51
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Blebbistatin modulates prostatic cell growth and contrapctility through myosin II signaling. Clin Sci (Lond) 2018; 132:2189-2205. [PMID: 30279228 DOI: 10.1042/cs20180294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/13/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023]
Abstract
To investigate the effect of blebbistatin (BLEB, a selective myosin inhibitor) on regulating contractility and growth of prostate cells and to provide insight into possible mechanisms associated with these actions. BLEB was incubated with cell lines of BPH-1 and WPMY-1, and intraprostatically injected into rats. Cell growth was determined by flow cytometry, and in vitro organ bath studies were performed to explore muscle contractility. Smooth muscle (SM) myosin isoform (SM1/2, SM-A/B, and LC17a/b) expression was determined via competitive reverse transcriptase PCR. SM myosin heavy chain (MHC), non-muscle (NM) MHC isoforms (NMMHC-A and NMMHC-B), and proteins related to cell apoptosis were further analyzed via Western blotting. Masson's trichrome staining was applied to tissue sections. BLEB could dose-dependently trigger apoptosis and retard the growth of BPH-1 and WPMY-1. Consistent with in vitro effect, administration of BLEB to the prostate could decrease rat prostatic epithelial and SM cells via increased apoptosis. Western blotting confirmed the effects of BLEB on inducing apoptosis through a mechanism involving MLC20 dephosphorylation with down-regulation of Bcl-2 and up-regulation of BAX and cleaved caspase 3. Meanwhile, NMMHC-A and NMMHC-B, the downstream proteins of MLC20, were found significantly attenuated in BPH-1 and WPMY-1 cells, as well as rat prostate tissues. Additionally, BLEB decreased SM cell number and SM MHC expression, along with attenuated phenylephrine-induced contraction and altered prostate SMM isoform composition with up-regulation of SM-B and down-regulation of LC17a, favoring a faster contraction. Our novel data demonstrate BLEB regulated myosin expression and functional activity. The mechanism involved MLC20 dephosphorylation and altered SMM isoform composition.
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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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53
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Norwood Toro LE, Wang Y, Condeelis JS, Jones JG, Backer JM, Bresnick AR. Myosin-IIA heavy chain phosphorylation on S1943 regulates tumor metastasis. Exp Cell Res 2018; 370:273-282. [PMID: 29953877 PMCID: PMC6117828 DOI: 10.1016/j.yexcr.2018.06.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/22/2018] [Accepted: 06/23/2018] [Indexed: 12/18/2022]
Abstract
Nonmuscle myosin-IIA (NMHC-IIA) heavy chain phosphorylation has gained recognition as an important feature of myosin-II regulation. In previous work, we showed that phosphorylation on S1943 promotes myosin-IIA filament disassembly in vitro and enhances EGF-stimulated lamellipod extension of breast tumor cells. However, the contribution of NMHC-IIA S1943 phosphorylation to the modulation of invasive cellular behavior and metastasis has not been examined. Stable expression of phosphomimetic (S1943E) or non-phosphorylatable (S1943A) NMHC-IIA in breast cancer cells revealed that S1943 phosphorylation enhances invadopodia function, and is critical for matrix degradation in vitro and experimental metastasis in vivo. These studies demonstrate a novel link between NMHC-IIA S1943 phosphorylation, the regulation of extracellular matrix degradation and tumor cell invasion and metastasis.
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Affiliation(s)
- Laura E Norwood Toro
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - Yarong Wang
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - John S Condeelis
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Integrated Imaging Program, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - Joan G Jones
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Integrated Imaging Program, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States
| | - Jonathan M Backer
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States; Department of Molecular Pharmacology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States.
| | - Anne R Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, United States.
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54
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Lyle MA, Brozovich FV. HFpEF, a Disease of the Vasculature: A Closer Look at the Other Half. Mayo Clin Proc 2018; 93:1305-1314. [PMID: 30064827 DOI: 10.1016/j.mayocp.2018.05.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 04/12/2018] [Accepted: 05/04/2018] [Indexed: 12/31/2022]
Abstract
Patients with heart failure are commonly divided into those with reduced ejection fraction (EF<40%) and those with preserved ejection fraction (HFpEF; EF>50%). For heart failure with reduced EF, a number of therapies have been found to improve patient morbidity and mortality, and treatment is guideline based. However for patients with HFpEF, no treatment has been found to have clinical benefit. To objectively assess treatments for HFpEF, a comprehensive PubMed literature search was performed using the terms HFpEF, heart failure, smooth muscle, myosin, myosin phosphatase, and PKG (up to December 31, 2017), with an unbiased focus on pathophysiology, cell signaling, and therapy. This review provides evidence that could explain the lack of clinical benefit in treating patients with HFpEF with sildenafil and long-acting nitrates. Furthermore, the review highlights the vascular abnormalities present in patients with HFpEF, and these abnormalities of the vasculature could potentially contribute to the pathophysiology of HFpEF. Thus, focusing on HFpEF as a vascular disease could result in the development of novel and effective treatment paradigms.
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Affiliation(s)
- Melissa A Lyle
- Department of Cadiovascular Diseases, Mayo Clinic College of Medicine and Science, Rochester, MN
| | - Frank V Brozovich
- Department of Cadiovascular Diseases, Mayo Clinic College of Medicine and Science, Rochester, MN.
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55
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Martino F, Perestrelo AR, Vinarský V, Pagliari S, Forte G. Cellular Mechanotransduction: From Tension to Function. Front Physiol 2018; 9:824. [PMID: 30026699 PMCID: PMC6041413 DOI: 10.3389/fphys.2018.00824] [Citation(s) in RCA: 511] [Impact Index Per Article: 85.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/12/2018] [Indexed: 12/15/2022] Open
Abstract
Living cells are constantly exposed to mechanical stimuli arising from the surrounding extracellular matrix (ECM) or from neighboring cells. The intracellular molecular processes through which such physical cues are transformed into a biological response are collectively dubbed as mechanotransduction and are of fundamental importance to help the cell timely adapt to the continuous dynamic modifications of the microenvironment. Local changes in ECM composition and mechanics are driven by a feed forward interplay between the cell and the matrix itself, with the first depositing ECM proteins that in turn will impact on the surrounding cells. As such, these changes occur regularly during tissue development and are a hallmark of the pathologies of aging. Only lately, though, the importance of mechanical cues in controlling cell function (e.g., proliferation, differentiation, migration) has been acknowledged. Here we provide a critical review of the recent insights into the molecular basis of cellular mechanotransduction, by analyzing how mechanical stimuli get transformed into a given biological response through the activation of a peculiar genetic program. Specifically, by recapitulating the processes involved in the interpretation of ECM remodeling by Focal Adhesions at cell-matrix interphase, we revise the role of cytoskeleton tension as the second messenger of the mechanotransduction process and the action of mechano-responsive shuttling proteins converging on stage and cell-specific transcription factors. Finally, we give few paradigmatic examples highlighting the emerging role of malfunctions in cell mechanosensing apparatus in the onset and progression of pathologies.
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Affiliation(s)
- Fabiana Martino
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
| | - Ana R. Perestrelo
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
| | - Vladimír Vinarský
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
| | - Stefania Pagliari
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
| | - Giancarlo Forte
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
- Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland
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56
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Lecarpentier Y, Schussler O, Sakic A, Rincon-Garriz JM, Soulie P, Bochaton-Piallat ML, Kindler V. Human Bone Marrow Contains Mesenchymal Stromal Stem Cells That Differentiate In Vitro into Contractile Myofibroblasts Controlling T Lymphocyte Proliferation. Stem Cells Int 2018; 2018:6134787. [PMID: 29853916 PMCID: PMC5949154 DOI: 10.1155/2018/6134787] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 02/20/2018] [Accepted: 03/08/2018] [Indexed: 01/22/2023] Open
Abstract
Mesenchymal stromal stem cells (MSC) that reside in the bone marrow (BM) can be amplified in vitro. In 2-dimension (D) cultures, MSC exhibit a morphology similar to fibroblasts, are able to inhibit T lymphocyte and natural killer cell proliferation, and can be differentiated into adipocytes, chondrocytes, or osteoblasts if exposed to specific media. Here we show that medullar MSC cultured in 2D formed an adherent stroma of cells expressing well-organized microfilaments containing α-smooth muscle actin and nonmuscle myosin heavy chain IIA. MSC could be grown in 3D in collagen membranes generating a structure which, upon exposition to 50 mM KCl or to an alternating electric current, developed a contractile strength that averaged 34 and 45 μN/mm2, respectively. Such mechanical tension was similar in intensity and in duration to that of human placenta and was annihilated by isosorbide dinitrate or 2,3-butanedione monoxime. Membranes devoid of MSC did not exhibit a significant contractility. Moreover, MSC nested in collagen membranes were able to control T lymphocyte proliferation, and differentiated into adipocytes, chondrocytes, or osteoblasts. Our observations show that BM-derived MSC cultured in collagen membranes spontaneously differentiate into contractile myofibroblasts exhibiting unexpected properties in terms of cell differentiation potential and of immunomodulatory function.
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Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francillien, 77104 Meaux, France
| | - Olivier Schussler
- Department of Cardiovascular Surgery, Research Laboratory, University Hospitals, Faculty of Medicine, Geneva, Switzerland
| | - Antonija Sakic
- Department of Pathology and Immunology, Centre Médical Universitaire Geneva Faculty of Medicine, Geneva, Switzerland
| | - José Maria Rincon-Garriz
- Department of Specialties in Medicine, Hematology Service, Geneva University Hospitals, Faculty of Medicine, Geneva, Switzerland
| | - Priscilla Soulie
- Department of Histology, Centre Médical Universitaire Geneva Faculty of Medicine, Geneva, Switzerland
| | - Marie-Luce Bochaton-Piallat
- Department of Pathology and Immunology, Centre Médical Universitaire Geneva Faculty of Medicine, Geneva, Switzerland
| | - Vincent Kindler
- Department of Specialties in Medicine, Hematology Service, Geneva University Hospitals, Faculty of Medicine, Geneva, Switzerland
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57
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Kuragano M, Uyeda TQP, Kamijo K, Murakami Y, Takahashi M. Different contributions of nonmuscle myosin IIA and IIB to the organization of stress fiber subtypes in fibroblasts. Mol Biol Cell 2018; 29:911-922. [PMID: 29467250 PMCID: PMC5896930 DOI: 10.1091/mbc.e17-04-0215] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 02/14/2018] [Accepted: 02/16/2018] [Indexed: 12/25/2022] Open
Abstract
We demonstrated that myosin IIA and IIB are essential for the formation of transverse arcs and ventral stress fibers, respectively. Furthermore, we illustrated the roles of both isoforms in lamellar flattening and also raised the possibility that actin filaments in ventral stress fibers are in a stretched conformation.
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Affiliation(s)
- Masahiro Kuragano
- Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Taro Q. P. Uyeda
- Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan
| | - Keiju Kamijo
- Department of Anatomy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi 981-8558, Japan
| | - Yota Murakami
- Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Masayuki Takahashi
- Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
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58
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Melli L, Billington N, Sun SA, Bird JE, Nagy A, Friedman TB, Takagi Y, Sellers JR. Bipolar filaments of human nonmuscle myosin 2-A and 2-B have distinct motile and mechanical properties. eLife 2018; 7:32871. [PMID: 29419377 PMCID: PMC5829915 DOI: 10.7554/elife.32871] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/22/2018] [Indexed: 12/26/2022] Open
Abstract
Nonmusclemyosin 2 (NM-2) powers cell motility and tissue morphogenesis by assembling into bipolar filaments that interact with actin. Although the enzymatic properties of purified NM-2 motor fragments have been determined, the emergent properties of filament ensembles are unknown. Using single myosin filament in vitro motility assays, we report fundamental differences in filaments formed of different NM-2 motors. Filaments consisting of NM2-B moved processively along actin, while under identical conditions, NM2-A filaments did not. By more closely mimicking the physiological milieu, either by increasing solution viscosity or by co-polymerization with NM2-B, NM2-A containing filaments moved processively. Our data demonstrate that both the kinetic and mechanical properties of these two myosins, in addition to the stochiometry of NM-2 subunits, can tune filament mechanical output. We propose altering NM-2 filament composition is a general cellular strategy for tailoring force production of filaments to specific functions, such as maintaining tension or remodeling actin.
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Affiliation(s)
- Luca Melli
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Neil Billington
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Sara A Sun
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Jonathan E Bird
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Attila Nagy
- Vaccine Production Program Laboratory, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Gaithersburg, United States
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Yasuharu Takagi
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - James R Sellers
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
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59
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Cardiomyocytes Sense Matrix Rigidity through a Combination of Muscle and Non-muscle Myosin Contractions. Dev Cell 2018; 44:326-336.e3. [PMID: 29396114 PMCID: PMC5807060 DOI: 10.1016/j.devcel.2017.12.024] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 11/09/2017] [Accepted: 12/22/2017] [Indexed: 12/31/2022]
Abstract
Mechanical properties are cues for many biological processes in health or disease. In the heart, changes to the extracellular matrix composition and cross-linking result in stiffening of the cellular microenvironment during development. Moreover, myocardial infarction and cardiomyopathies lead to fibrosis and a stiffer environment, affecting cardiomyocyte behavior. Here, we identify that single cardiomyocyte adhesions sense simultaneous (fast oscillating) cardiac and (slow) non-muscle myosin contractions. Together, these lead to oscillating tension on the mechanosensitive adaptor protein talin on substrates with a stiffness of healthy adult heart tissue, compared with no tension on embryonic heart stiffness and continuous stretching on fibrotic stiffness. Moreover, we show that activation of PKC leads to the induction of cardiomyocyte hypertrophy in a stiffness-dependent way, through activation of non-muscle myosin. Finally, PKC and non-muscle myosin are upregulated at the costameres in heart disease, indicating aberrant mechanosensing as a contributing factor to long-term remodeling and heart failure. Talin in cardiomyocytes is unstretched, cyclically stretched, or continuously stretched Talin stretching depends on stiffness, myofibrillar tension, and non-myofibrillar tension Non-myofibrillar contractility requires PKC, Src, FHOD1, and non-muscle myosin PKC and non-muscle myosin activity are enhanced in cardiac disease
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60
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Wollrab V, Belmonte JM, Baldauf L, Leptin M, Nédeléc F, Koenderink GH. Polarity sorting drives remodeling of actin-myosin networks. J Cell Sci 2018; 132:jcs.219717. [DOI: 10.1242/jcs.219717] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 11/01/2018] [Indexed: 12/18/2022] Open
Abstract
Cytoskeletal networks of actin filaments and myosin motors drive many dynamic cell processes. A key characteristic of these networks is their contractility. Despite intense experimental and theoretical efforts, it is not clear what mechanism favors network contraction over expansion. Recent work points to a dominant role for the nonlinear mechanical response of actin filaments, which can withstand stretching but buckle upon compression. Here we present an alternative mechanism. We study how interactions between actin and myosin-2 at the single filament level translate into contraction at the network scale by performing time-lapse imaging on reconstituted quasi-2D-networks mimicking the cell cortex. We observe myosin end-dwelling after it runs processively along actin filaments. This leads to transport and clustering of actin filament ends and the formation of transiently stable bipolar structures. Further we show that myosin-driven polarity sorting produces polar actin asters, which act as contractile nodes that drive contraction in crosslinked networks. Computer simulations comparing the roles of the end-dwelling mechanism and a buckling-dependent mechanism show that the relative contribution of end-dwelling contraction increases as the network mesh-size decreases.
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Affiliation(s)
| | - Julio M. Belmonte
- EMBL, Cell Biology and Developmental Biology Unit and Director's Research Unit, Meyerhofstraße 1, Heidelberg, Germany
| | - Lucia Baldauf
- AMOLF, Science Park 104, 1098 XG Amsterdam, the Netherlands
| | - Maria Leptin
- EMBL, Cell Biology and Developmental Biology Unit and Director's Research Unit, Meyerhofstraße 1, Heidelberg, Germany
| | - François Nédeléc
- EMBL, Cell Biology and Developmental Biology Unit and Director's Research Unit, Meyerhofstraße 1, Heidelberg, Germany
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61
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Chinthalapudi K, Heissler SM, Preller M, Sellers JR, Manstein DJ. Mechanistic insights into the active site and allosteric communication pathways in human nonmuscle myosin-2C. eLife 2017; 6:32742. [PMID: 29256864 PMCID: PMC5749951 DOI: 10.7554/elife.32742] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/18/2017] [Indexed: 01/10/2023] Open
Abstract
Despite a generic, highly conserved motor domain, ATP turnover kinetics and their activation by F-actin vary greatly between myosin-2 isoforms. Here, we present a 2.25 Å pre-powerstroke state (ADP⋅VO4) crystal structure of the human nonmuscle myosin-2C motor domain, one of the slowest myosins characterized. In combination with integrated mutagenesis, ensemble-solution kinetics, and molecular dynamics simulation approaches, the structure reveals an allosteric communication pathway that connects the distal end of the motor domain with the active site. Disruption of this pathway by mutation of hub residue R788, which forms the center of a cluster of interactions connecting the converter, the SH1-SH2 helix, the relay helix, and the lever, abolishes nonmuscle myosin-2 specific kinetic signatures. Our results provide insights into structural changes in the myosin motor domain that are triggered upon F-actin binding and contribute critically to the mechanochemical behavior of stress fibers, actin arcs, and cortical actin-based structures.
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Affiliation(s)
- Krishna Chinthalapudi
- Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany.,Division for Structural Biochemistry, OE8830, Hannover Medical School, Hannover, Germany.,Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States
| | - Sarah M Heissler
- Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany.,Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, United States
| | - Matthias Preller
- Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany.,Centre for Structural Systems Biology (CSSB), German Electron Synchrotron (DESY), Hamburg, Germany
| | - James R Sellers
- Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, United States
| | - Dietmar J Manstein
- Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany.,Division for Structural Biochemistry, OE8830, Hannover Medical School, Hannover, Germany
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62
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Vallée A, Lecarpentier Y, Vallée JN. Thermodynamic Aspects and Reprogramming Cellular Energy Metabolism during the Fibrosis Process. Int J Mol Sci 2017; 18:ijms18122537. [PMID: 29186898 PMCID: PMC5751140 DOI: 10.3390/ijms18122537] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/10/2017] [Accepted: 11/21/2017] [Indexed: 01/06/2023] Open
Abstract
Fibrosis is characterized by fibroblast proliferation and fibroblast differentiation into myofibroblasts, which generate a relaxation-free contraction mechanism associated with excessive collagen synthesis in the extracellular matrix, which promotes irreversible tissue retraction evolving towards fibrosis. From a thermodynamic point of view, the mechanisms leading to fibrosis are irreversible processes that can occur through changing the entropy production rate. The thermodynamic behaviors of metabolic enzymes involved in fibrosis are modified by the dysregulation of both transforming growth factor β (TGF-β) signaling and the canonical WNT/β-catenin pathway, leading to aerobic glycolysis, called the Warburg effect. Molecular signaling pathways leading to fibrosis are considered dissipative structures that exchange energy or matter with their environment far from the thermodynamic equilibrium. The myofibroblastic cells arise from exergonic processes by switching the core metabolism from oxidative phosphorylation to glycolysis, which generates energy and reprograms cellular energy metabolism to induce the process of myofibroblast differentiation. Circadian rhythms are far-from-equilibrium thermodynamic processes. They directly participate in regulating the TGF-β and WNT/β-catenin pathways involved in energetic dysregulation and enabling fibrosis. The present review focusses on the thermodynamic implications of the reprogramming of cellular energy metabolism, leading to fibroblast differentiation into myofibroblasts through the positive interplay between TGF-β and WNT/β-catenin pathways underlying in fibrosis.
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Affiliation(s)
- Alexandre Vallée
- Laboratory of Mathematics and Applications (LMA), DACTIM, UMR CNRS 7348, CHU de Poitiers and University of Poitiers, 86021 Poitiers, France.
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), 77100 Meaux, France.
| | - Jean-Noël Vallée
- Laboratory of Mathematics and Applications (LMA), DACTIM, UMR CNRS 7348, CHU de Poitiers and University of Poitiers, 86021 Poitiers, France.
- CHU Amiens Picardie, University of Picardie Jules Verne (UPJV), 80025 Amiens, France.
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63
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Lecarpentier Y, Schussler O, Claes V, Vallée A. The Myofibroblast: TGFβ-1, A Conductor which Plays a Key Role in Fibrosis by Regulating the Balance between PPARγ and the Canonical WNT Pathway. NUCLEAR RECEPTOR RESEARCH 2017. [DOI: 10.11131/2017/101299] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l’Est Francilien (GHEP), Meaux, France
| | - Olivier Schussler
- Department of Cardiovascular Surgery, Cardiovascular Research Laboratory, HUG/CMU, Geneva, Switzerland
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France
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64
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Vallée A, Lecarpentier Y, Guillevin R, Vallée JN. Interactions between TGF-β1, canonical WNT/β-catenin pathway and PPAR γ in radiation-induced fibrosis. Oncotarget 2017; 8:90579-90604. [PMID: 29163854 PMCID: PMC5685775 DOI: 10.18632/oncotarget.21234] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 08/17/2017] [Indexed: 12/16/2022] Open
Abstract
Radiation therapy induces DNA damage and inflammation leading to fibrosis. Fibrosis can occur 4 to 12 months after radiation therapy. This process worsens with time and years. Radiation-induced fibrosis is characterized by fibroblasts proliferation, myofibroblast differentiation, and synthesis of collagen, proteoglycans and extracellular matrix. Myofibroblasts are non-muscle cells that can contract and relax. Myofibroblasts evolve towards irreversible retraction during fibrosis process. In this review, we discussed the interplays between transforming growth factor-β1 (TGF-β1), canonical WNT/β-catenin pathway and peroxisome proliferator-activated receptor gamma (PPAR γ) in regulating the molecular mechanisms underlying the radiation-induced fibrosis, and the potential role of PPAR γ agonists. Overexpression of TGF-β and canonical WNT/β-catenin pathway stimulate fibroblasts accumulation and myofibroblast differentiation whereas PPAR γ expression decreases due to the opposite interplay of canonical WNT/β-catenin pathway. Both TGF-β1 and canonical WNT/β-catenin pathway stimulate each other through the Smad pathway and non-Smad pathways such as phosphatidylinositol 3-kinase/serine/threonine kinase (PI3K/Akt) signaling. WNT/β-catenin pathway and PPAR γ interact in an opposite manner. PPAR γ agonists decrease β-catenin levels through activation of inhibitors of the WNT pathway such as Smad7, glycogen synthase kinase-3 (GSK-3 β) and dickkopf-related protein 1 (DKK1). PPAR γ agonists also stimulate phosphatase and tensin homolog (PTEN) expression, which decreases both TGF-β1 and PI3K/Akt pathways. PPAR γ agonists by activating Smad7 decrease Smads pathway and then TGF-β signaling leading to decrease radiation-induced fibrosis. TGF-β1 and canonical WNT/β-catenin pathway promote radiation-induced fibrosis whereas PPAR γ agonists can prevent radiation-induced fibrosis.
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Affiliation(s)
- Alexandre Vallée
- Experimental and Clinical Neurosciences Laboratory, INSERM U1084, University of Poitiers, Poitiers, France.,Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, Poitiers, France
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), Meaux, France
| | - Rémy Guillevin
- DACTIM, UMR CNRS 7348, University of Poitiers et CHU de Poitiers, Poitiers, France
| | - Jean-Noël Vallée
- Laboratory of Mathematics and Applications (LMA), UMR CNRS 7348, University of Poitiers, Poitiers, France.,CHU Amiens Picardie, University of Picardie Jules Verne (UPJV), Amiens, France
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65
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Alvarado J, Sheinman M, Sharma A, MacKintosh FC, Koenderink GH. Force percolation of contractile active gels. SOFT MATTER 2017; 13:5624-5644. [PMID: 28812094 DOI: 10.1039/c7sm00834a] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Living systems provide a paradigmatic example of active soft matter. Cells and tissues comprise viscoelastic materials that exert forces and can actively change shape. This strikingly autonomous behavior is powered by the cytoskeleton, an active gel of semiflexible filaments, crosslinks, and molecular motors inside cells. Although individual motors are only a few nm in size and exert minute forces of a few pN, cells spatially integrate the activity of an ensemble of motors to produce larger contractile forces (∼nN and greater) on cellular, tissue, and organismal length scales. Here we review experimental and theoretical studies on contractile active gels composed of actin filaments and myosin motors. Unlike other active soft matter systems, which tend to form ordered patterns, actin-myosin systems exhibit a generic tendency to contract. Experimental studies of reconstituted actin-myosin model systems have long suggested that a mechanical interplay between motor activity and the network's connectivity governs this contractile behavior. Recent theoretical models indicate that this interplay can be understood in terms of percolation models, extended to include effects of motor activity on the network connectivity. Based on concepts from percolation theory, we propose a state diagram that unites a large body of experimental observations. This framework provides valuable insights into the mechanisms that drive cellular shape changes and also provides design principles for synthetic active materials.
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Affiliation(s)
- José Alvarado
- Systems Biophysics Department, AMOLF, 1098 XG Amsterdam, The Netherlands.
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66
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Lyle MA, Davis JP, Brozovich FV. Regulation of Pulmonary Vascular Smooth Muscle Contractility in Pulmonary Arterial Hypertension: Implications for Therapy. Front Physiol 2017; 8:614. [PMID: 28878690 PMCID: PMC5572347 DOI: 10.3389/fphys.2017.00614] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/09/2017] [Indexed: 12/23/2022] Open
Abstract
There are two primary components that produce pulmonary arterial hypertension (PAH); aberrant structural changes (smooth muscle cell proliferation, smooth muscle cell hypertrophy, and the deposition of matrix proteins within the media of pulmonary arterial vessels), and excess vasoconstriction. However, in PAH, the target and aim of all current therapeutic agents is to reduce the contractility of the pulmonary vasculature; prostaglandins, phosphodiesterase inhibitors, guanylate cyclase stimulators, endothelin antagonists, NO inhalation and Rho kinase inhibitors all influence signaling pathways in the pulmonary vascular smooth muscle to decrease vasoconstriction, and hence, pulmonary vascular resistance (PVR). This review will therefore primarily focus on discussing the signaling pathways regulating contractility in pulmonary vascular smooth muscle, the mechanism for current treatments, as well as highlighting potential targets for the development of novel therapies.
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Affiliation(s)
- Melissa A Lyle
- Department of Cardiovascular Diseases, Mayo ClinicRochester, MN, United States
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, Ohio State UniversityColumbus, OH, United States
| | - Frank V Brozovich
- Department of Cardiovascular Diseases, Mayo ClinicRochester, MN, United States
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67
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Effect of ATP and regulatory light-chain phosphorylation on the polymerization of mammalian nonmuscle myosin II. Proc Natl Acad Sci U S A 2017; 114:E6516-E6525. [PMID: 28739905 DOI: 10.1073/pnas.1702375114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Addition of 1 mM ATP substantially reduces the light scattering of solutions of polymerized unphosphorylated nonmuscle myosin IIs (NM2s), and this is reversed by phosphorylation of the regulatory light chain (RLC). It has been proposed that these changes result from substantial depolymerization of unphosphorylated NM2 filaments to monomers upon addition of ATP, and filament repolymerization upon RLC-phosphorylation. We now show that the differences in myosin monomer concentration of RLC-unphosphorylated and -phosphorylated recombinant mammalian NM2A, NM2B, and NM2C polymerized in the presence of ATP are much too small to explain their substantial differences in light scattering. Rather, we find that the decrease in light scattering upon addition of ATP to polymerized unphosphorylated NM2s correlates with the formation of dimers, tetramers, and hexamers, in addition to monomers, an increase in length, and decrease in width of the bare zones of RLC-unphosphorylated filaments. Both effects of ATP addition are reversed by phosphorylation of the RLC. Our data also suggest that, contrary to previous models, assembly of RLC-phosphorylated NM2s at physiological ionic strength proceeds from folded monomers to folded antiparallel dimers, tetramers, and hexamers that unfold and polymerize into antiparallel filaments. This model could explain the dynamic relocalization of NM2 filaments in vivo by dephosphorylation of RLC-phosphorylated filaments, disassembly of the dephosphorylated filaments to folded monomers, dimers, and small oligomers, followed by diffusion of these species, and reassembly of filaments at the new location following rephosphorylation of the RLC.
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68
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Milberg O, Shitara A, Ebrahim S, Masedunskas A, Tora M, Tran DT, Chen Y, Conti MA, Adelstein RS, Ten Hagen KG, Weigert R. Concerted actions of distinct nonmuscle myosin II isoforms drive intracellular membrane remodeling in live animals. J Cell Biol 2017; 216:1925-1936. [PMID: 28600434 PMCID: PMC5496622 DOI: 10.1083/jcb.201612126] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 04/02/2017] [Accepted: 05/02/2017] [Indexed: 12/11/2022] Open
Abstract
Membrane remodeling plays a fundamental role during a variety of biological events. However, the dynamics and the molecular mechanisms regulating this process within cells in mammalian tissues in situ remain largely unknown. In this study, we use intravital subcellular microscopy in live mice to study the role of the actomyosin cytoskeleton in driving the remodeling of membranes of large secretory granules, which are integrated into the plasma membrane during regulated exocytosis. We show that two isoforms of nonmuscle myosin II, NMIIA and NMIIB, control distinct steps of the integration process. Furthermore, we find that F-actin is not essential for the recruitment of NMII to the secretory granules but plays a key role in the assembly and activation of NMII into contractile filaments. Our data support a dual role for the actomyosin cytoskeleton in providing the mechanical forces required to remodel the lipid bilayer and serving as a scaffold to recruit key regulatory molecules.
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Affiliation(s)
- Oleg Milberg
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Akiko Shitara
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD.,Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Seham Ebrahim
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Andrius Masedunskas
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD.,School of Medical Sciences, University of New South Wales, Sidney, Australia
| | - Muhibullah Tora
- Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
| | - Duy T Tran
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | - Yun Chen
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Mary Anne Conti
- Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Robert S Adelstein
- Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | - Kelly G Ten Hagen
- Developmental Glycobiology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | - Roberto Weigert
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD .,Intracellular Membrane Trafficking Section, National Institutes of Health, Bethesda, MD
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69
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Dey SK, Singh RK, Chattoraj S, Saha S, Das A, Bhattacharyya K, Sengupta K, Sen S, Jana SS. Differential role of nonmuscle myosin II isoforms during blebbing of MCF-7 cells. Mol Biol Cell 2017; 28:1034-1042. [PMID: 28251924 PMCID: PMC5391180 DOI: 10.1091/mbc.e16-07-0524] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 01/26/2017] [Accepted: 02/21/2017] [Indexed: 11/21/2022] Open
Abstract
One molecular cue that regulates cellular protrusions such as blebbing and lamellipodia in tumor cells has been less explored than other environmental factors. NM II-A induces blebbing and NM II-C1 induces lamellipodia in tumor cells. NM-II isoforms can change the protrusive activity of a tumor cell. Bleb formation has been correlated with nonmuscle myosin II (NM-II) activity. Whether three isoforms of NM-II (NM-IIA, -IIB and -IIC) have the same or differential roles in bleb formation is not well understood. Here we report that ectopically expressed, GFP-tagged NM-II isoforms exhibit different types of membrane protrusions, such as multiple blebs, lamellipodia, combinations of both, or absence of any such protrusions in MCF-7 cells. Quantification suggests that 50% of NM-IIA-GFP–, 29% of NM-IIB-GFP–, and 19% of NM-IIC1-GFP–expressing MCF-7 cells show multiple bleb formation, compared with 36% of cells expressing GFP alone. Of interest, NM-IIB has an almost 50% lower rate of dissociation from actin filament than NM-IIA and –IIC1 as determined by FRET analysis both at cell and bleb cortices. We induced bleb formation by disruption of the cortex and found that all three NM-II-GFP isoforms can reappear and form filaments but to different degrees in the growing bleb. NM-IIB-GFP can form filaments in blebs in 41% of NM-IIB-GFP–expressing cells, whereas filaments form in only 12 and 3% of cells expressing NM-IIA-GFP and NM-IIC1-GFP, respectively. These studies suggest that NM-II isoforms have differential roles in the bleb life cycle.
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Affiliation(s)
- Sumit K Dey
- Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Raman K Singh
- Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Shyamtanu Chattoraj
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Shekhar Saha
- Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Alakesh Das
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Kankan Bhattacharyya
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Kaushik Sengupta
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India
| | - Shamik Sen
- Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Siddhartha S Jana
- Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
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70
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Baird MA, Billington N, Wang A, Adelstein RS, Sellers JR, Fischer RS, Waterman CM. Local pulsatile contractions are an intrinsic property of the myosin 2A motor in the cortical cytoskeleton of adherent cells. Mol Biol Cell 2017; 28:240-251. [PMID: 27881665 PMCID: PMC5231893 DOI: 10.1091/mbc.e16-05-0335] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 11/02/2016] [Accepted: 11/18/2016] [Indexed: 01/03/2023] Open
Abstract
The role of nonmuscle myosin 2 (NM2) pulsatile dynamics in generating contractile forces required for developmental morphogenesis has been characterized, but whether these pulsatile contractions are an intrinsic property of all actomyosin networks is not known. Here we used live-cell fluorescence imaging to show that transient, local assembly of NM2A "pulses" occurs in the cortical cytoskeleton of single adherent cells of mesenchymal, epithelial, and sarcoma origin, independent of developmental signaling cues and cell-cell or cell-ECM interactions. We show that pulses in the cortical cytoskeleton require Rho-associated kinase- or myosin light chain kinase (MLCK) activity, increases in cytosolic calcium, and NM2 ATPase activity. Surprisingly, we find that cortical cytoskeleton pulses specifically require the head domain of NM2A, as they do not occur with either NM2B or a 2B-head-2A-tail chimera. Our results thus suggest that pulsatile contractions in the cortical cytoskeleton are an intrinsic property of the NM2A motor that may mediate its role in homeostatic maintenance of tension in the cortical cytoskeleton of adherent cells.
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Affiliation(s)
- Michelle A Baird
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Neil Billington
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Aibing Wang
- Genetics and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China
| | - Robert S Adelstein
- Genetics and Developmental Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - James R Sellers
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Robert S Fischer
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Clare M Waterman
- Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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71
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Erdmann T, Bartelheimer K, Schwarz US. Sensitivity of small myosin II ensembles from different isoforms to mechanical load and ATP concentration. Phys Rev E 2016; 94:052403. [PMID: 27967122 DOI: 10.1103/physreve.94.052403] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Indexed: 02/02/2023]
Abstract
Based on a detailed crossbridge model for individual myosin II motors, we systematically study the influence of mechanical load and adenosine triphosphate (ATP) concentration on small myosin II ensembles made from different isoforms. For skeletal and smooth muscle myosin II, which are often used in actomyosin gels that reconstitute cell contractility, fast forward movement is restricted to a small region of phase space with low mechanical load and high ATP concentration, which is also characterized by frequent ensemble detachment. At high load, these ensembles are stalled or move backwards, but forward motion can be restored by decreasing ATP concentration. In contrast, small ensembles of nonmuscle myosin II isoforms, which are found in the cytoskeleton of nonmuscle cells, are hardly affected by ATP concentration due to the slow kinetics of the bound states. For all isoforms, the thermodynamic efficiency of ensemble movement increases with decreasing ATP concentration, but this effect is weaker for the nonmuscle myosin II isoforms.
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Affiliation(s)
- Thorsten Erdmann
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
| | - Kathrin Bartelheimer
- 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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72
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Highly selective inhibition of myosin motors provides the basis of potential therapeutic application. Proc Natl Acad Sci U S A 2016; 113:E7448-E7455. [PMID: 27815532 DOI: 10.1073/pnas.1609342113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Direct inhibition of smooth muscle myosin (SMM) is a potential means to treat hypercontractile smooth muscle diseases. The selective inhibitor CK-2018571 prevents strong binding to actin and promotes muscle relaxation in vitro and in vivo. The crystal structure of the SMM/drug complex reveals that CK-2018571 binds to a novel allosteric pocket that opens up during the "recovery stroke" transition necessary to reprime the motor. Trapped in an intermediate of this fast transition, SMM is inhibited with high selectivity compared with skeletal muscle myosin (IC50 = 9 nM and 11,300 nM, respectively), although all of the binding site residues are identical in these motors. This structure provides a starting point from which to design highly specific myosin modulators to treat several human diseases. It further illustrates the potential of targeting transition intermediates of molecular machines to develop exquisitely selective pharmacological agents.
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73
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Abstract
Mechanotransduction is the process through which cells survey the mechanical properties of their environment, convert these mechanical inputs into biochemical signals, and modulate their phenotype in response. These mechanical inputs, which may be encoded in the form of extracellular matrix stiffness, dimensionality, and adhesion, all strongly influence cell morphology, migration, and fate decisions. One mechanism through which cells on planar or pseudo-planar matrices exert tensile forces and interrogate microenvironmental mechanics is through stress fibers, which are bundles composed of actin filaments and, in most cases, non-muscle myosin II filaments. Stress fibers form a continuous structural network that is mechanically coupled to the extracellular matrix through focal adhesions. Furthermore, myosin-driven contractility plays a central role in the ability of stress fibers to sense matrix mechanics and generate tension. Here, we review the distinct roles that non-muscle myosin II plays in driving mechanosensing and focus specifically on motility. In a closely related discussion, we also describe stress fiber classification schemes and the differing roles of various myosin isoforms in each category. Finally, we briefly highlight recent studies exploring mechanosensing in three-dimensional environments, in which matrix content, structure, and mechanics are often tightly interrelated. Stress fibers and the myosin motors therein represent an intriguing and functionally important biological system in which mechanics, biochemistry, and architecture all converge.
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Affiliation(s)
- Stacey Lee
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Sanjay Kumar
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
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74
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Bai H, Zhu Q, Surcel A, Luo T, Ren Y, Guan B, Liu Y, Wu N, Joseph NE, Wang TL, Zhang N, Pan D, Alpini G, Robinson DN, Anders RA. Yes-associated protein impacts adherens junction assembly through regulating actin cytoskeleton organization. Am J Physiol Gastrointest Liver Physiol 2016; 311:G396-411. [PMID: 27229120 PMCID: PMC5076009 DOI: 10.1152/ajpgi.00027.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/11/2016] [Indexed: 01/31/2023]
Abstract
The Hippo pathway effector Yes-associated protein (YAP) regulates liver size by promoting cell proliferation and inhibiting apoptosis. However, recent in vivo studies suggest that YAP has important cellular functions other than controlling proliferation and apoptosis. Transgenic YAP expression in mouse hepatocytes results in severe jaundice. A possible explanation for the jaundice could be defects in adherens junctions that prevent bile from leaking into the blood stream. Indeed, immunostaining of E-cadherin and electron microscopic examination of bile canaliculi of Yap transgenic livers revealed abnormal adherens junction structures. Using primary hepatocytes from Yap transgenic livers and Yap knockout livers, we found that YAP antagonizes E-cadherin-mediated cell-cell junction assembly by regulating the cellular actin architecture, including its mechanical properties (elasticity and cortical tension). Mechanistically, we found that YAP promoted contractile actin structure formation by upregulating nonmuscle myosin light chain expression and cellular ATP generation. Thus, by modulating actomyosin organization, YAP may influence many actomyosin-dependent cellular characteristics, including adhesion, membrane protrusion, spreading, morphology, and cortical tension and elasticity, which in turn determine cell differentiation and tissue morphogenesis.
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Affiliation(s)
- Haibo Bai
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Qingfeng Zhu
- 2Institute of Biomedical Sciences (IBS), Fudan University, Shanghai, People's Republic of China; and Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Alexandra Surcel
- 3Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Tianzhi Luo
- 3Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Yixin Ren
- 3Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Bin Guan
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Ying Liu
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Nan Wu
- 6Research, Central Texas Veterans Health Care System, Temple, Texas; Department of Medicine, Division of Gastroenterology, Texas A&M Health Science Center College of Medicine, Temple, Texas; and Baylor Scott & White Health Digestive Disease Research Center, Temple, Texas
| | - Nora Eve Joseph
- 5Department of Pathology, University of Chicago, Chicago, Illinois; and
| | - Tian -Li Wang
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| | - Nailing Zhang
- 4Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Duojia Pan
- 4Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Gianfranco Alpini
- 6Research, Central Texas Veterans Health Care System, Temple, Texas; Department of Medicine, Division of Gastroenterology, Texas A&M Health Science Center College of Medicine, Temple, Texas; and Baylor Scott & White Health Digestive Disease Research Center, Temple, Texas
| | - Douglas N. Robinson
- 3Department of Cell Biology, Johns Hopkins School of Medicine, Baltimore, Maryland;
| | - Robert A. Anders
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland;
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75
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Bondzie PA, Chen HA, Cao MZ, Tomolonis JA, He F, Pollak MR, Henderson JM. Non-muscle myosin-IIA is critical for podocyte f-actin organization, contractility, and attenuation of cell motility. Cytoskeleton (Hoboken) 2016; 73:377-95. [PMID: 27232264 DOI: 10.1002/cm.21313] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 05/20/2016] [Accepted: 05/25/2016] [Indexed: 12/12/2022]
Abstract
Several glomerular pathologies resulting from podocyte injury are linked to genetic variation involving the MYH9 gene, which encodes the heavy chain of non-muscle myosin-IIA (NM-IIA). However, the functional role of NM-IIA has not been studied extensively in podocytes. We hypothesized that NM-IIA is critical for maintenance of podocyte structure and mechanical function. To test this hypothesis, we studied murine podocytes in vitro subjected to blebbistatin inhibition of NM-II activity, or RNA interference-mediated, isoform-specific ablation of Myh9 gene and protein (NM-IIA) or its paralog Myh10 gene and protein (NM-IIB). Using quantitative immunofluorescence microscopy, traction force microscopy, and attachment and "wound healing" assays, we found that NM-IIA ablation altered podocyte actin cytoskeletal structure and focal adhesion distribution, decreased cell attachment and contractility, and increased cell motility. Blebbistatin treatment had similar effects. NM-IIB ablation produced cells that exhibited poor attachment, but cytoskeletal structural organization, contractility and motility were maintained. These findings indicate that NM-IIA is essential for maintenance of podocyte cytoskeletal structure and mechanical function in vitro, and NM-IIB does not replace it in this role when NM-IIA expression is altered. We conclude that critical podocyte functions may be affected by MYH9 mutations or disease-associated haplotypes. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Philip A Bondzie
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Hui A Chen
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Mei Zhen Cao
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Julie A Tomolonis
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
| | - Fangfang He
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Martin R Pollak
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Joel M Henderson
- Department of Pathology and Laboratory Medicine, Boston Medical Center, Boston University School of Medicine, Boston, Massachusetts
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76
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Atluri K, De Jesus AM, Chinnathambi S, Brouillette MJ, Martin JA, Salem AK, Sander EA. Blebbistatin-Loaded Poly(d,l-lactide- co-glycolide) Particles For Treating Arthrofibrosis. ACS Biomater Sci Eng 2016; 2:1097-1107. [PMID: 33445238 DOI: 10.1021/acsbiomaterials.6b00082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Joint immobility is a debilitating complication of articular trauma that is characterized by thickening and stiffening of the joint capsule and the formation of fibrotic lesions inside joints. Capsule release surgery can temporarily restore mobility, but contraction often recurs due to the contractile activities of fibroblasts, which exert tension on the capsule ECM via nonmuscle myosin II. Based on these findings we hypothesized that blebbistatin, a drug that reversibly inhibits the activity of this protein, would relax ECM tension imposed by fibroblasts and reduce fibrosis. In this study, we characterized the effectiveness of blebbistatin as an anticontractile treatment. Given that sustained suppression of contractile activity may be required to achieve capsule release and reduce fibrosis, we compared the effects on fibroblast-mediated collagen ECM displacement of blebbistatin-loaded poly(lactide-co-gylcolide) (PLGA) particles versus bolus blebbistatin dosing. Time-lapse imaging of fluorescent microspheres embedded in collagen gels confirmed that PLGA/blebbistatin inhibited force generation and reduced both gel displacement and rate of displacement. In addition, collagen production at 10 days was significantly reduced. Taken together, these data indicate that blebbistatin-loaded PLGA particles can be used to inhibit fibroblast force-generation and reduce collagen production and lay the foundation for optimization of drug delivery technology for treating arthrofibrosis.
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Affiliation(s)
- K Atluri
- Division of Pharmaceutics and Translational Therapeutics, University of Iowa College of Pharmacy, 115 South Grand Avenue, Iowa City, Iowa 52242, United States
| | - A M De Jesus
- Department of Biomedical Engineering, University of Iowa College of Engineering, 1402 Seamans Center, Iowa City, Iowa 52242, United States
| | - S Chinnathambi
- Department of Biomedical Engineering, University of Iowa College of Engineering, 1402 Seamans Center, Iowa City, Iowa 52242, United States
| | - M J Brouillette
- Department of Orthopaedics and Rehabilitation, University of Iowa Roy J and Lucille A Carver College of Medicine, 25 South Grand Avenue, Iowa City, Iowa 52242, United States
| | - J A Martin
- Department of Orthopaedics and Rehabilitation, University of Iowa Roy J and Lucille A Carver College of Medicine, 25 South Grand Avenue, Iowa City, Iowa 52242, United States
| | - A K Salem
- Division of Pharmaceutics and Translational Therapeutics, University of Iowa College of Pharmacy, 115 South Grand Avenue, Iowa City, Iowa 52242, United States.,Department of Biomedical Engineering, University of Iowa College of Engineering, 1402 Seamans Center, Iowa City, Iowa 52242, United States
| | - E A Sander
- Department of Biomedical Engineering, University of Iowa College of Engineering, 1402 Seamans Center, Iowa City, Iowa 52242, United States
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77
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Greenberg MJ, Arpağ G, Tüzel E, Ostap EM. A Perspective on the Role of Myosins as Mechanosensors. Biophys J 2016; 110:2568-2576. [PMID: 27332116 PMCID: PMC4919425 DOI: 10.1016/j.bpj.2016.05.021] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 04/13/2016] [Accepted: 05/16/2016] [Indexed: 11/26/2022] Open
Abstract
Cells are dynamic systems that generate and respond to forces over a range of spatial and temporal scales, spanning from single molecules to tissues. Substantial progress has been made in recent years in identifying the molecules and pathways responsible for sensing and transducing mechanical signals to short-term cellular responses and longer-term changes in gene expression, cell identity, and tissue development. In this perspective article, we focus on myosin motors, as they not only function as the primary force generators in well-studied mechanobiological processes, but also act as key mechanosensors in diverse functions including intracellular transport, signaling, cell migration, muscle contraction, and sensory perception. We discuss how the biochemical and mechanical properties of different myosin isoforms are tuned to fulfill these roles in an array of cellular processes, and we highlight the underappreciated diversity of mechanosensing properties within the myosin superfamily. In particular, we use modeling and simulations to make predictions regarding how diversity in force sensing affects the lifetime of the actomyosin bond, the myosin power output, and the ability of myosin to respond to a perturbation in force for several nonprocessive myosin isoforms.
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Affiliation(s)
- Michael J Greenberg
- Biochemistry and Molecular Biophysics, Washington University, St. Louis, Missouri
| | - Göker Arpağ
- Worcester Polytechnic Institute, Worcester, Massachusetts
| | - Erkan Tüzel
- Worcester Polytechnic Institute, Worcester, Massachusetts
| | - E Michael Ostap
- Pennsylvania Muscle Institute and Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
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78
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Kruppa AJ, Kendrick-Jones J, Buss F. Myosins, Actin and Autophagy. Traffic 2016; 17:878-90. [PMID: 27146966 PMCID: PMC4957615 DOI: 10.1111/tra.12410] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 12/20/2022]
Abstract
Myosin motor proteins working together with the actin cytoskeleton drive a wide range of cellular processes. In this review, we focus on their roles in autophagy – the pathway the cell uses to ensure homeostasis by targeting pathogens, misfolded proteins and damaged organelles for degradation. The actin cytoskeleton regulated by a host of nucleating, anchoring and stabilizing proteins provides the filament network for the delivery of essential membrane vesicles from different cellular compartments to the autophagosome. Actin networks have also been implicated in structurally supporting the expanding phagophore, moving autophagosomes and enabling efficient fusion with the lysosome. Only a few myosins have so far been shown to play a role in autophagy. Non‐muscle myosin IIA functions in the early stages delivering membrane for the initial formation of the autophagosome, whereas myosin IC and myosin VI are involved in the final stages providing specific membranes for autophagosome maturation and its fusion with the lysosome.
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Affiliation(s)
- Antonina J Kruppa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
| | - John Kendrick-Jones
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY, UK
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79
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Kiss B, Kalmár L, Nyitray L, Pál G. Structural determinants governing S100A4-induced isoform-selective disassembly of nonmuscle myosin II filaments. FEBS J 2016; 283:2164-80. [PMID: 27029887 DOI: 10.1111/febs.13728] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/21/2016] [Accepted: 03/30/2016] [Indexed: 12/30/2022]
Abstract
The Ca(2+) -binding protein S100A4 interacts with the C terminus of nonmuscle myosin IIA (NMIIA) causing filament disassembly, which is correlated with an increased metastatic potential of tumor cells. Despite high sequence similarity of the three NMII isoforms, S100A4 discriminates against binding to NMIIB. We searched for structural determinants of this selectivity. Based on paralog scanning using phage display, we identified a single position as major determinant of isoform selectivity. Reciprocal single amino acid replacements showed that at position 1907 (NMIIA numbering), the NMIIA/NMIIC-specific alanine provides about 60-fold higher affinity than the NMIIB-specific asparagine. The structural background of this can be explained in part by a communication between the two consecutive α-helical binding segments. This communication is completely abolished by the Ala-to-Asn substitution. Mutual swapping of the disordered tailpieces only slightly affects the affinity of the NMII chimeras. Interestingly, we found that the tailpiece and position 1907 act in a nonadditive fashion. Finally, we also found that the higher stability of the C-terminal coiled-coil region of NMIIB also discriminates against interaction with S100A4. Our results clearly show that the isoform-selective binding of S100A4 is determined at multiple levels in the structure of the three NMII isoforms and the corresponding functional elements of NMII act synergistically with one another resulting in a complex interaction network. The experimental and in silico results suggest two divergent evolutionary pathways: NMIIA and NMIIB evolved to possess S100A4-dependent and -independent regulations, respectively.
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Affiliation(s)
- Bence Kiss
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Lajos Kalmár
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, Budapest, Hungary.,Department of Veterinary Medicine, University of Cambridge, Cambridgeshire, UK
| | - László Nyitray
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Pál
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
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80
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Popov K, Komianos J, Papoian GA. MEDYAN: Mechanochemical Simulations of Contraction and Polarity Alignment in Actomyosin Networks. PLoS Comput Biol 2016; 12:e1004877. [PMID: 27120189 PMCID: PMC4847874 DOI: 10.1371/journal.pcbi.1004877] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/22/2016] [Indexed: 11/29/2022] Open
Abstract
Active matter systems, and in particular the cell cytoskeleton, exhibit complex mechanochemical dynamics that are still not well understood. While prior computational models of cytoskeletal dynamics have lead to many conceptual insights, an important niche still needs to be filled with a high-resolution structural modeling framework, which includes a minimally-complete set of cytoskeletal chemistries, stochastically treats reaction and diffusion processes in three spatial dimensions, accurately and efficiently describes mechanical deformations of the filamentous network under stresses generated by molecular motors, and deeply couples mechanics and chemistry at high spatial resolution. To address this need, we propose a novel reactive coarse-grained force field, as well as a publicly available software package, named the Mechanochemical Dynamics of Active Networks (MEDYAN), for simulating active network evolution and dynamics (available at www.medyan.org). This model can be used to study the non-linear, far from equilibrium processes in active matter systems, in particular, comprised of interacting semi-flexible polymers embedded in a solution with complex reaction-diffusion processes. In this work, we applied MEDYAN to investigate a contractile actomyosin network consisting of actin filaments, alpha-actinin cross-linking proteins, and non-muscle myosin IIA mini-filaments. We found that these systems undergo a switch-like transition in simulations from a random network to ordered, bundled structures when cross-linker concentration is increased above a threshold value, inducing contraction driven by myosin II mini-filaments. Our simulations also show how myosin II mini-filaments, in tandem with cross-linkers, can produce a range of actin filament polarity distributions and alignment, which is crucially dependent on the rate of actin filament turnover and the actin filament’s resulting super-diffusive behavior in the actomyosin-cross-linker system. We discuss the biological implications of these findings for the arc formation in lamellipodium-to-lamellum architectural remodeling. Lastly, our simulations produce force-dependent accumulation of myosin II, which is thought to be responsible for their mechanosensation ability, also spontaneously generating myosin II concentration gradients in the solution phase of the simulation volume. Active matter systems have the distinct ability to convert energy from their surroundings into mechanical work, which gives rise to them having highly dynamic properties. Modeling active matter systems and capturing their complex behavior has been a great challenge in past years due to the many coupled interactions between their constituent parts, including not only distinct chemical and mechanical properties, but also feedback between them. One of the most intriguing biological active matter systems is the cell cytoskeleton, which can dynamically respond to chemical and mechanical cues to control cell structure and shape, playing a central role in many higher-order cellular processes. To model these systems and reproduce their behavior, we present a new modeling approach which combines the chemical, mechanical, and molecular transport aspects of active matter systems, all represented with equivalent complexity, while also allowing for various forms of mechanochemical feedback. This modeling approach, named MEDYAN, and software implementation is flexible so that a wide range of active matter systems can be simulated with a high level of detail, and ultimately can help to describe active matter phenomena, and in particular, the dynamics of the cell cytoskeleton. In this work, we have used MEDYAN to simulate a cytoskeletal network consisting of actin filaments, cross-linking proteins, and myosin II molecular motors. We found that these systems show rich dynamical behaviors, undergoing alignment and bundling transitions, with an emergent contractility, as the concentrations of myosin II and cross-linking proteins, as well as actin filament turnover rates, are varied.
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Affiliation(s)
- Konstantin Popov
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
| | - James Komianos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- Biophysics Graduate Program, University of Maryland, College Park, Maryland, United States of America
| | - Garegin A. Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, United States of America
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States of America
- * E-mail:
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81
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Brozovich FV, Nicholson CJ, Degen CV, Gao YZ, Aggarwal M, Morgan KG. Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders. Pharmacol Rev 2016; 68:476-532. [PMID: 27037223 PMCID: PMC4819215 DOI: 10.1124/pr.115.010652] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.
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Affiliation(s)
- F V Brozovich
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C J Nicholson
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - C V Degen
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - Yuan Z Gao
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - M Aggarwal
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
| | - K G Morgan
- Department of Health Sciences, Boston University, Boston, Massachusetts (C.J.N., Y.Z.G., M.A., K.G.M.); Department of Medicine, Mayo Clinic, Rochester, Minnesota (F.V.B.); and Paracelsus Medical University Salzburg, Salzburg, Austria (C.V.D.)
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82
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Heissler SM, Sellers JR. Kinetic Adaptations of Myosins for Their Diverse Cellular Functions. Traffic 2016; 17:839-59. [PMID: 26929436 DOI: 10.1111/tra.12388] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 02/25/2016] [Accepted: 02/25/2016] [Indexed: 12/18/2022]
Abstract
Members of the myosin superfamily are involved in all aspects of eukaryotic life. Their function ranges from the transport of organelles and cargos to the generation of membrane tension, and the contraction of muscle. The diversity of physiological functions is remarkable, given that all enzymatically active myosins follow a conserved mechanoenzymatic cycle in which the hydrolysis of ATP to ADP and inorganic phosphate is coupled to either actin-based transport or tethering of actin to defined cellular compartments. Kinetic capacities and limitations of a myosin are determined by the extent to which actin can accelerate the hydrolysis of ATP and the release of the hydrolysis products and are indispensably linked to its physiological tasks. This review focuses on kinetic competencies that - together with structural adaptations - result in myosins with unique mechanoenzymatic properties targeted to their diverse cellular functions.
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Affiliation(s)
- Sarah M Heissler
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, B50/3523, Bethesda, MD 20892-8015, USA
| | - James R Sellers
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, 50 South Drive, B50/3523, Bethesda, MD 20892-8015, USA
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83
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Hundt N, Steffen W, Pathan-Chhatbar S, Taft MH, Manstein DJ. Load-dependent modulation of non-muscle myosin-2A function by tropomyosin 4.2. Sci Rep 2016; 6:20554. [PMID: 26847712 PMCID: PMC4742800 DOI: 10.1038/srep20554] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 01/06/2016] [Indexed: 01/14/2023] Open
Abstract
Tropomyosin isoforms play an important role in the organisation of cytoplasmic actomyosin complexes in regard to function and cellular localisation. In particular, Tpm4.2 is upregulated in rapidly migrating cells and responsible for the specific recruitment of the cytoplasmic class-2 myosin NM-2A to actin filaments during the formation of stress fibres. Here, we investigate how the decoration of F-actin with Tpm4.2 affects the motor properties of NM-2A under conditions of low and high load. In the absence of external forces, decoration of actin filaments with Tpm4.2 does not affect the gated release of ADP from NM-2A and the transition from strong to weak actin-binding states. In the presence of resisting loads, our results reveal a marked increase in the mechanosensitive gating between the leading and trailing myosin head. Thereby, the processive behaviour of NM-2A is enhanced in the presence of resisting loads. The load- and Tpm4.2-induced changes in the functional behaviour of NM-2A are in good agreement with the role of this myosin in the context of stress fibres and the maintenance of cellular tension.
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Affiliation(s)
- Nikolas Hundt
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Walter Steffen
- Molecular and Cell Physiology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Salma Pathan-Chhatbar
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Manuel H Taft
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Dietmar J Manstein
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.,Division for Structural Analysis, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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84
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Vasquez CG, Martin AC. Force transmission in epithelial tissues. Dev Dyn 2016; 245:361-71. [PMID: 26756938 DOI: 10.1002/dvdy.24384] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 12/10/2015] [Accepted: 12/31/2015] [Indexed: 12/12/2022] Open
Abstract
In epithelial tissues, cells constantly generate and transmit forces between each other. Forces generated by the actomyosin cytoskeleton regulate tissue shape and structure and also provide signals that influence cells' decisions to divide, die, or differentiate. Forces are transmitted across epithelia because cells are mechanically linked through junctional complexes, and forces can propagate through the cell cytoplasm. Here, we review some of the molecular mechanisms responsible for force generation, with a specific focus on the actomyosin cortex and adherens junctions. We then discuss evidence for how these mechanisms promote cell shape changes and force transmission in tissues.
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Affiliation(s)
- Claudia G Vasquez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Adam C Martin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts
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85
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Lecarpentier Y, Claes V, Hébert JL, Krokidis X, Blanc FX, Michel F, Timbely O. Statistical Mechanics of the Human Placenta: A Stationary State of a Near-Equilibrium System in a Linear Regime. PLoS One 2015; 10:e0142471. [PMID: 26569482 PMCID: PMC4646433 DOI: 10.1371/journal.pone.0142471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/22/2015] [Indexed: 11/19/2022] Open
Abstract
All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley's equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system.
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Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Jean-Louis Hébert
- Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Xénophon Krokidis
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | | | - Francine Michel
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Oumar Timbely
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
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86
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Hindman B, Goeckeler Z, Sierros K, Wysolmerski R. Non-Muscle Myosin II Isoforms Have Different Functions in Matrix Rearrangement by MDA-MB-231 Cells. PLoS One 2015; 10:e0131920. [PMID: 26136073 PMCID: PMC4489869 DOI: 10.1371/journal.pone.0131920] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/08/2015] [Indexed: 01/15/2023] Open
Abstract
The role of a stiffening extra-cellular matrix (ECM) in cancer progression is documented but poorly understood. Here we use a conditioning protocol to test the role of nonmuscle myosin II isoforms in cell mediated ECM arrangement using collagen constructs seeded with breast cancer cells expressing shRNA targeted to either the IIA or IIB heavy chain isoform. While there are several methods available to measure changes in the biophysical characteristics of the ECM, we wanted to use a method which allows for the measurement of global stiffness changes as well as a dynamic response from the sample over time. The conditioning protocol used allows the direct measurement of ECM stiffness. Using various treatments, it is possible to determine the contribution of various construct and cellular components to the overall construct stiffness. Using this assay, we show that both the IIA and IIB isoforms are necessary for efficient matrix remodeling by MDA-MB-231 breast cancer cells, as loss of either isoform changes the stiffness of the collagen constructs as measured using our conditioning protocol. Constructs containing only collagen had an elastic modulus of 0.40 Pascals (Pa), parental MDA-MB-231 constructs had an elastic modulus of 9.22 Pa, while IIA and IIB KD constructs had moduli of 3.42 and 7.20 Pa, respectively. We also calculated the cell and matrix contributions to the overall sample elastic modulus. Loss of either myosin isoform resulted in decreased cell stiffness, as well as a decrease in the stiffness of the cell-altered collagen matrices. While the total construct modulus for the IIB KD cells was lower than that of the parental cells, the IIB KD cell-altered matrices actually had a higher elastic modulus than the parental cell-altered matrices (4.73 versus 4.38 Pa). These results indicate that the IIA and IIB heavy chains play distinct and non-redundant roles in matrix remodeling.
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Affiliation(s)
- Bridget Hindman
- Mary Babb Randolph Cancer Center, West Virginia University, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia, United States of America
| | - Zoe Goeckeler
- Center for Cardiovascular and Respiratory Diseases, West Virginia University, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia, United States of America
| | - Kostas Sierros
- Mechanical and Aerospace Engineering, Statler College of Engineering and Mineral Resources, West Virginia University, Morgantown, West Virginia, United States of America
| | - Robert Wysolmerski
- Mary Babb Randolph Cancer Center, West Virginia University, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia, United States of America
- Center for Cardiovascular and Respiratory Diseases, West Virginia University, Robert C. Byrd Health Sciences Center, Morgantown, West Virginia, United States of America
- * E-mail:
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87
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Zaidel-Bar R, Zhenhuan G, Luxenburg C. The contractome – a systems view of actomyosin contractility in non-muscle cells. J Cell Sci 2015; 128:2209-17. [DOI: 10.1242/jcs.170068] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/27/2015] [Indexed: 12/21/2022] Open
Abstract
ABSTRACT
Actomyosin contractility is a highly regulated process that affects many fundamental biological processes in each and every cell in our body. In this Cell Science at a Glance article and the accompanying poster, we mined the literature and databases to map the contractome of non-muscle cells. Actomyosin contractility is involved in at least 49 distinct cellular functions that range from providing cell architecture to signal transduction and nuclear activity. Containing over 100 scaffolding and regulatory proteins, the contractome forms a highly complex network with more than 230 direct interactions between its components, 86 of them involving phosphorylation. Mapping these interactions, we identify the key regulatory pathways involved in the assembly of actomyosin structures and in activating myosin to produce contractile forces within non-muscle cells at the exact time and place necessary for cellular function.
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Affiliation(s)
- Ronen Zaidel-Bar
- Mechanobiology Institute, National University of Singapore, T-lab building #05-01, 5A Engineering Drive 1, 117411, Singapore
| | - Guo Zhenhuan
- Mechanobiology Institute, National University of Singapore, T-lab building #05-01, 5A Engineering Drive 1, 117411, Singapore
| | - Chen Luxenburg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, P.O. Box 39040, Tel Aviv 69978, Israel
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88
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Eddinger TJ. Smooth muscle-protein translocation and tissue function. Anat Rec (Hoboken) 2015; 297:1734-46. [PMID: 25125185 DOI: 10.1002/ar.22970] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Revised: 03/18/2014] [Accepted: 03/18/2014] [Indexed: 01/25/2023]
Abstract
Smooth muscle (SM) tissue is a complex organization of multiple cell types and is regulated by numerous signaling molecules (neurotransmitters, hormones, cytokines, etc.). SM contractile function can be regulated via expression and distribution of the contractile and cytoskeletal proteins, and activation of any of the second messenger pathways that regulate them. Spatial-temporal changes in the contractile, cytoskeletal or regulatory components of SM cells (SMCs) have been proposed to alter SM contractile activity. Ca(2+) sensitization/desensitization can occur as a result of changes at any of these levels, and specific pathways have been identified at all of these levels. Understanding when and how proteins can translocate within the cytoplasm, or to-and-from the plasmalemma and the cytoplasm to alter contractile activity is critical. Numerous studies have reported translocation of proteins associated with the adherens junction and G protein-coupled receptor activation pathways in isolated SMC systems. Specific examples of translocation of vinculin to and from the adherens junction and protein kinase C (PKC) and 17 kDa PKC-potentiated inhibitor of myosin light chain phosphatase (CPI-17) to and from the plasmalemma in isolated SMC systems but not in intact SM tissues are discussed. Using both isolated SMC systems and SM tissues in parallel to pursue these studies will advance our understanding of both the role and mechanism of these pathways as well as their possible significance for Ca(2+) sensitization in intact SM tissues and organ systems.
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Affiliation(s)
- Thomas J Eddinger
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin
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89
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Stam S, Alberts J, Gardel ML, Munro E. Isoforms Confer Characteristic Force Generation and Mechanosensation by Myosin II Filaments. Biophys J 2015; 108:1997-2006. [PMID: 25902439 PMCID: PMC4407263 DOI: 10.1016/j.bpj.2015.03.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 01/27/2015] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
Myosin II isoforms with varying mechanochemistry and filament size interact with filamentous actin (F-actin) arrays to generate contractile forces in muscle and nonmuscle cells. How myosin II force production is shaped by isoform-specific motor properties and environmental stiffness remains poorly understood. Here, we used computer simulations to analyze force production by an ensemble of myosin motors against an elastically tethered actin filament. We found that force output depends on two timescales: the duration of F-actin attachment, which varies sharply with the ensemble size, motor duty ratio, and external load; and the time to build force, which scales with the ensemble stall force, gliding speed, and environmental stiffness. Although force-dependent kinetics were not required to sense changes in stiffness, the myosin catch bond produced positive feedback between the attachment time and force to trigger switch-like transitions from transient attachments, generating small forces, to high-force-generating runs. Using parameters representative of skeletal muscle myosin, nonmuscle myosin IIB, and nonmuscle myosin IIA revealed three distinct regimes of behavior, respectively: 1) large assemblies of fast, low-duty ratio motors rapidly build stable forces over a large range of environmental stiffness; 2) ensembles of slow, high-duty ratio motors serve as high-affinity cross-links with force buildup times that exceed physiological timescales; and 3) small assemblies of low-duty ratio motors operating at intermediate speeds are poised to respond sharply to changes in mechanical context-at low force or stiffness, they serve as low-affinity cross-links, but they can transition to force production via the positive-feedback mechanism described above. Together, these results reveal how myosin isoform properties may be tuned to produce force and respond to mechanical cues in their environment.
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Affiliation(s)
- Samantha Stam
- Biophysical Sciences Graduate Program, University of Washington, Friday Harbor, Washington; Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington
| | - Jon Alberts
- Center for Cell Dynamics, University of Washington, Friday Harbor, Washington
| | - Margaret L Gardel
- Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington; Physics Department, University of Chicago, Chicago, Illinois; James Franck Institute, University of Chicago, Chicago, Illinois; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois.
| | - Edwin Munro
- Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois.
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90
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Myosin 18A coassembles with nonmuscle myosin 2 to form mixed bipolar filaments. Curr Biol 2015; 25:942-8. [PMID: 25754640 DOI: 10.1016/j.cub.2015.02.012] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/22/2014] [Accepted: 02/02/2015] [Indexed: 12/14/2022]
Abstract
Class-18 myosins are most closely related to conventional class-2 nonmuscle myosins (NM2). Surprisingly, the purified head domains of Drosophila, mouse, and human myosin 18A (M18A) lack actin-activated ATPase activity and the ability to translocate actin filaments, suggesting that the functions of M18A in vivo do not depend on intrinsic motor activity. M18A has the longest coiled coil of any myosin outside of the class-2 myosins, suggesting that it might form bipolar filaments similar to conventional myosins. To address this possibility, we expressed and purified full-length mouse M18A using the baculovirus/Sf9 system. M18A did not form large bipolar filaments under any of the conditions tested. Instead, M18A formed an ∼ 65-nm-long bipolar structure with two heads at each end. Importantly, when NM2 was polymerized in the presence of M18A, the two myosins formed mixed bipolar filaments, as evidenced by cosedimentation, electron microscopy, and single-molecule imaging. Moreover, super-resolution imaging of NM2 and M18A using fluorescently tagged proteins and immunostaining of endogenous proteins showed that NM2 and M18A are present together within individual filaments inside living cells. Together, our in vitro and live-cell imaging data argue strongly that M18A coassembles with NM2 into mixed bipolar filaments. M18A could regulate the biophysical properties of these filaments and, by virtue of its extra N- and C-terminal domains, determine the localization and/or molecular interactions of the filaments. Given the numerous, fundamental cellular and developmental roles attributed to NM2, our results have far-reaching biological implications.
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91
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Heissler SM, Chinthalapudi K, Sellers JR. Kinetic characterization of the sole nonmuscle myosin-2 from the model organism Drosophila melanogaster. FASEB J 2015; 29:1456-66. [PMID: 25636739 DOI: 10.1096/fj.14-266742] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/01/2014] [Indexed: 12/31/2022]
Abstract
Nonmuscle myosin-2 is the primary enzyme complex powering contractility of the F-actin cytoskeleton in the model organism Drosophila. Despite myosin's essential function in fly development and homeostasis, its kinetic features remain elusive. The purpose of this in vitro study is a detailed steady-state and presteady-state kinetic characterization of the Drosophila nonmuscle myosin-2 motor domain. Kinetic features are a slow steady-state ATPase activity, high affinities for F-actin and ADP, and a low duty ratio. Comparative analysis of the overall enzymatic signatures across the nonmuscle myosin-2 complement from model organisms indicates that the Drosophila protein resembles nonmuscle myosin-2s from metazoa rather than protozoa, though modulatory aspects of myosin motor function are distinct. Drosophila nonmuscle myosin-2 is uniquely insensitive toward blebbistatin, a commonly used myosin-2 inhibitor. An in silico modeling approach together with kinetic studies indicate that the nonconsensus amino acid Met466 in the Drosophila nonmuscle myosin-2 active-site loop switch-2 acts as blebbistatin desensitizer. Introduction of the M466I mutation sensitized the protein for blebbistatin, resulting in a half-maximal inhibitory concentration of 36.3 ± 4.1 µM. Together, these data show that Drosophila nonmuscle myosin-2 is a bona fide molecular motor and establish an important link between switch-2 and blebbistatin sensitivity.
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Affiliation(s)
- Sarah M Heissler
- *Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; and The Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, USA
| | - Krishna Chinthalapudi
- *Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; and The Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, USA
| | - James R Sellers
- *Laboratory of Molecular Physiology, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; and The Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida, USA
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92
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Dulyaninova NG, Bresnick AR. The heavy chain has its day: regulation of myosin-II assembly. BIOARCHITECTURE 2015; 3:77-85. [PMID: 24002531 DOI: 10.4161/bioa.26133] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Nonmuscle myosin-II is an actin-based motor that converts chemical energy into force and movement, and thus functions as a key regulator of the eukaryotic cytoskeleton. Although it is established that phosphorylation on the regulatory light chain increases the actin-activated MgATPase activity of the motor and promotes myosin-II filament assembly, studies have begun to characterize alternative mechanisms that regulate filament assembly and disassembly. These investigations have revealed that all three nonmuscle myosin-II isoforms are subject to additional regulatory controls, which impact diverse cellular processes. In this review, we discuss current knowledge on mechanisms that regulate the oligomerization state of nonmuscle myosin-II filaments by targeting the myosin heavy chain.
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93
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Gutzman JH, Sahu SU, Kwas C. Non-muscle myosin IIA and IIB differentially regulate cell shape changes during zebrafish brain morphogenesis. Dev Biol 2014; 397:103-15. [PMID: 25446029 DOI: 10.1016/j.ydbio.2014.10.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 10/24/2022]
Abstract
During brain morphogenesis, the neuroepithelium must fold in specific regions to delineate functional units, and give rise to conserved embryonic brain shape. Individual cell shape changes are the basis for the morphogenetic events that occur during whole tissue shaping. We used the zebrafish to study the molecular mechanisms that regulate the first fold in the vertebrate brain, the highly conserved midbrain-hindbrain boundary (MHB). Since the contractile state of the neuroepithelium is tightly regulated by non-muscle myosin II (NMII) activity, we tested the role of NMIIA and NMIIB in regulating cell shape changes that occur during MHB morphogenesis. Using morpholino knockdown, we show that NMIIA and NMIIB are both required for normal MHB tissue angle. Quantification of cell shapes revealed that NMIIA is required for the shortening of cells specifically at the MHB constriction (MHBC), while NMIIB is required for the proper width of cells throughout the MHB region. NMIIA and NMIIB knockdown also correlated with abnormal distribution of actin within the cells of the MHBC. Thus, NMIIA and NMIIB perform distinct functions in regulating cell shape during MHB morphogenesis.
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Affiliation(s)
- Jennifer H Gutzman
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA.
| | - Srishti U Sahu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Constance Kwas
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
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94
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Lecarpentier Y, Claes V, Lecarpentier E, Guerin C, Hébert JL, Arsalane A, Moumen A, Krokidis X, Michel F, Timbely O. Ultraslow myosin molecular motors of placental contractile stem villi in humans. PLoS One 2014; 9:e108814. [PMID: 25268142 PMCID: PMC4182608 DOI: 10.1371/journal.pone.0108814] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 08/25/2014] [Indexed: 11/19/2022] Open
Abstract
Human placental stem villi (PSV) present contractile properties. In vitro mechanics were investigated in 40 human PSV. Contraction of PSV was induced by both KCl exposure (n = 20) and electrical tetanic stimulation (n = 20). Isotonic contractions were registered at several load levels ranging from zero-load up to isometric load. The tension-velocity relationship was found to be hyperbolic. This made it possible to apply the A. Huxley formalism for determining the rate constants for myosin cross-bridge (CB) attachment and detachment, CB single force, catalytic constant, myosin content, and maximum myosin ATPase activity. These molecular characteristics of myosin CBs did not differ under either KCl exposure or tetanus. A comparative approach was established from studies previously published in the literature and driven by mean of a similar method. As compared to that described in mammalian striated muscles, we showed that in human PSV, myosin CB rate constants for attachment and detachment were about 103 times lower whereas myosin ATPase activity was 105 times lower. Up to now, CB kinetics of contractile cells arranged along the long axis of the placental sheath appeared to be the slowest ever observed in any mammalian contractile tissue.
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Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Edouard Lecarpentier
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
- INSERM U767, Université Descartes Paris 5, Sorbonne Paris Cité, Paris, France
| | - Catherine Guerin
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Jean-Louis Hébert
- Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Abdelilah Arsalane
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Abdelouahab Moumen
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Xénophon Krokidis
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Francine Michel
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Oumar Timbely
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
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95
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Barua B, Nagy A, Sellers JR, Hitchcock-DeGregori SE. Regulation of nonmuscle myosin II by tropomyosin. Biochemistry 2014; 53:4015-24. [PMID: 24873380 PMCID: PMC4075986 DOI: 10.1021/bi500162z] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
The
actin cytoskeleton carries out cellular functions, including
division, migration, adhesion, and intracellular transport, that require
a variety of actin binding proteins, including myosins. Our focus
here is on class II nonmuscle myosin isoforms, NMIIA, NMIIB, and NMIIC,
and their regulation by the actin binding protein, tropomyosin. NMII
myosins are localized to different populations of stress fibers and
the contractile ring, structures involved in force generation required
for cell migration, adhesion, and cytokinesis. The stress fibers and
contractile ring that contain NMII myosins also contain tropomyosin.
Four mammalian genes encode more than 40 tropomyosins. Tropomyosins
inhibit or activate actomyosin MgATPase and motility depending on
the myosin and tropomyosin isoform. In vivo, tropomyosins
play a role in cell migration, adhesion, cytokinesis, and NMII isoform
localization in an isoform-specific manner. We postulate that the
isoform-specific tropomyosin localization and effect on NMII isoform
localization reflect modulation of NMII actomyosin kinetics and motile
function. In this study, we compare the ability of different tropomyosin
isoforms to support actin filament motility with NMIIA, NMIIB, and
NMIIC as well as skeletal muscle myosin. Tropomyosins activated, inhibited,
or had no effect on motility depending on the myosin, indicating that
the myosin isoform is the primary determinant of the isoform-specific
effect of tropomyosin on actomyosin regulation. Activation of motility
of nonmuscle tropomyosin–actin filaments by NMII myosin correlates
with an increased Vmax of the myosin MgATPase,
implying a direct effect on the myosin MgATPase, in contrast to the
skeletal tropomyosin–actin filament that has no effect on the Vmax or maximal filament velocity.
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Affiliation(s)
- Bipasha Barua
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers University , Piscataway, New Jersey 08854, United States
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96
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Beach JR, Shao L, Remmert K, Li D, Betzig E, Hammer JA. Nonmuscle myosin II isoforms coassemble in living cells. Curr Biol 2014; 24:1160-6. [PMID: 24814144 DOI: 10.1016/j.cub.2014.03.071] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 11/16/2022]
Abstract
Nonmuscle myosin II (NM II) powers myriad developmental and cellular processes, including embryogenesis, cell migration, and cytokinesis [1]. To exert its functions, monomers of NM II assemble into bipolar filaments that produce a contractile force on the actin cytoskeleton. Mammalian cells express up to three isoforms of NM II (NM IIA, IIB, and IIC), each of which possesses distinct biophysical properties and supports unique as well as redundant cellular functions [2-8]. Despite previous efforts [9-13], it remains unclear whether NM II isoforms assemble in living cells to produce mixed (heterotypic) bipolar filaments or whether filaments consist entirely of a single isoform (homotypic). We addressed this question using fluorescently tagged versions of NM IIA, IIB, and IIC, isoform-specific immunostaining of the endogenous proteins, and two-color total internal reflection fluorescence structured-illumination microscopy, or TIRF-SIM, to visualize individual myosin II bipolar filaments inside cells. We show that NM II isoforms coassemble into heterotypic filaments in a variety of settings, including various types of stress fibers, individual filaments throughout the cell, and the contractile ring. We also show that the differential distribution of NM IIA and NM IIB typically seen in confocal micrographs of well-polarized cells is reflected in the composition of individual bipolar filaments. Interestingly, this differential distribution is less pronounced in freshly spread cells, arguing for the existence of a sorting mechanism acting over time. Together, our work argues that individual NM II isoforms are potentially performing both isoform-specific and isoform-redundant functions while coassembled with other NM II isoforms.
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Affiliation(s)
- Jordan R Beach
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Lin Shao
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Kirsten Remmert
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dong Li
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - John A Hammer
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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97
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Ngo MA, Müller A, Li Y, Neumann S, Tian G, Dixon IMC, Arora RC, Freed DH. Human mesenchymal stem cells express a myofibroblastic phenotype in vitro: comparison to human cardiac myofibroblasts. Mol Cell Biochem 2014; 392:187-204. [PMID: 24691634 DOI: 10.1007/s11010-014-2030-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 03/14/2014] [Indexed: 01/12/2023]
Abstract
Cardiac fibrosis accompanies a variety of myocardial disorders, and is induced by myofibroblasts. These cells may be composed of a heterogeneous population of parent cells, including interstitial fibroblasts and circulating progenitor cells. Direct comparison of human bone marrow-derived mesenchymal stem cells (BM-MSCs) and cardiac myofibroblasts (CMyfbs) has not been previously reported. We hypothesized that BM-MSCs readily adopt a myofibroblastic phenotype in culture. Human primary BM-MSCs and human CMyfbs were isolated from patients undergoing open heart surgery and expanded under standard culture conditions. We assessed and compared their phenotypic and functional characteristics by examining their gene expression profile, their ability to contract collagen gels and synthesize collagen type I. In addition, we examined the role of non-muscle myosin II (NMMII) in modulating MSC myogenic function using NMMII siRNA knockdown and blebbistatin, a specific small molecule inhibitor of NMMII. We report that, while human BM-MSCs retain pluripotency, they adopt a myofibroblastic phenotype in culture and stain positive for the myofibroblast markers α-SMA, vimentin, NMMIIB, ED-A fibronectin, and collagen type 1 at each passage. In addition, they contract collagen gels in response to TGF-β1 and synthesize collagen similar to human CMyfbs. Moreover, inhibition of NMMII activity with blebbistatin completely attenuates gel contractility without affecting cell viability. Thus, human BM-MSCs share and exhibit similar physiological and functional characteristics as human CMyfbs in vitro, and their propensity to adopt a myofibroblast phenotype in culture may contribute to cardiac fibrosis.
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Affiliation(s)
- Melanie A Ngo
- Department of Physiology, Faculty of Medicine, Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, University of Manitoba, Winnipeg, MB, Canada
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98
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Menko AS, Bleaken BM, Libowitz AA, Zhang L, Stepp MA, Walker JL. A central role for vimentin in regulating repair function during healing of the lens epithelium. Mol Biol Cell 2014; 25:776-90. [PMID: 24478454 PMCID: PMC3952848 DOI: 10.1091/mbc.e12-12-0900] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A unique ex vivo mock cataract surgery model is used to study the role of vimentin in repair cell function during wound healing within a clinically relevant setting. Vimentin is found to be critical for the function of repair cells in directing the collective migration of the epithelium during wound healing. Mock cataract surgery provides a unique ex vivo model for studying wound repair in a clinically relevant setting. Here wound healing involves a classical collective migration of the lens epithelium, directed at the leading edge by an innate mesenchymal subpopulation of vimentin-rich repair cells. We report that vimentin is essential to the function of repair cells as the directors of the wound-healing process. Vimentin and not actin filaments are the predominant cytoskeletal elements in the lamellipodial extensions of the repair cells at the wound edge. These vimentin filaments link to paxillin-containing focal adhesions at the lamellipodial tips. Microtubules are involved in the extension of vimentin filaments in repair cells, the elaboration of vimentin-rich protrusions, and wound closure. The requirement for vimentin in repair cell function is revealed by both small interfering RNA vimentin knockdown and exposure to the vimentin-targeted drug withaferin A. Perturbation of vimentin impairs repair cell function and wound closure. Coimmunoprecipitation analysis reveals for the first time that myosin IIB is associated with vimentin, linking vimentin function in cell migration to myosin II motor proteins. These studies reveal a critical role for vimentin in repair cell function in regulating the collective movement of the epithelium in response to wounding.
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Affiliation(s)
- A S Menko
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107 Wills Vision Research Center at Jefferson, Philadelphia, PA 19107 Department of Anatomy and Regenerative Biology, George Washington University, Washington, DC 20037
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99
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The role of pulmonary vascular contractile protein expression in pulmonary arterial hypertension. J Mol Cell Cardiol 2013; 65:147-55. [PMID: 24161910 DOI: 10.1016/j.yjmcc.2013.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 09/30/2013] [Accepted: 10/15/2013] [Indexed: 12/13/2022]
Abstract
Pulmonary arterial hypertension (PAH) is associated with refractory vasoconstriction and impaired NO-mediated vasodilatation of the pulmonary vasculature. Vascular tone is regulated by light chain (LC) phosphorylation of both nonmuscle (NM) and smooth muscle (SM) myosins, which are determined by the activities of MLC kinase and MLC phosphatase. Further, NO mediated vasodilatation requires the expression of a leucine zipper positive (LZ+) isoform of the myosin targeting subunit (MYPT1) of MLC phosphatase. The objective of this study was to define contractile protein expression in the pulmonary arterial vasculature and vascular reactivity in PAH. In severe PAH, compared to controls, relative LZ+MYPT1 expression was decreased (100 ± 14% vs. 60 ± 6%, p<0.05, n=7-8), and NM myosin expression was increased (1 5 ± 4% vs. 53 ± 5% of total myosin, p<0.05, n=4-6). These changes in contractile protein expression should alter vascular reactivity; following activation with Ang II, force activation and relaxation were slowed, and sustained force was increased. Further, the sensitivity to ACh-mediated relaxation was reduced. These results demonstrate that changes in the pulmonary arterial SM contractile protein expression may participate in the molecular mechanism producing both the resting vasoconstriction and the decreased sensitivity to NO-mediated vasodilatation associated with PAH.
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100
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Chang W, Folker ES, Worman HJ, Gundersen GG. Emerin organizes actin flow for nuclear movement and centrosome orientation in migrating fibroblasts. Mol Biol Cell 2013; 24:3869-80. [PMID: 24152738 PMCID: PMC3861083 DOI: 10.1091/mbc.e13-06-0307] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Emerin, a nuclear membrane protein, and myosin IIB contribute to nuclear movement by regulating the directionality of nuclear movement and dorsal actin cable flow. Emerin interacts with myosin IIB and is required for its perinuclear localization. The results show that the nuclear envelope actively organizes cytoplasmic polarity. In migrating fibroblasts, rearward movement of the nucleus orients the centrosome toward the leading edge. Nuclear movement results from coupling rearward-moving, dorsal actin cables to the nucleus by linear arrays of nesprin-2G and SUN2, termed transmembrane actin-associated nuclear (TAN) lines. A-type lamins anchor TAN lines, prompting us to test whether emerin, a nuclear membrane protein that interacts with lamins and TAN line proteins, contributes to nuclear movement. In fibroblasts depleted of emerin, nuclei moved nondirectionally or completely failed to move. Consistent with these nuclear movement defects, dorsal actin cable flow was nondirectional in cells lacking emerin. TAN lines formed normally in cells lacking emerin and were coordinated with the erratic nuclear movements, although in 20% of the cases, TAN lines slipped over immobile nuclei. Myosin II drives actin flow, and depletion of myosin IIB, but not myosin IIA, showed similar nondirectional nuclear movement and actin flow as in emerin-depleted cells. Myosin IIB specifically coimmunoprecipitated with emerin, and emerin depletion prevented myosin IIB localization near nuclei. These results show that emerin functions with myosin IIB to polarize actin flow and nuclear movement in fibroblasts, suggesting a novel function for the nuclear envelope in organizing directional actin flow and cytoplasmic polarity.
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Affiliation(s)
- Wakam Chang
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032 Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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