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Myosin II

Kien Xuan Ngo, Nobuhisa Umeki, Saku T Kijima, Noriyuki Kodera, Hiroaki Ueno, Nozomi Furutani-Umezu, Jun Nakajima, Taro Q P Noguchi, Akira Nagasaki, Kiyotaka Tokuraku, Taro Q P Uyeda
Heavy meromyosin (HMM) of myosin II and cofilin each binds to actin filaments cooperatively and forms clusters along the filaments, but it is unknown whether the two cooperative bindings are correlated and what physiological roles they have. Fluorescence microscopy demonstrated that HMM-GFP and cofilin-mCherry each bound cooperatively to different parts of actin filaments when they were added simultaneously in 0.2 μM ATP, indicating that the two cooperative bindings are mutually exclusive. In 0.1 mM ATP, the motor domain of myosin (S1) strongly inhibited the formation of cofilin clusters along actin filaments...
October 20, 2016: Scientific Reports
Jenna K Zalewski, Joshua H Mo, Simone Heber, Annie Heroux, Richard G Gardner, Jeffrey D Hildebrand, Andrew P VanDemark
Shroom-mediated remodeling of the actomyosin cytoskeleton is a critical driver of cellular shape and tissue morphology that underlies the development of many tissues, including the neural tube, eye, intestines, and vasculature. Shroom uses a conserved SD2 domain to direct the subcellular localization of Rho-kinase (Rock) which in turn drives changes in the cytoskeleton and cellular morphology through its ability to phosphorylate and activate non-muscle myosin II. Here, we present the structure of the human Shroom-Rock binding module, revealing an unexpected stoichiometry for Shrm in which two Shrm SD2 domains bind independent surfaces on Rock...
October 10, 2016: Journal of Biological Chemistry
Limin Liu, Lin Chen, Zhihui Mai, Zhuli Peng, Kafung Yu, Guanqi Liu, Hong Ai
The role of myosin light chain II (MLC‑II) in cellular differentiation of rat mandibular condylar chondrocytes (MCCs) induced by cyclical uniaxial compressive stress (CUCS) remains unclear. In the current study, a four‑point bending system was used to apply CUCS to primary cultured MCCs from rats. It was identified that CUCS stimulated features of cellular differentiation including morphological alterations, cytoskeleton rearrangement and overproduction of proteoglycans. Furthermore, CUCS promoted runt‑related transcription factor‑2 (RUNX2) expression at mRNA (P<0...
September 26, 2016: Molecular Medicine Reports
Priscila de Souza, Karla Lorena Guarido, Karin Scheschowitsch, Luísa Mota da Silva, Maria Fernanda Werner, Jamil Assreuy, José Eduardo da Silva-Santos
We investigated long-lasting changes in endothelial and vascular function in adult rat survivors of severe sepsis induced by cecal ligation and puncture (CLP) model. For this, male Wistar rats (200-350g) had their cecum punctured once (non-transfixing hole) with a 14-gauge needle. Performed in this way, a mortality rate around 30% was achieved in the first 72h. The survivors, together with age-matched control rats (not subjected to CLP), were maintained in our holding room for 60 days (S60 group) and had the descending thoracic aorta processed for functional, histological, biochemical or molecular analyses...
September 30, 2016: Redox Biology
Matthias Schuppler, Felix C Keber, Martin Kröger, Andreas R Bausch
Cells set up contractile actin arrays to drive various shape changes and to exert forces to their environment. To understand their assembly process, we present here a reconstituted contractile system, comprising F-actin and myosin II filaments, where we can control the local activation of myosin by light. By stimulating different symmetries, we show that the force balancing at the boundaries determine the shape changes as well as the dynamics of the global contraction. Spatially anisotropic attachment of initially isotropic networks leads to a self-organization of highly aligned contractile fibres, being reminiscent of the order formation in muscles or stress fibres...
October 14, 2016: Nature Communications
Anita Roy, Larissa Lordier, Stefania Mazzi, Yunhua Chang, Valérie Lapierre, Jérome Larghero, Najet Debili, Hana Raslova, William Vainchenker
Megakaryocyte polyploidy is characterized by cytokinesis failure due to defects in contractile forces at the cleavage furrow. Although immature megakaryocytes express two nonmuscle myosin II isoforms (NMIIA and NMIIB); only NMIIB localizes at the cleavage furrow and its subsequent absence contributes to polyploidy. In this study, we tried to understand why the abundant NMIIA does not localize at the furrow by focusing on RhoA/ROCK pathway that has a low activity in polyploid megakaryocytes. We observed that under low RhoA activity, NMII isoforms presented different activity that determined their localization...
October 13, 2016: Blood
Wei Miao, Xiujuan Wu, Kang Wang, Wenjing Wang, Yumei Wang, Zhigang Li, Jingjing Liu, Li Li, Luying Peng
As a physiological small molecular product from the microbial fermentation of dietary fibers, butyrate plays an important role in maintaining intestinal health. Our previous works have proved that the effect of sodium butyrate (NaB) on the intestinal barrier function is mediated by activation of AMP-activated protein kinase (AMPK). However, the detailed pathway involved remains unknown. Using the calcium switch assay in the Caco-2 cell monolayer model, we found here that NaB activated AMPK mainly by increasing the calcium level, but not the ATP concentration, via promoting store-operated calcium entry (SOCE)...
October 10, 2016: International Journal of Molecular Sciences
M Moazzem Hossain, Guangyi Zhao, Moon-Sook Woo, James H-C Wang, Jian-Ping Jin
Cell traction force (CTF) plays a critical role in controlling cell shape, enabling cell motility, and maintaining cellular homeostasis in many biological processes such as angiogenesis, development, wound healing, and cancer metastasis. Calponin is an actin filament-associated cytoskeletal protein in smooth muscles and multiple types of non-muscle cells. An established biochemical function of calponin is the inhibition of myosin ATPase in smooth muscle cells. Vertebrates have three calponin isoforms. Among them, calponin 2 is expressed in epithelial cells, endothelial cells, macrophages, myoblasts and fibroblasts, and plays a role in regulating cytoskeleton activities such as cell adhesion, migration and cytokinesis...
October 13, 2016: Biochemistry
Michael J Susienka, Benjamin T Wilks, Jeffrey R Morgan
Tissue fusion, whereby two or more spheroids coalesce, is a process that is fundamental to biofabrication. We have designed a quantitative, high-throughput platform to investigate the fusion of multicellular spheroids using agarose micro-molds. Spheroids of primary human chondrocytes (HCH) or human breast cancer cells (MCF-7) were self-assembled for 24 h and then brought together to form an array comprised of two spheroids (one doublet) per well. To quantify spheroid fusogenicity, we developed two assays: (1) an initial tack assay, defined as the minimum amount of time for two spheroids to form a mechanically stable tissue complex or doublet, and (2) a fusion assay, in which we defined and tracked key morphological parameters of the doublets as a function of time using wide-field fluorescence microscopy over a 24 h time-lapse...
October 10, 2016: Biofabrication
Parisa Kakanj, Bernard Moussian, Sebastian Grönke, Victor Bustos, Sabine A Eming, Linda Partridge, Maria Leptin
The TOR and Insulin/IGF signalling (IIS) network controls growth, metabolism and ageing. Although reducing TOR or insulin signalling can be beneficial for ageing, it can be detrimental for wound healing, but the reasons for this difference are unknown. Here we show that IIS is activated in the cells surrounding an epidermal wound in Drosophila melanogaster larvae, resulting in PI3K activation and redistribution of the transcription factor FOXO. Insulin and TOR signalling are independently necessary for normal wound healing, with FOXO and S6K as their respective effectors...
October 7, 2016: Nature Communications
Markela Ibo, Vasudha Srivastava, Douglas N Robinson, Zachary R Gagnon
Migrating cells can extend their leading edge by forming myosin-driven blebs and F-actin-driven pseudopods. When coerced to migrate in resistive environments, Dictyostelium cells switch from using predominately pseudopods to blebs. Bleb formation has been shown to be chemotactic and can be influenced by the direction of the chemotactic gradient. In this study, we determine the blebbing responses of developed cells of Dictyostelium discoideum to cAMP gradients of varying steepness produced in microfluidic channels with different confining heights, ranging between 1...
2016: PloS One
Zhongjun Hu, Dianne W Taylor, Michael K Reedy, Robert J Edwards, Kenneth A Taylor
We describe a cryo-electron microscopy three-dimensional image reconstruction of relaxed myosin II-containing thick filaments from the flight muscle of the giant water bug Lethocerus indicus. The relaxed thick filament structure is a key element of muscle physiology because it facilitates the reextension process following contraction. Conversely, the myosin heads must disrupt their relaxed arrangement to drive contraction. Previous models predicted that Lethocerus myosin was unique in having an intermolecular head-head interaction, as opposed to the intramolecular head-head interaction observed in all other species...
September 2016: Science Advances
Xiong Liu, Shi Shu, Neil Billington, Chad D Williamson, Shuhua Yu, Hanna Brzeska, Julie G Donaldson, James R Sellers, Edward D Korn
Mammalian cells express three Class II nonmuscle myosins (NM): NM2A, NM2B and NM2C. The three NM2s have well-established essential roles in cell motility, adhesion and cytokinesis, and less well defined roles in vesicle transport and other processes that would require association of NM2s with cell membranes. Previous evidence for the mechanism of NM2-membrane association includes direct interaction of NM2s with membrane lipids and indirect interaction by association of NM2s with membrane-bound F-actin or peripheral membrane proteins...
October 3, 2016: Journal of Biological Chemistry
Michael M Kreusser, Lorenz H Lehmann, Nora Wolf, Stanislav Keranov, Andreas Jungmann, Hermann-Josef Gröne, Oliver J Müller, Hugo A Katus, Johannes Backs
CaM kinase II (CaMKII) has been suggested to drive pathological cardiac remodeling and heart failure. However, the evidence provided so far is based on inhibitory strategies using chemical compounds and peptides that also exert off-target effects and followed exclusively preventive strategies. Therefore, the aim of this study was to investigate whether specific CaMKII inhibition after the onset of cardiac stress delays or reverses maladaptive cardiac remodeling and dysfunction. Combined genetic deletion of the two redundant CaMKII genes δ and γ was induced after the onset of overt heart failure as the result of pathological pressure overload induced by transverse aortic constriction (TAC)...
November 2016: Basic Research in Cardiology
Rashmi Priya, Kenneth Wee, Srikanth Budnar, Guillermo A Gomez, Alpha S Yap, Magdalene Michael
Non-muscle myosin II (NMII) motor proteins are responsible for generating contractile forces inside eukaryotic cells. There is also a growing interest in the capacity for these motor proteins to influence cell signaling through scaffolding, especially in the context of RhoA GTPase signaling. We previously showed that NMIIA accumulation and stability within specific regions of the cell cortex, such as the zonula adherens (ZA), allows the formation of a stable RhoA signaling zone. Now we demonstrate a key role for Coronin 1B in maintaining this junctional pool of NMIIA, as depletion of Coronin 1B significantly compromised myosin accumulation and stability at junctions...
September 20, 2016: Cell Cycle
Kevin A Murach, R Grace Walton, Christopher S Fry, Sami L Michaelis, Jason S Groshong, Brian S Finlin, Philip A Kern, Charlotte A Peterson
This investigation evaluated whether moderate-intensity cycle ergometer training affects satellite cell and molecular responses to acute maximal concentric/eccentric resistance exercise in middle-aged women. Baseline and 72 h postresistance exercise vastus lateralis biopsies were obtained from seven healthy middle-aged women (56 ± 5 years, BMI 26 ± 1, VO2max 27 ± 4) before and after 12 weeks of cycle training. Myosin heavy chain (MyHC) I- and II-associated satellite cell density and cross-sectional area was determined via immunohistochemistry...
September 2016: Physiological Reports
Caroline Laplante, Fang Huang, Irene R Tebbs, Joerg Bewersdorf, Thomas D Pollard
Cytokinesis in animals, fungi, and amoebas depends on the constriction of a contractile ring built from a common set of conserved proteins. Many fundamental questions remain about how these proteins organize to generate the necessary tension for cytokinesis. Using quantitative high-speed fluorescence photoactivation localization microscopy (FPALM), we probed this question in live fission yeast cells at unprecedented resolution. We show that nodes, protein assembly precursors to the contractile ring, are discrete structural units with stoichiometric ratios and distinct distributions of constituent proteins...
October 4, 2016: Proceedings of the National Academy of Sciences of the United States of America
Mateusz M Urbanski, Lyle Kingsbury, Daniel Moussouros, Imran Kassim, Saraf Mehjabeen, Navid Paknejad, Carmen V Melendez-Vasquez
The mechanical properties of living tissues have a significant impact on cell differentiation, but remain unexplored in the context of myelin formation and repair. In the PNS, the extracellular matrix (ECM) incorporates a basal lamina significantly denser than the loosely organized CNS matrix. Inhibition of non-muscle myosin II (NMII) enhances central but impairs peripheral myelination and NMII has been implicated in cellular responses to changes in the elasticity of the ECM. To directly evaluate whether mechanotransduction plays a role in glial cell differentiation, we cultured Schwann cells (SC) and oligodendrocytes (OL) on matrices of variable elastic modulus, mimicking either their native environment or conditions found in injured tissue...
2016: Scientific Reports
Qi-Hong Yu, Jie-Fang Guo, Yan Chen, Xiao-Rong Guo, Yi-Qi Du, Zhao-Shen Li
Acute pancreatitis (AP) usually causes acute lung injury, which is also known as acute pancreatitis associated lung injury (APALI). This study aimed to investigate whether captopril pretreatment was able to protect lung against APALI via inhibiting angiotensin II (Ang II) production and suppressing Rho/ROCK (Rho kinase) pathway in rats. Severe AP (SAP) was introduced to rats by bile-pancreatic duct retrograde injection of 5% sodium taurocholate. Rats were randomly divided into three groups. In the sham group, sham operation was performed; in the SAP group, SAP was introduced; in the pre-cpl + SAP group, rats were intragastrically injected with 5 mg/kg captopril 1 hour prior to SAP induction...
September 2016: Kaohsiung Journal of Medical Sciences
Stacey Lee, Sanjay Kumar
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...
2016: F1000Research
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