scholarly journals Cytokinesis in vertebrate cells initiates by contraction of an equatorial actomyosin network composed of randomly oriented filaments

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Felix Spira ◽  
Sara Cuylen-Haering ◽  
Shalin Mehta ◽  
Matthias Samwer ◽  
Anne Reversat ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Local Network ◽  
Polarization Microscopy ◽  
Cleavage Furrow ◽  
Mechanical Forces ◽  
Biological Processes ◽  
Actin Network ◽  
Animal Cells ◽  
Mechanical Tension ◽  
Cortical Tension

The actomyosin ring generates force to ingress the cytokinetic cleavage furrow in animal cells, yet its filament organization and the mechanism of contractility is not well understood. We quantified actin filament order in human cells using fluorescence polarization microscopy and found that cleavage furrow ingression initiates by contraction of an equatorial actin network with randomly oriented filaments. The network subsequently gradually reoriented actin filaments along the cell equator. This strictly depended on myosin II activity, suggesting local network reorganization by mechanical forces. Cortical laser microsurgery revealed that during cytokinesis progression, mechanical tension increased substantially along the direction of the cell equator, while the network contracted laterally along the pole-to-pole axis without a detectable increase in tension. Our data suggest that an asymmetric increase in cortical tension promotes filament reorientation along the cytokinetic cleavage furrow, which might have implications for diverse other biological processes involving actomyosin rings.

scholarly journals Distinct contributions of tensile and shear stress on E-cadherin levels during morphogenesis

2018 ◽  
Author(s):  
Girish R. Kale ◽  
Xingbo Yang ◽  
Jean-Marc Philippe ◽  
Madhav Mani ◽  
Pierre-François Lenne ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Epithelial Morphogenesis ◽  
Shear Stresses ◽  
Mechanical Forces ◽  
Mechanical Tension ◽  
Tensile Forces ◽  
Axis Elongation ◽  
Persistent Cell ◽  
Adhesive Forces ◽  
E Cadherin

AbstractDuring epithelial morphogenesis, cell contacts (junctions) are constantly remodeled by mechanical forces that work against adhesive forces. E-cadherin complexes play a pivotal role in this process by providing persistent cell adhesion and by transmitting mechanical tension. In this context, it is unclear how mechanical forces affect E-cadherin adhesion and junction dynamics.During Drosophila embryo axis elongation, Myosin-II activity in the apico-medial and junctional cortex generates mechanical forces to drive junction remodeling. Here we report that the ratio between Vinculin and E-cadherin intensities acts as a ratiometric readout for these mechanical forces (load) at E-cadherin complexes. Medial Myosin-II loads E-cadherin complexes on all junctions, exerts tensile forces, and increases levels of E-cadherin. Junctional Myosin-II, on the other hand, biases the distribution of load between junctions of the same cell, exerts shear forces, and decreases the levels of E-cadherin. This work suggests distinct effects of tensile versus shear stresses on E-cadherin adhesion.

scholarly journals The interplay of stiffness and force anisotropies drives embryo elongation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Thanh Thi Kim Vuong-Brender ◽  
Martine Ben Amar ◽  
Julien Pontabry ◽  
Michel Labouesse
Keyword(s):  
Experimental Data ◽  
Material Properties ◽  
Myosin Ii ◽  
Mechanical Forces ◽  
Cell Behaviour ◽  
Cortical Tension ◽  
Actin Cortex ◽  
Stiffness Anisotropy ◽  
Spatiotemporal Changes ◽  
Tissue Material

The morphogenesis of tissues, like the deformation of an object, results from the interplay between their material properties and the mechanical forces exerted on them. The importance of mechanical forces in influencing cell behaviour is widely recognized, whereas the importance of tissue material properties, in particular stiffness, has received much less attention. Using Caenorhabditis elegans as a model, we examine how both aspects contribute to embryonic elongation. Measuring the opening shape of the epidermal actin cortex after laser nano-ablation, we assess the spatiotemporal changes of actomyosin-dependent force and stiffness along the antero-posterior and dorso-ventral axis. Experimental data and analytical modelling show that myosin-II-dependent force anisotropy within the lateral epidermis, and stiffness anisotropy within the fiber-reinforced dorso-ventral epidermis are critical in driving embryonic elongation. Together, our results establish a quantitative link between cortical tension, material properties and morphogenesis of an entire embryo.

scholarly journals Classical and Emerging Regulatory Mechanisms of Cytokinesis in Animal Cells

Biology ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 55 ◽  
Author(s):  
Vikash Verma ◽  
Alex Mogilner ◽  
Thomas J. Maresca
Keyword(s):  
Molecular Mechanisms ◽  
Myosin Ii ◽  
Dynamic Structure ◽  
Regulatory Proteins ◽  
Cleavage Furrow ◽  
Filamentous Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Sister Chromatids

The primary goal of cytokinesis is to produce two daughter cells, each having a full set of chromosomes. To achieve this, cells assemble a dynamic structure between segregated sister chromatids called the contractile ring, which is made up of filamentous actin, myosin-II, and other regulatory proteins. Constriction of the actomyosin ring generates a cleavage furrow that divides the cytoplasm to produce two daughter cells. Decades of research have identified key regulators and underlying molecular mechanisms; however, many fundamental questions remain unanswered and are still being actively investigated. This review summarizes the key findings, computational modeling, and recent advances in understanding of the molecular mechanisms that control the formation of the cleavage furrow and cytokinesis.

scholarly journals The interplay of stiffness and force anisotropies drive embryo elongation

2016 ◽  
Author(s):  
Thanh TK Vuong-Brender ◽  
Martine Ben Amar ◽  
Julien Pontabry ◽  
Michel Labouesse
Keyword(s):  
Material Properties ◽  
Myosin Ii ◽  
Mechanical Forces ◽  
Cell Behaviour ◽  
Cortical Tension ◽  
C Elegans ◽  
Actin Cortex ◽  
Stiffness Anisotropy ◽  
Spatiotemporal Changes ◽  
Tissue Material

AbstractThe morphogenesis of tissues, like the deformation of an object, results from the interplay between their material properties and the mechanical forces exerted on them. Whereas the importance of mechanical forces in influencing cell behaviour is widely recognized, the importance of tissue material properties, in particular stiffness, has received much less attention. Using C. elegans as a model, we examine how both aspects contribute to embryonic elongation. Measuring the opening shape of the epidermal actin cortex after laser nano-ablation, we assess the spatiotemporal changes of actomyosin-dependent force and stiffness along the antero-posterior and dorso-ventral axis. Experimental data and analytical modelling show that myosin II-dependent force anisotropy within the lateral epidermis, and stiffness anisotropy within the fiber-reinforced dorso-ventral epidermis are critical to drive embryonic elongation. Together, our results establish a quantitative link between cortical tension, material properties and morphogenesis of an entire embryo.

scholarly journals Dictyostelium Aurora Kinase Has Properties of both Aurora A and Aurora B Kinases

2008 ◽  
Vol 7 (5) ◽  
pp. 894-905 ◽  
Author(s):  
Hui Li ◽  
Qian Chen ◽  
Markus Kaller ◽  
Wolfgang Nellen ◽  
Ralph Gräf ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Aurora Kinase ◽  
Equatorial Region ◽  
Aurora B ◽  
Cleavage Furrow ◽  
Aurora A ◽  
Animal Cells ◽  
Aurora Kinases ◽  
Spindle Poles ◽  
Early Mitosis

ABSTRACT Aurora kinases are highly conserved proteins with important roles in mitosis. Metazoans contain two kinases, Aurora A and B, which contribute distinct functions at the spindle poles and the equatorial region respectively. It is not currently known whether the specialized functions of the two kinases arose after their duplication in animal cells or were already present in their ancestral kinase. We show that Dictyostelium discoideum contains a single Aurora kinase, DdAurora, that displays characteristics of both Aurora A and B. Like Aurora A, DdAurora has an extended N-terminal domain with an A-box sequence and localizes at the spindle poles during early mitosis. Like Aurora B, DdAurora binds to its partner DdINCENP and localizes on centromeres at metaphase, the central spindle during anaphase, and the cleavage furrow at the end of cytokinesis. DdAurora also has several unusual properties. DdAurora remains associated with centromeres in anaphase, and this association does not require an interaction with DdINCENP. DdAurora then localizes at the cleavage furrow, but only at the end of cytokinesis. This localization is dependent on DdINCENP and the motor proteins Kif12 and myosin II. Thus, DdAurora may represent the ancestral kinase that gave rise to the different Aurora kinases in animals and also those in other organisms.

scholarly journals Molecular Mechanism of Cytokinesis

2019 ◽  
Vol 88 (1) ◽  
pp. 661-689 ◽  
Author(s):  
Thomas D. Pollard ◽  
Ben O'Shaughnessy
Keyword(s):  
Cell Cycle ◽  
Computer Simulations ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Cleavage Furrow ◽  
Animal Cells ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Ancient Proteins ◽  
Biochemical Mechanisms

Division of amoebas, fungi, and animal cells into two daughter cells at the end of the cell cycle depends on a common set of ancient proteins, principally actin filaments and myosin-II motors. Anillin, formins, IQGAPs, and many other proteins regulate the assembly of the actin filaments into a contractile ring positioned between the daughter nuclei by different mechanisms in fungi and animal cells. Interactions of myosin-II with actin filaments produce force to assemble and then constrict the contractile ring to form a cleavage furrow. Contractile rings disassemble as they constrict. In some cases, knowledge about the numbers of participating proteins and their biochemical mechanisms has made it possible to formulate molecularly explicit mathematical models that reproduce the observed physical events during cytokinesis by computer simulations.

scholarly journals Extent of myosin penetration within the actin cortex regulates cell surface mechanics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Binh An Truong Quang ◽  
Ruby Peters ◽  
Davide A. D. Cassani ◽  
Priyamvada Chugh ◽  
Andrew G. Clark ◽  
...  
Keyword(s):  
Cell Surface ◽  
Network Architecture ◽  
Super Resolution ◽  
Actin Network ◽  
Cortical Actin ◽  
Animal Cells ◽  
Cortical Tension ◽  
Protein Size ◽  
Myosin Motors ◽  
Surface Mechanics

AbstractIn animal cells, shape is mostly determined by the actomyosin cortex, a thin cytoskeletal network underlying the plasma membrane. Myosin motors generate tension in the cortex, and tension gradients result in cellular deformations. As such, many cell morphogenesis studies have focused on the mechanisms controlling myosin activity and recruitment to the cortex. Here, we demonstrate using super-resolution microscopy that myosin does not always overlap with actin at the cortex, but remains restricted towards the cytoplasm in cells with low cortex tension. We propose that this restricted penetration results from steric hindrance, as myosin minifilaments are considerably larger than the cortical actin meshsize. We identify myosin activity and actin network architecture as key regulators of myosin penetration into the cortex, and show that increasing myosin penetration increases cortical tension. Our study reveals that the spatial coordination of myosin and actin at the cortex regulates cell surface mechanics, and unveils an important mechanism whereby myosin size controls its action by limiting minifilament penetration into the cortical actin network. More generally, our findings suggest that protein size could regulate function in dense cytoskeletal structures.

The Role of Mechanical Tension in Neurons

2010 ◽  
Vol 1274 ◽  
Author(s):  
Taher Saif ◽  
Jagannathan Rajagopalan ◽  
Alireza Tofangchi
Keyword(s):  
Mechanical Response ◽  
Mechanical Forces ◽  
Active Tension ◽  
Mechanical Tension ◽  
Deformation Response ◽  
Linear Force ◽  
Tension Regulation ◽  
Over Time

AbstractWe used high resolution micromechanical force sensors to study the in vivo mechanical response of embryonic Drosophila neurons. Our experiments show that Drosophila axons have a rest tension of a few nN and respond to mechanical forces in a manner characteristic of viscoelastic solids. In response to fast externally applied stretch they show a linear force-deformation response and when the applied stretch is held constant the force in the axons relaxes to a steady state value over time. More importantly, when the tension in the axons is suddenly reduced by releasing the external force the neurons actively restore the tension, sometimes close to their resting value. Along with the recent findings of Siechen et al (Proc. Natl. Acad. Sci. USA 106, 12611 (2009)) showing a link between mechanical tension and synaptic plasticity, our observation of active tension regulation in neurons suggest an important role for mechanical forces in the functioning of neurons in vivo.

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