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Filopodium retraction is controlled by adhesion to its tip.
- Source :
-
Journal of cell science [J Cell Sci] 2012 Nov 01; Vol. 125 (Pt 21), pp. 4999-5004. Date of Electronic Publication: 2012 Aug 16. - Publication Year :
- 2012
-
Abstract
- Filopodia 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 β1 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.
- Subjects :
- Bacterial Outer Membrane Proteins metabolism
Bacterial Secretion Systems
Biomechanical Phenomena
Cell Adhesion
Epithelial Cells microbiology
Epithelial Cells physiology
HeLa Cells
Host-Pathogen Interactions
Humans
Integrin beta1 metabolism
Ligands
Microscopy, Confocal
Microspheres
Optical Tweezers
Protein Binding
Pseudopodia microbiology
Pseudopodia physiology
Single-Cell Analysis
Time-Lapse Imaging
Epithelial Cells ultrastructure
Pseudopodia ultrastructure
Shigella physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1477-9137
- Volume :
- 125
- Issue :
- Pt 21
- Database :
- MEDLINE
- Journal :
- Journal of cell science
- Publication Type :
- Academic Journal
- Accession number :
- 22899718
- Full Text :
- https://doi.org/10.1242/jcs.104778