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Chinthalapudi K, Heissler SM. Structure, regulation, and mechanisms of nonmuscle myosin-2. Cell Mol Life Sci 2024; 81:263. [PMID: 38878079 DOI: 10.1007/s00018-024-05264-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/24/2024] [Accepted: 04/30/2024] [Indexed: 06/23/2024]
Abstract
Members of the myosin superfamily of molecular motors are large mechanochemical ATPases that are implicated in an ever-expanding array of cellular functions. This review focuses on mammalian nonmuscle myosin-2 (NM2) paralogs, ubiquitous members of the myosin-2 family of filament-forming motors. Through the conversion of chemical energy into mechanical work, NM2 paralogs remodel and shape cells and tissues. This process is tightly controlled in time and space by numerous synergetic regulation mechanisms to meet cellular demands. We review how recent advances in structural biology together with elegant biophysical and cell biological approaches have contributed to our understanding of the shared and unique mechanisms of NM2 paralogs as they relate to their kinetics, regulation, assembly, and cellular function.
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Affiliation(s)
- Krishna Chinthalapudi
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, 43210, USA
| | - Sarah M Heissler
- Department of Physiology and Cell Biology, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, OH, 43210, USA.
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2
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Quintanilla MA, Patel H, Wu H, Sochacki KA, Chandrasekar S, Akamatsu M, Rotty JD, Korobova F, Bear JE, Taraska JW, Oakes PW, Beach JR. Local monomer levels and established filaments potentiate non-muscle myosin 2 assembly. J Cell Biol 2024; 223:e202305023. [PMID: 38353656 PMCID: PMC10866686 DOI: 10.1083/jcb.202305023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 01/02/2024] [Accepted: 01/26/2024] [Indexed: 02/16/2024] Open
Abstract
The ability to dynamically assemble contractile networks is required throughout cell physiology, yet direct biophysical mechanisms regulating non-muscle myosin 2 filament assembly in living cells are lacking. Here, we use a suite of dynamic, quantitative imaging approaches to identify deterministic factors that drive myosin filament appearance and amplification. We find that actin dynamics regulate myosin assembly, but that the static actin architecture plays a less clear role. Instead, remodeling of actin networks modulates the local myosin monomer levels and facilitates assembly through myosin:myosin-driven interactions. Using optogenetically controlled myosin, we demonstrate that locally concentrating myosin is sufficient to both form filaments and jump-start filament amplification and partitioning. By counting myosin monomers within filaments, we demonstrate a myosin-facilitated assembly process that establishes filament stacks prior to partitioning into clusters that feed higher-order networks. Together, these findings establish the biophysical mechanisms regulating the assembly of non-muscle contractile structures that are ubiquitous throughout cell biology.
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Affiliation(s)
- Melissa A. Quintanilla
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Hiral Patel
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Huini Wu
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Kem A. Sochacki
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shreya Chandrasekar
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Matthew Akamatsu
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Jeremy D. Rotty
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Farida Korobova
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - James E. Bear
- Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Justin W. Taraska
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Patrick W. Oakes
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Jordan R. Beach
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
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3
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Zhang L, Zhang Y, Wang Y, Chen X. Thermo-reversible gelation of myofibrillar protein: Relationship between coiled-coil and thermal reversibility. Curr Res Food Sci 2023; 7:100611. [PMID: 37860144 PMCID: PMC10582366 DOI: 10.1016/j.crfs.2023.100611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/29/2023] [Accepted: 10/02/2023] [Indexed: 10/21/2023] Open
Abstract
Thermo-reversible gel of myofibrillar protein (MP) can be made by tactics of elaborate deamidation using protein-glutaminase (PG), and this work aimed to disclose the link between thermally reversible gelation of MP and the coiled-coil (CC). Enzymatic deamidation fragmented myofibril filaments and triggered structural reassembly to create small-sized aggregates. The coiling and dissociation of CC structure in the myosin tails is the fundamental structural basis of the PG deamidated MP (DMP) in the dynamic evolution of reversible gelation. After specific inhibition of CC assembly by trifluoroethanol (TFE), the thermo-reversible gel ability of DMP was impaired, which confirmed that the dynamic assembly of CC with temperature response played a key role in the thermo-reversible gelation of DMP. The findings may broaden the molecular basis of natural CC reversible gelation and foster advances for the development of new muscle protein products.
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Affiliation(s)
- Lingying Zhang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Yanna Zhang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Yue Wang
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China
| | - Xing Chen
- State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu, 214122, China
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China
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4
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Ge L, Wang N, Li X, Huang Y, Li K, Zuo Y. Phosphoproteomic insight into the changes in structural proteins of muscle architecture associated with texture softening of grass carp (Ctenopharyngodon idella) fillets during chilling storage. Food Chem 2023; 422:136262. [PMID: 37141753 DOI: 10.1016/j.foodchem.2023.136262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 04/11/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023]
Abstract
Texture is an important sensory attribute of fish affected by modifications of structural proteins in muscle architecture. To investigate the changes in protein phosphorylation during texture softening of fish, the proteins of grass carp muscle after chilling storage of 0 day and 6 days were compared by phosphoproteomics, and their association with texture was analyzed. Totally 1026 unique phosphopeptides on 656 phosphoproteins were identified as differential. They were mainly classified as intracellular myofibril and cytoskeleton, and extracellular matrix, of which the molecular function and biological process were binding into supramolecular assembly and myofilament contraction. The concomitant dephosphorylation of kinases and assembly regulators indicated dephosphorylation and disassembly tendency of sarcomeric architecture. Correlation analysis defined the relation between texture and dephosphorylation of myosin light chain, actin, collagen and cytoskeleton. This study revealed that protein phosphorylation may affect the texture of fish muscle through regulating sarcomeric assembly of structural proteins in muscle architecture.
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Affiliation(s)
- Lihong Ge
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China.
| | - Ningxiaoxuan Wang
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China
| | - Xin Li
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China
| | - Yuli Huang
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China
| | - Kejuan Li
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China
| | - Yong Zuo
- Key Laboratory for Land Resources Evaluation and Monitoring in Southwest, Ministry of Education, College of Life Science, Sichuan Normal University, Chengdu, China.
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5
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Abstract
Non-muscle myosin 2 (NM2) motors are the major contractile machines in most cell types. Unsurprisingly, these ubiquitously expressed actin-based motors power a plethora of subcellular, cellular and multicellular processes. In this Cell Science at a Glance article and the accompanying poster, we review the biochemical properties and mechanisms of regulation of this myosin. We highlight the central role of NM2 in multiple fundamental cellular processes, which include cell migration, cytokinesis, epithelial barrier function and tissue morphogenesis. In addition, we highlight recent studies using advanced imaging technologies that have revealed aspects of NM2 assembly hitherto inaccessible. This article will hopefully appeal to both cytoskeletal enthusiasts and investigators from outside the cytoskeleton field who have interests in one of the many basic cellular processes requiring actomyosin force production.
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Affiliation(s)
- Melissa A. Quintanilla
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60525, USA
| | - John A. Hammer
- National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jordan R. Beach
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60525, USA
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6
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Morris T, Sue E, Geniesse C, Brieher WM, Tang VW. Synaptopodin stress fiber and contractomere at the epithelial junction. J Cell Biol 2022; 221:213132. [PMID: 35416930 PMCID: PMC9011326 DOI: 10.1083/jcb.202011162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 10/07/2021] [Accepted: 02/09/2022] [Indexed: 12/27/2022] Open
Abstract
The apical junction of epithelial cells can generate force to control cell geometry and perform contractile processes while maintaining barrier function and adhesion. Yet, the structural basis for force generation at the apical junction is not fully understood. Here, we describe two synaptopodin-dependent actomyosin structures that are spatially, temporally, and structurally distinct. The first structure is formed by the retrograde flow of synaptopodin initiated at the apical junction, creating a sarcomeric stress fiber that lies parallel to the apical junction. Contraction of the apical stress fiber is associated with either clustering of membrane components or shortening of junctional length. Upon junction maturation, apical stress fibers are disassembled. In mature epithelial monolayer, a motorized “contractomere” capable of “walking the junction” is formed at the junctional vertex. Actomyosin activities at the contractomere produce a compressive force evident by actin filament buckling and measurement with a new α-actinin-4 force sensor. The motility of contractomeres can adjust junctional length and change cell packing geometry during cell extrusion and intercellular movement. We propose a model of epithelial homeostasis that utilizes contractomere motility to support junction rearrangement while preserving the permeability barrier.
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Affiliation(s)
- Timothy Morris
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Eva Sue
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Caleb Geniesse
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - William M Brieher
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
| | - Vivian W Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, IL
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7
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Halder D, Mallick D, Chatterjee A, Jana SS. Nonmuscle Myosin II in cancer cell migration and mechanotransduction. Int J Biochem Cell Biol 2021; 139:106058. [PMID: 34400319 DOI: 10.1016/j.biocel.2021.106058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 07/16/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022]
Abstract
Cell migration is a key step of cancer metastasis, immune-cell navigation, homing of stem cells and development. What adds complexity to it is the heterogeneity of the tissue environment that gives rise to a vast diversity of migratory mechanisms utilized by cells. A majority of cell motility mechanisms reported elsewhere largely converge in depicting the importance of the activity and complexity of actomyosin networks in the cell. In this review, we highlight the less discussed functional diversity of these actomyosin complexes and describe in detail how the major cellular actin-binding molecular motor proteins, nonmuscle myosin IIs are regulated and how they participate and mechanically reciprocate to changes in the microenvironment during cancer cell migration and tumor progression. Understanding the role of nonmuscle myosin IIs in the cancer cell is important for designing efficient therapeutic strategies to prevent cancer metastasis.
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Affiliation(s)
- Debdatta Halder
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, India; Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel(2)
| | - Ditipriya Mallick
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, India
| | - Ananya Chatterjee
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, India
| | - Siddhartha S Jana
- School of Biological Sciences, Indian Association for the Cultivation of Science, Kolkata, India.
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8
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Wang L, Chitano P, Seow CY. Filament evanescence of myosin II and smooth muscle function. J Gen Physiol 2021; 153:211814. [PMID: 33606000 PMCID: PMC7901143 DOI: 10.1085/jgp.202012781] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/19/2021] [Indexed: 01/02/2023] Open
Abstract
Smooth muscle is an integral part of hollow organs. Many of them are constantly subjected to mechanical forces that alter organ shape and modify the properties of smooth muscle. To understand the molecular mechanisms underlying smooth muscle function in its dynamic mechanical environment, a new paradigm has emerged that depicts evanescence of myosin filaments as a key mechanism for the muscle’s adaptation to external forces in order to maintain optimal contractility. Unlike the bipolar myosin filaments of striated muscle, the side-polar filaments of smooth muscle appear to be less stable, capable of changing their lengths through polymerization and depolymerization (i.e., evanescence). In this review, we summarize accumulated knowledge on the structure and mechanism of filament formation of myosin II and on the influence of ionic strength, pH, ATP, myosin regulatory light chain phosphorylation, and mechanical perturbation on myosin filament stability. We discuss the scenario of intracellular pools of monomeric and filamentous myosin, length distribution of myosin filaments, and the regulatory mechanisms of filament lability in contraction and relaxation of smooth muscle. Based on recent findings, we suggest that filament evanescence is one of the fundamental mechanisms underlying smooth muscle’s ability to adapt to the external environment and maintain optimal function. Finally, we briefly discuss how increased ROCK protein expression in asthma may lead to altered myosin filament stability, which may explain the lack of deep-inspiration–induced bronchodilation and bronchoprotection in asthma.
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Affiliation(s)
- Lu Wang
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,The Centre for Heart Lung Innovation, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pasquale Chitano
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,The Centre for Heart Lung Innovation, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chun Y Seow
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,The Centre for Heart Lung Innovation, University of British Columbia, Vancouver, British Columbia, Canada
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9
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Grewe J, Schwarz US. Mechanosensitive self-assembly of myosin II minifilaments. Phys Rev E 2021; 101:022402. [PMID: 32168598 DOI: 10.1103/physreve.101.022402] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/15/2020] [Indexed: 01/23/2023]
Abstract
Self-assembly and force generation are two central processes in biological systems that usually are considered in separation. However, the signals that activate nonmuscle myosin II molecular motors simultaneously lead to self-assembly into myosin II minifilaments as well as progression of the motor heads through the cross-bridge cycle. Here we investigate theoretically the possible effects of coupling these two processes. Our assembly model, which builds on a consensus architecture of the minifilament, predicts a critical aggregation concentration at which the assembly kinetics slows down dramatically. The combined model predicts that increasing actin filament concentration and force both lead to a decrease in the critical aggregation concentration. We suggest that due to these effects, myosin II minifilaments in a filamentous context might be in a critical state that reacts faster to varying conditions than in solution. We finally compare our model to experiments by simulating fluorescence recovery after photobleaching.
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Affiliation(s)
- Justin Grewe
- Institute for Theoretical Physics and Bioquant, Heidelberg University, Heidelberg, Germany
| | - Ulrich S Schwarz
- Institute for Theoretical Physics and Bioquant, Heidelberg University, Heidelberg, Germany
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10
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Yang S, Tiwari P, Lee KH, Sato O, Ikebe M, Padrón R, Craig R. Cryo-EM structure of the inhibited (10S) form of myosin II. Nature 2020; 588:521-525. [PMID: 33268893 PMCID: PMC7746622 DOI: 10.1038/s41586-020-3007-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/01/2020] [Indexed: 01/14/2023]
Abstract
Myosin II is the motor protein that enables muscle cells to contract and nonmuscle cells to move and change shape1. The molecule has two identical heads attached to an elongated tail, and can exist in two conformations: 10S and 6S, named for their sedimentation coefficients2,3. The 6S conformation has an extended tail and assembles into polymeric filaments, which pull on actin filaments to generate force and motion. In 10S myosin, the tail is folded into three segments and the heads bend back and interact with each other and the tail3-7, creating a compact conformation in which ATPase activity, actin activation and filament assembly are all highly inhibited7,8. This switched-off structure appears to function as a key energy-conserving storage molecule in muscle and nonmuscle cells9-12, which can be activated to form functional filaments as needed13-but the mechanism of its inhibition is not understood. Here we have solved the structure of smooth muscle 10S myosin by cryo-electron microscopy with sufficient resolution to enable improved understanding of the function of the head and tail regions of the molecule and of the key intramolecular contacts that cause inhibition. Our results suggest an atomic model for the off state of myosin II, for its activation and unfolding by phosphorylation, and for understanding the clustering of disease-causing mutations near sites of intramolecular interaction.
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Affiliation(s)
- Shixin Yang
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
- Cryo-EM Shared Resources, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Prince Tiwari
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Kyoung Hwan Lee
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
- Massachusetts Facility for High-Resolution Electron Cryo-microscopy, University of Massachusetts Medical School, Worcester, MA, USA
| | - Osamu Sato
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - Mitsuo Ikebe
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, TX, USA
| | - Raúl Padrón
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA, USA.
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11
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Costa AR, Sousa MM. Non-Muscle Myosin II in Axonal Cell Biology: From the Growth Cone to the Axon Initial Segment. Cells 2020; 9:cells9091961. [PMID: 32858875 PMCID: PMC7563147 DOI: 10.3390/cells9091961] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 08/21/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022] Open
Abstract
By binding to actin filaments, non-muscle myosin II (NMII) generates actomyosin networks that hold unique contractile properties. Their dynamic nature is essential for neuronal biology including the establishment of polarity, growth cone formation and motility, axon growth during development (and axon regeneration in the adult), radial and longitudinal axonal tension, and synapse formation and function. In this review, we discuss the current knowledge on the spatial distribution and function of the actomyosin cytoskeleton in different axonal compartments. We highlight some of the apparent contradictions and open questions in the field, including the role of NMII in the regulation of axon growth and regeneration, the possibility that NMII structural arrangement along the axon shaft may control both radial and longitudinal contractility, and the mechanism and functional purpose underlying NMII enrichment in the axon initial segment. With the advances in live cell imaging and super resolution microscopy, it is expected that in the near future the spatial distribution of NMII in the axon, and the mechanisms by which it participates in axonal biology will be further untangled.
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12
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Horváth ÁI, Gyimesi M, Várkuti BH, Képiró M, Szegvári G, Lőrincz I, Hegyi G, Kovács M, Málnási-Csizmadia A. Effect of allosteric inhibition of non-muscle myosin 2 on its intracellular diffusion. Sci Rep 2020; 10:13341. [PMID: 32769996 PMCID: PMC7415145 DOI: 10.1038/s41598-020-69853-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 07/03/2020] [Indexed: 12/12/2022] Open
Abstract
Subcellular dynamics of non-muscle myosin 2 (NM2) is crucial for a broad-array of cellular functions. To unveil mechanisms of NM2 pharmacological control, we determined how the dynamics of NM2 diffusion is affected by NM2′s allosteric inhibitors, i.e. blebbistatin derivatives, as compared to Y-27632 inhibiting ROCK, NM2′s upstream regulator. We found that NM2 diffusion is markedly faster in central fibers than in peripheral stress fibers. Y-27632 accelerated NM2 diffusion in both peripheral and central fibers, whereas in peripheral fibers blebbistatin derivatives slightly accelerated NM2 diffusion at low, but markedly slowed it at high inhibitor concentrations. In contrast, rapid NM2 diffusion in central fibers was unaffected by direct NM2 inhibition. Using our optopharmacological tool, Molecular Tattoo, sub-effective concentrations of a photo-crosslinkable blebbistatin derivative were increased to effective levels in a small, irradiated area of peripheral fibers. These findings suggest that direct allosteric inhibition affects the diffusion profile of NM2 in a markedly different manner compared to the disruption of the upstream control of NM2. The pharmacological action of myosin inhibitors is channeled through autonomous molecular processes and might be affected by the load acting on the NM2 proteins.
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Affiliation(s)
- Ádám I Horváth
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Máté Gyimesi
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Boglárka H Várkuti
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Miklós Képiró
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Gábor Szegvári
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - István Lőrincz
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - György Hegyi
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Mihály Kovács
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary.
| | - András Málnási-Csizmadia
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary.
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13
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Wang M, Zhou Y, Zhang F, Fan Z, Bai X, Wang H. A novel MYH14 mutation in a Chinese family with autosomal dominant nonsyndromic hearing loss. BMC MEDICAL GENETICS 2020; 21:154. [PMID: 32711451 PMCID: PMC7382048 DOI: 10.1186/s12881-020-01086-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 07/02/2020] [Indexed: 01/10/2023]
Abstract
Background MYH14 gene mutations have been suggested to be associated with nonsyndromic/syndromic sensorineural hearing loss. It has been reported that mutations in MYH14 can result in autosomal dominant nonsyndromic deafness-4A (DFNA4). Methods In this study, we examined a four-generation Han Chinese family with nonsyndromic hearing loss. Targeted next-generation sequencing of deafness genes was employed to identify the pathogenic variant. Sanger sequencing and PCR-RFLP analysis were performed in affected members of this family and 200 normal controls to further confirm the mutation. Results Four members of this family were diagnosed as nonsyndromic bilateral sensorineural hearing loss with postlingual onset and progressive impairment. A novel missense variant, c.5417C > A (p.A1806D), in MYH14 in the tail domain of NMH II C was successfully identified as the pathogenic cause in three affected individuals. The family member II-5 was suggested to have noise-induced deafness. Conclusion In this study, a novel missense mutation, c.5417C > A (p.A1806D), in MYH14 that led to postlingual nonsyndromic autosomal dominant SNHL were identified. The findings broadened the phenotype spectrum of MYH14 and highlighted the combined application of gene capture and Sanger sequencing is an efficient approach to screen pathogenic variants associated with genetic diseases.
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Affiliation(s)
- Mingming Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yicui Zhou
- Department of Otorhinolaryngology Head and Neck Surgery, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Fengguo Zhang
- Shandong Institute of Otolaryngology, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Zhaomin Fan
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xiaohui Bai
- Shandong Institute of Otolaryngology, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China. .,Department of Clinical Laboratory, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
| | - Haibo Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China. .,Shandong Institute of Otolaryngology, Shandong Provincial ENT Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
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14
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Muscle myosins form folded monomers, dimers, and tetramers during filament polymerization in vitro. Proc Natl Acad Sci U S A 2020; 117:15666-15672. [PMID: 32571956 PMCID: PMC7354935 DOI: 10.1073/pnas.2001892117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Muscle myosins polymerize into thick filaments that drive muscle contraction by interaction with actin thin filaments. The details of muscle myosin polymerization into thick filaments are not known. Current hypotheses are that elongated myosin monomers form antiparallel dimers that polymerize into filaments. However, we find polymerization in vitro of skeletal, cardiac, and smooth muscle myosins involves formation of monomers with folded tails, tail-folded dimers, and tail-folded tetramers. These observations should stimulate studies of the pathway of formation of muscle myosins in vitro and in vivo including the possible roles of the multiple myosin-associated proteins on in vivo polymerization. Muscle contraction depends on the cyclical interaction of myosin and actin filaments. Therefore, it is important to understand the mechanisms of polymerization and depolymerization of muscle myosins. Muscle myosin 2 monomers exist in two states: one with a folded tail that interacts with the heads (10S) and one with an unfolded tail (6S). It has been thought that only unfolded monomers assemble into bipolar and side-polar (smooth muscle myosin) filaments. We now show by electron microscopy that, after 4 s of polymerization in vitro in both the presence (smooth muscle myosin) and absence of ATP, skeletal, cardiac, and smooth muscle myosins form tail-folded monomers without tail–head interaction, tail-folded antiparallel dimers, tail-folded antiparallel tetramers, unfolded bipolar tetramers, and small filaments. After 4 h, the myosins form thick bipolar and, for smooth muscle myosin, side-polar filaments. Nonphosphorylated smooth muscle myosin polymerizes in the presence of ATP but with a higher critical concentration than in the absence of ATP and forms only bipolar filaments with bare zones. Partial depolymerization in vitro of nonphosphorylated smooth muscle myosin filaments by the addition of MgATP is the reverse of polymerization.
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15
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Asensio-Juárez G, Llorente-González C, Vicente-Manzanares M. Linking the Landscape of MYH9-Related Diseases to the Molecular Mechanisms that Control Non-Muscle Myosin II-A Function in Cells. Cells 2020; 9:E1458. [PMID: 32545517 PMCID: PMC7348894 DOI: 10.3390/cells9061458] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/09/2020] [Accepted: 06/10/2020] [Indexed: 12/13/2022] Open
Abstract
The MYH9 gene encodes the heavy chain (MHCII) of non-muscle myosin II A (NMII-A). This is an actin-binding molecular motor essential for development that participates in many crucial cellular processes such as adhesion, cell migration, cytokinesis and polarization, maintenance of cell shape and signal transduction. Several types of mutations in the MYH9 gene cause an array of autosomal dominant disorders, globally known as MYH9-related diseases (MYH9-RD). These include May-Hegglin anomaly (MHA), Epstein syndrome (EPS), Fechtner syndrome (FTS) and Sebastian platelet syndrome (SPS). Although caused by different MYH9 mutations, all patients present macrothrombocytopenia, but may later display other pathologies, including loss of hearing, renal failure and presenile cataracts. The correlation between the molecular and cellular effects of the different mutations and clinical presentation are beginning to be established. In this review, we correlate the defects that MYH9 mutations cause at a molecular and cellular level (for example, deficient filament formation, altered ATPase activity or actin-binding) with the clinical presentation of the syndromes in human patients. We address why these syndromes are tissue restricted, and the existence of possible compensatory mechanisms, including residual activity of mutant NMII-A and/ or the formation of heteropolymers or co-polymers with other NMII isoforms.
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Affiliation(s)
| | | | - Miguel Vicente-Manzanares
- Molecular Mechanisms Program, Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC)-University of Salamanca, 37007 Salamanca, Spain; (G.A.-J.); (C.L.-G.)
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16
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Alvarado J, Cipelletti L, Koenderink GH. Uncovering the dynamic precursors to motor-driven contraction of active gels. SOFT MATTER 2019; 15:8552-8565. [PMID: 31637398 DOI: 10.1039/c9sm01172b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cells and tissues have the remarkable ability to actively generate the forces required to change their shape. This active mechanical behavior is largely mediated by the actin cytoskeleton, a crosslinked network of actin filaments that is contracted by myosin motors. Experiments and active gel theories have established that the length scale over which gel contraction occurs is governed by a balance between molecular motor activity and crosslink density. By contrast, the dynamics that govern the contractile activity of the cytoskeleton remain poorly understood. Here we investigate the microscopic dynamics of reconstituted actin-myosin networks using simultaneous real-space video microscopy and Fourier-space dynamic light scattering. Light scattering reveals different regimes of microscopic dynamics as a function of sample age. We uncover two dynamical precursors that precede macroscopic gel contraction. One is characterized by a progressive acceleration of stress-induced rearrangements, while the other consists of sudden, heterogeneous rearrangements. Intriguingly, our findings suggest a qualitative analogy between self-driven rupture and collapse of active gels and the delayed rupture of passive gels observed in earlier studies of colloidal gels under external loads.
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Affiliation(s)
- José Alvarado
- AMOLF, Living Matter Department, 1098 XG Amsterdam, The Netherlands.
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17
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Yang S, Lee KH, Woodhead JL, Sato O, Ikebe M, Craig R. The central role of the tail in switching off 10S myosin II activity. J Gen Physiol 2019; 151:1081-1093. [PMID: 31387899 PMCID: PMC6719407 DOI: 10.1085/jgp.201912431] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 07/08/2019] [Indexed: 01/06/2023] Open
Abstract
Myosin II is a motor protein with two heads and an extended tail that plays an essential role in cell motility. Its active form is a polymer (myosin filament) that pulls on actin to generate motion. Its inactive form is a monomer with a compact structure (10S sedimentation coefficient), in which the tail is folded and the two heads interact with each other, inhibiting activity. This conformation is thought to function in cells as an energy-conserving form of the molecule suitable for storage as well as transport to sites of filament assembly. The mechanism of inhibition of the compact molecule is not fully understood. We have performed a 3-D reconstruction of negatively stained 10S myosin from smooth muscle in the inhibited state using single-particle analysis. The reconstruction reveals multiple interactions between the tail and the two heads that appear to trap ATP hydrolysis products, block actin binding, hinder head phosphorylation, and prevent filament formation. Blocking these essential features of myosin function could explain the high degree of inhibition of the folded form of myosin thought to underlie its energy-conserving function in cells. The reconstruction also suggests a mechanism for unfolding when myosin is activated by phosphorylation.
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Affiliation(s)
- Shixin Yang
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
| | - Kyoung Hwan Lee
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
| | - John L Woodhead
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
| | - Osamu Sato
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, TX
| | - Mitsuo Ikebe
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, TX
| | - Roger Craig
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA
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18
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Vogt EJ, Tokuhiro K, Guo M, Dale R, Yang G, Shin SW, Movilla MJ, Shroff H, Dean J. Anchoring cortical granules in the cortex ensures trafficking to the plasma membrane for post-fertilization exocytosis. Nat Commun 2019; 10:2271. [PMID: 31118423 PMCID: PMC6531442 DOI: 10.1038/s41467-019-10171-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 04/24/2019] [Indexed: 01/13/2023] Open
Abstract
Following fertilization, cortical granules exocytose ovastacin, a metalloendopeptidase that cleaves ZP2 in the zona pellucida surrounding mouse eggs to prevent additional sperm binding. Using high- and super-resolution imaging with ovastacinmCherry as a fluorescent marker, we characterize cortical granule dynamics at single granule resolution in transgenic mouse eggs. Newly-developed imaging protocols provide an unprecedented view of vesicular dynamics near the plasma membrane in mouse eggs. We discover that cortical granule anchoring in the cortex is dependent on maternal MATER and document that myosin IIA is required for biphasic trafficking to the plasma membrane. We observe local clearance of cortical actin during exocytosis and determine that pharmacologic or genetic disruption of trafficking to the plasma membrane impairs secretion of cortical granules and results in polyspermy. Thus, the regulation of cortical granule dynamics at the cortex-plasma membrane interface is critical for exocytosis and the post-fertilization block to sperm binding that ensures monospermic fertilization.
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Affiliation(s)
- Edgar-John Vogt
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA
- Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Keizo Tokuhiro
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA
- Department of Genome Editing, Institute of Biomedical Science, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, Osaka, 573-1010, Japan
| | - Min Guo
- Section on High Resolution Optical Imaging, NIBIB, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ryan Dale
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA
- Bioinformatics and Scientific Programming Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Guanghui Yang
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Seung-Wook Shin
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Maria Jimenez Movilla
- Department of Cell Biology and Histology, Medical School, University of Murcia, IMIB, 30100, Murcia, Spain
| | - Hari Shroff
- Section on High Resolution Optical Imaging, NIBIB, National Institutes of Health, Bethesda, MD, 20892, USA
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jurrien Dean
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, 20892, USA.
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19
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Network Contractility During Cytokinesis-from Molecular to Global Views. Biomolecules 2019; 9:biom9050194. [PMID: 31109067 PMCID: PMC6572417 DOI: 10.3390/biom9050194] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/30/2019] [Accepted: 04/30/2019] [Indexed: 12/28/2022] Open
Abstract
Cytokinesis is the last stage of cell division, which partitions the mother cell into two daughter cells. It requires the assembly and constriction of a contractile ring that consists of a filamentous contractile network of actin and myosin. Network contractility depends on network architecture, level of connectivity and myosin motor activity, but how exactly is the contractile ring network organized or interconnected and how much it depends on motor activity remains unclear. Moreover, the contractile ring is not an isolated entity; rather, it is integrated into the surrounding cortex. Therefore, the mechanical properties of the cell cortex and cortical behaviors are expected to impact contractile ring functioning. Due to the complexity of the process, experimental approaches have been coupled to theoretical modeling in order to advance its global understanding. While earlier coarse-grained descriptions attempted to provide an integrated view of the process, recent models have mostly focused on understanding the behavior of an isolated contractile ring. Here we provide an overview of the organization and dynamics of the actomyosin network during cytokinesis and discuss existing theoretical models in light of cortical behaviors and experimental evidence from several systems. Our view on what is missing in current models and should be tested in the future is provided.
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20
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Shutova MS, Svitkina TM. Common and Specific Functions of Nonmuscle Myosin II Paralogs in Cells. BIOCHEMISTRY (MOSCOW) 2019; 83:1459-1468. [PMID: 30878021 DOI: 10.1134/s0006297918120040] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Various forms of cell motility critically depend on pushing, pulling, and resistance forces generated by the actin cytoskeleton. Whereas pushing forces largely depend on actin polymerization, pulling forces responsible for cell contractility and resistance forces maintaining the cell shape require interaction of actin filaments with the multivalent molecular motor myosin II. In contrast to muscle-specific myosin II paralogs, nonmuscle myosin II (NMII) functions in virtually all mammalian cells, where it executes numerous mechanical tasks. NMII is expressed in mammalian cells as a tissue-specific combination of three paralogs, NMIIA, NMIIB, and NMIIC. Despite overall similarity, these paralogs differ in their molecular properties, which allow them to play both unique and common roles. Importantly, the three paralogs can also cooperate with each other by mixing and matching their unique capabilities. Through specialization and cooperation, NMII paralogs together execute a great variety of tasks in many different cell types. Here, we focus on mammalian NMII paralogs and review novel aspects of their kinetics, regulation, and functions in cells from the perspective of how distinct features of the three myosin II paralogs adapt them to perform specialized and joint tasks in the cells.
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Affiliation(s)
- M S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - T M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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21
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Ecsédi P, Billington N, Pálfy G, Gógl G, Kiss B, Bulyáki É, Bodor A, Sellers JR, Nyitray L. Multiple S100 protein isoforms and C-terminal phosphorylation contribute to the paralog-selective regulation of nonmuscle myosin 2 filaments. J Biol Chem 2018; 293:14850-14867. [PMID: 30087119 PMCID: PMC6153290 DOI: 10.1074/jbc.ra118.004277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/06/2018] [Indexed: 12/27/2022] Open
Abstract
Nonmuscle myosin 2 (NM2) has three paralogs in mammals, NM2A, NM2B, and NM2C, which have both unique and overlapping functions in cell migration, formation of cell-cell adhesions, and cell polarity. Their assembly into homo- and heterotypic bipolar filaments in living cells is primarily regulated by phosphorylation of the N-terminally bound regulatory light chain. Here, we present evidence that the equilibrium between these filaments and single NM2A and NM2B molecules can be controlled via S100 calcium-binding protein interactions and phosphorylation at the C-terminal end of the heavy chains. Furthermore, we show that in addition to S100A4, other members of the S100 family can also mediate disassembly of homotypic NM2A filaments. Importantly, these proteins can selectively remove NM2A molecules from heterotypic filaments. We also found that tail phosphorylation (at Ser-1956 and Ser-1975) of NM2B by casein kinase 2, as well as phosphomimetic substitutions at sites targeted by protein kinase C (PKC) and transient receptor potential cation channel subfamily M member 7 (TRPM7), down-regulates filament assembly in an additive fashion. Tail phosphorylation of NM2A had a comparatively minor effect on filament stability. S100 binding and tail phosphorylation therefore preferentially disassemble NM2A and NM2B, respectively. These two distinct mechanisms are likely to contribute to the temporal and spatial sorting of the two NM2 paralogs within heterotypic filaments. The existence of multiple NM2A-depolymerizing S100 paralogs offers the potential for diverse regulatory inputs modulating NM2A filament disassembly in cells and provides functional redundancy under both physiological and pathological conditions.
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Affiliation(s)
| | - Neil Billington
- the Laboratory of Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Gyula Pálfy
- the Laboratory of Structural Chemistry and Biology, Institute of Chemistry, and
| | | | | | - Éva Bulyáki
- From the Department of Biochemistry
- the ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, 1117 Budapest, Hungary and
| | - Andrea Bodor
- the Laboratory of Structural Chemistry and Biology, Institute of Chemistry, and
| | - James R Sellers
- the Laboratory of Physiology, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
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22
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Abstract
The three mammalian nonmuscle myosin 2 (NM2) monomers, like all class 2 myosin monomers, are hexamers of two identical heavy (long) chains and two pairs of light (short) chains bound to the heavy chains. The heavy chains have an N-terminal globular motor domain (head) with actin-activated ATPase activity, a lever arm (neck) to which the two light chains bind, and a coiled-coil helical tail. Monomers polymerize into bipolar filaments, with globular heads at each end separated by a bare zone, by antiparallel association of their coiled-coil tails. NM2 filaments are highly dynamic in situ, frequently disassembling and reassembling at different locations within the cell where they are essential for multiple biological functions. Therefore, it is important to understand the mechanisms of filament polymerization and depolymerization. Monomers can exist in two states: folded and unfolded. It has been thought that unfolded monomers form antiparallel dimers that assemble into bipolar filaments. We now show that polymerization in vitro proceeds from folded monomers to folded antiparallel dimers to folded antiparallel tetramers that unfold forming antiparallel bipolar tetramers. Folded dimers and tetramers then associate with the unfolded tetramer and unfold, forming a mature bipolar filament consisting of multiple unfolded tetramers with an entwined bare zone. We also demonstrate that depolymerization is essentially the reverse of the polymerization process. These results will advance our understanding of NM2 filament dynamics in situ.
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23
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Shutova MS, Svitkina TM. Mammalian nonmuscle myosin II comes in three flavors. Biochem Biophys Res Commun 2018; 506:394-402. [PMID: 29550471 DOI: 10.1016/j.bbrc.2018.03.103] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/13/2018] [Indexed: 12/16/2022]
Abstract
Nonmuscle myosin II is an actin-based motor that executes numerous mechanical tasks in cells including spatiotemporal organization of the actin cytoskeleton, adhesion, migration, cytokinesis, tissue remodeling, and membrane trafficking. Nonmuscle myosin II is ubiquitously expressed in mammalian cells as a tissue-specific combination of three paralogs. Recent studies reveal novel specific aspects of their kinetics, intracellular regulation and functions. On the other hand, the three paralogs also can copolymerize and cooperate in cells. Here we review the recent advances from the prospective of how distinct features of the three myosin II paralogs adapt them to perform specialized and joint tasks in the cell.
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Affiliation(s)
- Maria S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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24
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Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals. Proc Natl Acad Sci U S A 2018; 115:E1991-E2000. [PMID: 29444861 DOI: 10.1073/pnas.1715247115] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Electron microscope studies have shown that the switched-off state of myosin II in muscle involves intramolecular interaction between the two heads of myosin and between one head and the tail. The interaction, seen in both myosin filaments and isolated molecules, inhibits activity by blocking actin-binding and ATPase sites on myosin. This interacting-heads motif is highly conserved, occurring in invertebrates and vertebrates, in striated, smooth, and nonmuscle myosin IIs, and in myosins regulated by both Ca2+ binding and regulatory light-chain phosphorylation. Our goal was to determine how early this motif arose by studying the structure of inhibited myosin II molecules from primitive animals and from earlier, unicellular species that predate animals. Myosin II from Cnidaria (sea anemones, jellyfish), the most primitive animals with muscles, and Porifera (sponges), the most primitive of all animals (lacking muscle tissue) showed the same interacting-heads structure as myosins from higher animals, confirming the early origin of the motif. The social amoeba Dictyostelium discoideum showed a similar, but modified, version of the motif, while the amoeba Acanthamoeba castellanii and fission yeast (Schizosaccharomyces pombe) showed no head-head interaction, consistent with the different sequences and regulatory mechanisms of these myosins compared with animal myosin IIs. Our results suggest that head-head/head-tail interactions have been conserved, with slight modifications, as a mechanism for regulating myosin II activity from the emergence of the first animals and before. The early origins of these interactions highlight their importance in generating the inhibited (relaxed) state of myosin in muscle and nonmuscle cells.
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