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Cell Biology

Sticky Cells

When two cells meet, they don't simply stay side by side–they actively stick to one another. Molecular cell biology has shown which proteins are involved in these neighboring junctions, but not how they physically behave with time. “When you put up wallpaper, even if you know what the glue is made of–its chemical composition–you will not be able to predict if the wallpaper will hold,” says LSP1 researcher Daniel Riveline, who directed this study.2 Using a fluorescent protein from the junctions, the cadherin, researchers observed its behavior during establishment of a junction between two cells. And what the team discovered was fascinating. One cell projects an adhesive extension towards its neighboring cell and the adhesive contact can be extended or reduced by local forces of the recipient cell. The physical contacts are fingerlike structures which grow perpendicular to the cell-cell interface. Where needed, more adhesion proteins are recruited to the growing contacts, to make them stronger.

“This is a bit like if the glue became stronger on parts of the paper that were about to peel off,” adds Riveline. “We don't know how to create glue that reinforces itself locally, but cells seem to have found a solution.” And to illustrate reinforcement–what this process is called–he uses another metaphor, rock climbing. “The climber raises his hand, feels the rock. If it's stable enough, he grabs it and climbs higher. This is what reinforcement is all about.”

Understanding how two cells physically interact is very important for studying the processes of scar tissue formation and inflammation, especially since this kind of interaction takes place in monolayers that line the interior surface of blood vessels.

This work also benefits medical research in cystic fibrosis and cancer. In cystic fibrosis, a defect in cell adhesion leads to the opening of the cell layer, which becomes permeable to lymphocytes when it should not. As for cancer, the loss of contact inhibition between neighboring cells–which lets cells multiply indefinitely–is a phenomenon probably linked to cell adhesion impairment.


Samantha Maguire

Notes :

1. Laboratoire de spectrométrie physique (CNRS / Université Joseph Fourier).
2. J. Brevier et al., “Force-Extension Relationship of Cell-Cell Contacts,” Physical Review Letters. 98(26): 268101. 2007.

Contacts :

Daniel Riveline,
LSP, Saint-Martin d'Hères.


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