Cellular functions of WASP family proteins at a glance

Alekhina, Olga; Burstein, Ezra; Billadeau, Daniel D.

doi:10.1242/jcs.199570

Cited by 168 publications

(181 citation statements)

References 86 publications

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“…Because WASp and WAVE proteins are integral signaling activators of the Arp2/3 complex (15), we hypothesized that LAT-independent SLP-76 microclusters associated with WASp and WAVE. Using TIRF microscopy, we found that GML did not affect the association between phosphorylated SLP-76 microclusters and phosphorylated WASp microclusters in activated T cells (Fig.…”

Section: Resultsmentioning

confidence: 99%

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

et al. 2018

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Glycerol monolaurate (GML) is a monoglyceride with potent antimicrobial properties that suppresses T cell receptor (TCR)-induced signaling and T cell effector function. Actin rearrangement is needed for the interaction of T cells with antigen presenting cells and for migration to sites of infection. Because of the critical role actin rearrangement plays in T cell effector function, we analyzed the effect of GML on the rearrangement of the actin cytoskeleton after TCR activation. We found that GML-treated human T cells were less adherent than untreated T cells and did not form actin ring structures, but instead developed numerous inappropriate actin-mediated filopodia. The formation of these filopodia was not due to disruption of TCR-proximal regulators of actin or microtubule polymerization. Instead, total internal reflection fluorescence microscopy demonstrated mislocalization of actin nucleation protein Arp2 microclusters, but not those containing the adaptor proteins SLP-76 and WASp, or the actin nucleation protein ARPC3, which are necessary for TCR-induced actin rearrangement. Additionally, SLP-76 microclusters colocalized with WASp and WAVE microclusters, but not LAT. Together, our data suggest that GML alters actin cytoskeletal rearrangements and identify diverse functions for GML as a T cell-suppressive agent.

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Section: Resultsmentioning

confidence: 99%

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

et al. 2018

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“…This lower potency likely stems from a fewer (than in formins and Ena/VASP) number of G-actin binding domains and, possibly, a less favorable geometry for oligomer binding to NPFs. Of note, depending on the involvement in a particular cellular process (i.e., remodeling of cytoplasmic [31], endosomal [32], autophagosomal [33, 34], Golgi and ER membranes [35, 36], or contribution to cytoplasmic streaming [37], etc. ), the Arp2/3 complex can be activated by different NPFs, of which only two were tested in the present study: VCA fragment of N-WASP in the in vitro assays (Figures 2G–O) and WAVE in the cellular context (Figures 2D–F).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, JMY, an NPF that regulates transcription in the nucleus and vesicle trafficking between the ER and trans -Golgi network [38-40], with its three WH2-domains, is likely to be inhibited more efficiently than N-WASP and WHAMM (each containing two WH2-domains), which regulate endocytosis [41] and autophagosome formation [33], respectively. Furthermore, all these NPFs are likely to be more efficiently inhibited than single WH2-domain NPFs WASP, WAVE, and WASH, which are involved in endocytosis, cell migration and endosomal trafficking (recently reviewed in [31]). Notably, inhibition of many of these processes would be beneficial for pathogenic bacteria to interrupt migration, phagocytosis, and activation of immune cells, disrupt epithelial contacts, inhibit Golgi-dependent maturation of granules in immune effector cells and their release, and inhibit autophagy.…”

Section: Discussionmentioning

confidence: 99%

Actin Cross-Linking Toxin Is a Universal Inhibitor of Tandem-Organized and Oligomeric G-Actin Binding Proteins

et al. 2018

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Delivery of bacterial toxins to host cells is hindered by host protective barriers. This obstruction dictates a remarkable efficiency of toxins, a single copy of which may kill a host cell. Efficiency of actin-targeting toxins is further hampered by an overwhelming abundance of their target. The actin cross-linking domain (ACD) toxins of Vibrio species and related bacterial genera catalyze the formation of covalently cross-linked actin oligomers. Recently, we reported that the ACD toxicity can be amplified via a multivalent inhibitory association of actin oligomers with actin assembly factors formins, suggesting that the oligomers may act as secondary toxins. Importantly, many proteins involved in nucleation, elongation, severing, branching, and bundling of actin filaments contain G-actin-binding Wiskott-Aldrich syndrome protein (WASP)-homology motifs 2 (WH2) organized in tandem and therefore may act as a multivalent platform for high-affinity interaction with the ACD-cross-linked actin oligomers. Using live-cell single-molecule speckle (SiMS) microscopy, total internal reflection fluorescence (TIRF) microscopy, and actin polymerization assays, we show that, in addition to formins, the oligomers bind with high affinity and potently inhibit several families of actin assembly factors: Ena/vasodilator-stimulated phosphorprotein (VASP); Spire; and the Arp2/3 complex, both in vitro and in live cells. As a result, ACD blocks the actin retrograde flow and membrane dynamics and disrupts association of Ena/VASP with adhesion complexes. This study defines ACD as a universal inhibitor of tandem-organized G-actin binding proteins that overcomes the abundance of actin by redirecting the toxicity cascade toward less abundant targets and thus leading to profound disorganization of the actin cytoskeleton and disruption of actin-dependent cellular functions.

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“…Wash encodes several biochemical activities, including actin nucleation and actin/MT binding, bundling, and crosslinking (Liu et al, 2009;Verboon et al, 2018;Verboon et al, 2015a); however, when working in concert with the SHRC, Wash often functions upstream of the Arp2/3 complex to promote branched actin filament formation (cf. (Alekhina et al, 2017;Rottner et al, 2010). Mounting evidence has also demonstrated roles for actin and Arp2/3 complexes in diverse nuclear functions (Alekhina et al, 2017;Kyheroinen and Vartiainen, 2019;Percipalle and Vartiainen, 2019).…”

Section: The Arp2/3 Complex Is Required For Ne-buddingmentioning

confidence: 99%

Wash and the WASH Regulatory Complex function in Nuclear Envelope budding

Verboon

Nakamura

Decker

et al. 2019

Preprint

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Nuclear envelope budding is a recently described phenomenon wherein large macromolecular complexes can be packaged inside the nucleus and be extruded through the nuclear membranes, completely bypassing nuclear pores. While factors have been identified both as cargos or actively involved in this process, much remains unknown about the molecules that generate the forces and membrane deformations which appear inherent. Using fluorescence and electron microscopy, biochemical and cell biological assays, and genetic perturbations in the Drosophila model, we identify Wash, its regulatory complex, and Arp2/3 as novel players in NE-budding. Surprisingly, Wash's role in this process is bipotent and, independent of Recently, Nuclear Envelope (NE-) budding was identified as an alternative pathway for nuclear exit, particularly for large developmentally-required ribonucleoprotein (megaRNP) complexes that would otherwise need to unfold/remodel to fit through the NPCs (Fradkin and Budnik, 2016;Hatch and Hetzer, 2014;Hatch and Hetzer, 2012;Jokhi et al., 2013;Li et al., 2016;Parchure et al., 2017;Speese et al., 2012). In this pathway, large macromolecule complexes, such as megaRNPs, are encircled by the nuclear lamina (type-A and type-B lamins) and inner nuclear membrane, are pinched off from the inner nuclear membrane, cross the perinuclear space, fuse with the outer nuclear membrane, and release the megaRNPs into the cytoplasm (Figure 1A-C).Strikingly, NE-budding shares many features with the nuclear egress mechanism used by herpesviruses, common pathogens that cause and/or contribute to a diverse array of human diseases (Bigalke and Heldwein, 2016;Hagen et al., 2015;Lye et al., 2017;Mettenleiter et al., 2013;Parchure et al., 2017;Roller and Baines, 2017). As viruses often take advantage of preexisting host pathways for their livelihoods, the parallel between nuclear exit of herpesvirus nucleocapsids and that of megaRNPs suggests that NE-budding may be a general cellular mechanism that elegantly allows for the nuclear export of endogenous megaRNPs and/or other large cargos (cf. (Fradkin and Budnik, 2016;Mettenleiter et al., 2013;Parchure et al., 2017;Roller and Baines, 2017). Indeed, this pathway has also been implicated in the removal of obsolete macromolecular complexes or other material (i.e., large protein aggregates, polyubiquitylated proteins) from the nucleus (Jokhi et al., 2013;Ramaswami et al., 2013;Rose and Schlieker, 2012).The NE-budding pathway was first demonstrated in Drosophila synapse development, proving to be essential for neuromuscular junction integrity. Here, a C-terminal fragment (dFz2C) of the fly Wingless receptor, dFz2C, was shown to associate with megaRNPs that formed foci at the nuclear periphery and exited the nucleus by budding through the nuclear envelope ( Figure 1B-C) (Speese et al., 2012). Failure of this process resulted in aberrant

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Cellular functions of WASP family proteins at a glance

Cited by 168 publications

References 86 publications

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

Glycerol monolaurate induces filopodia formation by disrupting the association between LAT and SLP-76 microclusters

Actin Cross-Linking Toxin Is a Universal Inhibitor of Tandem-Organized and Oligomeric G-Actin Binding Proteins

Wash and the WASH Regulatory Complex function in Nuclear Envelope budding

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