Mammalian nonmuscle myosin II comes in three flavors

Shutova, Maria S.; Svitkina, Tatyana

doi:10.1016/j.bbrc.2018.03.103

Cited by 55 publications

(62 citation statements)

References 131 publications

(197 reference statements)

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“…However, phosphorylation of the regulatory light chain of myosin-II not only increases its ATPase activity but also promotes assembly of myosin-II bipolar thick filaments (for review, see ref. 47 ), which could sterically perturb the local capture of kinetochores by MTs. In the future, it would be interesting to address it by computational modeling or using in-vitro models as described in refs.…”

Section: Discussionmentioning

confidence: 99%

Artificially decreasing cortical tension generates aneuploidy in mouse oocytes

et al. 2020

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Human and mouse oocytes' developmental potential can be predicted by their mechanical properties. Their development into blastocysts requires a specific stiffness window. In this study, we combine live-cell and computational imaging, laser ablation, and biophysical measurements to investigate how deregulation of cortex tension in the oocyte contributes to early developmental failure. We focus on extra-soft cells, the most common defect in a natural population. Using two independent tools to artificially decrease cortical tension, we show that chromosome alignment is impaired in extra-soft mouse oocytes, despite normal spindle morphogenesis and dynamics, inducing aneuploidy. The main cause is a cytoplasmic increase in myosin-II activity that could sterically hinder chromosome capture. We describe here an original mode of generation of aneuploidies that could be very common in oocytes and could contribute to the high aneuploidy rate observed during female meiosis, a leading cause of infertility and congenital disorders.

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Section: Discussionmentioning

confidence: 99%

Artificially decreasing cortical tension generates aneuploidy in mouse oocytes

et al. 2020

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“…Smith et al (6) next sought evidence that NM2A is active in RBCs. Cells regulate the activity of NM2 by regulating where and when NM2 monomers are assembled into bipolar filaments through the action of multiple regulatory light-chain (RLC) kinases (4,5). RLC phosphorylation activates NM2s by converting them from folded monomers, which are mechanically silent and incapable of assembling into filaments, into extended monomers, which readily assemble into filaments and are capable of walking on F-actin.…”

Section: Myosin 2 Regulates the Rbc Membrane Cytoskeletonmentioning

confidence: 99%

“…When considering actin function in many cellular contexts, nonmuscle myosin 2 (NM2) naturally comes to mind, as these motors are the major actin-based contractile machines in most cell types (4,5). Consistently, NM2s power a wide range of fundamental cellular processes, including cell migration, cytokinesis, tissue morphogenesis, and epithelial barrier function.…”

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confidence: 99%

Myosin goes for blood

Hammer¹

2018

Proc. Natl. Acad. Sci. U.S.A.

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“…Therefore electrostatics has to be 38 the prime consideration to understand the architecture of NM2-minifilaments. 39 Due to a 196-residue charge repeat, favorable staggers between two parallel rods 40 should be shifted at odd multiples of 98 amino acids with respect to each other [20,21]. 41 Electron microscopy and scattering experiments of myosin II and myosin II 42 rod-fragments revealed prominent axial staggers of 14.3 nm, 43.2 nm and (less 43 frequently observed) 72.0 nm between adjacent parallel myosin rods [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

“…However, in the cell new 338 minifilaments are mainly created at the leading edge by NM2A. These filaments then 339 move backwards with the retrograde flow and NM2A is increasingly replaced by 340 NM2B [2,39,40]. In this context, a higher contact time for NM2A-NM2A and 341 NM2A-NM2B in fact seems very reasonable.…”

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confidence: 98%

Electrostatic and bending energies predict staggering and splaying in nonmuscle myosin II minifilaments

Kaufmann

Schwarz

2020

Preprint

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Recent experiments with super-resolution live cell microscopy revealed that nonmuscle myosin II minifilaments are much more dynamic than formerly appreciated, often showing plastic processes such as splitting, concatenation and stacking. Here we combine sequence information, electrostatics and elasticity theory to demonstrate that the parallel staggers at 14.3, 43.2 and 72 nm have a strong tendency to splay their heads away from the minifilament, thus potentially initiating the diverse processes seen in live cells. In contrast, the straight antiparallel stagger with an overlap of 43 nm is very stable and likely initiates minifilament nucleation. Using stochastic dynamics in a newly defined energy landscape, we predict that the optimal parallel staggers between the myosin rods are obtained by a trial-and-error process in which two rods attach and re-attach at different staggers by rolling and zipping motion. The experimentally observed staggers emerge as the configurations with the largest contact times. We find that contact times increase from isoforms C to B to A, that A-B-heterodimers are surprisingly stable and that myosin 18A should incorporate into mixed filaments with a small stagger. Our findings suggest that nonmuscle myosin II minifilaments in the cell are first formed by isoform A and then convert to mixed A-B-filaments, as observed experimentally. Author summaryNonmuscle myosin II (NM2) is a non-processive molecular motor that assembles into minifilaments with a typical size of 300 nm to generate force and motion in the actin cytoskeleton. This process is essential for many cellular processes such as adhesion, migration, division and mechanosensing. Due to their small size below the resolution limit, minifilaments are a challenge for imaging with traditional light microscopy. With the advent of super-resolution microscopy, however, it has become apparent that the formation of NM2-minifilaments is much more dynamic than formerly appreciated. Modeling the electrostatic interaction between the rigid rods of the myosin monomers has confirmed the main staggers observed in experiments, but cannot explain these high dynamics. Here we complement electrostatics by elasticity theory and stochastic dynamics to show that the parallel staggers are likely to splay away from the main axis of the minifilament and that monomers attach and deattach with rolling and zipping motions. Based on the sequences of the different NM2-isoforms, we predict that isoform A forms the most stable homofilaments and that A-B-heterofilaments are also very stable.

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Mammalian nonmuscle myosin II comes in three flavors

Cited by 55 publications

References 131 publications

Artificially decreasing cortical tension generates aneuploidy in mouse oocytes

Artificially decreasing cortical tension generates aneuploidy in mouse oocytes

Myosin goes for blood

Electrostatic and bending energies predict staggering and splaying in nonmuscle myosin II minifilaments

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