Micromechanics of filopodia mediated capture of pathogens by macrophages

Vonna, Laurent; Wiedemann, Agnès; Aepfelbacher, Martin; Sackmann, E.

doi:10.1007/s00249-006-0118-y

Cited by 62 publications

(57 citation statements)

References 25 publications

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“…Forces as low as 34 pN can induce a lengthening of microvilli (Shao et al, 1998). Slightly higher forces will induce actindependent membrane protrusions (Vonna et al, 2003) and activate signalling cascades, calcium fluctuations and tyrosine phosphorylation of numerous proteins (Holm et al, 1999;Sawada et al, 2006;Schmidt et al, 1998). These forces are within the range measured for Tfp retraction (50 pN to 1 nN; Biais et al, 2008;Opitz et al, 2009) 2006).…”

Section: Discussionmentioning

confidence: 66%

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

et al. 2009

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Early in infection, Neisseria gonorrhoeae can be observed to attach to the epithelial cell surface as microcolonies and induce dramatic changes to the host cell cortex. We tested the hypothesis that type IV pili (Tfp) retraction plays a role in the ultrastructure of both the host cell cortex and the bacterial microcolony. Using serial ultrathin sectioning, transmission electron microscopy and 3D reconstruction of serial 2D images, we have obtained what we believe to be the first 3D reconstructions of the N. gonorrhoeae-host cell interface, and determined the architecture of infected cell microvilli as well as the attached microcolony. Tfp connect both wild-type (wt) and Tfp retraction-deficient bacteria with each other, and with the host cell membrane. Tfp fibres and microvilli form a lattice in the wt microcolony and at its periphery. Wt microcolonies induce microvilli formation and increases of surface area, leading to an approximately ninefold increase in the surface area of the host cell membrane at the site of attachment. In contrast, Tfp retractiondeficient microcolonies do not affect these parameters. Wt microcolonies had a symmetrical, dome-shaped structure with a circular 'footprint', while Tfp retraction-deficient microcolonies were notably less symmetrical. These findings support a major role for Tfp retraction in microvilli and microcolony architecture. They are consistent with the biophysical attributes of Tfp and the effects of Tfp retraction on epithelial cell signalling. INTRODUCTIONNeisseria gonorrhoeae (the gonococcus, or GC) remains a significant public health concern. The Gram-negative diplococcus causes a million cases of gonorrhoea annually in Western Europe and North America, and over 62 million cases worldwide (World Health Organization). Humans are the only known reservoir for GC. The exquisite tropism of GC for man and the ability of GC to establish a carrier state (Turner et al., 2002) reflect a highly evolved relationship between pathogen and host.Gonococcal attachment is promoted by type IV pili (Tfp), peritrichous fibres that are 6 nm in width and up to several micrometres in length. The Tfp filament is composed of helical polymers of pilin subunits (Craig et al., 2006;Parge et al., 1995) and minor proteins (Carbonnelle et al., 2005;Winther-Larsen et al., 2005). Tfp participate in important biological processes such as DNA uptake/genetic exchange, twitching motility, attachment, and host cell signalling (Mattick, 2002;. These activities require, or are enhanced by, the retraction of Tfp fibres (Wolfgang et al., 2000).Gonococcal Tfp retraction is an activity that requires PilT, the Tfp retraction motor subunit (Wolfgang et al., 1998). Retracting Tfp generate strong 'pull' forces, ranging from 50 picoNewtons (pN) to 1 nanoNewton (nN) (Biais et al., 2008;Opitz et al., 2009). Repeated cycles of Tfp extension, substrate attachment and Tfp retraction allow GC to crawl over surfaces and aggregate into microcolonies. Tfp retraction from bacteria in a microcolony allows the community to craw...

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Section: Discussionmentioning

confidence: 66%

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

et al. 2009

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“…Briefly, prior to acquisition cells labelled with a fluorescent membrane dye were incubated with beads. We first used as a bead coating ligand the Yersinia Invasin protein, which specifically binds to b1 integrins and triggers filopodial retraction (Young et al, 1992;Isberg and Barnes, 2001;Vonna et al, 2007). A bead was immobilized in the OTs and approached to a single filopodium emanating from the cell (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Several bacteria or viruses also hijack filopodia to invade epithelial or endothelial cells (Lehmann et al, 2005;Romero et al, 2011;Schelhaas et al, 2008;Smith et al, 2008;Young et al, 1992). For example, the Yersinia Invasin protein that binds to b1 integrins and the Shigella Type III Secretion System (T3SS) have been shown to interact with and trigger retraction of filopodia (Romero et al, 2011;Vonna et al, 2007;Young et al, 1992). While forces exerted during cell adhesion or migration have been analysed in many studies, forces associated with filopodia have been characterized in only a few systems (Howard, 2001;Kress et al, 2007;Moore et al, 2010;Vonna et al, 2007).…”

Section: Filopodium Retraction Is Controlled By Adhesion To Its Tipmentioning

confidence: 99%

“…For example, the Yersinia Invasin protein that binds to b1 integrins and the Shigella Type III Secretion System (T3SS) have been shown to interact with and trigger retraction of filopodia (Romero et al, 2011;Vonna et al, 2007;Young et al, 1992). While forces exerted during cell adhesion or migration have been analysed in many studies, forces associated with filopodia have been characterized in only a few systems (Howard, 2001;Kress et al, 2007;Moore et al, 2010;Vonna et al, 2007). Filopodia generate pushing forces of a few pN during their elongation (Cojoc et al, 2007), consistent with pushing forces exerted by polymerizing actin of typically 1 pN per filament (Footer et al, 2007;Mogilner and Rubinstein, 2005).…”

Section: Filopodium Retraction Is Controlled By Adhesion To Its Tipmentioning

confidence: 99%

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Filopodium retraction is controlled by adhesion to its tip

Roméro

Quatela

Bornschlögl

et al. 2012

Journal of Cell Science

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SummaryFilopodia are thin cell extensions sensing the environment. They play an essential role during cell migration, cell-cell or cell-matrix adhesion, by initiating contacts and conveying signals to the cell cortex. Pathogenic microorganisms can hijack filopodia to invade cells by inducing their retraction towards the cell body. Because their dynamics depend on a discrete number of actin filaments, filopodia provide a model of choice to study elementary events linked to adhesion and downstream signalling. However, the determinants controlling filopodial sensing are not well characterized. In this study, we used beads functionalized with different ligands that triggered filopodial retraction when in contact with filopodia of epithelial cells. With optical tweezers, we were able to measure forces stalling the retraction of a single filopodium. We found that the filopodial stall force depends on the coating of the bead. Stall forces reached 8 pN for beads coated with the b1 integrin ligand Yersinia Invasin, whereas retraction was stopped with a higher force of 15 pN when beads were functionalized with carboxyl groups. In all cases, stall forces increased in relation to the density of ligands contacting filopodial tips and were independent of the optical trap stiffness. Unexpectedly, a discrete and small number of Shigella type three secretion systems induced stall forces of 10 pN. These results suggest that the number of receptor-ligand interactions at the filopodial tip determines the maximal retraction force exerted by filopodia but a discrete number of clustered receptors is sufficient to induce high retraction stall forces.

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“…Cellular vitality was monitored during uptake assays by intercellular dynamics and presence of membrane protrusions, the latter being typical for functional macrophages (Vonna et al, 2007, Venter et al, 2014. Over a period of 48 h, no apparent cell death or abnormalities were observed while visualizing the subcellular bio-distribution of the Ag NPs.…”

Section: Ag Nps Localization and Uptake Dynamicsmentioning

confidence: 99%

In vitro assays for hazard identification of nanoparticles

Kloet¹

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Micromechanics of filopodia mediated capture of pathogens by macrophages

Cited by 62 publications

References 25 publications

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

Influence of type IV pilus retraction on the architecture of the Neisseria gonorrhoeae-infected cell cortex

Filopodium retraction is controlled by adhesion to its tip

In vitro assays for hazard identification of nanoparticles

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