry I - Biophysical Chemistry
- D-44227 Dortmund
- Germany
| |
Collapse
|
6
|
Gholami Z, Brunsveld L, Hanley Q. PNA-induced assembly of fluorescent proteins using DNA as a framework. Bioconjug Chem 2013; 24:1378-86. [PMID: 23848261 DOI: 10.1021/bc400202s] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Controlled alignment of proteins on molecular frameworks requires the development of facile and orthogonal chemical approaches and molecular scaffolds. In this work, protein-PNA conjugates are brought forward as new chemical components allowing efficient assembly and alignment on DNA scaffolds. Site-selective monomeric teal fluorescent protein (mTFP)-peptide nucleic acid (PNA) (mTFP-PNA) conjugation was achieved by covalent linkage of the PNA to the protein through expressed protein ligation (EPL). A DNA beacon, with 6-Fam and Dabcyl at its ends, acts as a framework to create an assembled hetero-FRET system with the mTFP-PNA conjugate. Using fluorescence intensity, frequency domain lifetime measurements, and anisotropy measurements, the system was shown to produce FRET as indicated by decreased donor intensity, decreased donor lifetime, and increased donor anisotropy. Extension of the DNA scaffold allowed for the assembly of multiple mTFP-PNA constructs. Efficient formation of protein dimers and oligomers on the DNA-PNA frameworks could be shown, as visualized via size exclusion chromatography (SEC) and electrophoresis (SDS-PAGE). Assembly of multiple proteins in a row induced homo-FRET for the mTFP-PNA's assembled on the DNA scaffolds. The oligonucleotide framework allows an induced and controllable assembly of proteins by fusing them to PNAs directed to align on DNA scaffolds.
Collapse
Affiliation(s)
- Zahra Gholami
- School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom
| | | | | |
Collapse
|
7
|
Delle Monache S, Sanità P, Trapasso E, Ursino MR, Dugo P, Russo M, Ferlazzo N, Calapai G, Angelucci A, Navarra M. Mechanisms underlying the anti-tumoral effects of Citrus Bergamia juice. PLoS One 2013; 8:e61484. [PMID: 23613861 PMCID: PMC3628853 DOI: 10.1371/journal.pone.0061484] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 03/13/2013] [Indexed: 12/28/2022] Open
Abstract
Based on the growing deal of data concerning the biological activity of flavonoid-rich natural products, the aim of the present study was to explore in vitro the potential anti-tumoral activity of Citrus Bergamia (bergamot) juice (BJ), determining its molecular interaction with cancer cells. Here we show that BJ reduced growth rate of different cancer cell lines, with the maximal growth inhibition observed in neuroblastoma cells (SH-SY5Y) after 72 hs of exposure to 5% BJ. The SH-SY5Y antiproliferative effect elicited by BJ was not due to a cytotoxic action and it did not induce apoptosis. Instead, BJ stimulated the arrest in the G1 phase of cell cycle and determined a modification in cellular morphology, causing a marked increase of detached cells. The inhibition of adhesive capacity on different physiologic substrates and on endothelial cells monolayer were correlated with an impairment of actin filaments, a reduction in the expression of the active form of focal adhesion kinase (FAK) that in turn caused inhibition of cell migration. In parallel, BJ seemed to hinder the association between the neural cell adhesion molecule (NCAM) and FAK. Our data suggest a mechanisms through which BJ can inhibit important molecular pathways related to cancer-associated aggressive phenotype and offer new suggestions for further studies on the role of BJ in cancer treatment.
Collapse
Affiliation(s)
- Simona Delle Monache
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
| | - Patrizia Sanità
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
| | - Elena Trapasso
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
| | - Maria Rita Ursino
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
| | - Paola Dugo
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
| | - Marina Russo
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
| | - Nadia Ferlazzo
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
| | - Gioacchino Calapai
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Adriano Angelucci
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy
| | - Michele Navarra
- Department of Drug Sciences and Health Products, University of Messina, Messina, Italy
- Istituto Di Ricovero e Cura a Carattere Scientifico centro neurolesi “Bonino-Pulejo”, Messina, Italy
- * E-mail:
| |
Collapse
|
8
|
Rahman MA, Shinjo R, Oomori T, Wörheide G. Analysis of the proteinaceous components of the organic matrix of calcitic sclerites from the soft coral Sinularia sp. PLoS One 2013; 8:e58781. [PMID: 23527022 PMCID: PMC3597568 DOI: 10.1371/journal.pone.0058781] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 02/08/2013] [Indexed: 01/20/2023] Open
Abstract
An organic matrix consisting of a protein-polysaccharide complex is generally accepted as an important medium for the calcification process. While the role this "calcified organic matrix" plays in the calcification process has long been appreciated, the complex mixture of proteins that is induced and assembled during the mineral phase of calcification remains uncharacterized in many organisms. Thus, we investigated organic matrices from the calcitic sclerites of a soft coral, Sinularia sp., and used a proteomic approach to identify the functional matrix proteins that might be involved in the biocalcification process. We purified eight organic matrix proteins and performed in-gel digestion using trypsin. The tryptic peptides were separated by nano-liquid chromatography (nano-LC) and analyzed by tandem mass spectrometry (MS/MS) using a matrix-assisted laser desorption/ionization (MALDI) - time-of-flight-time-of-flight (TOF-TOF) mass spectrometer. Periodic acid Schiff staining of an SDS-PAGE gel indicated that four proteins were glycosylated. We identified several proteins, including a form of actin, from which we identified a total of 183 potential peptides. Our findings suggest that many of those peptides may contribute to biocalcification in soft corals.
Collapse
Affiliation(s)
- M Azizur Rahman
- Department of Earth and Environmental Sciences, Palaeontology and Geobiology, Ludwig-Maximilians-Universität München, München, Germany.
| | | | | | | |
Collapse
|
9
|
King KL, Stewart M, Roberts TM. Supramolecular assemblies of the Ascaris suum major sperm protein (MSP) associated with amoeboid cell motility. J Cell Sci 1994; 107 ( Pt 10):2941-9. [PMID: 7876359 DOI: 10.1242/jcs.107.10.2941] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sperm of the nematode, Ascaris suum, are amoeboid cells that do not require actin or myosin to crawl over solid substrata. In these cells, the role usually played by actin has been taken over by major sperm protein (MSP), which assembles into filaments that pack the sperm pseudopod. These MSP filaments are organized into multi-filament arrays called fiber complexes that flow centripetally from the leading edge of the pseudopod to the cell body in a pattern that is intimately associated with motility. We have characterized structurally a hierarchy of helical assemblies formed by MSP. The basic unit of the MSP cytoskeleton is a filament formed by two subfilaments coiled around one another along right-handed helical tracks. In vitro, higher-order assemblies (macrofibers) are formed by MSP filaments that coil around one another in a left-handed helical sense. The multi-filament assemblies formed by MSP in vitro are strikingly similar to the fiber complexes that characterize the sperm cytoskeleton. Thus, self-association is an intrinsic property of MSP filaments that distinguishes these fibers from actin filaments. The results obtained with MSP help clarify the roles of different aspects of the actin cytoskeleton in the generation of locomotion and, in particular, emphasize the contributions made by vectorial assembly and filament bundling.
Collapse
Affiliation(s)
- K L King
- Department of Biological Science, Florida State University, Tallahassee 32306-3050
| | | | | |
Collapse
|
10
|
Gat Y, Sheves M. THE ORIGIN OF THE RED-SHIFTED ABSORPTION MAXIMUM OF THE M412INTERMEDIATE IN THE BACTERIORHODOPSIN PHOTOCYCLE. Photochem Photobiol 1994. [DOI: 10.1111/j.1751-1097.1994.tb05050.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
11
|
DalleDonne I, Milzani A, Contini P, Bernardini G, Colombo R. Interaction of cardiac alpha-actinin and actin in the presence of doxorubicin. Exp Mol Pathol 1992; 56:229-38. [PMID: 1639182 DOI: 10.1016/0014-4800(92)90039-e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The therapeutic use of doxorubicin (an antitumoral antibiotic belonging to the anthracycline group) is limited by its cardiotoxicity. Adriamycin (DXR) causes myocardial subcellular damage, such as myocytolysis, disarray of actin filaments, and alterations in the Z-band with loss of sarcomeric organization. We studied the effect of stoichiometrical concentrations of DXR on the interaction between cardiac actin and alpha-actinin in solution. Doxorubicin inhibits the formation of alpha-actinin/actin tridimensional networks and bundles. The main effect of the drug seems to be on the size of the actin polymers.
Collapse
Affiliation(s)
- I DalleDonne
- Department of Biology, University of Milan, Italy
| | | | | | | | | |
Collapse
|
12
|
Abstract
The diffusion of monodisperse polystyrene latex spheres (PLS) in column-purified 0.65 mg/mL actin solutions, polymerized with 100 mM KCl in the absence and presence of a cross-linker, actin binding protein (ABP), has been studied using dynamic light scattering. Measurements over a wide range of scattering angles from 90 degrees to 8 degrees, corresponding to inverse scattering vector probing distances of about 40-400 nm, respectively, give a measure of both the fraction of PLS mobile over the probing distance (from the normalized time autocorrelation function amplitude) and the average diffusion coefficient of the mobile PLS. Both 100- and 500-nm diameter PLS are fully mobile in polymerized actin solutions over distances of less than 100 nm, as reported previously (Newman, J., Schick, K. S. & Gukelberger, G. Biophys. J. 53, 573a, and Newman, J., Mroczka, N. & Schick, K. L. Biopolymers, 28, 655-666). At increasing probing distances, or when ABP is added at molar ratios of 1:750 or 1:150, greater fractions of the PLS are immobilized, up to almost 99% at the conditions of a 400-nm probing distance with 500-nm probes and at a ratio of 1:150 added ABP to actin. The degree of immobilization correlated well with the amount of added ABP, the size of the PLS, and the probing distance. At increasing probe distances, as the degree of immobilization increases, the remaining mobile fraction of PLS has an increasing average diffusion coefficient. These results suggest a range of pore sizes in the actin gels with a mean size of a few hundred nanometers.
Collapse
|
13
|
Yamashita S, Szabo AG, Krajcarski DT, Yamasaki N. Fluorescence Studies on the Phase Dependence of Interactions between a Tripeptide, Lys–Trp–Lys, and Dimyristoylphosphatidylserine. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1989. [DOI: 10.1246/bcsj.62.3075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|