PIR121 Regulates Pseudopod Dynamics and SCAR Activity in Dictyostelium

Blagg, Simone L.; Stewart, Michael G.; Sambles, Christine; Insall, Robert H.

doi:10.1016/s0960-9822(03)00580-3

Cited by 139 publications

(167 citation statements)

References 37 publications

(3 reference statements)

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“…S4 E and H). Because there are presently no convenient means to test this prediction pharmacologically, we studied a null mutant of PIR121, a component of the SCAR/WAVE complex, that is known to exhibit an excessive amount of polymerized actin (32). We found that occurrence of PIP3 nucleation was markedly enhanced in the mutant as expected (Fig.…”

Section: Phase-map Analysis Reveals Birth and Death Of Spatial Phasementioning

confidence: 72%

Phase geometries of two-dimensional excitable waves govern self-organized morphodynamics of amoeboid cells

Taniguchi¹,

Ishihara

Oonuki³

et al. 2013

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

134

182

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In both randomly moving Dictyostelium and mammalian cells, phosphatidylinositol (3,4,5)-trisphosphate and F-actin are known to propagate as waves at the membrane and act to push out the protruding edge. To date, however, the relationship between the wave geometry and the patterns of amoeboid shape change remains elusive. Here, by using phase map analysis, we show that morphology dynamics of randomly moving Dictyostelium discoideum cells can be characterized by the number, topology, and position of spatial phase singularities, i.e., points that represent organizing centers of rotating waves. A single isolated singularity near the cellular edge induced a rotational protrusion, whereas a pair of singularities supported a symmetric extension. These singularities appeared by strong phase resetting due to de novo nucleation at the back of preexisting waves. Analysis of a theoretical model indicated excitability of the system that is governed by positive feedback from phosphatidylinositol (3,4,5)-trisphosphate to PI3-kinase activation, and we showed experimentally that this requires F-actin. Furthermore, by incorporating membrane deformation into the model, we demonstrated that geometries of competing waves explain most of the observed semiperiodic changes in amoeboid morphology.reaction-diffusion | oscillations | excitable media | self-organization | PTEN

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Section: Phase-map Analysis Reveals Birth and Death Of Spatial Phasementioning

confidence: 72%

Phase geometries of two-dimensional excitable waves govern self-organized morphodynamics of amoeboid cells

Taniguchi¹,

Ishihara

Oonuki³

et al. 2013

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

134

182

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“…Previous models suggested that WAVE/SCAR proteins act downstream of PIP 3 to regulate actin polymerization through the Arp2/3 complex. However, recent findings indicate that the SCAR complex is not required for chemoattractant-induced actin polymerization, suggesting an important role for other proteins (2). Finally, we may also have a very limited understanding of the complexity of the signaling pathways involved in chemotaxis.…”

Section: Discussionmentioning

confidence: 96%

Moving Forward: Mechanisms of Chemoattractant Gradient Sensing

Franca-Koh

Devreotes

2004

Physiology

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“…Importantly, recent genetic evidence indicates that this structure of complex is also important for the regulation of invertebrate Wave proteins, known as Scar proteins. Indeed, inactivation of the Sra homolog in Dictyostelium or of Sra, Nap, and Abi homologs in Drosophila leads in both cases to Scar͞Wave phenotypes (18)(19)(20)(21). In addition, in both systems, on genetic removal of the subunits, Scar͞Wave is degraded.…”

Section: Discussionmentioning

confidence: 99%

Purification and architecture of the ubiquitous Wave complex

Gautreau

et al. 2004

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

212

286

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The Wave proteins are major activators of the Arp2͞3 complex. The ubiquitous Wave-2 is required for actin polymerization at the leading edge of migrating cells. Here we purify Wave-2 from HeLa cells. Five proteins, Sra, Nap, Wave-2, Abi, and Hspc, are copurified, indicating that they form a tight complex. These proteins are only present in the complexed form, with the exception of Hspc, which displays a free pool. We reconstitute the Wave-2 complex by cotranslating in vitro the five subunits and use this system together with specific immunoprecipitations to study the molecular architecture of the complex. The complex is organized around a core of Nap and Abi. Sra is a peripheral subunit recruited on the Nap side, whereas the Wave and Hspc subunits are recruited on the Abi side of the core.

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PIR121 Regulates Pseudopod Dynamics and SCAR Activity in Dictyostelium

Cited by 139 publications

References 37 publications

Phase geometries of two-dimensional excitable waves govern self-organized morphodynamics of amoeboid cells

Phase geometries of two-dimensional excitable waves govern self-organized morphodynamics of amoeboid cells

Moving Forward: Mechanisms of Chemoattractant Gradient Sensing

Purification and architecture of the ubiquitous Wave complex

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