Dynamics of the <i>Dictyostelium</i> Arp2/3 complex in endocytosis, cytokinesis, and chemotaxis

Insall, Robert H.; Müller‐Taubenberger, Annette; Machesky, Laura M.; Köhler, Jana; Simmeth, Evelyn; Atkinson, Simon J.; Weber, Igor; Gerisch, Günther

doi:10.1002/cm.10005

Cited by 130 publications

(97 citation statements)

References 60 publications

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“…In very recent complementary micro-fluorescence studies of cells moving over rods generated on glass surfaces, we found that these actin assemblies can move even faster ($0.5 lm/s, D. Heinrich, G. Gerisch, unpublished data) than reported in Ref. [50]. The migrating assemblies are suppressed by latrunculin but not by knock out of myosin II, in agreement with our findings.…”

Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resisupporting

confidence: 92%

“…A second mechanism generating pre-stresses and driving the tangential irregular walks of the actin coupled MT ends could be the spontaneous generation and decay of ($1 lm 2 large) dynamic micro-domains of actin assemblies [50]. (These can consist of actin, crosslinked by passive linkers such as Arp2/3 [47,50] and filamin, or of actin/myosin micro-bundles.)…”

Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resimentioning

confidence: 99%

“…(These can consist of actin, crosslinked by passive linkers such as Arp2/3 [47,50] and filamin, or of actin/myosin micro-bundles.) They form mostly at the leading front of pseudopods and at the cytoplasmic side of the cell surface contacting the substrate.…”

Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resimentioning

confidence: 99%

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Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Heinrich

Sackmann²

2006

Acta Biomaterialia

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The micro-viscoelasticity of the intracellular space of Dictyostelium discoideum cells is studied by evaluating the intracellular transport of magnetic force probes and their viscoelastic responses to force pulses of 20-700 pN. The role of the actin cortex, the microtubule (MT) aster and their crosstalk is explored by comparing the behaviour of wild-type cells, myosin II null mutants, latrunculin A and benomyl treated cells. The MT coupled beads perform irregular local and long range directed motions which are characterized by measuring their velocity distributions (P(v)). The correlated motion of the MT and the centrosome are evaluated by microfluorescence of GFP-labelled MTs. P(v) can be represented by log-normal distributions with long tails and it is determined by random sweeping motions (v $ 0.5 lm/s) of the MTs (caused by tangential forces on the filament ends coupled to the actin cortex) and by intermittent bead transports parallel to the MTs (v max $ 1.5 lm/s). The tails are due to spontaneous filament deflections (with speeds up to 10 lm/s) attributed to pre-stressing of the MT by local cortical tensions, generated by dynactin motors generating plus-end directed forces in the MTs. The viscoelastic responses are strongly non-linear and are mostly directed opposite or perpendicular to the force, showing that the cytoplasm behaves as an active viscoplastic body with time and force dependent drag coefficients. Nano-Newton loads exerted on the soft MT are balanced by traction forces arising at the MT ends coupled to the actin cortex and the centrosome, respectively. The mechanical coupling between the soft microtubules and the viscoelastic actin cortex provides cells with high mechanical stability despite the softness of the cytoplasm.

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Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resisupporting

confidence: 92%

Section: How the Viscoplastic Cytoplasmic Space Can Generate And Resimentioning

confidence: 99%

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Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Heinrich

Sackmann²

2006

Acta Biomaterialia

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“…It is certain that the Stokes radius similarity is serendipitous. However, it is intriguing that the Arp2/3 complex localizes to cell surface protrusions and is found most concentrated at the poles of the cell during cytokinesis (31), which are similar to the patterns of localization seen for dynacortin (3). So far, preliminary experiments have not indicated an effect by dynacortin on Arp2/3-mediated nucleation of actin polymerization.…”

Section: Table I Quantitation Of the Dynamics Gfp-dynacortin Coroninsupporting

confidence: 53%

Dynacortin Is a Novel Actin Bundling Protein That Localizes to Dynamic Actin Structures

Robinson¹,

Ocon

Rock

et al. 2002

Journal of Biological Chemistry

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Dynacortin is a novel protein that was discovered in a genetic suppressor screen of a Dictyostelium discoideum cytokinesis-deficient mutant cell line devoid of the cleavage furrow actin bundling protein, cortexillin I. While dynacortin is highly enriched in the cortex, particularly in cell-surface protrusions, it is excluded from the cleavage furrow cortex during cytokinesis. Here, we describe the biochemical characterization of this new protein. Purified dynacortin is an 80-kDa dimer with a large 5.7-nm Stokes radius. Dynacortin cross-links actin filaments into parallel arrays with a mole ratio of one dimer to 1.3 actin monomers and a 3.1 M K d . Using total internal reflection fluorescence microscopy, GFP-dynacortin and the actin bundling protein coronin-GFP are seen to concentrate in highly dynamic cortical structures with assembly and disassembly half-lives of about 15 s. These results indicate that cells have evolved different actin-filament cross-linking proteins with complementary cellular distributions that collaborate to orchestrate complex cell shape changes.

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“…Indeed, many actin-binding proteins involved in regulation of actin polymerization, cross-linking and depolymerization are localized to both zones in Dictyostelium cells, e.g. Arp 2/3 complex (Insall et al, 2001), DAip1 (Konzok et al, 1999), coronin (Gerisch et al, 1995), p34 (Weber et al, 1999a), cofilin (Aizawa et al, 1995), talin A (Niewöhner et al, 1997), and myosin VII (Tuxworth et al, 2001). Since a dividing cell is immobilized, actin polymerized at the front has to be depolymerized to prevent accumulation of F-actin in the middle of the cell.…”

Section: A Continuous Actin Turnover During Cytokinesismentioning

confidence: 99%

Advances in Cytokinesis Research. On the Mechanism of Cleavage Furrow Ingression in Dictyostelium.

Weber

2001

Cell Struct. Funct.

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ABSTRACT. The ability of Dictyostelium cells to divide without myosin II in a cell cycle-coupled manner has opened two questions about the mechanism of cleavage furrow ingression. First, are there other possible functions for myosin II in this process except for generating contraction of the furrow by a sliding filament mechanism? Second, what could be an alternative mechanical basis for the furrowing? Using aberrant changes of the cell shape and anomalous localization of the actin-binding protein cortexillin I during asymmetric cytokinesis in myosin IIdeficient cells as clues, it is proposed that myosin II filaments act as a mechanical lens in cytokinesis. The mechanical lens serves to focus the forces that induce the furrowing to the center of the midzone, a cortical region where cortexillins are enriched in dividing cells. Additionally, continual disassembly of a filamentous actin meshwork at the midzone is a prerequisite for normal ingression of the cleavage furrow and a successful cytokinesis. If this process is interrupted, as it occurs in cells that lack cortexillins, an overassembly of filamentous actin at the midzone obstructs the normal cleavage. Disassembly of the crosslinked actin network can generate entropic contractile forces in the cortex, and may be considered as an alternative mechanism for driving ingression of the cleavage furrow. Instead of invoking different types of cytokinesis that operate under attached and unattached conditions in Dictyostelium, it is anticipated that these cells use a universal multifaceted mechanism to divide, which is only moderately sensitive to elimination of its constituent mechanical processes.Key words: cytokinesis/cell division/mechanical lens/actin disassembly/bending stiffness/cortexillin Since the discovery of myosin II-independent mitotic cell division in Dictyostelium discoideum (Neujahr et al., 1997a), several attempts have been undertaken to clarify its mechanism and relate it to the classical model of cytokinesis, which is based on the concept of contractile ring Uyeda et al., 2000). Basic assumption in these propositions is that cytokinesis in wild-type Dictyostelium cells is driven by contraction of a contractile ring, an annular structure that assembles at the central zone of a dividing cell and consists of actin and myosin II filaments. Thus, cells that express myosin II are assumed to divide primarily by the standard sliding-filament mechanism, and this mode of cell division was termed cytokinesis A. It was argued that myosin II-null cells use a different mechanism to divide by a process termed cytokinesis B, apparently not used by wild-type cells. In this view, cytokinesis B depends on expansion of the polar regions of a dividing cell, which induces a passive ingression at the cleavage furrow by drawing the cytoplasmic material out of the midzone (Uyeda et al., 2000). Traction forces between the ventral cell surface and a substratum are viewed as necessary in order to support the polar expansion. A sufficient magnitude of the traction forces and t...

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Dynamics of the Dictyostelium Arp2/3 complex in endocytosis, cytokinesis, and chemotaxis

Cited by 130 publications

References 60 publications

Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Active mechanical stabilization of the viscoplastic intracellular space of Dictyostelia cells by microtubule–actin crosstalk

Dynacortin Is a Novel Actin Bundling Protein That Localizes to Dynamic Actin Structures

Advances in Cytokinesis Research. On the Mechanism of Cleavage Furrow Ingression in Dictyostelium.

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