scholarly journals Robust maintenance of cell surface tension in mitosis by RhoA-driven myosin II mechanoresponse

2021 ◽  
Author(s):  
Jingjing Ding ◽  
Chao Wang ◽  
Qiaodong Wei ◽  
Shoukang Du ◽  
Xiaobo Gong ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cell Surface ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Cell Cortex ◽  
Tail Domain ◽  
Rhoa Activation ◽  
Head Domain ◽  
Confined Environment ◽  
Muscle Myosin

AbstractAs cells enter mitosis, cell cortex contraction generates surface tension to establish a geometry feasible for division in a physically confined environment. Cell surface tension rises in prophase and continues to stay constant during metaphase to support mitosis. How the cell surface tension is maintained throughout mitosis is not well explored. We show that the cell surface tension is actively maintained by a mechanosensitive RhoA pathway at the cell cortex during mitosis. Mechanical activation of RhoA leads to non-muscle myosin IIB (NMIIB) stabilization and mechanosensitive accumulation at the cell cortex via Rho kinase (ROCK) regulation of the NMIIB head domain. Interestingly, when the NMIIB tail domain regulation is perturbed, the NMIIB has reduced ability to generate tension but could still support mitotic cells to withstand compressive stress by undergoing mechanosensitive accumulation at the cell cortex. Thus, mechanical RhoA activation drives NMIIB mechanoresponse via its head domain regulation to maintain cell surface tension during mitosis.

scholarly journals Dia- and Rok-dependent enrichment of capping proteins in a cortical region

2021 ◽  
Author(s):  
Anja Schmidt ◽  
Long Li ◽  
Zhiyi Lv ◽  
Shuling Yan ◽  
Jörg Großhans
Keyword(s):  
Myosin Ii ◽  
Rho Kinase ◽  
Cortical Region ◽  
Protein Enrichment ◽  
Cortical Actin ◽  
Capping Protein ◽  
Capping Proteins ◽  
Muscle Myosin ◽  
Drosophila Embryos

Rho signaling with its major targets the formin Dia, Rho kinase (Rok) and non-muscle myosin II control turnover, amount and contractility of actomyosin. Much less investigated has been a potential function for the distribution of F-actin plus and minus ends. In syncytial Drosophila embryos Rho1 signaling is high between actin caps, i. e. the cortical intercap region. Capping protein binds to free plus ends of F-actin to prevent elongation of the filament. Capping protein has served as a marker to visualize the distribution of F-actin plus ends in cells and in vitro. Here, we probed the distribution of plus ends with capping protein in syncytial Drosophila embryos. We found that Capping proteins are specifically enriched in the intercap region similar to Dia and MyoII but distinct from overall F-actin. The intercap enrichment of Capping protein was impaired in dia mutants and embryos, in which Rok and MyoII activation was inhibited. Our observations reveal that Dia and Rok/MyoII control Capping protein enrichment and support a model that Dia and Rok/MyoII control the organization of cortical actin cytoskeleton downstream of Rho1 signaling.

scholarly journals Cortical contraction drives the 3D patterning of epithelial cell surfaces

2019 ◽  
Author(s):  
Aaron P. van Loon ◽  
Ivan S. Erofeev ◽  
Ivan V. Maryshev ◽  
Andrew B. Goryachev ◽  
Alvaro Sagasti
Keyword(s):  
Surface Tension ◽  
Myosin Ii ◽  
Biomechanical Model ◽  
Cell Surfaces ◽  
Apical Constriction ◽  
Skin Cells ◽  
In Vivo Experiments ◽  
Surface Topographies ◽  
Muscle Myosin

ABSTRACTCellular protrusions create complex cell surface topographies, but biomechanical mechanisms regulating their formation and arrangement are largely unknown. To study how protrusions form, we focused on the morphogenesis of microridges, elongated actin-based structures projecting from the apical surfaces of zebrafish skin cells that are arranged in labyrinthine patterns. Microridges form by accreting simple finger-like precursors. Live imaging demonstrated that microridge morphogenesis is linked to apical constriction. A non-muscle myosin II (NMII) reporter revealed pulsatile contractions of the actomyosin cortex; inhibiting NMII demonstrated that contractions are required for apical constriction and microridge formation. A biomechanical model suggested that contraction reduces surface tension to permit the fusion of precursors into microridges. Indeed, reducing surface tension with hyperosmolar media promoted microridge formation. In anisotropically stretched cells, microridges formed by precursor fusion along the stretch axis, which computational modeling explained as a consequence of stretch-induced cortical flow. Collectively, our results demonstrate how contraction within the 2D plane of the cortex patterns 3D cell surfaces.SUMMARYMicroridges, elongated 3D protrusions arranged in maze-like patterns on zebrafish skin cells, form by the accretion of simple precursor projections. Modeling and in vivo experiments showed that cortical contractions promote the coalescence of precursors into microridges by reducing membrane tension.

Abstract 480: Non-muscle Myosin II Regulates Aortic Stiffness via Tension-dependent Phosphorylation of Specific Focal Adhesion Proteins

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Kuldeep Singh ◽  
Anne B Kim ◽  
Kathleen G Morgan
Keyword(s):  
Smooth Muscle ◽  
Muscle Cell ◽  
Focal Adhesion ◽  
Aortic Stiffness ◽  
Myosin Ii ◽  
Cell Cortex ◽  
Dependent Manner ◽  
Adhesion Proteins ◽  
Focal Adhesion Proteins ◽  
Muscle Myosin

Non-muscle myosin II plays a role in many fundamental cellular processes including cell adhesion, migration, and cytokinesis. However, its role in vascular function is not well understood. Here, we investigated the function of non-muscle myosin II in the biomechanical properties of mouse proximal aorta. We found that blebbistatin, a specific inhibitor of non-muscle myosin II decreases agonist-induced aortic stress and stiffness in a dose-dependent manner. We also specifically demonstrate, in freshly isolated contractile aortic smooth muscle cells, using deconvolution microscopy that the NM myosin IIA isoform co-localizes with contractile filaments in the core of the cell as well as in the non-muscle cell cortex. However, the NM myosin IIB isoform is only colocalized with contractile filaments, and is excluded from the cell cortex. Furthermore, both the siRNA knockdown of NMIIA and NMIIB isoforms in a differentiated smooth muscle cell line A7r5 and blebbistatin-mediated inhibition of NM myosin II suppresses agonist-activated increases in phosphorylation of FAK Y925 and paxillin Y118. Thus, in the present study, we show, for the first time, that NM myosin II regulates aortic stiffness and that this regulation is mediated at least in part through the tension-dependent phosphorylation of focal adhesion proteins FAK and paxillin.

scholarly journals In vivo optochemical control of cell contractility at single cell resolution by Ca2+ induced myosin activation

2018 ◽  
Author(s):  
Deqing Kong ◽  
Zhiyi Lv ◽  
Matthias Häring ◽  
Fred Wolf ◽  
Joerg Grosshans
Keyword(s):  
Single Cell ◽  
Temporal Dynamics ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Target Cells ◽  
Tissue Morphogenesis ◽  
Cross Sectional ◽  
Cell Contractility ◽  
Muscle Myosin

The spatial and temporal dynamics of cell contractility plays a key role in tissue morphogenesis, wound healing and cancer invasion. Here we report a simple, single cell resolution, optochemical method to induce minute-scale cell contractions in vivo during morphogenesis. We employed the photolabile Ca2+ chelator o-nitrophenyl EGTA to induce bursts of intracellular free Ca2+ by laser photolysis. Ca2+ bursts appear within seconds and are restricted to individual target cells. Cell contraction reliably followed within a minute, to about half of the cross-sectional area. Increased Ca2+ levels and contraction were reversible and the target cells further participated in tissue morphogenesis. Depending on Rho kinase (Rok) activity but not RhoGEF2, cell contractions are paralleled with non-muscle myosin-II accumulation in the apico-medial cortex, indicating that Ca2+ bursts trigger non-muscle myosin II activation. Our approach can be easily adapted to many experimental systems and species, as no specific genetic elements are required and a widely used reagent is employed.

scholarly journals Generation of stress fibers through myosin-driven re-organization of the actin cortex

2020 ◽  
Author(s):  
JI Lehtimäki ◽  
EK Rajakylä ◽  
S Tojkander ◽  
P Lappalainen
Keyword(s):  
De Novo ◽  
Myosin Ii ◽  
Focal Adhesions ◽  
Stress Fibers ◽  
Cell Cortex ◽  
Cortical Actin ◽  
Cellular Processes ◽  
Actin Cortex ◽  
Muscle Myosin ◽  
Subsequent Stabilization

SummaryContractile actomyosin bundles, stress fibers, govern key cellular processes including migration, adhesion, and mechanosensing. Stress fibers are thus critical for developmental morphogenesis. The most prominent actomyosin bundles, ventral stress fibers, are generated through coalescence of pre-existing stress fiber precursors. However, whether stress fibers can assemble through other mechanisms has remained elusive. We report that stress fibers can also form without requirement of pre-existing actomyosin bundles. These structures, which we named cortical stress fibers, are embedded in the cell cortex and assemble preferentially underneath the nucleus. In this process, non-muscle myosin II pulses orchestrate the reorganization of cortical actin meshwork into regular bundles, which promote reinforcement of nascent focal adhesions, and subsequent stabilization of the cortical stress fibers. These results identify a new mechanism by which stress fibers can be generated de novo from the actin cortex, and establish role for stochastic myosin pulses in the assembly of functional actomyosin bundles.

scholarly journals Generation of stress fibers through myosin-driven reorganization of the actin cortex

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jaakko I Lehtimäki ◽  
Eeva Kaisa Rajakylä ◽  
Sari Tojkander ◽  
Pekka Lappalainen
Keyword(s):  
De Novo ◽  
Myosin Ii ◽  
Focal Adhesions ◽  
Stress Fibers ◽  
Cell Cortex ◽  
Cortical Actin ◽  
Cellular Processes ◽  
Actin Cortex ◽  
Muscle Myosin ◽  
Subsequent Stabilization

Contractile actomyosin bundles, stress fibers, govern key cellular processes including migration, adhesion, and mechanosensing. Stress fibers are thus critical for developmental morphogenesis. The most prominent actomyosin bundles, ventral stress fibers, are generated through coalescence of pre-existing stress fiber precursors. However, whether stress fibers can assemble through other mechanisms has remained elusive. We report that stress fibers can also form without requirement of pre-existing actomyosin bundles. These structures, which we named cortical stress fibers, are embedded in the cell cortex and assemble preferentially underneath the nucleus. In this process, non-muscle myosin II pulses orchestrate the reorganization of cortical actin meshwork into regular bundles, which promote reinforcement of nascent focal adhesions, and subsequent stabilization of the cortical stress fibers. These results identify a new mechanism by which stress fibers can be generated de novo from the actin cortex and establish role for stochastic myosin pulses in the assembly of functional actomyosin bundles.

Myosin II-independent processes in mitotic cells of Dictyostelium discoideum: redistribution of the nuclei, re-arrangement of the actin system and formation of the cleavage furrow

1997 ◽  
Vol 110 (2) ◽  
pp. 123-137 ◽  
Author(s):  
R. Neujahr ◽  
C. Heizer ◽  
G. Gerisch
Keyword(s):  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Solid Surface ◽  
Myosin Ii ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Multinucleated Cells ◽  
Dynamic Cell ◽  
Separated Sets ◽  
Mutant Cells

Mitosis was studied in multinucleated and mononucleated mutant cells of Dictyostelium discoideum that lack myosin II (Manstein et al. (1989) EMBO J. 8, 923–932). Multinucleated cells were produced by culture in suspension, mononucleated cells were enriched by growth on a solid surface (DeLozanne and Spudich (1987) Science 236, 1086–1091). The multinucleated cells disclosed interactions of mitotic complexes with the cell cortex that were not apparent in normal, mononucleated cells. During the anaphase stage, entire mitotic complexes consisting of spindle, microtubule asters, and separated sets of chromosomes were translocated to the periphery of the cells. These complexes were appended at a distance of about 3 microns from the cell surface, in a way that the spindle became orientated in parallel to the surface. Subsequently, lobes of the cell surface were formed around the asters of microtubules. These lobes were covered with tapered protrusions rich in coronin, an actin associated protein that typically accumulates in dynamic cell-surface projections (DeHostos et al. (1991) EMBO J. 10, 4097–4104). During their growth on a solid surface, mononucleated myosin II-null cells passed through the mitotic cleavage stages with a speed comparable to wild-type cells. Cytokinesis as linked to mitosis is distinguishable by several parameters from traction mediated cytofission, which results in the pinching off of pieces of a multinucleated cell in the interphase. The possibility is discussed that cells can cleave during mitosis without forming a contractile ring at the site of the cleavage furrow.

scholarly journals Patterns of periodic holes created by increased cell motility

2012 ◽  
Vol 2 (4) ◽  
pp. 457-464 ◽  
Author(s):  
Ting-Hsuan Chen ◽  
Chunyan Guo ◽  
Xin Zhao ◽  
Yucheng Yao ◽  
Kristina I. Boström ◽  
...  
Keyword(s):  
Cell Motility ◽  
Myosin Ii ◽  
Rho Kinase ◽  
Spongy Tissue ◽  
Experimental Control ◽  
Direct Measurements ◽  
Local Cell ◽  
Biological Patterns ◽  
Muscle Myosin ◽  
And Diffusion

The reaction and diffusion of morphogens is a mechanism widely used to explain many spatial patterns in physics, chemistry and developmental biology. However, because experimental control is limited in most biological systems, it is often unclear what mechanisms account for the biological patterns that arise. Here, we study a biological model of cultured vascular mesenchymal cells (VMCs), which normally self-organize into aggregates that form into labyrinthine configurations. We use an experimental control and a mathematical model that includes reacting and diffusing morphogens and a third variable reflecting local cell density. With direct measurements showing that cell motility was increased ninefold and threefold by inhibiting either Rho kinase or non-muscle myosin-II, respectively, our experimental results and mathematical modelling demonstrate that increased motility alters the multicellular pattern of the VMC cultures, from labyrinthine to a pattern of periodic holes. These results suggest implications for the tissue engineering of functional replacements for trabecular or spongy tissue such as endocardium and bone.

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