Kinetics of actin networks formation measured by time resolved particle-tracking microrheology

Levin, Maayan; Sorkin, Raya; Pine, David; Granek, Rony; Bernheim‐Groswasser, Anne; Roichman, Yael

doi:10.1039/d0sm00290a

Cited by 12 publications

(15 citation statements)

References 57 publications

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“…Based on this definition, the polymerizing nucleus in our model is composed of three monomers (the bond of the last G-actin is destabilized), and therefore, F-actin is defined when formed by three or more G-actin monomers. This is in agreement with recent experimental observations [ 91 ].…”

Section: Methodssupporting

confidence: 94%

A coarse-grained approach to model the dynamics of the actomyosin cortex

et al. 2022

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Background The dynamics of the actomyosin machinery is at the core of many important biological processes. Several relevant cellular responses such as the rhythmic compression of the cell cortex are governed, at a mesoscopic level, by the nonlinear interaction between actin monomers, actin crosslinkers, and myosin motors. Coarse-grained models are an optimal tool to study actomyosin systems, since they can include processes that occur at long time and space scales, while maintaining the most relevant features of the molecular interactions. Results Here, we present a coarse-grained model of a two-dimensional actomyosin cortex, adjacent to a three-dimensional cytoplasm. Our simplified model incorporates only well-characterized interactions between actin monomers, actin crosslinkers and myosin, and it is able to reproduce many of the most important aspects of actin filament and actomyosin network formation, such as dynamics of polymerization and depolymerization, treadmilling, network formation, and the autonomous oscillatory dynamics of actomyosin. Conclusions We believe that the present model can be used to study the in vivo response of actomyosin networks to changes in key parameters of the system, such as alterations in the attachment of actin filaments to the cell cortex.

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Section: Methodssupporting

confidence: 94%

A coarse-grained approach to model the dynamics of the actomyosin cortex

et al. 2022

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“…Based in this definition, the polymerizing nucleus in our model is composed of three monomers (the bond of the last G-Actin is destabilized), and therefore, F-Actin is defined when formed by three or more G-Actin monomers. This is in agreement with recent experimental observations Levin et al (2020).…”

Section: Time Calibrationsupporting

confidence: 94%

A coarse-grained approach to model the dynamics of the actomyosin cortex

Hernández-Del-Valle

Valencia-Expósito

López-Izquierdo

et al. 2021

Preprint

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The dynamics of the actomyosin machinery is at the core of many important biological processes. Several relevant cellular responses such as the rhythmic compression of the cell cortex are governed, at a mesoscopic level, by the nonlinear interaction between actin monomers, actin crosslinkers and myosin motors. Coarse grained models are an optimal tool to study actomyosin systems, since they can include processes that occur at long time and space scales, while maintaining the most relevant features of the molecular interactions. Here, we present a coarse grained model of a two-dimensional actomyosin cortex, adjacent to a three-dimensional cytoplasm. Our simplified model incorporates only well characterized interactions between actin monomers, actin cross- linkers and myosin, and it is able to reproduce many of the most important aspects of actin filament and actomyosin network formation, such as dynamics of polymerization and depolymerization, treadmilling, network formation and the autonomous oscilla- tory dynamics of actomyosin. Furthermore, the model can be used to predict the in vivo response of actomyosin networks to changes in key parameters of the system, such as alterations in the anchor of actin filaments to the cell cortex.

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“…Later the nonlinear growth of a water-rich droplet around the cap dominates, leading to a complex non-monotonic time dependence of ∆φ(t) 2 , with a maximum followed by a subsequent decay until it saturates to a mean constant value corresponding to the final nonequilibrium steady concentration field. It is worth noting that this behavior of the spatial variance of φ is similar to the initial overshoot in response to an external field found in diverse soft materials, such as actin networks [42], colloidal suspensions [43,44], polymer melts [45], or a yield-stress fluids [46]. In our system, the maximum in ∆φ(t) 2 results from local phase separation around the warmer part of the colloid after switching on illumination, which proceeds via a two-step process under a step-like temperature variation across the critical temperature-This mechanism shares some similarities with the origin of the overshoot in the nonlinear response of entangled polymer solutions [47], where the stress overshoot is also a consequence of a two-step process under a step-like shear rate.…”

Section: Resultssupporting

confidence: 66%

Relaxation to steady states of a binary liquid mixture around an optically heated colloid

Araki,

Gomez-Solano,

Maciołek

2022

Preprint

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We study the relaxation dynamics of a binary liquid mixture near a light-absorbing Janus particle after switching on and off illumination using experiments and theoretical models. The dynamics is controlled by the temperature gradient formed around the heated particle. Our results show that the relaxation is asymmetric: the approach to a nonequilibrium steady state is much slower than the return to thermal equilibrium. Approaching a nonequilibrium steady state after a sudden temperature change is a two-step process that overshoots the response of spatial variance of the concentration field. The initial growth of concentration fluctuations after switching on illumination follows a power law in agreement with the hydrodynamic and purely diffusive model. The energy out-flow from the system after switching off illumination is well described by a stretched exponential function of time with characteristic time proportional to the ratio of the energy stored in the steady state to the total energy flux in this state.

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Kinetics of actin networks formation measured by time resolved particle-tracking microrheology

Abstract: Actin is one of the most studied cytoskeleton proteins showing a very rich span of structures and functions. For example, Adenosine triphosphate (ATP)-assisted polymerization of actin is used to push...

Cited by 12 publications

References 57 publications

A coarse-grained approach to model the dynamics of the actomyosin cortex

A coarse-grained approach to model the dynamics of the actomyosin cortex

A coarse-grained approach to model the dynamics of the actomyosin cortex

Relaxation to steady states of a binary liquid mixture around an optically heated colloid

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