Free Brick1 Is a Trimeric Precursor in the Assembly of a Functional Wave Complex

Derivery, Emmanuel; Fink, Jenny; Martin, Davy; Houdusse, Anne; Piel, Matthieu; Stradal, Theresia E. B.; Louvard, Daniel; Gautreau, Alexis

doi:10.1371/journal.pone.0002462

Cited by 66 publications

(107 citation statements)

References 38 publications

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“…S8). Furthermore, we observe a slight reduction in the levels of Abi1 in transient WAVE2-knockdown myoblasts, which has been described by other groups (Carabeo et al, 2007;Derivery et al, 2008;Ryu et al, 2009). These data suggest that the fusion defect that we observe in Nap1-knockdown myoblasts is due to the action of Nap1 as a component of the WAVE regulatory complex.…”

Section: Pharmacological Inhibition Of Actin-cytoskeletal Remodelingsupporting

confidence: 89%

“…Our live imaging of Nap1-knockdown myoblasts revealed a putative third actin-based behavior in fusing myoblasts as revealed by the localization of the PH-GFP reporter in these cells. These PH-GFP-reporter aggregates seem to be similar to structures previously identified as membrane blebs (Beli et al, 2008;Derivery et al, 2008). Their prevalence suggests that the dynamics of actin-cytoskeleton remodeling at cell membranes is impaired in Nap1-knockdown myoblasts, and that this might be crucial for mammalian myoblast fusion.…”

Section: Journal Of Cell Science 122 (18)supporting

confidence: 61%

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Nap1-mediated actin remodeling is essential for mammalian myoblast fusion

Nowak

Nahirney

Hadjantonakis

et al. 2009

Journal of Cell Science

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Myoblast fusion is crucial for the formation, growth, maintenance and regeneration of healthy skeletal muscle. Unfortunately, the molecular machinery, cell behaviors, and membrane and cytoskeletal remodeling events that govern fusion and myofiber formation remain poorly understood. Using time-lapse imaging approaches on mouse C2C12 myoblasts, we identify discrete and specific molecular events at myoblast membranes during fusion and myotube formation. These events include rearrangement of cell shape from fibroblast to spindle-like morphologies, changes in lamellipodial and filopodial extensions during different periods of differentiation, and changes in membrane alignment and organization during fusion. We find that actin-cytoskeleton remodeling is crucial for these events: pharmacological inhibition of F-actin polymerization leads to decreased lamellipodial and filopodial extensions and to reduced myoblast fusion. Additionally, shRNA-mediated inhibition of Nap1, a member of the WAVE actin-remodeling complex, results in accumulations of F-actin structures at the plasma membrane that are concomitant with a decrease in myoblast fusion. Our data highlight distinct and essential roles for actin cytoskeleton remodeling during mammalian myoblast fusion, provide a platform for cellular and molecular dissection of the fusion process, and suggest a functional conservation of Nap1-regulated actin-cytoskeleton remodeling during myoblast fusion between mammals and Drosophila.Supplementary material available online at

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Section: Pharmacological Inhibition Of Actin-cytoskeletal Remodelingsupporting

confidence: 89%

Section: Journal Of Cell Science 122 (18)supporting

confidence: 61%

Nap1-mediated actin remodeling is essential for mammalian myoblast fusion

Nowak

Nahirney

Hadjantonakis

et al. 2009

Journal of Cell Science

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“…It could be that the putative pool of apical NAP1 at or near the distal plasma membrane was either selectively extracted by detergents during permeabilization or obscured by the relatively large pools of intracellular, organelle-associated NAP1. The nonoverlapping localizations of BRK1 and SCAR1 (Dyachok et al, 2008) and reports in metazoan cells that NAP1 and BRK1 homologs have important activities that are independent of fully assembled W/SRC (Weiner et al, 2006;Derivery et al, 2008) suggest that W/SRC assembly is a point of regulation (Derivery and Gautreau, 2010). In this scenario, the punctate localization of SCAR1 and NAP1 in trichomes may correspond to an ER domain where W/SRC assembly and positive regulation by SPK1 serves as one level of regulation that enables full W/SRC assembly and its relocalization to another membrane surface, such as the plasma membrane.…”

Section: Discussionmentioning

confidence: 93%

The Endoplasmic Reticulum Is a Reservoir for WAVE/SCAR Regulatory Complex Signaling in the Arabidopsis Leaf

et al. 2013

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During plant cell morphogenesis, signal transduction and cytoskeletal dynamics interact to locally organize the cytoplasm and define the geometry of cell expansion. The WAVE/SCAR (for WASP family verprolin homologous/suppressor of cyclic AMP receptor) regulatory complex (W/SRC) is an evolutionarily conserved heteromeric protein complex. Within the plant kingdom W/SRC is a broadly used effector that converts Rho-of-Plants (ROP)/Rac small GTPase signals into Actin-Related Protein2/3 and actin-dependent growth responses. Although the components and biochemistry of the W/SRC pathway are well understood, a basic understanding of how cells partition W/SRC into active and inactive pools is lacking. In this paper, we report that the endoplasmic reticulum (ER) is an important organelle for W/SRC regulation. We determined that a large intracellular pool of the core W/SRC subunit NAP1, like the known positive regulator of W/SRC, the DOCK family guanine nucleotide-exchange factor SPIKE1 (SPK1), localizes to the surface of the ER. The ER-associated NAP1 is inactive because it displays little colocalization with the actin network, and ER localization requires neither activating signals from SPK1 nor a physical association with its W/SRC-binding partner, SRA1. Our results indicate that in Arabidopsis (Arabidopsis thaliana) leaf pavement cells and trichomes, the ER is a reservoir for W/SRC signaling and may have a key role in the early steps of W/SRC assembly and/or activation.

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“…Only few studies previously addressed the involvement of specific actin nucleators in PM blebbing. Using experimental systems in which PM blebbing was induced by genetic manipulation or protein overexpression, nucleators such as mDia1, mDia2, FHOD1, Arp2/3 that are also involved in the regulation of diverse additional cellular actin remodeling events were implicated in blebbing [12,[41][42][43]. In this present study, we conducted a comprehensive analysis of the involvement of endogenously expressed human actin nucleators in PM blebbing of adhering HeLa cells.…”

Section: Discussionmentioning

confidence: 99%

Differing and isoform-specific roles for the formin DIAPH3 in plasma membrane blebbing and filopodia formation

et al. 2011

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Plasma membrane (PM) blebs are dynamic actin-rich cell protrusions that occur, e.g., during cytokinesis, amoeboid cell motility and cell attachment. Using a targeted siRNA screen against 21 actin nucleation factors, we identify a novel and essential role of the human diaphanous formin DIAPH3 in PM blebbing during cell adhesion. Suppression of DIAPH3 inhibited blebbing to promote rapid cell spreading involving β1-integrin. Multiple isoforms of DIAPH3 were detected on the mRNA and protein level of which isoforms 3 and 7 were the largest and most abundant isoforms that however did not induce formation of actin-rich protrusions. Rather, PM blebbing specifically involved the low abundance isoform 1 of DIAPH3 and activation of isoform 7 by deletion of the diaphanous-autoregulatory domain caused the formation of filopodia. Dimerization and actin assembly activity were essential for induction of specific cell protrusions by DIAPH3 isoforms 1 and 7. Our data suggest that the N-terminal region comprising the GTPasebinding domain determined the subcellular localization of the formin as well as its protrusion activity between blebs and filopodia. We propose that isoform-selective actin assembly by DIAPH3 exerts specific and differentially regulated functions during cell adhesion and motility.

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Free Brick1 Is a Trimeric Precursor in the Assembly of a Functional Wave Complex

Cited by 66 publications

References 38 publications

Nap1-mediated actin remodeling is essential for mammalian myoblast fusion

Nap1-mediated actin remodeling is essential for mammalian myoblast fusion

The Endoplasmic Reticulum Is a Reservoir for WAVE/SCAR Regulatory Complex Signaling in the Arabidopsis Leaf

Differing and isoform-specific roles for the formin DIAPH3 in plasma membrane blebbing and filopodia formation

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