1
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Ioannou IA, Brooks NJ, Kuimova MK, Elani Y. Visualizing Actin Packing and the Effects of Actin Attachment on Lipid Membrane Viscosity Using Molecular Rotors. JACS AU 2024; 4:2041-2049. [PMID: 38818078 PMCID: PMC11134356 DOI: 10.1021/jacsau.4c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 06/01/2024]
Abstract
The actin cytoskeleton and its elaborate interplay with the plasma membrane participate in and control numerous biological processes in eukaryotic cells. Malfunction of actin networks and changes in their dynamics are related to various diseases, from actin myopathies to uncontrolled cell growth and tumorigenesis. Importantly, the biophysical and mechanical properties of actin and its assemblies are deeply intertwined with the biological functions of the cytoskeleton. Novel tools to study actin and its associated biophysical features are, therefore, of prime importance. Here we develop a new approach which exploits fluorescence lifetime imaging microscopy (FLIM) and environmentally sensitive fluorophores termed molecular rotors, acting as quantitative microviscosity sensors, to monitor dynamic viscoelastic properties of both actin structures and lipid membranes. In order to reproduce a minimal actin cortex in synthetic cell models, we encapsulated and attached actin networks to the lipid bilayer of giant unilamellar vesicles (GUVs). Using a cyanine-based molecular rotor, DiSC2(3), we show that different types of actin bundles are characterized by distinct packing, which can be spatially resolved using FLIM. Similarly, we show that a lipid bilayer-localized molecular rotor can monitor the effects of attaching cross-linked actin networks to the lipid membrane, revealing an increase in membrane viscosity upon actin attachment. Our approach bypasses constraints associated with existing methods for actin imaging, many of which lack the capability for direct visualization of biophysical properties. It can therefore contribute to a deeper understanding of the role that actin plays in fundamental biological processes and help elucidate the underlying biophysics of actin-related diseases.
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Affiliation(s)
- Ion A. Ioannou
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
- Department
of Chemical Engineering, Imperial College
London, South Kensington, London SW7 2AZ, U.K.
| | - Nickolas J. Brooks
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
| | - Marina K. Kuimova
- Department
of Chemistry, Imperial College London, Molecular
Sciences Research Hub, London W12 0BZ, U.K.
| | - Yuval Elani
- Department
of Chemical Engineering, Imperial College
London, South Kensington, London SW7 2AZ, U.K.
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2
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Park J, Bird JE. The actin cytoskeleton in hair bundle development and hearing loss. Hear Res 2023; 436:108817. [PMID: 37300948 PMCID: PMC10408727 DOI: 10.1016/j.heares.2023.108817] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/18/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Inner ear hair cells assemble mechanosensitive hair bundles on their apical surface that transduce sounds and accelerations. Each hair bundle is comprised of ∼ 100 individual stereocilia that are arranged into rows of increasing height and width; their specific and precise architecture being necessary for mechanoelectrical transduction (MET). The actin cytoskeleton is fundamental to establishing this architecture, not only by forming the structural scaffold shaping each stereocilium, but also by composing rootlets and the cuticular plate that together provide a stable foundation supporting each stereocilium. In concert with the actin cytoskeleton, a large assortment of actin-binding proteins (ABPs) function to cross-link actin filaments into specific topologies, as well as control actin filament growth, severing, and capping. These processes are individually critical for sensory transduction and are all disrupted in hereditary forms of human hearing loss. In this review, we provide an overview of actin-based structures in the hair bundle and the molecules contributing to their assembly and functional properties. We also highlight recent advances in mechanisms driving stereocilia elongation and how these processes are tuned by MET.
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Affiliation(s)
- Jinho Park
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States
| | - Jonathan E Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32610, United States; Myology Institute, University of Florida, Gainesville, FL 32610, United States.
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3
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Bhavna R, Sonawane M. A deep learning framework for quantitative analysis of actin microridges. NPJ Syst Biol Appl 2023; 9:21. [PMID: 37268613 DOI: 10.1038/s41540-023-00276-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 05/03/2023] [Indexed: 06/04/2023] Open
Abstract
Microridges are evolutionarily conserved actin-rich protrusions present on the apical surface of squamous epithelial cells. In zebrafish epidermal cells, microridges form self-evolving patterns due to the underlying actomyosin network dynamics. However, their morphological and dynamic characteristics have remained poorly understood owing to a lack of computational methods. We achieved ~95% pixel-level accuracy with a deep learning microridge segmentation strategy enabling quantitative insights into their bio-physical-mechanical characteristics. From the segmented images, we estimated an effective microridge persistence length of ~6.1 μm. We discovered the presence of mechanical fluctuations and found relatively greater stresses stored within patterns of yolk than flank, indicating distinct regulation of their actomyosin networks. Furthermore, spontaneous formations and positional fluctuations of actin clusters within microridges were associated with pattern rearrangements over short length/time-scales. Our framework allows large-scale spatiotemporal analysis of microridges during epithelial development and probing of their responses to chemical and genetic perturbations to unravel the underlying patterning mechanisms.
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Affiliation(s)
- Rajasekaran Bhavna
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, 400005, India.
- Department of Data Science and Engineering, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, 462066, India.
| | - Mahendra Sonawane
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, 400005, India
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4
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Sun T, Krishnan V, Pan DC, Filippov SK, Ravid S, Sarode A, Kim J, Zhang Y, Power C, Aday S, Guo J, Karp JM, McDannold NJ, Mitragotri SS. Ultrasound-mediated delivery of flexibility-tunable polymer drug conjugates for treating glioblastoma. Bioeng Transl Med 2023; 8:e10408. [PMID: 36925708 PMCID: PMC10013755 DOI: 10.1002/btm2.10408] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/07/2022] [Accepted: 05/14/2022] [Indexed: 11/21/2022] Open
Abstract
Effective chemotherapy delivery for glioblastoma multiforme (GBM) is limited by drug transport across the blood-brain barrier and poor efficacy of single agents. Polymer-drug conjugates can be used to deliver drug combinations with a ratiometric dosing. However, the behaviors and effectiveness of this system have never been well investigated in GBM models. Here, we report flexible conjugates of hyaluronic acid (HA) with camptothecin (CPT) and doxorubicin (DOX) delivered into the brain using focused ultrasound (FUS). In vitro toxicity assays reveal that DOX-CPT exhibited synergistic action against GBM in a ratio-dependent manner when delivered as HA conjugates. FUS is employed to improve penetration of DOX-HA-CPT conjugates into the brain in vivo in a murine GBM model. Small-angle x-ray scattering characterizations of the conjugates show that the DOX:CPT ratio affects the polymer chain flexibility. Conjugates with the highest flexibility yield the highest efficacy in treating mouse GBM in vivo. Our results demonstrate the association of FUS-enhanced delivery of combination chemotherapy and the drug-ratio-dependent flexibility of the HA conjugates. Drug ratio in the polymer nanocomplex may thus be employed as a key factor to modulate FUS drug delivery efficiency via controlling the polymer flexibility. Our characterizations also highlight the significance of understanding the flexibility of drug carriers in ultrasound-mediated drug delivery systems.
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Affiliation(s)
- Tao Sun
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
- Focused Ultrasound Laboratory, Department of RadiologyBrigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Vinu Krishnan
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
| | - Daniel C. Pan
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
| | - Sergey K. Filippov
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Present address:
Pharmaceutical Sciences LaboratoryÅbo Akademi University, Turku BioscienceTurkuFinland
| | - Sagi Ravid
- Focused Ultrasound Laboratory, Department of RadiologyBrigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Apoorva Sarode
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
| | - Jayoung Kim
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
| | - Yongzhi Zhang
- Focused Ultrasound Laboratory, Department of RadiologyBrigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Chanikarn Power
- Focused Ultrasound Laboratory, Department of RadiologyBrigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Sezin Aday
- Department of AnesthesiologyPerioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
- Center for Nanomedicine, Harvard Stem Cell Institute, Brigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
- Harvard‐MIT Division of Health Sciences and TechnologyCambridgeMassachusettsUSA
- Proteomics Platform, Broad Institute of MIT and HarvardCambridgeMassachusettsUSA
| | - Junling Guo
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
- Present address:
College of Biomass Science and EngineeringSichuan UniversityChengduSichuanChina
| | - Jeffrey M. Karp
- Department of AnesthesiologyPerioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
- Center for Nanomedicine, Harvard Stem Cell Institute, Brigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
- Harvard‐MIT Division of Health Sciences and TechnologyCambridgeMassachusettsUSA
- Proteomics Platform, Broad Institute of MIT and HarvardCambridgeMassachusettsUSA
| | - Nathan J. McDannold
- Focused Ultrasound Laboratory, Department of RadiologyBrigham and Women's Hospital, Harvard Medical SchoolBostonMassachusettsUSA
| | - Samir S. Mitragotri
- John A. Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeMassachusettsUSA
- Wyss Institute for Biologically Inspired Engineering, Harvard UniversityBostonMassachusettsUSA
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5
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Månsson A. The potential of myosin and actin in nanobiotechnology. J Cell Sci 2023; 136:292584. [PMID: 36861886 DOI: 10.1242/jcs.261025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
Since the late 1990s, efforts have been made to utilize cytoskeletal filaments, propelled by molecular motors, for nanobiotechnological applications, for example, in biosensing and parallel computation. This work has led to in-depth insights into the advantages and challenges of such motor-based systems, and has yielded small-scale, proof-of-principle applications but, to date, no commercially viable devices. Additionally, these studies have also elucidated fundamental motor and filament properties, as well as providing other insights obtained from biophysical assays in which molecular motors and other proteins are immobilized on artificial surfaces. In this Perspective, I discuss the progress towards practically viable applications achieved so far using the myosin II-actin motor-filament system. I also highlight several fundamental pieces of insights derived from the studies. Finally, I consider what may be required to achieve real devices in the future or at least to allow future studies with a satisfactory cost-benefit ratio.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Science, Linnaeus University, SE-391 82 Kalmar, Sweden
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6
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Zhou H, Jung W, Farhana TI, Fujimoto K, Kim T, Yokokawa R. Durability of Aligned Microtubules Dependent on Persistence Length Determines Phase Transition and Pattern Formation in Collective Motion. ACS NANO 2022; 16:14765-14778. [PMID: 36098647 DOI: 10.1021/acsnano.2c05593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Collective motion is a ubiquitous phenomenon in nature. The collective motion of cytoskeleton filaments results mainly from dynamic collisions and alignments; however, the detailed mechanism of pattern formation still needs to be clarified. In particular, the influence of persistence length, which is a measure of filament flexibility, on collective motion is still unclear and lacks experimental verifications although it is likely to directly affect the orientational flexibility of filaments. Here, we investigated the collective motion of microtubules with different persistence lengths using a microtubule-kinesin motility system. We showed that local interactions between microtubules significantly vary depending on their persistence length. We demonstrated that the bundling of microtubules is enhanced by more durable alignment, rather than by greater likelihood of alignment. An agent-based computational model confirmed that the rigidity-dependent durability of microtubule alignment dominates their collective behavior.
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Affiliation(s)
- Hang Zhou
- Department of Micro Engineering, Kyoto University, Kyoto daigaku-katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Wonyeong Jung
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tamanna Ishrat Farhana
- Department of Micro Engineering, Kyoto University, Kyoto daigaku-katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Kazuya Fujimoto
- Department of Micro Engineering, Kyoto University, Kyoto daigaku-katsura, Nishikyo-ku, Kyoto 615-8540, Japan
| | - Taeyoon Kim
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ryuji Yokokawa
- Department of Micro Engineering, Kyoto University, Kyoto daigaku-katsura, Nishikyo-ku, Kyoto 615-8540, Japan
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7
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Xin Y, Piskunen P, Suma A, Li C, Ijäs H, Ojasalo S, Seitz I, Kostiainen MA, Grundmeier G, Linko V, Keller A. Environment-Dependent Stability and Mechanical Properties of DNA Origami Six-Helix Bundles with Different Crossover Spacings. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2107393. [PMID: 35363419 DOI: 10.1002/smll.202107393] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/14/2022] [Indexed: 05/25/2023]
Abstract
The internal design of DNA nanostructures defines how they behave in different environmental conditions, such as endonuclease-rich or low-Mg2+ solutions. Notably, the inter-helical crossovers that form the core of such DNA objects have a major impact on their mechanical properties and stability. Importantly, crossover design can be used to optimize DNA nanostructures for target applications, especially when developing them for biomedical environments. To elucidate this, two otherwise identical DNA origami designs are presented that have a different number of staple crossovers between neighboring helices, spaced at 42- and 21- basepair (bp) intervals, respectively. The behavior of these structures is then compared in various buffer conditions, as well as when they are exposed to enzymatic digestion by DNase I. The results show that an increased number of crossovers significantly improves the nuclease resistance of the DNA origami by making it less accessible to digestion enzymes but simultaneously lowers its stability under Mg2+ -free conditions by reducing the malleability of the structures. Therefore, these results represent an important step toward rational, application-specific DNA nanostructure design.
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Affiliation(s)
- Yang Xin
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098, Paderborn, Germany
| | - Petteri Piskunen
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Antonio Suma
- Dipartimento di Fisica, Università di Bari and Sezione INFN di Bari, Bari, 70126, Italy
| | - Changyong Li
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098, Paderborn, Germany
| | - Heini Ijäs
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Sofia Ojasalo
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Iris Seitz
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Mauri A Kostiainen
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Guido Grundmeier
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098, Paderborn, Germany
| | - Veikko Linko
- Biohybrid Materials, Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, Aalto, 00076, Finland
| | - Adrian Keller
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098, Paderborn, Germany
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8
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Measurement of the Persistence Length of Cytoskeletal Filaments using Curvature Distributions. Biophys J 2022; 121:1813-1822. [PMID: 35450824 DOI: 10.1016/j.bpj.2022.04.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/16/2022] [Accepted: 04/14/2022] [Indexed: 11/23/2022] Open
Abstract
Cytoskeletal filaments such as microtubules and actin filaments play important roles in the mechanical integrity of cells and the ability of cells to respond to their environment. Measuring the mechanical properties of cytoskeletal structures is crucial for gaining insight into intracellular mechanical stresses and their role in regulating cellular processes. One of the ways to characterize these mechanical properties is by measuring their persistence length, the average length over which filaments stay straight. There are several approaches in the literature for measuring filament deformations, such as Fourier analysis of images obtained using fluorescence microscopy. Here, we show how curvature distributions can be used as an alternative tool to quantify bio-filament deformations, and investigate how the apparent stiffness of filaments depends on the resolution and noise of the imaging system. We present analytical calculations of the scaling curvature distributions as a function of filament discretization, and test our predictions by comparing Monte Carlo simulations to results from existing techniques. We also apply our approach to microtubules and actin filaments obtained from in vitro gliding assay experiments with high densities of non-functional motors, and calculate the persistence length of these filaments. The presented curvature analysis is significantly more accurate compared to existing approaches for small data sets, and can be readily applied to both in vitro or in vivo filament data through the use of the open-source codes we provide.
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9
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Windoffer R, Schwarz N, Yoon S, Piskova T, Scholkemper M, Stegmaier J, Bönsch A, Di Russo J, Leube R. Quantitative mapping of keratin networks in 3D. eLife 2022; 11:75894. [PMID: 35179484 PMCID: PMC8979588 DOI: 10.7554/elife.75894] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/15/2022] [Indexed: 11/26/2022] Open
Abstract
Mechanobiology requires precise quantitative information on processes taking place in specific 3D microenvironments. Connecting the abundance of microscopical, molecular, biochemical, and cell mechanical data with defined topologies has turned out to be extremely difficult. Establishing such structural and functional 3D maps needed for biophysical modeling is a particular challenge for the cytoskeleton, which consists of long and interwoven filamentous polymers coordinating subcellular processes and interactions of cells with their environment. To date, useful tools are available for the segmentation and modeling of actin filaments and microtubules but comprehensive tools for the mapping of intermediate filament organization are still lacking. In this work, we describe a workflow to model and examine the complete 3D arrangement of the keratin intermediate filament cytoskeleton in canine, murine, and human epithelial cells both, in vitro and in vivo. Numerical models are derived from confocal airyscan high-resolution 3D imaging of fluorescence-tagged keratin filaments. They are interrogated and annotated at different length scales using different modes of visualization including immersive virtual reality. In this way, information is provided on network organization at the subcellular level including mesh arrangement, density and isotropic configuration as well as details on filament morphology such as bundling, curvature, and orientation. We show that the comparison of these parameters helps to identify, in quantitative terms, similarities and differences of keratin network organization in epithelial cell types defining subcellular domains, notably basal, apical, lateral, and perinuclear systems. The described approach and the presented data are pivotal for generating mechanobiological models that can be experimentally tested.
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Affiliation(s)
- Reinhard Windoffer
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Nicole Schwarz
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Sungjun Yoon
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | - Teodora Piskova
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
| | | | - Johannes Stegmaier
- Institute of Imaging and Computer Vision, RWTH Aachen University, Aachen, Germany
| | - Andrea Bönsch
- Visual Computing Institute, RWTH Aachen University, Aachen, Germany
| | - Jacopo Di Russo
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Aachen, Germany
| | - Rudolf Leube
- Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Aachen, Germany
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10
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Lee G, Leech G, Lwin P, Michel J, Currie C, Rust MJ, Ross JL, McGorty RJ, Das M, Robertson-Anderson RM. Active cytoskeletal composites display emergent tunable contractility and restructuring. SOFT MATTER 2021; 17:10765-10776. [PMID: 34792082 PMCID: PMC9239752 DOI: 10.1039/d1sm01083b] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The cytoskeleton is a model active matter system that controls processes as diverse as cell motility and mechanosensing. While both active actomyosin dynamics and actin-microtubule interactions are key to the cytoskeleton's versatility and adaptability, an understanding of their interplay is lacking. Here, we couple microscale experiments with mechanistic modeling to elucidate how connectivity, rigidity, and force-generation affect emergent material properties in composite networks of actin, tubulin, and myosin. We use multi-spectral imaging, time-resolved differential dynamic microscopy and spatial image autocorrelation to show that ballistic contraction occurs in composites with sufficient flexibility and motor density, but that a critical fraction of microtubules is necessary to sustain controlled dynamics. The active double-network models we develop, which recapitulate our experimental findings, reveal that while percolated actomyosin networks are essential for contraction, only composites with comparable actin and microtubule densities can simultaneously resist mechanical stresses while supporting substantial restructuring. The comprehensive phase map we present not only provides important insight into the different routes the cytoskeleton can use to alter its dynamics and structure, but also serves as a much-needed blueprint for designing cytoskeleton-inspired materials that couple tunability with resilience and adaptability for diverse applications ranging from wound healing to soft robotics.
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Affiliation(s)
- Gloria Lee
- Department of Physics and Biophysics, University of San Diego, USA.
| | - Gregor Leech
- Department of Physics and Biophysics, University of San Diego, USA.
| | - Pancy Lwin
- School of Physics and Astronomy, Rochester Institute of Technology, USA
| | - Jonathan Michel
- School of Physics and Astronomy, Rochester Institute of Technology, USA
| | | | - Michael J Rust
- Department of Molecular Genetics and Cell Biology, University of Chicago, USA
| | | | - Ryan J McGorty
- Department of Physics and Biophysics, University of San Diego, USA.
| | - Moumita Das
- School of Physics and Astronomy, Rochester Institute of Technology, USA
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11
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Bashirzadeh Y, Redford SA, Lorpaiboon C, Groaz A, Moghimianavval H, Litschel T, Schwille P, Hocky GM, Dinner AR, Liu AP. Actin crosslinker competition and sorting drive emergent GUV size-dependent actin network architecture. Commun Biol 2021. [PMID: 34584211 DOI: 10.1101/2020.10.03.322354v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
The proteins that make up the actin cytoskeleton can self-assemble into a variety of structures. In vitro experiments and coarse-grained simulations have shown that the actin crosslinking proteins α-actinin and fascin segregate into distinct domains in single actin bundles with a molecular size-dependent competition-based mechanism. Here, by encapsulating actin, α-actinin, and fascin in giant unilamellar vesicles (GUVs), we show that physical confinement can cause these proteins to form much more complex structures, including rings and asters at GUV peripheries and centers; the prevalence of different structures depends on GUV size. Strikingly, we found that α-actinin and fascin self-sort into separate domains in the aster structures with actin bundles whose apparent stiffness depends on the ratio of the relative concentrations of α-actinin and fascin. The observed boundary-imposed effect on protein sorting may be a general mechanism for creating emergent structures in biopolymer networks with multiple crosslinkers.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Steven A Redford
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
- The graduate program in Biophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | | | - Alessandro Groaz
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Aaron R Dinner
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.
- Department of Chemistry, University of Chicago, Chicago, IL, 60637, USA.
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Biophysics, University of Michigan, Ann Arbor, MI, 48109, USA.
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.
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12
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Bashirzadeh Y, Redford SA, Lorpaiboon C, Groaz A, Moghimianavval H, Litschel T, Schwille P, Hocky GM, Dinner AR, Liu AP. Actin crosslinker competition and sorting drive emergent GUV size-dependent actin network architecture. Commun Biol 2021; 4:1136. [PMID: 34584211 PMCID: PMC8478941 DOI: 10.1038/s42003-021-02653-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/08/2021] [Indexed: 02/07/2023] Open
Abstract
The proteins that make up the actin cytoskeleton can self-assemble into a variety of structures. In vitro experiments and coarse-grained simulations have shown that the actin crosslinking proteins α-actinin and fascin segregate into distinct domains in single actin bundles with a molecular size-dependent competition-based mechanism. Here, by encapsulating actin, α-actinin, and fascin in giant unilamellar vesicles (GUVs), we show that physical confinement can cause these proteins to form much more complex structures, including rings and asters at GUV peripheries and centers; the prevalence of different structures depends on GUV size. Strikingly, we found that α-actinin and fascin self-sort into separate domains in the aster structures with actin bundles whose apparent stiffness depends on the ratio of the relative concentrations of α-actinin and fascin. The observed boundary-imposed effect on protein sorting may be a general mechanism for creating emergent structures in biopolymer networks with multiple crosslinkers. By encapsulating proteins in giant unilamellar vesicles, Bashirzadeh et al find that actin crosslinkers, α-actinin and fascin, can self-assemble with actin into complex structures that depend on the degree of confinement. Further analysis and modeling show that α-actinin and fascin sort to separate domains of these structures. These insights may be generalizable to other biopolymer networks containing crosslinkers.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Steven A Redford
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.,The graduate program in Biophysical Sciences, University of Chicago, Chicago, IL, 60637, USA
| | | | - Alessandro Groaz
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, NY, 10003, USA
| | - Aaron R Dinner
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA. .,Department of Chemistry, University of Chicago, Chicago, IL, 60637, USA.
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Biophysics, University of Michigan, Ann Arbor, MI, 48109, USA. .,Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, 48109, USA.
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13
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Schneider M, Al-Shaer A, Forde NR. AutoSmarTrace: Automated chain tracing and flexibility analysis of biological filaments. Biophys J 2021; 120:2599-2608. [PMID: 34022242 DOI: 10.1016/j.bpj.2021.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/12/2021] [Accepted: 05/17/2021] [Indexed: 11/19/2022] Open
Abstract
Single-molecule imaging is widely used to determine statistical distributions of molecular properties. One such characteristic is the bending flexibility of biological filaments, which can be parameterized via the persistence length. Quantitative extraction of persistence length from images of individual filaments requires both the ability to trace the backbone of the chains in the images and sufficient chain statistics to accurately assess the persistence length. Chain tracing can be a tedious task, performed manually or using algorithms that require user input and/or supervision. Such interventions have the potential to introduce user-dependent bias into the chain selection and tracing. Here, we introduce a fully automated algorithm for chain tracing and determination of persistence lengths. Dubbed "AutoSmarTrace," the algorithm is built off a neural network, trained via machine learning to identify filaments within images recorded using atomic force microscopy. We validate the performance of AutoSmarTrace on simulated images with widely varying levels of noise, demonstrating its ability to return persistence lengths in agreement with input simulation parameters. Persistence lengths returned from analysis of experimental images of collagen and DNA agree with previous values obtained from these images with different chain-tracing approaches. Although trained on atomic-force-microscopy-like images, the algorithm also shows promise to identify chains in other single-molecule imaging approaches, such as rotary-shadowing electron microscopy and fluorescence imaging.
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Affiliation(s)
- Mathew Schneider
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Alaa Al-Shaer
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Nancy R Forde
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada.
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14
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Cavanna F, Alvarado J. Quantification of the mesh structure of bundled actin filaments. SOFT MATTER 2021; 17:5034-5043. [PMID: 33912871 DOI: 10.1039/d1sm00428j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Biopolymer networks are essential for a wide variety of cellular functions. The biopolymer actin is known to self-assemble into a variety of spatial structures in response to physiological and physical mechanisms. So far, the mechanics of networks of single actin filaments and bundles has previously been described. However, the spatial structure of actin bundles remains poorly understood. Here, we investigate this question by bundling actin filaments with systematically varied concentrations of known physical bundling agents (MgCl2 and PEG) and physiological bundling agents (α-actinin and fascin). We image bundled actin networks with confocal microscopy and perform analysis to describe their mesh size and the nearest-distance distribution, which we call "mesh structure". We find that the mesh size ξ scales universally with actin concentration as ξ ∼ [actin]-1/2. However, the dependence of ξ on the concentration of the bundling agent depends on the agent used. Finally, we find that nearest-distance distributions are best fit by Weibull and Gamma distributions. A complete understanding of the mesh structure of biopolymer networks leads to a more mechanistic understanding of the structure of the cytoskeleton, and can be exploited to design filters with variable porosity for microfluidic devices.
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Affiliation(s)
- Francis Cavanna
- UT Austin Department of Physics, 2515 Speedway, Austin, Texas, USA.
| | - José Alvarado
- UT Austin Department of Physics, 2515 Speedway, Austin, Texas, USA.
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15
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Castaneda N, Park J, Kang EH. Regulation of Actin Bundle Mechanics and Structure by Intracellular Environmental Factors. FRONTIERS IN PHYSICS 2021; 9:675885. [PMID: 34422787 PMCID: PMC8376200 DOI: 10.3389/fphy.2021.675885] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The mechanical and structural properties of actin cytoskeleton drive various cellular processes, including structural support of the plasma membrane and cellular motility. Actin monomers assemble into double-stranded helical filaments as well as higher-ordered structures such as bundles and networks. Cells incorporate macromolecular crowding, cation interactions, and actin-crosslinking proteins to regulate the organization of actin bundles. Although the roles of each of these factors in actin bundling have been well-known individually, how combined factors contribute to actin bundle assembly, organization, and mechanics is not fully understood. Here, we describe recent studies that have investigated the mechanisms of how intracellular environmental factors influence actin bundling. This review highlights the effects of macromolecular crowding, cation interactions, and actin-crosslinking proteins on actin bundle organization, structure, and mechanics. Understanding these mechanisms is important in determining in vivo actin biophysics and providing insights into cell physiology.
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Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, United States
| | - Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, United States
- Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, United States
- Department of Physics, University of Central Florida, Orlando, FL, United States
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16
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Litschel T, Kelley CF, Holz D, Adeli Koudehi M, Vogel SK, Burbaum L, Mizuno N, Vavylonis D, Schwille P. Reconstitution of contractile actomyosin rings in vesicles. Nat Commun 2021; 12:2254. [PMID: 33859190 PMCID: PMC8050101 DOI: 10.1038/s41467-021-22422-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 03/04/2021] [Indexed: 12/31/2022] Open
Abstract
One of the grand challenges of bottom-up synthetic biology is the development of minimal machineries for cell division. The mechanical transformation of large-scale compartments, such as Giant Unilamellar Vesicles (GUVs), requires the geometry-specific coordination of active elements, several orders of magnitude larger than the molecular scale. Of all cytoskeletal structures, large-scale actomyosin rings appear to be the most promising cellular elements to accomplish this task. Here, we have adopted advanced encapsulation methods to study bundled actin filaments in GUVs and compare our results with theoretical modeling. By changing few key parameters, actin polymerization can be differentiated to resemble various types of networks in living cells. Importantly, we find membrane binding to be crucial for the robust condensation into a single actin ring in spherical vesicles, as predicted by theoretical considerations. Upon force generation by ATP-driven myosin motors, these ring-like actin structures contract and locally constrict the vesicle, forming furrow-like deformations. On the other hand, cortex-like actin networks are shown to induce and stabilize deformations from spherical shapes. Cytoskeletal networks support and direct cell shape and guide intercellular transport, but relatively little is understood about the self-organization of cytoskeletal components on the scale of an entire cell. Here, authors use an in vitro system and observe the assembly of different types of actin networks and the condensation of membrane-bound actin into single rings.
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Affiliation(s)
- Thomas Litschel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Charlotte F Kelley
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Danielle Holz
- Department of Physics, Lehigh University, Bethlehem, PA, USA
| | | | - Sven K Vogel
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Laura Burbaum
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Naoko Mizuno
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Martinsried, Germany.
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17
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Bashirzadeh Y, Wubshet NH, Liu AP. Confinement Geometry Tunes Fascin-Actin Bundle Structures and Consequently the Shape of a Lipid Bilayer Vesicle. Front Mol Biosci 2020; 7:610277. [PMID: 33240934 PMCID: PMC7680900 DOI: 10.3389/fmolb.2020.610277] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
Depending on the physical and biochemical properties of actin-binding proteins, actin networks form different types of membrane protrusions at the cell periphery. Actin crosslinkers, which facilitate the interaction of actin filaments with one another, are pivotal in determining the mechanical properties and protrusive behavior of actin networks. Short crosslinkers such as fascin bundle F-actin to form rigid spiky filopodial protrusions. By encapsulation of fascin and actin in giant unilamellar vesicles (GUVs), we show that fascin-actin bundles cause various GUV shape changes by forming bundle networks or straight single bundles depending on GUV size and fascin concentration. We also show that the presence of a long crosslinker, α-actinin, impacts fascin-induced GUV shape changes and significantly impairs the formation of filopodia-like protrusions. Actin bundle-induced GUV shape changes are confirmed by light-induced disassembly of actin bundles leading to the reversal of GUV shape. Our study contributes to advancing the design of shape-changing minimal cells for better characterization of the interaction between lipid bilayer membranes and actin cytoskeleton.
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Affiliation(s)
- Yashar Bashirzadeh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Nadab H. Wubshet
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Allen P. Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Biophysics, University of Michigan, Ann Arbor, MI, United States
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, United States
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18
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Park J, Lee M, Lee B, Castaneda N, Tetard L, Kang EH. Crowding tunes the organization and mechanics of actin bundles formed by crosslinking proteins. FEBS Lett 2020; 595:26-40. [PMID: 33020904 DOI: 10.1002/1873-3468.13949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 01/05/2023]
Abstract
Fascin and α-actinin form higher-ordered actin bundles that mediate numerous cellular processes including cell morphogenesis and movement. While it is understood crosslinked bundle formation occurs in crowded cytoplasm, how crowding affects the bundling activities of the two crosslinking proteins is not known. Here, we demonstrate how solution crowding modulates the organization and mechanical properties of fascin- and α-actinin-induced bundles, utilizing total internal reflection fluorescence and atomic force microscopy imaging. Molecular dynamics simulations support the inference that crowding reduces binding interaction between actin filaments and fascin or the calponin homology 1 domain of α-actinin evidenced by interaction energy and hydrogen bonding analysis. Based on our findings, we suggest a mechanism of crosslinked actin bundle assembly and mechanics in crowded intracellular environments.
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Affiliation(s)
- Jinho Park
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA
| | - Myeongsang Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Briana Lee
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA
| | - Nicholas Castaneda
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL, USA
| | - Laurene Tetard
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
| | - Ellen Hyeran Kang
- NanoScience Technology Center, University of Central Florida, Orlando, FL, USA.,Department of Materials Science and Engineering, University of Central Florida, Orlando, FL, USA.,Department of Physics, University of Central Florida, Orlando, FL, USA
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19
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Stoddard PR, Lynch EM, Farrell DP, Dosey AM, DiMaio F, Williams TA, Kollman JM, Murray AW, Garner EC. Polymerization in the actin ATPase clan regulates hexokinase activity in yeast. Science 2020; 367:1039-1042. [PMID: 32108112 DOI: 10.1126/science.aay5359] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 01/27/2020] [Indexed: 01/03/2023]
Abstract
The actin fold is found in cytoskeletal polymers, chaperones, and various metabolic enzymes. Many actin-fold proteins, such as the carbohydrate kinases, do not polymerize. We found that Glk1, a Saccharomyces cerevisiae glucokinase, forms two-stranded filaments with ultrastructure that is distinct from that of cytoskeletal polymers. In cells, Glk1 polymerized upon sugar addition and depolymerized upon sugar withdrawal. Polymerization inhibits enzymatic activity; the Glk1 monomer-polymer equilibrium sets a maximum rate of glucose phosphorylation regardless of Glk1 concentration. A mutation that eliminated Glk1 polymerization alleviated concentration-dependent enzyme inhibition. Yeast containing nonpolymerizing Glk1 were less fit when growing on sugars and more likely to die when refed glucose. Glk1 polymerization arose independently from other actin-related filaments and may allow yeast to rapidly modulate glucokinase activity as nutrient availability changes.
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Affiliation(s)
- Patrick R Stoddard
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.,Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Eric M Lynch
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Daniel P Farrell
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.,Institute for Protein Design, University of Washington, Seattle, WA 98195, USA
| | - Annie M Dosey
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Frank DiMaio
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.,Institute for Protein Design, University of Washington, Seattle, WA 98195, USA
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Justin M Kollman
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Andrew W Murray
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA. .,Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA. .,Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
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20
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Keya JJ, Kabir AMR, Kakugo A. Synchronous operation of biomolecular engines. Biophys Rev 2020; 12:401-409. [PMID: 32125657 PMCID: PMC7242543 DOI: 10.1007/s12551-020-00651-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 02/16/2020] [Indexed: 12/12/2022] Open
Abstract
Biomolecular motor systems are the smallest natural machines with an ability to convert chemical energy into mechanical work with remarkably high efficiency. Such attractive features enabled biomolecular motors to become classic tools in soft matter research over the past decade. For designing suitably engineered biomimetic systems, the biomolecular motors can potentially be used as molecular engines that can transform energy and ensure great advantages for the construction of bio-nanodevices and molecular robots. From the optimization of their prolonged lifetime to coordinate them into highly complex and ordered structures, enormous efforts have been devoted to make them useful in the synthetic environment. Synchronous operation of the biomolecular engines is one of the key criteria to coordinate them into certain different patterns, which depends on the local interaction of biomolecular motors. Utilizing chemical and physical stimuli, synchronization of biomolecular motor systems has become possible, which allows them to coordinate into different higher ordered patterns with different modes of functionality. Recently, programmed synchronous operation of the biomolecular engines has also been demonstrated, using a smart biomaterial to build up swarms reminiscent of nature. Here, we review the recent progress in the synchronized operation of biomolecular motors in engineered systems to explicitly program their interaction and further their applications. Such developments in the coordination of biomolecular motors have opened a broad way to explore the construction of future autonomous molecular machines and robots based on synchronization of biomolecular engines.
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Affiliation(s)
- Jakia Jannat Keya
- Faculty of Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan
| | | | - Akira Kakugo
- Faculty of Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
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21
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Adeli Koudehi M, Rutkowski DM, Vavylonis D. Organization of associating or crosslinked actin filaments in confinement. Cytoskeleton (Hoboken) 2019; 76:532-548. [PMID: 31525281 DOI: 10.1002/cm.21565] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 09/09/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
Abstract
A key factor of actin cytoskeleton organization in cells is the interplay between the dynamical properties of actin filaments and cell geometry, which restricts, confines and directs their orientation. Crosslinking interactions among actin filaments, together with geometrical cues and regulatory proteins can give rise to contractile rings in dividing cells and actin rings in neurons. Motivated by recent in vitro experiments, in this work we performed computer simulations to study basic aspects of the interplay between confinement and attractive interactions between actin filaments. We used a spring-bead model and Brownian dynamics to simulate semiflexible actin filaments that polymerize in a confining sphere with a rate proportional to the monomer concentration. We model crosslinking, or attraction through the depletion interaction, implicitly as an attractive short-range potential between filament beads. In confining geometries smaller than the persistence length of actin filaments, we show rings can form by curving of filaments of length comparable to, or longer than the confinement diameter. Rings form for optimal ranges of attractive interactions that exist in between open bundles, irregular loops, aggregated, and unbundled morphologies. The probability of ring formation is promoted by attraction to the confining sphere boundary and decreases for large radii and initial monomer concentrations, in agreement with prior experimental data. The model reproduces ring formation along the flat plane of oblate ellipsoids.
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22
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Jiang T, Harris TJC. Par-1 controls the composition and growth of cortical actin caps during Drosophila embryo cleavage. J Cell Biol 2019; 218:4195-4214. [PMID: 31641019 PMCID: PMC6891076 DOI: 10.1083/jcb.201903152] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 08/21/2019] [Accepted: 09/22/2019] [Indexed: 11/22/2022] Open
Abstract
The cell cortex is populated by various proteins, but it is unclear how they interact to change cell shape. Jiang and Harris find that the kinase Par-1 is required for Diaphanous-based actin bundles, and that these bundles intersperse with separately induced Arp2/3 networks to form an actin cap that grows into a metaphase compartment of the syncytial Drosophila embryo. Cell structure depends on the cortex, a thin network of actin polymers and additional proteins underlying the plasma membrane. The cell polarity kinase Par-1 is required for cells to form following syncytial Drosophila embryo development. This requirement stems from Par-1 promoting cortical actin caps that grow into dome-like metaphase compartments for dividing syncytial nuclei. We find the actin caps to be a composite material of Diaphanous (Dia)-based actin bundles interspersed with independently formed, Arp2/3-based actin puncta. Par-1 and Dia colocalize along extended regions of the bundles, and both are required for the bundles and for each other’s bundle-like localization, consistent with an actin-dependent self-reinforcement mechanism. Par-1 helps establish or maintain these bundles in a cortical domain with relatively low levels of the canonical formin activator Rho1-GTP. Arp2/3 is required for displacing the bundles away from each other and toward the cap circumference, suggesting interactions between these cytoskeletal components could contribute to the growth of the cap into a metaphase compartment.
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Affiliation(s)
- Tao Jiang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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23
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Affiliation(s)
- Gadiel Saper
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
| | - Henry Hess
- Department of Biomedical Engineering, Columbia University, New York, New York 10027, United States
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24
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Gu W, Chen K, Zhao X, Geng H, Li J, Qin Y, Bai X, Chang YN, Xia S, Zhang J, Ma S, Wu Z, Xing G, Xing G. Highly Dispersed Fullerenols Hamper Osteoclast Ruffled Border Formation by Perturbing Ca 2+ Bundles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1802549. [PMID: 30334332 DOI: 10.1002/smll.201802549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/29/2018] [Indexed: 06/08/2023]
Abstract
Osteoporosis, a common and serious bone disorder affecting aged people and postmenopausal women, is characterized by osteoclast overactivity. One therapeutic strategy is suppressing the bone resorption function of hyperactive osteoclasts, but there is no effective drug in clinical practice so far. Herein, it is demonstrated that fullerenols suppress the bone resorption of osteoclasts by inhibiting ruffled borders (RBs) formation. The RBs formation, which is supported by well-aligned actin bundles (B-actins), is a critical event for osteoclast bone resorption. To facilitate this function, osteoclast RBs dynamics is regulated by variable microenvironments to bundle F-actins, protrude cell membrane, and so on. B-actin perturbation by fullerenols is determined here, offering an opportunity to regulate osteoclast function by destroying RBs. In vivo, the therapeutic effect of fullerenols on overactive osteoclasts is confirmed in a mouse model of lipopolysaccharide-induced bone erosion. Collectively, the findings suggest that fullerenols adhere to F-actin surfaces and inhibit RBs formation in osteoclasts, mainly through hampering Ca2+ from bundling F-actins, and this is likely due to the stereo-hindrance effect caused by adherent fullerenols.
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Affiliation(s)
- Weihong Gu
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kui Chen
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoyi Zhao
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China
| | - Huan Geng
- Department of Orthopedics, General Hospital of Chinese People's Armed Police Forces, Beijing, 100039, China
| | - Juan Li
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanxia Qin
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Xue Bai
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ya-Nan Chang
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Shibo Xia
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiaxin Zhang
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sihan Ma
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhonghua Wu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing, 100049, China
| | - Gengyan Xing
- Department of Orthopedics, General Hospital of Chinese People's Armed Police Forces, Beijing, 100039, China
| | - Gengmei Xing
- CAS Key Laboratory for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China
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25
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Schön M, Mey I, Steinem C. Influence of cross-linkers on ezrin-bound minimal actin cortices. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 144:91-101. [PMID: 30093083 DOI: 10.1016/j.pbiomolbio.2018.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/13/2018] [Accepted: 07/31/2018] [Indexed: 12/21/2022]
Abstract
The actin cortex is a thin network coupled to the plasma membrane of cells, responsible for e.g., cell shape, motility, growth and division. Several model systems for minimal actin cortices (MACs) have been discussed in literature trying to mimic the complex interplay of membrane and actin. We recapitulate on different types of MACs using either three dimensional droplet interfaces or lipid bilayers to which F-actin networks are attached to or planar lipid bilayers with bound actin networks. Binding of the network to the membrane interface significantly influences its properties as well as its dynamics. This in turn also influences, how cross-linkers as well as myosin motors act on the network. Here, we describe the coupling of a filamentous actin network to a model membrane via the protein ezrin, a member of the ezrin-radixin-moesin family, which forms a direct linkage between the plasma membrane and the cortical web. Ezrin binding to the membrane is achieved by the lipid PtdIns(4,5)P2, while attachment to F-actin is mediated via the C-terminal domain of the protein leading to a two dimensional arrangement of actin filaments on the membrane. Addition of cross-linkers such as fascin and α-actinin influences the architecture of the actin network, which we have investigated by means of fluorescence microscopy. The results are discussed in terms of the dynamics of the filaments on the membrane surface.
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Affiliation(s)
- Markus Schön
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Ingo Mey
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
| | - Claudia Steinem
- Georg-August Universität Göttingen, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
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26
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Ghosh S, Park J, Thomas M, Cruz E, Cardona O, Kang H, Jewett T. Biophysical characterization of actin bundles generated by the Chlamydia trachomatis Tarp effector. Biochem Biophys Res Commun 2018; 500:423-428. [PMID: 29660331 DOI: 10.1016/j.bbrc.2018.04.093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 04/12/2018] [Indexed: 11/24/2022]
Abstract
Chlamydia trachomatis entry into host cells is mediated by pathogen-directed remodeling of the actin cytoskeleton. The chlamydial type III secreted effector, translocated actin recruiting phosphoprotein (Tarp), has been implicated in the recruitment of actin to the site of internalization. Tarp harbors G-actin binding and proline rich domains required for Tarp-mediated actin nucleation as well as unique F-actin binding domains implicated in the formation of actin bundles. Little is known about the mechanical properties of actin bundles generated by Tarp or the mechanism by which Tarp mediates actin bundle formation. In order to characterize the actin bundles and elucidate the role of different Tarp domains in the bundling process, purified Tarp effectors and Tarp truncation mutants were analyzed using Total Internal Reflection Fluorescence (TIRF) microscopy. Our data indicate that Tarp mediated actin bundling is independent of actin nucleation and the F-actin binding domains are sufficient to bundle actin filaments. Additionally, Tarp-mediated actin bundles demonstrate distinct bending stiffness compared to those crosslinked by the well characterized actin bundling proteins fascin and alpha-actinin, suggesting Tarp may employ a novel actin bundling strategy. The capacity of the Tarp effector to generate novel actin bundles likely contributes to chlamydia's efficient mechanism of entry into human cells.
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Affiliation(s)
- Susmita Ghosh
- Division of Immunity and Pathogenesis, College of Medicine, University of Central Florida, United States
| | - Jinho Park
- NanoScience Technology Center, University of Central Florida, United States; Depatrment of Materials Science and Engineering, University of Central Florida, United States
| | - Mitchell Thomas
- Division of Immunity and Pathogenesis, College of Medicine, University of Central Florida, United States
| | - Edgar Cruz
- NanoScience Technology Center, University of Central Florida, United States
| | - Omar Cardona
- Division of Immunity and Pathogenesis, College of Medicine, University of Central Florida, United States
| | - Hyeran Kang
- NanoScience Technology Center, University of Central Florida, United States; Department of Physics, University of Central Florida, United States
| | - Travis Jewett
- Division of Immunity and Pathogenesis, College of Medicine, University of Central Florida, United States.
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Castaneda N, Zheng T, Rivera-Jacquez HJ, Lee HJ, Hyun J, Balaeff A, Huo Q, Kang H. Cations Modulate Actin Bundle Mechanics, Assembly Dynamics, and Structure. J Phys Chem B 2018; 122:3826-3835. [PMID: 29608304 DOI: 10.1021/acs.jpcb.8b00663] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Actin bundles are key factors in the mechanical support and dynamic reorganization of the cytoskeleton. High concentrations of multivalent counterions promote bundle formation through electrostatic attraction between actin filaments that are negatively charged polyelectrolytes. In this study, we evaluate how physiologically relevant divalent cations affect the mechanical, dynamic, and structural properties of actin bundles. Using a combination of total internal reflection fluorescence microscopy, transmission electron microscopy, and dynamic light scattering, we demonstrate that divalent cations modulate bundle stiffness, length distribution, and lateral growth. Molecular dynamics simulations of an all-atom model of the actin bundle reveal specific actin residues coordinate cation-binding sites that promote the bundle formation. Our work suggests that specific cation interactions may play a fundamental role in the assembly, structure, and mechanical properties of actin bundles.
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Affiliation(s)
- Nicholas Castaneda
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States.,Burnett School of Biomedical Sciences, College of Medicine , University of Central Florida , Orlando , Florida 32827 , United States
| | - Tianyu Zheng
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Hector J Rivera-Jacquez
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Hyun-Ju Lee
- Electron Microscopy Research Center , Korea Basic Science Institute (KBSI) , Cheongju-si , Chungcheongbuk-do 28119 , Republic of Korea
| | - Jaekyung Hyun
- Electron Microscopy Research Center , Korea Basic Science Institute (KBSI) , Cheongju-si , Chungcheongbuk-do 28119 , Republic of Korea
| | - Alexander Balaeff
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Qun Huo
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
| | - Hyeran Kang
- NanoScience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
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28
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Gubarev AS, Monnery BD, Lezov AA, Sedlacek O, Tsvetkov NV, Hoogenboom R, Filippov SK. Conformational properties of biocompatible poly(2-ethyl-2-oxazoline)s in phosphate buffered saline. Polym Chem 2018. [DOI: 10.1039/c8py00255j] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Kuhn segment length of PEtOx as a flexible macromolecule under physiological conditions is undoubtedly decreasing when approaching the LCST.
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Affiliation(s)
- Alexander S. Gubarev
- Department of Molecular Biophysics and Physics of Polymers
- St. Petersburg State University
- 199034 St. Petersburg
- Russian Federation
| | - Bryn D. Monnery
- Supramolecular Chemistry Group
- Department of Organic and Macromolecular Chemistry
- Ghent University Krijgslaan 281-S4
- 9000 Ghent
- Belgium
| | - Alexey A. Lezov
- Department of Molecular Biophysics and Physics of Polymers
- St. Petersburg State University
- 199034 St. Petersburg
- Russian Federation
| | - Ondrej Sedlacek
- Supramolecular Chemistry Group
- Department of Organic and Macromolecular Chemistry
- Ghent University Krijgslaan 281-S4
- 9000 Ghent
- Belgium
| | - Nikolai V. Tsvetkov
- Department of Molecular Biophysics and Physics of Polymers
- St. Petersburg State University
- 199034 St. Petersburg
- Russian Federation
| | - Richard Hoogenboom
- Supramolecular Chemistry Group
- Department of Organic and Macromolecular Chemistry
- Ghent University Krijgslaan 281-S4
- 9000 Ghent
- Belgium
| | - Sergey K. Filippov
- Institute of Macromolecular Chemistry
- v. v. i
- Academy of Sciences of the Czech Republic
- 162 06 Prague 6
- Czech Republic
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29
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Stoddard PR, Williams TA, Garner E, Baum B. Evolution of polymer formation within the actin superfamily. Mol Biol Cell 2017; 28:2461-2469. [PMID: 28904122 PMCID: PMC5597319 DOI: 10.1091/mbc.e15-11-0778] [Citation(s) in RCA: 18] [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: 05/22/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 01/02/2023] Open
Abstract
While many are familiar with actin as a well-conserved component of the eukaryotic cytoskeleton, it is less often appreciated that actin is a member of a large superfamily of structurally related protein families found throughout the tree of life. Actin-related proteins include chaperones, carbohydrate kinases, and other enzymes, as well as a staggeringly diverse set of proteins that use the energy from ATP hydrolysis to form dynamic, linear polymers. Despite differing widely from one another in filament structure and dynamics, these polymers play important roles in ordering cell space in bacteria, archaea, and eukaryotes. It is not known whether these polymers descended from a single ancestral polymer or arose multiple times by convergent evolution from monomeric actin-like proteins. In this work, we provide an overview of the structures, dynamics, and functions of this diverse set. Then, using a phylogenetic analysis to examine actin evolution, we show that the actin-related protein families that form polymers are more closely related to one another than they are to other nonpolymerizing members of the actin superfamily. Thus all the known actin-like polymers are likely to be the descendants of a single, ancestral, polymer-forming actin-like protein.
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Affiliation(s)
- Patrick R Stoddard
- Molecular and Cellular Biology, Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Ethan Garner
- Molecular and Cellular Biology, Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Buzz Baum
- MRC-Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
- Institute of Physics of Living Systems, University College London, London WC1E 6BT, UK
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30
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The dynamics of filament assembly define cytoskeletal network morphology. Nat Commun 2016; 7:13827. [PMID: 28000681 PMCID: PMC5187503 DOI: 10.1038/ncomms13827] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/04/2016] [Indexed: 11/22/2022] Open
Abstract
The actin cytoskeleton is a key component in the machinery of eukaryotic cells, and it self-assembles out of equilibrium into a wide variety of biologically crucial structures. Although the molecular mechanisms involved are well characterized, the physical principles governing the spatial arrangement of actin filaments are not understood. Here we propose that the dynamics of actin network assembly from growing filaments results from a competition between diffusion, bundling and steric hindrance, and is responsible for the range of observed morphologies. Our model and simulations thus predict an abrupt dynamical transition between homogeneous and strongly bundled networks as a function of the actin polymerization rate. This suggests that cells may effect dramatic changes to their internal architecture through minute modifications of their nonequilibrium dynamics. Our results are consistent with available experimental data.
The dynamics of actin cytoskeleton is essential to the function of living cells. Here, Foffano et al. describe a nonequilibrium filament model to mimic the formation of cytoskeleton and pinpoint the key role played by the actin entanglement during the transition from homogeneous to bundled networks.
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31
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Bengtsson E, Persson M, Rahman MA, Kumar S, Takatsuki H, Månsson A. Myosin-Induced Gliding Patterns at Varied [MgATP] Unveil a Dynamic Actin Filament. Biophys J 2016; 111:1465-1477. [PMID: 27705769 PMCID: PMC5052455 DOI: 10.1016/j.bpj.2016.08.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 11/29/2022] Open
Abstract
Actin filaments have key roles in cell motility but are generally claimed to be passive interaction partners in actin-myosin-based motion generation. Here, we present evidence against this static view based on an altered myosin-induced actin filament gliding pattern in an in vitro motility assay at varied [MgATP]. The statistics that characterize the degree of meandering of the actin filament paths suggest that for [MgATP] ≥ 0.25 mM, the flexural rigidity of heavy meromyosin (HMM)-propelled actin filaments is similar (without phalloidin) or slightly lower (with phalloidin) than that of HMM-free filaments observed in solution without surface tethering. When [MgATP] was reduced to ≤0.1 mM, the actin filament paths in the in vitro motility assay became appreciably more winding in both the presence and absence of phalloidin. This effect of lowered [MgATP] was qualitatively different from that seen when HMM was mixed with ATP-insensitive, N-ethylmaleimide-treated HMM (NEM-HMM; 25-30%). In particular, the addition of NEM-HMM increased a non-Gaussian tail in the path curvature distribution as well as the number of events in which different parts of an actin filament followed different paths. These effects were the opposite of those observed with reduced [MgATP]. Theoretical modeling suggests a 30-40% lowered flexural rigidity of the actin filaments at [MgATP] ≤ 0.1 mM and local bending of the filament front upon each myosin head attachment. Overall, the results fit with appreciable structural changes in the actin filament during actomyosin-based motion generation, and modulation of the actin filament mechanical properties by the dominating chemomechanical actomyosin state.
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Affiliation(s)
- Elina Bengtsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
| | - Malin Persson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
| | - Mohammad A Rahman
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
| | - Saroj Kumar
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
| | - Hideyo Takatsuki
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden
| | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.
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Kumar S, Milani G, Takatsuki H, Lana T, Persson M, Frasson C, te Kronnie G, Månsson A. Sensing protein antigen and microvesicle analytes using high-capacity biopolymer nano-carriers. Analyst 2015; 141:836-46. [PMID: 26617251 DOI: 10.1039/c5an02377g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Lab-on-a-chip systems with molecular motor driven transport of analytes attached to cytoskeletal filament shuttles (actin filaments, microtubules) circumvent challenges with nanoscale liquid transport. However, the filaments have limited cargo-carrying capacity and limitations either in transportation speed (microtubules) or control over motility direction (actin). To overcome these constraints we here report incorporation of covalently attached antibodies into self-propelled actin bundles (nanocarriers) formed by cross-linking antibody conjugated actin filaments via fascin, a natural actin-bundling protein. We demonstrate high maximum antigen binding activity and propulsion by surface adsorbed myosin motors. Analyte transport capacity is tested using both protein antigens and microvesicles, a novel class of diagnostic markers. Increased incubation concentration with protein antigen in the 0.1-100 nM range (1 min) reduces the fraction of motile bundles and their velocity but maximum transportation capacity of >1 antigen per nm of bundle length is feasible. At sub-nanomolar protein analyte concentration, motility is very well preserved opening for orders of magnitude improved limit of detection using motor driven concentration on nanoscale sensors. Microvesicle-complexing to monoclonal antibodies on the nanocarriers compromises motility but nanocarrier aggregation via microvesicles shows unique potential in label-free detection with the aggregates themselves as non-toxic reporter elements.
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Affiliation(s)
- Saroj Kumar
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE-391 82 Kalmar, Sweden.
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33
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Ishigure Y, Nitta T. Simulating an Actomyosin in Vitro Motility Assay: Toward the Rational Design of Actomyosin-Based Microtransporters. IEEE Trans Nanobioscience 2015; 14:641-8. [PMID: 26087497 DOI: 10.1109/tnb.2015.2443373] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We present a simulation study of an actomyosin in vitro motility assay. In vitro motility assays have served as an essential element facilitating the application of actomyosin in nanotechnology; such applications include biosensors and biocomputation. Although actomyosin in vitro motility assays have been extensively investigated, some ambiguities remain, as a result of the limited spatio-temporal resolution and unavoidable uncertainties associated with the experimental process. These ambiguities hamper the rational design of nanodevices for practical applications. Here, with the aim of moving toward a rational design process, we developed a 3D computer simulation method of an actomyosin in vitro motility assay, based on a Brownian dynamics simulation. The simulation explicitly included the ATP hydrolysis cycle of myosin. The simulation was validated by the reproduction of previous experimental results. More importantly, the simulation provided new insights that are difficult to obtain experimentally, including data on the number of myosin motors actually binding to actin filaments, the mechanism responsible for the guiding of actin filaments by chemical edges, and the effect of the processivity of motor proteins on the guiding probabilities. The simulations presented here will be useful in interpreting experimental results, and also in designing future nanodevices integrated with myosin motors.
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34
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Türmer K, Orbán J, Gróf P, Nyitrai M. FASCIN and alpha-actinin can regulate the conformation of actin filaments. Biochim Biophys Acta Gen Subj 2015; 1850:1855-61. [PMID: 26025636 DOI: 10.1016/j.bbagen.2015.05.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/21/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND Actin filament bundling proteins mediate numerous processes in cells such as the formation of cell membrane protrusions or cell adhesions and stress fiber based locomotion. Among them alpha-actinin and fascin are the most abundant ones. This work characterizes differences in molecular motions in actin filaments due to the binding of these two actin bundling proteins. METHODS We investigated how alpha-actinin and fascin binding modify the conformation of actin filaments by using conventional and saturation transfer EPR methods. RESULTS The result characteristic for motions on the microsecond time scale showed that both actin bundling proteins made the bending and torsional twisting of the actin filaments slower. When nanosecond time scale molecular motions were described the two proteins were found to induce opposite changes in the actin filaments. The binding of one molecule of alpha-actinin or fascin modified the conformation of numerous actin protomers. CONCLUSION As fascin and alpha-actinin participates in different cellular processes their binding can serve the proper tuning of the structure of actin by establishing the right conformation for the interactions with other actin binding proteins. Our observations are in correlation with the model where actin filaments fulfill their biological functions under the regulation by actin-binding proteins. GENERAL SIGNIFICANCE Supporting the general model for the cellular regulation of the actin cytoskeleton we showed that two abundant actin bundling proteins, fascin and alpha-actinin, alter the conformation of actin filaments through long range allosteric interactions in two different ways providing the structural framework for the adaptation to specific biological functions.
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Affiliation(s)
- Katalin Türmer
- Department of Biophysics, Medical School, University of Pécs, Szigeti u. 12, Pécs H-7624, Hungary; János Szentágothai Research Center, Pécs H-7624, Hungary
| | - József Orbán
- Department of Biophysics, Medical School, University of Pécs, Szigeti u. 12, Pécs H-7624, Hungary; János Szentágothai Research Center, Pécs H-7624, Hungary; MTA-PTE High Intensity Terahertz Research Group, Hungary
| | - Pál Gróf
- Department of Biophysics and Radiation Biology, Semmelweis University of Medicine, IX. Tűzoltó u. 37-47, Budapest H-1095, Hungary
| | - Miklós Nyitrai
- Department of Biophysics, Medical School, University of Pécs, Szigeti u. 12, Pécs H-7624, Hungary; János Szentágothai Research Center, Pécs H-7624, Hungary; MTA-PTE Nuclear-Mitochondrial Interactions Research Group, Hungary.
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35
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Pothapragada S, Zhang P, Sheriff J, Livelli M, Slepian MJ, Deng Y, Bluestein D. A phenomenological particle-based platelet model for simulating filopodia formation during early activation. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2015; 31:e02702. [PMID: 25532469 PMCID: PMC4509790 DOI: 10.1002/cnm.2702] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 10/29/2014] [Accepted: 12/11/2014] [Indexed: 05/13/2023]
Abstract
We developed a phenomenological three-dimensional platelet model to characterize the filopodia formation observed during early stage platelet activation. Departing from continuum mechanics based approaches, this coarse-grained molecular dynamics (CGMD) particle-based model can deform to emulate the complex shape change and filopodia formation that platelets undergo during activation. The platelet peripheral zone is modeled with a two-layer homogeneous elastic structure represented by spring-connected particles. The structural zone is represented by a cytoskeletal assembly comprising of a filamentous core and filament bundles supporting the platelet's discoid shape, also modeled by spring-connected particles. The interior organelle zone is modeled by homogeneous cytoplasm particles that facilitate the platelet deformation. Nonbonded interactions among the discrete particles of the membrane, the cytoskeletal assembly, and the cytoplasm are described using the Lennard-Jones potential with empirical constants. By exploring the parameter space of this CGMD model, we have successfully simulated the dynamics of varied filopodia formations. Comparative analyses of length and thickness of filopodia show that our numerical simulations are in agreement with experimental measurements of flow-induced activated platelets. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Seetha Pothapragada
- Department of Applied Mathematics and Statistics, Stony Brook University, NY 11794, United States
| | - Peng Zhang
- Department of Biomedical Engineering, Stony Brook University, NY 11794, United States
| | - Jawaad Sheriff
- Department of Biomedical Engineering, Stony Brook University, NY 11794, United States
| | - Mark Livelli
- Department of Biomedical Engineering, Stony Brook University, NY 11794, United States
| | - Marvin J. Slepian
- Department of Biomedical Engineering, Stony Brook University, NY 11794, United States
- Departments of Medicine and Biomedical Engineering and Sarver Heart Center, University of Arizona, Tucson, AZ, 85721, United States
| | - Yuefan Deng
- Department of Applied Mathematics and Statistics, Stony Brook University, NY 11794, United States
| | - Danny Bluestein
- Department of Biomedical Engineering, Stony Brook University, NY 11794, United States
- Corresponding Author: Danny Bluestein, Ph.D., Department of Biomedical Engineering, Stony Brook University, HSC T15-090, Stony Brook, NY 11794-8151, 631-444-2156, Fax 631-444-7530,
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36
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Ishigure Y, Nitta T. Understanding the guiding of kinesin/microtubule-based microtransporters in microfabricated tracks. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12089-12096. [PMID: 25238638 DOI: 10.1021/la5021884] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Microtransporters using cargo-laden microtubules propelled by kinesin motors are attractive for numerous applications in nanotechnology. To improve the efficiency of transport, the movement of microtubules must be guided by microfabricated tracks. However, the mechanisms of the guiding methods used are not fully understood. Here, using computer simulation, we systematically studied the guiding of such microtransporters by three different types of guiding methods: a chemical boundary, a physical barrier, and their combination. The simulation reproduced the probabilities of guiding previously observed experimentally for the three methods. Moreover, the simulation provided further insight into the mechanisms of guiding, which overturn previous assumptions and models.
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Affiliation(s)
- Yuki Ishigure
- Department of Mathematical Design and Engineering and ‡Applied Physics Course, Gifu University , Gifu 501-1193, Japan
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