scholarly journals Drosophila non-muscle myosin II motor activity determines the rate of tissue folding

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Claudia G Vasquez ◽  
Sarah M Heissler ◽  
Neil Billington ◽  
James R Sellers ◽  
Adam C Martin
Keyword(s):  
Motor Activity ◽  
Molecular Motor ◽  
Myosin Ii ◽  
Cell Contractility ◽  
Myosin Motor ◽  
Muscle Myosin ◽  
Shape Changes ◽  
Drosophila Embryos

Non-muscle cell contractility is critical for tissues to adopt shape changes. Although, the non-muscle myosin II holoenzyme (myosin) is a molecular motor that powers contraction of actin cytoskeleton networks, recent studies have questioned the importance of myosin motor activity cell and tissue shape changes. Here, combining the biochemical analysis of enzymatic and motile properties for purified myosin mutants with in vivo measurements of apical constriction for the same mutants, we show that in vivo constriction rate scales with myosin motor activity. We show that so-called phosphomimetic mutants of the Drosophila regulatory light chain (RLC) do not mimic the phosphorylated RLC state in vitro. The defect in the myosin motor activity in these mutants is evident in developing Drosophila embryos where tissue recoil following laser ablation is decreased compared to wild-type tissue. Overall, our data highlights that myosin activity is required for rapid cell contraction and tissue folding in developing Drosophila embryos.

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 Tropomyosin and Myosin-II Cellular Levels Promote Actomyosin Ring Assembly in Fission Yeast

2010 ◽  
Vol 21 (6) ◽  
pp. 989-1000 ◽  
Author(s):  
Benjamin C. Stark ◽  
Thomas E. Sladewski ◽  
Luther W. Pollard ◽  
Matthew Lord
Keyword(s):  
Motor Activity ◽  
Atpase Activity ◽  
Fission Yeast ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Bound State ◽  
Contractile Ring ◽  
Ring Assembly

Myosin-II (Myo2p) and tropomyosin are essential for contractile ring formation and cytokinesis in fission yeast. Here we used a combination of in vivo and in vitro approaches to understand how these proteins function at contractile rings. We find that ring assembly is delayed in Myo2p motor and tropomyosin mutants, but occurs prematurely in cells engineered to express two copies of myo2. Thus, the timing of ring assembly responds to changes in Myo2p cellular levels and motor activity, and the emergence of tropomyosin-bound actin filaments. Doubling Myo2p levels suppresses defects in ring assembly associated with a tropomyosin mutant, suggesting a role for tropomyosin in maximizing Myo2p function. Correspondingly, tropomyosin increases Myo2p actin affinity and ATPase activity and promotes Myo2p-driven actin filament gliding in motility assays. Tropomyosin achieves this by favoring the strong actin-bound state of Myo2p. This mode of regulation reflects a role for tropomyosin in specifying and stabilizing actomyosin interactions, which facilitates contractile ring assembly in the fission yeast system.

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 Flow-independent accumulation of motor-competent non-muscle myosin II in the contractile ring is essential for cytokinesis

2018 ◽  
Author(s):  
DS Osorio ◽  
FY Chan ◽  
J Saramago ◽  
J Leite ◽  
AM Silva ◽  
...  
Keyword(s):  
Motor Activity ◽  
Myosin Ii ◽  
Minor Role ◽  
Cortical Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Myosin Motor ◽  
C Elegans ◽  
Ring Assembly ◽  
Muscle Myosin

AbstractCytokinesis in animal cells requires the assembly of a contractile actomyosin ring, whose subsequent constriction physically separates the two daughter cells. Non-muscle myosin II (myosin) is essential for cytokinesis, but the role of its motor activity remains poorly defined. Here, we examine cytokinesis in C. elegans one-cell embryos expressing myosin motor mutants generated by genome editing. Motor-dead myosin, which is capable of binding F-actin, does not support cytokinesis, and embryos co-expressing motor-dead and wild-type myosin are delayed in cytokinesis. Partially motor-impaired myosin also delays cytokinesis and renders contractile rings more sensitive to reduced myosin levels. Thus, myosin motor activity, rather than its ability to cross-link actin filaments, drives contractile ring assembly and constriction. We further demonstrate that myosin motor activity is required for long-range cortical actin flows, but that flows per se play a minor role in contractile ring assembly. Our results suggest that flow-independent recruitment of motor-competent myosin to the cell equator is both essential and rate-limiting for cytokinesis.

scholarly journals Hypertrophy-Reduced Autophagy Causes Cardiac Dysfunction by Directly Impacting Cardiomyocyte Contractility

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 805
Author(s):  
Christiane Ott ◽  
Tobias Jung ◽  
Sarah Brix ◽  
Cathleen John ◽  
Iris R. Betz ◽  
...  
Keyword(s):  
Cardiomyocyte Hypertrophy ◽  
Aortic Constriction ◽  
Cell Contractility ◽  
Neonatal Cardiomyocytes ◽  
Cardiomyocyte Contractility ◽  
Cardioprotective Effects ◽  
Modified Proteins ◽  
Cardiomyocyte Autophagy

Cardiac remodeling and contractile dysfunction are leading causes in hypertrophy-associated heart failure (HF), increasing with a population’s rising age. A hallmark of aged and diseased hearts is the accumulation of modified proteins caused by an impaired autophagy-lysosomal-pathway. Although, autophagy inducer rapamycin has been described to exert cardioprotective effects, it remains to be shown whether these effects can be attributed to improved cardiomyocyte autophagy and contractility. In vivo hypertrophy was induced by transverse aortic constriction (TAC), with mice receiving daily rapamycin injections beginning six weeks after surgery for four weeks. Echocardiographic analysis demonstrated TAC-induced HF and protein analyses showed abundance of modified proteins in TAC-hearts after 10 weeks, both reduced by rapamycin. In vitro, cardiomyocyte hypertrophy was mimicked by endothelin 1 (ET-1) and autophagy manipulated by silencing Atg5 in neonatal cardiomyocytes. ET-1 and siAtg5 decreased Atg5–Atg12 and LC3-II, increased natriuretic peptides, and decreased amplitude and early phase of contraction in cardiomyocytes, the latter two evaluated using ImageJ macro Myocyter recently developed by us. ET-1 further decreased cell contractility in control but not in siAtg5 cells. In conclusion, ET-1 decreased autophagy and cardiomyocyte contractility, in line with siAtg5-treated cells and the results of TAC-mice demonstrating a crucial role for autophagy in cardiomyocyte contractility and cardiac performance.

In vitro and in vivo relaxation of urinary bladder smooth muscle by the selective myosin II inhibitor, blebbistatin

2011 ◽  
Vol 107 (2) ◽  
pp. 310-317 ◽  
Author(s):  
Xinhua Zhang ◽  
Dwaraka Srinivasa R. Kuppam ◽  
Arnold Melman ◽  
Michael E. DiSanto
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Myosin Ii ◽  
Bladder Smooth Muscle ◽  
Urinary Bladder Smooth Muscle

Molecular Motors: Force and Movement Generated by Single Myosin II Molecules

Physiology ◽  
2002 ◽  
Vol 17 (5) ◽  
pp. 213-218 ◽  
Author(s):  
Caspar Rüegg ◽  
Claudia Veigel ◽  
Justin E. Molloy ◽  
Stephan Schmitz ◽  
John C. Sparrow ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Molecular Motors ◽  
Molecular Motor ◽  
Myosin Ii ◽  
Force Production ◽  
Myosin Isoforms ◽  
Single Molecule Level ◽  
Recent Developments ◽  
Muscle Myosin

Muscle myosin II is an ATP-driven, actin-based molecular motor. Recent developments in optical tweezers technology have made it possible to study movement and force production on the single-molecule level and to find out how different myosin isoforms may have adapted to their specific physiological roles.

scholarly journals Myosin-dependent remodeling of adherens junctions protects junctions from Snail-dependent disassembly

2016 ◽  
Vol 212 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Mo Weng ◽  
Eric Wieschaus
Keyword(s):  
Cell Shape ◽  
Adherens Junctions ◽  
Myosin Ii ◽  
Cell Junctions ◽  
Snail Expression ◽  
Quantitative Image ◽  
Early Expression ◽  
Temporally Correlated ◽  
Shape Changes

Although Snail is essential for disassembly of adherens junctions during epithelial–mesenchymal transitions (EMTs), loss of adherens junctions in Drosophila melanogaster gastrula is delayed until mesoderm is internalized, despite the early expression of Snail in that primordium. By combining live imaging and quantitative image analysis, we track the behavior of E-cadherin–rich junction clusters, demonstrating that in the early stages of gastrulation most subapical clusters in mesoderm not only persist, but move apically and enhance in density and total intensity. All three phenomena depend on myosin II and are temporally correlated with the pulses of actomyosin accumulation that drive initial cell shape changes during gastrulation. When contractile myosin is absent, the normal Snail expression in mesoderm, or ectopic Snail expression in ectoderm, is sufficient to drive early disassembly of junctions. In both cases, junctional disassembly can be blocked by simultaneous induction of myosin contractility. Our findings provide in vivo evidence for mechanosensitivity of cell–cell junctions and imply that myosin-mediated tension can prevent Snail-driven EMT.

scholarly journals Myosin and gelsolin cooperate in actin filament severing and actomyosin motor activity

2020 ◽  
pp. jbc.RA120.015863
Author(s):  
Venukumar Vemula ◽  
Tamás Huber ◽  
Marko Ušaj ◽  
Beáta Bugyi ◽  
Alf Mansson
Keyword(s):  
Motor Activity ◽  
Actin Filament ◽  
Single Molecule ◽  
Actin Filaments ◽  
Actin Binding ◽  
In Vitro Motility Assay ◽  
Cooperative Effects ◽  
Myosin Motor ◽  
Filament Dynamics

Actin is a major intracellular protein with key functions in cellular motility, signaling and structural rearrangements. Its dynamic behavior, such as polymerisation and depolymerisation of actin filaments in response to intra- and extracellular cues, is regulated by an abundance of actin binding proteins. Out of these, gelsolin is one of the most potent for filament severing. However, myosin motor activity also fragments actin filaments through motor induced forces, suggesting that these two proteins could cooperate to regulate filament dynamics and motility. To test this idea, we used an in vitro motility assay, where actin filaments are propelled by surface-adsorbed heavy meromyosin (HMM) motor fragments. This allows studies of both motility and filament dynamics using isolated proteins. Gelsolin, at both nanomolar and micromolar Ca2+ concentration, appreciably enhanced actin filament severing caused by HMM-induced forces at 1 mM MgATP, an effect that was increased at higher HMM motor density. This finding is consistent with cooperativity between actin filament severing by myosin-induced forces and by gelsolin. We also observed reduced sliding velocity of the HMM-propelled filaments in the presence of gelsolin, providing further support of myosin-gelsolin cooperativity. Total internal reflection fluorescence microscopy based single molecule studies corroborated that the velocity reduction was a direct effect of gelsolin-binding to the filament and revealed different filament severing pattern of stationary and HMM propelled filaments. Overall, the results corroborate cooperative effects between gelsolin-induced alterations in the actin filaments and changes due to myosin motor activity leading to enhanced F-actin severing of possible physiological relevance.

scholarly journals Linking the Landscape of MYH9-Related Diseases to the Molecular Mechanisms that Control Non-Muscle Myosin II-A Function in Cells

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1458 ◽  
Author(s):  
Gloria Asensio-Juárez ◽  
Clara Llorente-González ◽  
Miguel Vicente-Manzanares
Keyword(s):  
Molecular Mechanisms ◽  
Clinical Presentation ◽  
Molecular Motor ◽  
Myosin Ii ◽  
Residual Activity ◽  
Cellular Level ◽  
Actin Binding ◽  
Compensatory Mechanisms ◽  
Myh9 Gene ◽  
Muscle Myosin

The MYH9 gene encodes the heavy chain (MHCII) of non-muscle myosin II A (NMII-A). This is an actin-binding molecular motor essential for development that participates in many crucial cellular processes such as adhesion, cell migration, cytokinesis and polarization, maintenance of cell shape and signal transduction. Several types of mutations in the MYH9 gene cause an array of autosomal dominant disorders, globally known as MYH9-related diseases (MYH9-RD). These include May-Hegglin anomaly (MHA), Epstein syndrome (EPS), Fechtner syndrome (FTS) and Sebastian platelet syndrome (SPS). Although caused by different MYH9 mutations, all patients present macrothrombocytopenia, but may later display other pathologies, including loss of hearing, renal failure and presenile cataracts. The correlation between the molecular and cellular effects of the different mutations and clinical presentation are beginning to be established. In this review, we correlate the defects that MYH9 mutations cause at a molecular and cellular level (for example, deficient filament formation, altered ATPase activity or actin-binding) with the clinical presentation of the syndromes in human patients. We address why these syndromes are tissue restricted, and the existence of possible compensatory mechanisms, including residual activity of mutant NMII-A and/or the formation of heteropolymers or co-polymers with other NMII isoforms.

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