Ultrastructure of the actin cytoskeleton

Svitkina, Tatyana

doi:10.1016/j.ceb.2018.02.007

Cited by 97 publications

(84 citation statements)

References 56 publications

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“…This meshwork of stress fibers and cortical filaments form a mechanical continuum. Our conclusion is in agreement with the previous ultrastructural observations of the cortical-actin-network connections to stress fibers and the more recent electron-microscopy demonstration that these connections depend on filamin A Marek et al, 1982;Svitkina, 2018). It also fits well with highresolution imaging showing lateral interactions of myofibrils, which support a long range selforganization of contractile structures (Hu et al, 2017).…”

Section: Resultssupporting

confidence: 92%

Stress fibers are embedded in a contractile cortical network

Vignaud

Copos

Leterrier

et al. 2020

Preprint

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Contractile actomyosin networks generate intracellular forces essential for the regulation of cell shape, migration, and cell-fate decisions, ultimately leading to the remodeling and patterning of tissues. Although actin filaments aligned in bundles represent the main source of traction-force production in adherent cells, there is increasing evidence that these bundles form interconnected and interconvertible structures with the rest of the intracellular actin network. In this study, we explored how these bundles are connected to the surrounding cortical network and the mechanical impact of these interconnected structures on the production and distribution of traction forces on the extracellular matrix and throughout the cell. By using a combination of hydrogel micropatterning, traction-force microscopy and laser photoablation, we measured the relaxation of the cellular traction field in response to local photoablations at various positions within the cell. Our experimental results and modeling of the mechanical response of the network revealed that bundles were fully embedded along their entire length in a continuous and contractile network of cortical filaments. Moreover, the propagation of the contraction of these bundles throughout the entire cell was dependent on this embedding. In addition, these bundles appeared to originate from the alignment and coalescence of thin and unattached cortical actin filaments from the surrounding mesh.

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Section: Resultssupporting

confidence: 92%

Stress fibers are embedded in a contractile cortical network

Vignaud

Copos

Leterrier

et al. 2020

Preprint

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“…The assembly of actin filaments is a key element of how cells control their shape, move about, and exert force. Actin filaments grow and shrink by the addition and loss of subunits from their ends, both barbed and pointed (3)(4)(5)(6). The dynamics of subunit addition and loss at barbed ends of actin filaments is controlled by a number of proteins, including the heterodimeric alpha/beta actin capping protein (CP), which is nearly ubiquitous among eukaryotic cells and tissues.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of CPI-motif regulation of biochemical functions of actin capping protein

McConnell¹,

Mekel²,

Козлов³

et al. 2020

Preprint

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The heterodimeric actin capping protein (CP) is regulated by a set of proteins that contain CP-interacting (CPI) motifs. Outside of the CPI motif, the sequences of these proteins are unrelated and distinct. The CPI motif and surrounding sequences are conserved within a given protein family, when compared to those of other CPI-motif protein families. Using biochemical assays with purified proteins, we compared the ability of CPI-motif-containing peptides from different protein families to a) bind to CP, b) allosterically inhibit barbed-end capping by CP, and c) allosterically inhibit interaction of CP with V-1, another regulator of CP.We found large differences in potency among the different CPI-motif-containing peptides, and the different functional assays showed different orders of potency. These biochemical differences among the CPI-motif peptides presumably reflect interactions between CP and CPI-motif peptides involving amino-acid residues that are conserved but are not part of the strictly defined

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“…Cell morphology depends on the organization of the cytoskeleton, that is, its alignment, orientation, and mesh‐like network (Fletcher & Mullins, ; Huber, Boire, López, & Koenderink, ; Pollard, ; Rottner, Faix, Bogdan, Linder, & Kerkhoff, ; Svitkina, ). To explore the ability of cytoskeletal protein assembly to drive cell deformation, reconstituted systems based on artificial membranes have been widely employed.…”

Section: Introductionmentioning

confidence: 99%

Condensed desmin and actin cytoskeletal communication in lipid droplets

et al. 2019

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The interplay between intermediate filaments (IFs) and other cytoskeletal components is important for the integrity and motility of cells. The impact of IF assembly on other components and cell morphology is not yet fully understood. Therefore, we examined the effects of combined desmin and actin assembly on cytoskeletal network arrangement in artificial cell‐sized droplets. Fluorescently labeled desmin, with or without actin, was enclosed in droplets prepared with 1,2‐dioleoyl‐sn‐glycero‐3‐phosphoethanolamine (DOPE) using the water‐in‐oil method. Protein networks were observed using fluorescence microscopy in the presence of 150 mM KCl, 20 mM imidazole–HCl (pH 7.4), 2 mM MgCl2, and 1 mM adenosine 5'‐triphosphate for both desmin and actin assembly. As desmin alone can assemble into filaments within seconds, desmin networks mainly localizing at the inner margins of the droplets were observed within 10 min after assembly initiation. Subsequently, deformations of droplets appeared. Furthermore, a portion of droplets formed desmin‐rich protrusions of several micrometers. Notably, actin alone rarely formed protrusions under the same conditions. When 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine was used instead of DOPE, protrusions became less frequent. The combination of desmin and actin increased the number of deformed droplets in which the proteins were considerably colocalized. The assembly process of desmin facilitated colocalization. Atomic force microscopy failed to reveal interactions between the two filament types. These results suggest that the mechanical properties of desmin networks may influence the behavior of actin networks, as well as membrane morphology, possibly reflecting the mechanical function of desmin filaments in muscle cells.

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Ultrastructure of the actin cytoskeleton

Cited by 97 publications

References 56 publications

Stress fibers are embedded in a contractile cortical network

Stress fibers are embedded in a contractile cortical network

Comparative analysis of CPI-motif regulation of biochemical functions of actin capping protein

Condensed desmin and actin cytoskeletal communication in lipid droplets

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